U.S. patent number 3,853,100 [Application Number 05/332,988] was granted by the patent office on 1974-12-10 for free piston engine with antiknock means.
Invention is credited to Anton Braun.
United States Patent |
3,853,100 |
Braun |
December 10, 1974 |
FREE PISTON ENGINE WITH ANTIKNOCK MEANS
Abstract
A free piston engine in which knocking of the engine is
prevented by changing the return energy available to move the
piston in its compression stroke and hence to vary the compression
ratio. The apparatus includes a condition responsive means
associated with possible knocking of the engine, which controls
some controlling means for varying the return energy. Where the
free piston engine employs a bounce chamber for controlling the
return energy, the controlling means may be effective to change the
pressure in this bounce chamber. Where the free piston engine has
two power pistons acting alternately on a single assembly, the
pressure ratio may be varied by controlling the amount of fuel
admitted into one or more of the power cylinders. The apparatus
also contemplates means for changing the return energy if a movable
member driven by the piston moves too far with respect to an
associated stationary member.
Inventors: |
Braun; Anton (Edina, MN) |
Family
ID: |
23300774 |
Appl.
No.: |
05/332,988 |
Filed: |
February 16, 1973 |
Current U.S.
Class: |
123/46R;
123/46SC; 123/198DA |
Current CPC
Class: |
F02B
75/04 (20130101); F04B 17/05 (20130101); F02B
71/04 (20130101) |
Current International
Class: |
F04B
17/05 (20060101); F02B 75/04 (20060101); F02B
71/04 (20060101); F04B 17/00 (20060101); F02B
71/00 (20060101); F02B 75/00 (20060101); F02b
071/00 (); F02d 039/10 () |
Field of
Search: |
;123/46R,46SC,198DA |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Antonakas; Manuel A.
Assistant Examiner: O'Connor; Daniel J.
Attorney, Agent or Firm: Dorsey, Marquart, Windhorst, West
& Halladay
Claims
I claim as my invention:
1. A free piston engine comprising:
a power cylinder having a power piston reciprocally movable in said
cylinder and defining an internal combustion chamber with said
power cylinder, and means for introducing air and fuel into said
power cylinder between said piston and the head of said cylinder to
form a mixture therein consisting of fuel and air, said piston
being movable toward the head of said cylinder to compress the fuel
mixture on a compression stroke and away from said head upon firing
of the fuel mixture,
return energy means operatively connected to said piston for
applying return energy to said piston, said means being effective
to apply sufficient return energy to said piston following the
firing stroke of said engine to cause said piston to move towards
the head of said power cylinder to compress the fuel mixture to the
desired extent,
and controlling means for so varying the amount of the return
energy applied to said piston as to prevent sustained knocking of
the engine, said controlling means comprising a condition
responsive means having a condition sensing element located
adjacent the engine and responsive to a condition normally followed
by sustained knocking of the engine, and adjusting means controlled
by said condition responsive means for variably controlling said
return energy means to adjust the return energy in a direction and
by an amount sufficient that the resulting change in the
compression ratio in said cylinder will, without interrupting the
operation of said engine, prevent the occurrence of sustained
knocking thereof.
2. The free piston engine of claim 1 in which the return energy
means includes a bounce chamber and in which said controlling means
is effective to change the pressure in said bounce chamber.
3. The free piston engine of claim 1 in which the return energy
means includes a positive bounce chamber and an opposing negative
bounce chamber and in which said controlling means is effective to
change the pressure in one of said bounce chambers.
4. The free piston engine of claim 2 in which the bounce chamber
has a check valve for admitting fluid to said chamber and a biased
outlet valve for permitting escape of fluid from said chamber and
in which said controlling means is effective to change the bias on
said outlet valve to change the pressure in said bounce
chamber.
5. The free piston engine of claim 4 in which a fluid motor having
a pressure chamber is effective to change the bias on said outlet
valve and in which said condition responsive means is effective to
vary the pressure in the pressure chamber of said fluid motor.
6. The free piston engine of claim 1 in which said controlling
means includes a fluid motor for changing the return energy
available to move the power piston and in which said condition
responsive means is effective to vary the pressure in the pressure
chamber of said fluid motor.
7. The free piston engine of claim 1 in which there are two power
pistons each movable in a power cylinder, and in which the return
energy means for either piston includes the other power piston and
associated power cylinder.
8. The free piston engine of claim 7 in which the controlling means
is effective to control the amount of fuel admitted into the power
cylinder associated with the other power piston.
9. The free piston engine of claim 7 in which there is a fuel pump
for injecting fuel into such power cylinder associated with the
other power piston and in which said controlling means controls the
amount of fuel delivered by said pump.
10. The free piston ngine of claim 7 in which said condition
responsive means is associated with said engine in such a manner as
to detect possible knocking in either cylinder and in which said
controlling means is controlled by said condition responsive means
in such a manner that if said condition responsive means detects
possible knocking in either cylinder of the engine, said
controlling means is effective to reduce the amount of fuel
admitted into both power cylinders.
11. The free piston engine of claim 10 in which said condition
responsive means consists of a separate condition sensor associated
with each cylinder and in which the controlling means is controlled
by both of said condition sensors in such a manner that if either
one of said condition sensors detects possible knocking of the
engine, said controlling means is effective to reduce the amount of
fuel admitted into both power cylinders.
12. The free piston engine of claim 10 in which there is a fuel
pump associated with each cylinder with a common adjusting means
for adjusting the amount of fuel delivered by both pumps and in
which said controlling means operates upon said common adjusting
means.
13. The free piston engine of claim 1 in which the condition
responsive means is responsive to mechanical vibration associated
with knocking of the engine.
14. The free piston engine of claim 1 in which there is a movable
member driven by said power piston and a stationary member with
respect to which said movable member is moved and in which there is
means responsive to said movable member moving too far with respect
to said stationary member to cause said controlling means to
decrease the compression ratio in said power cylinder to decrease
the power output so as to decrease the extent to which said movable
member is moved by said power piston with respect to said
stationary member.
15. The free piston engine of claim 14 in which the movable member
and the stationary element are elements of an air compressor and in
which a portion of the air compressed thereby is employed to cause
said controlling means to decrease the compression ratio in said
power cylinder.
16. The free piston engine of claim 14 in which the excessive
movement of said movable member is sensed by a control member lying
in the path of said movable member and engaged thereby when said
movable member moves too far with respect to said stationary
member.
Description
BACKGROUND OF THE INVENTIONS
Numerous devices have been employed for adjusting the operation of
an engine to prevent knocking. By knocking, as used in this
application, is meant any abnormal combustion condition, such as
preignition, autoignition or rumble resulting in abnormal pressure
rises in the cylinder. Such knocking can cause severe damage to an
engine and it also reduces the efficiency of the engine. On the
other hand, the engine usually operates at its maximum efficiency
just before it begins to knock. Hence, it is desirable to operate
the engine as close as possible to the point at which it would
knock but provide some means for reducing the tendency of the
engine to knock. One of these is to change the point in the cycle
at which the ignition means is achieved. Changing the nature of the
fuel mixture also can be employed. Another very satisfactory
expedient is that of reducing the compression ratio.
Normally, when an attempt has been made to reduce the compression
ratio to reduce knocking, this has been done in connection with a
crank shaft type of engine. This requires some complicated way of
mechanically adjusting elements of the engine. These may be
satisfactory for purposes such as testing the quality of a fuel
where a special test engine can be employed but they are very
impractical in connection with an operating engine intended for
broad commercial applications.
SUMMARY OF THE PRESENT INVENTION
The present invention is concerned with a free piston engine in
which knocking is prevented by sensing an incipient knocking
condition and changing the total return energy available to move
the piston in its compression stroke and thus changing its
compression ratio to reduce the tendency to knock. By adjusting the
return energy from time to time so that the compression ratio is
always near the maximum value possible for a given set of
conditions without producing sustained knocking, very efficient
operation of the engine is obtained.
Where the free piston engine has a bounce chamber, the adjustment
of the return energy can be accomplished by varying the pressure in
the bounce chamber. In the case of a spark ignition engine with a
positive bounce chamber, the pressure in the chamber is decreased
when a knocking tendency occurs. Where the bounce chamber is a
negative bounce chamber, the pressure is increased to prevent
knocking.
Free piston engines are often employed to operate compressors.
Where this is done, some of the compressed air in the compressor
may be used to control the apparatus for adjusting the return
energy. For example, the means for sensing incipient knock may
control a pilot valve of a pressure motor, the pressure of which is
supplied by the compressor driven by the free piston. In the case
of a tandem type of free piston engine in which there are
alternately acting power pistons each operating in its own power
cylinder and in which one piston and cylinder acts to provide the
return energy for the compression stroke of the opposite power
piston and cylinder, the return energy for a cylinder in which a
knock condition is incipient can be adjusted by varying the fuel
supplied to the opposite cylinder. If desired, the fuel to both
cylinders can be adjusted simultaneously. Since, however, a
knocking condition may occur in one cylinder and not in another, it
is desirable to employ either a sensor responsive to the occurence
of a knocking condition in either cylinder or two sensors, each
associated with a different cylinder. The delivery of fuel may be
adjusted by adjusting the output of a fuel injection apparatus.
This fuel injection apparatus may be either of a mechanical or
electrical type.
It is also contemplated that the apparatus for adjusting the return
energy to adjust the compression ratio can incorporate means for
detecting excessive movement of a member driven by the engine. It
is customary to employ some energy absorbing device in connection
with such a free piston engine, this energy absorbing device
constituting the load. Such devices commonly employ a movable
member driven by the power piston and a stationary element. For
example, the energy absorbing device may be in the form of a
compressor having a piston movable in a cylinder. My apparatus
contemplates that where the movable member moves too far as, for
instance, if the compressor piston moves too close to the
compressor cylinder head, means responsive to such excessive
movement causes the return energy to be adjusted independently of
the knock responsive means so as to reduce the compression ratio
and hence to educe the extent to which the movable driven member is
moved by the power piston. The sensing means in such case may take
the form of an element directly engaged by the movable member when
it moves too far. Thus, in the case of a compressor, the element
may be a member directly engaged by the piston when it moves too
close to the cylinder head. Again, a portion of the air in the
compressor chamber may be employed for the controlling action.
Various other objects and features of the present invention will be
apparent from a consideration of the accompanying specification,
claims and drawings.
BRIEF DESCRIPTIONS OF THE DRAWINGS
FIG. 1 is a schematic view showing a free piston engine in
longitudinal cross section and incorporating the improved knock
control features of the present invention;
FIG. 2 is a schematic view of modified form of my invention
employing a pneumatic control for varying the return energy and
also showing means for guarding against excess movement of the
movable member driven by the power piston;
FIG. 3 is a fragmentary view showing a modified arrangement for
sensing excessive movement of the driven member;
FIG. 4 is a schematic view of a further modification in which there
are alternately acting power pistons, each power piston and
cylinder acting to provide the return energy for the other piston
and in which there are sensors responsive to incipient engine
knock, which are operative through a suitable mechanism to control
the fuel to both cylinders;
FIG. 5 is a view of a modification of the apparatus of FIG. 4, in
which an electrically operated injector pump is employed and in
which the control apparatus adjusts the operation of this pump;
and
FIG. 6 shows a further modification of the apparatus of FIG. 4 in
which instead of adjusting simultaneously the delivery of the fuel
pumps for both cylinders, these fuel pumps are individually
adjusted depending upon the incipient knock condition in the
cylinder opposite to that with which the fuel pump is
associated.
Throughout the various figures of the drawings, the same reference
numerals have been used to designate the same or identical parts or
elements in the various embodiments of the engines shown.
Furthermore, when the terms "right," "left," "right end," and "left
end" are used herein, it should be understood that these terms have
reference only to the structure shown in the drawings, as it would
appear to a person viewing the drawings and are utilized only to
facilitate describing the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
EMBODIMENT OF FIG. 1
In FIG. 1, I have shown my invention as applied to a free piston
engine of the type shown in my prior U.S. Pat. NO. 3,501,088. Such
a free piston engine includes a power section 12, a
balancer-synchronizer section 13 and an energy absorbing device
shown schematically at 14. The energy absorbing device 14 may be a
compressor such as shown in the drawing, a pump, a generator, or
other device which utilizes or absorbs reciprocatory power.
Describing first the power section 12, this comprises a cylinder
housing 15 which has a power cylinder 16 formed therein. A power
piston 17 having an outer face 18 is positioned within the cylinder
16 for reciprocal movement therein. The piston 17 is provided with
a skirted side wall 21. Piston rings 22 are carried in grooves
formed in the piston 17 for minimizing the leakage of gases between
the cylinder 16 and the piston 17. The left-hand end of the
cylinder housing 15 is closed to form a cylinder head 24, which
with the outer face 18 of the piston 17 define a combustion chamber
26 in the cylinder 16.
Secured in and extending through the head 24 is a spark plug 25
which is connected to any suitable ignition wire 28 leading to a
suitable source of ignition voltage. Also secured and extending
through the head 24 is a conventional fuel injector unit 27 which
is connected to a suitable fuel supply pipe 29. As will be
described later, the piston 17 is moved towards the head 24 by a
return energy means. By proper selection of the amount of return
energy, air is compressed to a desired extent in combustion chamber
26 by the leftward movement of piston 17. During the compression
stroke, fuel is introduced into the cylinder through the injector
27 and at an appropriate time in the compression cycle, the spark
plug 25 is fired to cause the mixture of the fuel introduced by
injector 27 and the air to be ignited. The compression ratio is the
ratio between the volume of the combustion chamber at the time when
the compression of the air in the chamber begins and that at the
time in the engine cycle that piston 17 moves closest to the head
24. This compression ratio depends upon the return energy available
to move the piston and, as will be described, the present invention
contemplates means for varying this return energy in order to
control the compression ratio so as to prevent knocking.
The cylinder housing 15 is provided with inlet and exhaust ports.
Typical inlet openings are indicated by the numeral 31 and a
typical one of these exhaust openings is indicated by reference
numeral 32. It will be understood that there may be a plurality of
intake openings 31 and exhaust openings 32. The exhaust openings 32
are somewhat closer to the cylinder head than the inlet openings 31
to insure scavenging of the exhaust gases.
Referring now to the balance and synchronizing mechanism, the
details of this mechanism form no part of the present invention,
being described in detail in U.S. Pat. No. 3,525,102, granted Aug.
18, 1970, to the present inventor. Briefly, the synchronizer
balancer is located in the housing 35 and comprises a double rack
member 36 which is connected to and coaxial with the piston rod 37
secured to the piston 17. The synchronizing mechanism 13 also
includes a pair of pinions 38 and 39 which are mounted for rotation
about fixed axes. The pinions 38 and 39 engage two spaced rack
members 40 and 41 which are held together by side plates, only 42
of which appears in the drawing. As the piston rod 37 moves to the
right as a result of the firing of the combustible mixture within
the combustion chamber 26, the rack member 36 operating through the
pinions 38 and 39 is effective to move the assemblage comprising
the rack members 40 and 41 and the side plates to the left and
hence balance the forces imparted to the engine by the movement of
all of the parts movable with rod 37. The function of the
synchronizer assembly is, as pointed out above, more fully
described in the above-mentioned Braun U.S. Pat. No. 3,525,102.
As pointed out above, the energy absorbing device 14 is shown as a
compressor. This consists of a cylinder housing 50 forming a
compressor cylinder 51 in which moves a compressor piston 52
secured to a piston rod 53 which in turn is secured to the double
rack member 36 and the power piston rod 37, compressor piston rod
53 being coaxial with power piston rod 37. In other words, power
piston 17, double rack 36, piston rod 53, and compressor piston 52
move as a unit. The piston 52, like power piston 17, may be
provided with piston rings 55 carried in grooves formed in the
piston 52.
Secured to the end of the cylinder housing 50 is a cylinder head
56. The cylinder head 56 is provided with an inlet passage 58
therethrough which is closed during the compression stroke of
piston 52 by a check valve 59 which opens inwardly to admit air on
the suction stroke of piston 52. The cylinder head 56 is also
provided with an outlet passage 61 which is closed during the
suction stroke of piston 52 by an outwardly opening check valve 62.
Passage 61 may lead to a suitable reservoir for maintaining the
compressed air under pressure. Valves 59 and 62 are normally biased
so as to aid the seating of these valves.
In normal operation, piston 52 and power piston 17 are abruptly
moved to the left by reason of the pressure existing on the
right-hand side of piston 52. As piston 52 moves to the left,
outlet valve 62 will close as soon as the pressure on the outlet
side of valve 62 is greater than the pressure between the piston 52
and the head 56. Inlet valve 59 will open as soon as the pressure
between the piston 52 and the head 56 falls below the pressure
existing upstream of valve 59 and air is drawn into the compression
chamber between piston 52 and head 56. The two pistons 17 and 52
continue to move to the left. During the time the inlet openings 31
were opened by movement of the piston 17 to the right, air was
admitted into the combustion chamber through the inlet openings 31.
As previously explained, fuel is injected through injector 27 and
the compressed fuel mixture is ignited by the spark plug 25. Upon
firing taking place within the combustion chamber, the piston 17 is
moved rapidly to the right, also moving the compressor piston 52 to
the right to compress the air which has drawn in through the inlet
opening 58. As the air is compressed, it passes out through the
outlet opening 61 to a suitable air reservoir under pressure.
The air compressed by compressor piston 52 thus is not only
supplied to a reservoir but also acts as the medium in which the
return energy necessary to move the piston 17 in its compression
stroke is stored. In other words, the compressor piston 52 and the
compressor cylinder 51 act as part of the return energy means for
power piston 18. The action of this return energy means is
partially opposed by a bounce chamber 65 on the left-hand side of
piston 52. This chamber exists between the left-hand side of piston
52 and a partition wall 66 between the left-hand end of cylinder 51
and the housing 35 for the synchronizer 13. The bounce chamber may
be either a positive or negative bounce chamber depending upon
whether the effect of the chamber is to add to or subtract from the
return energy available to move the power piston on its compression
stroke. As illustrated, the chamber functions as a negative bounce
chamber in that a pressure is built up as piston 52 moves to the
left, this pressure retarding the movement of compressor piston 52
and power piston 17 during the compression stroke of the latter. An
opening 67 extends through the wall of the cylinder housing 50 and
inserted into this opening is an inwardly opening check valve 68,
biased to closed position, which communicates at its outer end with
a restricted orifice member 69. An opening 71 also extends through
the wall of cylinder housing 50 and secured in this opening is a
pressure biased outlet valve 72. This outlet valve 72 has a passage
73 communicating at its lower end with the interior of the bounce
chamber 65. At its upper end, the passage 73 terminates in a valve
seat upon which a valve member 75 is adapted to seat. The valve
member 75 controls the communication between passage 73 and an
exhaust opening 74. A chamber 76 is formed between the upper space
of valve member 75 and the outer wall of the housing of the valve
72. The pressure in this chamber determines the bias on valve
member 75. Air is supplied to chamber 76 through the conduit 78
leading from a source of control fluid 79. The flow of control
fluid from source 79 to the chamber 76 is controlled by a valve 80.
Air or any other control fluid being used is allowed to
continuously escape from chamber 76 through a bleed orifice 81.
Thus, the pressure in chamber 76 is dependent upon the size of the
orifice 81 and the extent to which valve 80 is opened. While the
valve 80 is open, the pressure tends to build up in chamber 76
forcing valve member 75 harder against its seat. Whenever valve 80
is closed, the pressure bleeds off through orifice 81. Fluid
escaping through orifice 81 may be suitably recirculated, if
desirable.
The valve 80 is operated by an electrical solenoid 82 or any other
suitable actuator. The energization of solenoid 82 is controlled by
a sensor 84 secured to the head 24 of the power cylinder 15. Sensor
84 may be any suitable device for responding to vibrations of an
engine element indicating incipient knocking and which is effective
when subjected to such vibrations to produce an electrical signal.
Devices of this type are well known and need not be described in
detail. A typical device of this type is that shown in the Lancor
U.S. Pat. No. 2,619,605. The output of sensor 84 is connected
through an electrical conductor 85 and a ground connection 86 to a
suitable electronic amplifier 87 supplied with power by input power
leads 88 and 89. The amplifier preferably has some conventional
means for filtering or otherwise modifying the signal to provide a
relatively uniform output. The output of amplifier 87 is applied
through conductors 90 and 91 to the solenoid operator 82 of valve
80. Thus, whenever sensor 84 detects incipient knocking of the
engine 12, it produces a signal which is amplified and filtered in
amplifier 87 and causes energization of the solenoid 82 to open
valve 80 admitting pressure fluid from the source 79 through line
78 to the chamber 76.
Referring now to the operation of the bounce chamber 65, whenever
the compressor piston 52 moves to the right in a compressing
direction, air tends to be drawn into the bounce chamber 65 through
the restricted orifice 69 and the check valve 68. By reason of the
restricted orifice 69, the amount of air so drawn in is somewhat
limited. When compressor piston 52 moves to the left during the
compression stroke of the power piston 17 as a result of the energy
stored in the air which has been compressed between compressor
piston 52 and cylinder head 56, the check valve 68 closes and the
ressure in bounce chamber 65 tends to build up. If it builds up
beyond a predetermined value corresponding to the pressure in the
pressure chamber 76 of valve 72, the valve member 75 is moved away
from its seat to permit escape of air through the passage 3 and the
exhaust passage 74. The pressure finally existing in bounce chamber
65 as the compressor piston 52 approaches the end of its stroke to
the left, thus depends upon the pressure in chamber 76 which in
turn depends upon the operation of sensor 84.
Referring now to the overall operation of the unit of FIG. 1, when
the fuel mixture within the combustion chamber 26 is fired after
the compression stroke of the power piston 17, the piston is driven
to the right to cause compressor piston 52 to likewise move to the
right and compress the air which has been drawn in through inlet
opening 58. This not only results in compressed air being delivered
to a suitable reservoir through the outlet passage 61 but also
results in energy being stored on the right-hand side of the piston
52 for causing its return to the left. At the same time that piston
52 moves to the right, air in the bounce chamber 65 expands and a
very small amount of air is drawn into the chamber 65 through the
check valve 68. The return energy stored in the air which has been
compressed to the right of piston 52 is now effective to move
compressor piston 52 to the left and hence to move power piston 17
to the left so as to cause compression of the air which has entered
chamber 26 through air inlet openings 31. The extent to which
piston 17 moves to the left is dependent upon the amount of return
energy available. This is determined not only by the amount of air
and its pressure on the right-hand side of piston 52 when the
piston 52 is at its normal reversal point near cylinder head 56,
but also by the pressure in negative bounce chamber 65. The
pressure of the air on the right-hand side of piston 52 is normally
relatively constant due to the demand for a constant pressure in
the air reservoir to which outlet passage 61 is connected. In other
words, the pressure available for moving power piston 17 in its
compression stroke is dependent upon the total return energy
available, this return energy being the result of the opposing
energy factors on opposite sides of compressor piston 52. Since,
the energy on the right-hand side of piston 52 is normally
relatively constant and cannot be adjusted independently of load
and compressor discharge pressure, adjustment is made of the
pressure in the bounce chamber 65. This is done by adjusting the
pressure in the pressure chamber 76 acting on the valve member
75.
Whenever the vibration sensor 84 senses the vibration associated
with an incipient knock of the engine, the sensor is effective to
produce an output which results in the energization of solenoid
operator 82 to open valve 80 admitting pressure from the source 79
of control fluid to the pressure chamber 76. This will result in an
increase in the pressure in this chamber to bias valve member 75
more firmly into engagement with its seat requiring a greater
pressure in chamber 65 before valve member 75 can be released. This
in turn prevents compressor piston 52 and power piston 17 from
moving as far to the left as was previously the case. Thus, the
compression ratio is reduced to in turn reduce the tendency of the
engine to knock. The solenoid operated valve 80 will reopen each
cycle until the sensor has detected that any tendency to knock has
disappeared. Thereafter, the solenoid valve 80 remains closed and
the pressure accumulated in chamber 76 starts to reduce due to the
control fluid bleeding off through the bleed orifice 81. This will
reduce the pressure in chamber 76 reducing the bias on valve member
75 and hence reducing the ultimate pressure in bounce chamber 76.
This will in turn permit pistons 52 and 17 to move further to the
left, again increasing the compression ratio. This effect will
continue until the sensor 84 again detects an incipient knock
condition at which time the process will be repeated. It will thus
be apparent that the pressure in negative bounce chamber 65 is
continuously adjusted up and down in such a manner that the
compression ratio within the power cylinder 12 is always close to
but slightly less than the value at which sustained knocking
occurs. Since, as previously pointed out above, it is desirable to
operate an engine as close to a knock condition as possible, this
will result in maximum efficiency of the engine under any given set
of operating conditions.
MODIFICATION OF FIG. 2
In FIG. 2, I have shown a modified form of my invention in which a
mechanical instead of an electrical means is employed for sensing
an incipient knock condition and controlling the bias on the outlet
valve of the bounce chamber and in which the bias on this valve is
also controlled by means responsive to the position of a movable
member driven by the power piston.
Except for the means for sensing an incipient knock condition, the
power section 12 is the same as in FIG. 1. The same reference
numerals have been applied and it is believed unnecessary to repeat
the description of this section of the apparatus except for the
knock sensing element which will be described later. Similarly, the
balancer synchronizing section 13 is the same and similar reference
characters have been applied to this.
As with the species of FIG. 1, the energy absorbing device 14 is in
the form of an air compressor having a compressor piston 52 movable
in a compressor cylinder housing 50 defining a compressor cylinder
51. There are also inlet and outlet check valves 59 and 62 which
function in the same manner as the inlet valves 59 and 62 of FIG.
1.
One difference between the engine of FIG. 2 and that of FIG. 1 is
that in addition to the negative bounce chamber 65, there is also a
positive bounce chamber 102. This is formed by elongating the
housing 50 so that it is somewhat longer than the one in the engine
of FIG. 1. An inner cylindrical housing 103 extends to the right
from the partition wall 66 and this housing defines a cylinder 105
in which moves a bounce piston 106. The space within cylinder 105
to the left of piston 106 may be in free communication with the
space within the balancer synchronizer section or may communicate
with any other area at atmospheric pressure so that no substantial
pressure exists to the left of piston 106. The cylindrical housing
103 is provided with suitable means (not shown) for admitting air
on the right-hand side of piston 106 when the piston is moving to
the left but not permitting its escape when the piston is movign to
the right. The result is that when the piston 106, which is driven
by the power piston 17, is moved to the right after the firing of
the combustible mixture takes place, a very high pressure can be
built up on the right-hand side of piston 106. This pressure acts
to aid the pressure on the right-hand side of compressor piston 52
in causing movement of the power piston 17 in its compression
stroke. In other words, the energy stored to the right-hand side of
the bounce piston 106 becomes part of the total return energy
available to move the power piston in its compression stroke.
If desired, the pressure in the positive bounce chamber existing on
the right-hand side of bounce piston 106 could be controlled to
prevent knock. In such a case, the pressure in this chamber would
be reduced whenever an incipient knock condition exists. I have,
however, again shown the control of the return energy as being
effective through a control of the pressure in the negative bounce
chamber 65 just as in FIG. 1. As in FIG. 1, there is an inlet check
valve 68 through which air can be drawn when the compressor piston
52 is moving in its compression stroke, that is to the right. The
air is drawn through a restricted orifice 69. Similarly, there is a
biased outlet valve 110 for permitting escape of some of this air.
This biased outlet valve 110 corresponds generally in function to
valve 72 of FIG. 1. It is secured in an opening 111 in the
extension of the cylinder housing 50 and has a passage 112
communicating with the interior of the bounce chamber 65. This
passage 112 is adapted to communicate with a bleed opening 117
under the control of a valve member 113. The valve member 113 is
provided with a stem 114 secured to a diaphragm 115 forming part of
a pressure motor 116. The pressure motor is formed of two housing
members 124 and 118 between the flanges of which the diaphragm 115
is clamped. The chamber between the diaphragm 115 and upper housing
member 124 is open to the atmosphere, there being a passage 119
therethrough. The chamber between the lower housing member 118 and
diaphragm 115 constitutes the pressure chamber of the pressure
motor 116. Fluid is admitted to this chamber through a conduit 120
extending into the chamber. A restricted bleed 121 is also
connected to the chamber below diaphragm 115. A suitable biasing
means, such as spring 125, is interposed between the inner wall of
housing member 118 and diaphragm 115 and acts to bias valve member
113 against its seat. The biasing effect of spring 125 is augmented
by the fluid pressure in the chamber beneath diaphragm 115 so that
the total bias exerted on valve member 113 is the sum of that
exerted by spring 125 and the fluid pressure exerted on diaphragm
115. In a manner similar to the way in which pressure is maintained
in the pressure chamber 76 of valve 72 of the species of FIG. 1,
the pressure in the chamber beneath diaphragm 115 is varied by
selectively admitting air through conduit 120 to this pressure
chamber at a rate greater than it can bleed off through the
restricted bleed 121. The conduit 120 is connected through a
conduit 122 to the outlet opening of a pilot valve 126, the inlet
of which is connected to a source 127 of compressed air. This
source of compressed air, like source 79 of FIG. 1, may be the
reservoir of compressed air which is supplied by the compressor 14.
The pilot valve 126 includes a valve member 128 biased into
engagement with a valve seat 129 by a spring 130. The valve member
128 is normally maintained in engagement with the valve seat 129 by
the spring 130; in other words, the pilot valve 126 is normally
closed.
Connected to valve member 128 is a valve stem 131, the outer end of
which engages a rocker arm 133 pivotally secured to cylinder head
24 by a pivot pin 134. The opposite end of rocker arm 133 has an
adjusting screw 135 extending therethrough. The inner end of this
adjusting screw 135 engages an anvil 136 secured to the head 24.
The adjusting screw 135 is normally adjusted so that valve member
128 is held in closed position by biasing spring 130 when the
engine is operating in a normal manner. When, however, an incipient
knock condition occurs, the anvil 136 is vibrated causing arm 133
to be rocked in a counterclockwise direction to open the pilot
valve 126 and admit air from the source 27 of compressed air
through conduits 122 and 120 to the underside of the diaphragm 115.
This results in the pressure in the chamber beneath diaphragm 115
increasing to bias valve member 113 more firmly against its valve
seat.
The operation of the apparatus of FIG. 2, as described so far, is
very similar to that of the apparatus of FIG. 1. Whenever the anvil
136 detects incipient knocking, pilot valve 126 is opened to
increase the pressure beneath diaphragm 115 and hence to increase
the bias on valve member 113. Just as with pilot valve 72, this
results in increasing the pressure in the negative bounce chamber
65 to decrease the movement of the power piston 17 towards the
cylinder head during its compression stroke. This, in turn, reduces
the compression ratio to reduce the tendency of the engine to
knock. This, in turn, results in reclosure of pilot valve 126 to
interrupt the flow of fluid through conduit 120 to the underside of
diaphragm 115 to reduce the bias on valve 113. This will in turn
result in the piston 17 moving closer to the cylinder head 24 and
again increasing the compression ratio. This will continue until
incipient knocking is again detected at which time the process will
be repeated. Thus, as with FIG. 1, the compression ratio is
constantly adjusted to maintain the engine operating at a point
close to that at which it could knock.
In FIG. 2, I have provided an additional means of varying the
return energy to vary the compression ratio. In a free piston
engine in which there is no crankshaft, it is possible under some
conditions for the movable member of the energy absorbing device to
be moved too far by the power piston when combustion occurs. In a
crankshaft type of engine, the movement of the driven member is
definitely limited by the crankshaft. This is not true, however, in
a free piston engine. The present invention contemplates the
provision of means to change the compression ratio of the engine if
the movement of the movable member of the energy absorbing device
becomes too great. Where the energy absorbing device is, for
example, a compressor having a compressor piston movable within a
cylinder, the present apparatus senses when the compressor piston
approaches too close to the cylinder head of the compressor
cylinder.
Referring specifically to the apparatus shown in the drawing, a
pilot valve 140 is provided for controlling the flow of fluid from
a pipe 141 connected to a source of air under pressure through a
pipe 123 to conduit 120 leading to the chamber beneath diaphragm
115. The pilot valve 140 comprises a valve member 142 normally
biased into engagement with a valve seat 144 to interrupt the flow
of fluid from the air source through pipe 141. The valve member 142
is normally biased into engagement with seat 144 by a spring 143.
Secured to valve member 142 and extending through the housing of
pilot valve 140 is a valve stem 145, the inner end of which lies in
the path of compressor piston 52 and which will be engaged by the
head of compressor piston 52 if the piston 52 approaches too
closely to cylinder head 56. When this happens, the piston head is
effective to force valve steam 145 and valve member 142 to the
right, moving valve member 142 away from its seat 144 and
permitting air to flow from the source of air through pipe 141 and
conduits 123 and 120 to the interior of the pressure chamber
beneath diaphragm 115. This results in increasing the bias on
outlet valve 113 to increase the pressure in the bounce chamber 65
and hence decrease the compression ratio in the manner previously
described in connection with the action of the detonation sensor.
Thus, even though the detonation sensor including rocker arm 133
and anvil 136 may not be sensing any incipient knock condition, the
apparatus including pilot valve 140 will still reduce the
compression ratio if the piston 52 approaches too closely to the
piston head 56. It will be obvious that if the compression ratio is
reduced, the force exerted on the piston 17 during the firing
operation will be decreased and the piston 17 will not move
compressor piston 52 as far as it would otherwise. Thus, the
apparatus of FIG. 2 is effective to cause the return energy
operating the piston to be changed either in the event of an
incipient knock condition or in the event of the movable member of
the energy storage device moving too far. Furthermore, the
arrangement of FIG. 2 exerts its controlling action without the use
of electrical energy so that electrical connections to an external
source of electrical power are unnecessary.
MODIFICATION OF FIG. 3
In FIG. 3, I have shown a slight modification of the apparatus of
FIG. 2. In FIG. 2, the conduit 141 led to some external source of
compressed air. In the arrangement of FIG. 3, this connection to an
external source of compressed air is omitted and the compressed air
on the right-hand side of piston 52 is used for the controlling
effect. The pilot valve 150 of this unit is similar to pilot valve
140 of FIG. 2 with the exception that instead of being connected to
a conduit 141 leading to a source of compressed air, the valve seat
144 communicates with the interior of the chamber between piston 52
and cylinder head 56 through a passage 151. Thus, when the stem 145
of valve member 142 is engaged by the head of the compressor piston
52 to move valve member 142 away from its seat 144, fluid is
admitted directly from the chamber on the right-hand side of
compressor piston 52 through conduit 123 to the space beneath the
diaphragm 115.
While the arrangement of FIG. 3 is simpler in avoiding connection
to an external source of pressure fluid, it is only feasible where
the fluid being compressed is some harmless fluid, such as air
which can be readily used as the controlling fluid. Where the fluid
being compressed is a dangerous gas, it is desirable to use the
arrangement of FIG. 2 in which it is possible to use a relatively
harmless fluid from a different source as the control fluid.
SPECIFS OF FIG. 4
In FIG. 4, I have shown a modification in which there are two
alternately acting power pistons. In this case, the combustion
chamber of each power piston acts to provide the return energy for
the other power piston. In this modification, the return energy
available is changed by modifying the amount of fuel admitted to
the combustion chamber of the cylinder opposite to that in which
knocking is occurring. Actually, in FIG. 4, when knocking is about
to occur in either cylinder, the amount of fuel delivered to both
cylinders is decreased.
Since the left-hand power section is identical to power section 12
of FIG. 1 as far as the present invention is concerned, the same
numerals have been employed in connection with the left-hand power
section as were employed in connection with power section 12 of
FIG. 1. It is not believed necessary to again describe this power
section since its structure and operation correspond with that of
FIG. 1. Similarly, the right-hand power section is a mirror image
of the left-hand power section. In order to enable a ready
comparison of the reference numerals of the two power sections,
equivalent elements in the right-hand power section have been
assigned numbers 200 higher than are assigned to the same elements
of the left-hand power section. Thus, the right-hand power section
is designated by the reference numeral 212 and the power piston by
the numeral 217. Again, it is believed unnecessary to describe
power section 212 since its operation will be obvious through the
previously described operation of power section 12 of FIG. 1.
The balancer synchronizer section 13 is likewise the same as that
of FIG. 1 and the same reference characters have been employed in
connection with this balancer synchronizer section as were employed
in connection with this section in FIG. 1.
The energy absorbing device 14 is driven by both power sections 12
and 212. Again, this takes the form of a compressor with a
compressor piston 252 moving within a cylinder 251 formed by the
cylinder housing 250. Due to the fact that the compressor is a
double-acting compressor, its construction is somewhat different
from that of the compressor of FIG. 1. Accordingly, for those
elements which do not correspond with elements of the compressor of
FIG. 1, numerals in the 100 series are assigned to these elements.
Secured to the opposite ends of cylinder housing 250 are end walls
155 and 156. These end walls are secured in gastight relation to
the ends of the cylinder housing 250 by means (not shown) and
constitute the ends of the cylinder 250. End wall member 155 is
provided with a curved inlet passage 161 leading to the interior of
the cylinder 251 on the left-hand side of piston 252. It will be
understood that there will be an outwardly closing check valve in
series with passage 161 so as to prevent escape of the gas
compressed by piston 252. Similarly, end member 155 has an outlet
opening 162 communicating at its inner end with the interior of the
cylinder 251 on the left-hand side of piston 252. The passage 162
may lead to a suitable air reservoir for storing air under
pressure. Interposed in the connection extending from passage 162
will be an inwardly closing check valve to prevent return of air to
the cylinder from the air reservoir. Similarly, end wall 156 is
provided with passages 163 and 164 which correspond in function to
passages 161 and 162, respectively. Again, passage 163 will lead to
a source of gas to be compressed and will be provided with an
outwardly closing check valve whereas passage 164 will lead to a
container for the compressed gas and will be provided with an
inwardly closing check valve. It will be obvious that when piston
252 moves to the right, air or other gas to be compressed is drawn
in through passage 161. At the same time, compressed gas on the
right-hand side of the piston is forced out through outlet passage
164. When the piston 252 moves to the left, the gas being pumped
will be drawn in on the right-hand side through opening 163 and
compressed gas will be forced out through passage 162.
A pair of mechanically operated fuel injection pumps 166 and 167
are secured to the housing 35 of the synchronizer balancer section
13. The rank section 240 corresponding to rack section 40 of FIG. 1
is provided with a cam slot 168. This cam slot has a flat
intermediate portion and sloping end portions. Cooperating with
this cam slot are plungers 169 and 170 which act, when
reciprocated, as the pumping elements of pumps 166 and 167,
respectively. Whenever these are reciprocated, fuel is pumped from
inlet pipes 172 and 173 to outlet pipes 174 and 175. The outlet
pipes or conduits lead to injectors 27 and 227, respectively. The
inlet pipes or conduits 172 and 173 are connected to a suitable
fuel source through a conduit 175 and branch conduits 176 and 177.
The amount of fuel pumped by pumps 166 and 167 as plungers 169 and
170 are reciprocated depends upon the position of the fuel rack
180. Such fuel racks are quite customary in connection with fuel
injector pumps. They may, for example, be employed to vary the
proportion of the effective stroke of the piston during which the
intake valve is open. Since such fuel racks are quite common in
connection with fuel pumps, it is believed unnecessary to describe
this operation beyond stating that when rack 180 is moved to the
right, as viewed in FIG. 4, the amount of fuel delivered by pumps
166 and 167 is decreased. Conversely, when the rack is moved to the
left, the amount of fuel delivered is increased.
Referring now to the overall operation of fuel pumps 166 and 167,
it will be apparent that when the rack member 240 of the
synchronizer balancer section 13 is moved to the left to the
position shown as a result of power piston 17 being forced to the
right during the firing stroke, plunger 170 of fuel pump 167 is
raised. When the fuel mixture in chamber 226 of the right-hand
power unit 212 is fired so that power piston 217 moves to the left,
the rack 240 will move to the right causing the plunger 170 to ride
downwardly in the groove 168 and plunger 169 to be raised upwardly
as it is engaged by the inclined portion on the left-hand side of
groove 168. Thus, as the pistons 17 and 217 are alternately moved
in their firing strokes, plungers 169 and 170 are alternately
operated to cause alternate operation of pumps 166 and 167. Pump
166 is operated to supply fuel to injector 27 during the
compression stroke of power piston 17; pump 167 is operated to
supply fuel to injector 227 when power piston 217 is moving in its
compression stroke. The amount of fuel being delivered in each case
depends upon the position of rack 180. This in turn depends upon
the pressure within the pressure chamber of a fluid motor 182. The
fluid motor 182 generally corresponds with motor 116 of FIG. 2,
there being a diaphragm 183 forming one wall of a pressure chamber
184 having an inlet 185 for air under pressure and a restricted
constant bleed 186. The diaphragm 184 may be spring biased, as
shown at 187. The pressure in chamber 184 will oppose this biasing
means. The diaphragm 183 is connected to a rod 188 which connects
to rack 180. The position that diaphragm 183, rod 188 and rack 180
take depends upon the pressure in chamber 184. This pressure
depends upon the extent of time in which a valve 189 is open. This
valve 189 controls the flow of fluid from a suitable source 191 to
the pressure chamber 184. When the valve 189 is opened, air flows
from the source 191 into the pressure chamber 184 at a rate greater
than the air or other pressure fluid leaks off through the bleed
186, so that the pressure in chamber 184 rises. when valve 189 is
closed, no air is admitted from source 191 and since air continues
to leak off through the bleed 186, the pressure in chamber 184
falls. The valve 189, like valve 80 of FIG. 1, is controlled by an
amplifier 87 corresponding to the amplifier 87 of FIG. 1. The input
to this amplifier is controlled by a vibration sensitive device 84
which responds to any incipient knocking of the engine to produce
an input signal to amplifier 87 which is effective to cause
energization of solenoid 190 to open valve 189 and admit fluid from
the source 191 to the pressure chamber 184 of the pressure motor
182 so as to tend to cause movement of rack 180 to the right. As
previously explained, when rack 180 is moved to the right, the
amount of fuel delivered by pumps 166 and 167 is decreased. This
will in turn decrease the power by which pistons 17 and 217 are
moved during their firing stroke.
The energization of solenoid operator 190 is also controlled by the
vibration sensor 284 associated with the other power cylinder 212.
This sensor functions in the same manner as sensor 84 to detect any
incipient knock condition in connection with the engine 212 and
when such a condition occurs to produce a signal which is supplied
to the input of an amplifier 287. The output terminals of amplifier
287 are connected to the solenoid 190 so that the solenoid 190 may
be energized either from amplifier 87 or amplifier 287. Thus, in
the event of an incipient knock condition in connection with either
one of the power sections 12 or 212, the solenoid operator 190 is
energized to open the valve 189 to permit fluid to flow from the
source 191 of control fluid to the pressure chamber 184 of fluid
motor 182. This will in turn cause movement of the rack 180 to the
right to decrease the amount of fuel delivered by pumps 166 and 167
to their respective fuel injectors 27 and 227. This in turn results
in a decrease in the amount of fuel delivered to both cylinders and
a decrease in the combustion energy available. This in turn results
in a decrease in the return energy available to move the opposite
cylinder since the amount of fuel being supplied to both cylinders
is being decreased, neither cylinder will move as far in the
compressing direction as it did previously. The reason for
employing two vibration sensors is that it may occasionally happen
that one cylinder and not the other will have knock condition. If
either cylinder shows a tendency to knock, then it is desirable to
reduce the amount of fuel supplied to both cylinders so as to stop
the incipient knock condition.
While I have shown two vibration sensors, one for each cylinder, it
is possible in some cases to employ a single such sensor located so
as to sense an incipient knock condition in either cylinder. Such a
sensor may be located, for example, adjacent to the middle of the
engine. In such a case, this single sensor would control the amount
of fuel supplied to both cylinders. For example, such a sensor
could control through an amplifier the operation of solenoid
190.
OPERATION OF SPECIES OF FIG. 5
In FIG. 5, I have shown a modification in which instead of using a
mechanically operated fuel pump such as fuel pumps 166 or 167, I
use an electrically operated fuel injector. The fluid motor 182
corresponds to fluid motor 182 of FIG. 4 and has the pressure
within its pressure chamber 184 controlled in the same manner by a
solenoid valve 189 operated by a solenoid 190 controlled by an
amplifier 87, the input signal to which is controlled by a sensor
84. The stem 188 of fluid motor 182 is in this modification
connected to an arm 306 controlling a potentiometer 304 forming
part of a programmer for the injector, the programmer being
designated by the reference numeral 305. The output of this
programmer is in turn connected to an electrically operated
injector 302. Programmers of this type are quite old, being used in
connection with a common type of pressure-time controlled system in
which the fuel is held at a relatively constant pressure and is
admitted for variable periods of time under the control of the
programmer. The potentiometer 304 is shown as illustrative of any
of various means by which the program of the programmer can be
altered. For the purposes of the present invention, when the arm
306 is moved upwardly the potentiometer 304 is adjusted to change
the program for the injector in such a manner as to decrease the
amount of fuel supplied by the electrically operated injector 302
to the interior of the combustion chamber 26. Whenever the pressure
within pressure chamber 184 of fluid motor 182 increases, the arm
306 is moved upwardly to decrease the fuel in the manner just
described. Thus, the operation of the modification of FIG. 5 is the
same as that of FIG. 4 with the sole exception that instead of the
injectors being mechanical injectors supplied by mechanically
driven pumps, the injectors are electrical injectors which inject
the fluid, the amount of fluid being injected being controlled by a
programmer. While I have shown only one injector 302, it is to be
understood that the programmer 305 can control a similar injector
for the other power cylinder so that, as in FIG. 4, if the sensor
associated with either cylinder senses an incipient knock
condition, the amount of fuel injected into both cylinders is
decreased.
MODIFICATION OF FIG. 6
The modification of FIG. 6 differs from that of FIG. 4 in that the
fuel pumps are individually controlled in accordance with a knock
condition existing in the opposite cylinder. In other words, if an
incipient knock in one cylinder is detected, the mechanism is
effective to alter the output only of the fuel pump delivering fuel
to the opposite cylinder.
Referring specifically to the drawing, two fuel injection pumps are
indicated by the reference numerals 315 and 316. These pumps may be
driven by any suitable means such as by a connection to a moving
part of the engine, as in FIG. 4. Fuel pump 315 has associated
therewith a rack 319 for adjusting the fuel output of pump 315 in a
manner similar to that in which rack 180 adjusted the fuel output
of the two fuel pumps 166 and 167. The position of rack 319 is
controlled by a pressure motor 320 which has the pressure in its
pressure chamber varied in accordance with the operation of a
solenoid valve 321 which is in turn controlled by one of the
vibration sensors. Referring to FIG. 4 for the moment, the fuel
pump 315 of FIG. 6 controls the fuel to the power section 212 and
the solenoid valve 321 is controlled by the vibration sensor 84
associated with the power section 12. Thus, if an incipient knock
condition is detected in connection with power section 12, the
solenoid valve 321 will be opened to supply fluid to the pressure
chamber of pressure motor 320 to cause rack 319 to be moved to the
right to decrease the delivery of fuel by pump 315 to the
combustion chamber of power section 212. This will decrease the
extent to which power piston 17 of power section 12 is moved in its
compression stroke and thus decrease the likelihood of any knock
occurring in cylinder 26. Again, as with all of the other
modifications, the absence of any incipient knock condition will
result in closure of valve 321 and the pressure in the pressure
chamber of pressure motor 320 will gradually decrease so as to
increase again the delivery of fuel by fuel pump 315 to power
section 212. The return energy supplied by power section 212 to
power section 12 will thus be constantly adjusted back and forth
between a value in which a knock condition is about to occur in
power section 12 and one in which no knock condition occurs. Thus,
the power section 12 is always operated very close to the point at
which a knock condition would occur.
Referring now to the other injection pump 316, this is connected
with an outlet pipe 318 leading to the combustion chamber of power
section 12. The output of fuel pump 316 is adjusted by a rack 324
which is connected to a pressure motor 325, the pressure in the
pressure chamber of which is controlled by a solenoid valve 326. In
this case, when the rack 324 is moved to the left, the delivery of
fuel by pump 316 is decreased. The solenoid valve 326 is controlled
by the vibration sensor 284 associated with power section 212.
Thus, if the sensor 284 detects an incipient knock in connection
with power section 212, the solenoid valve 326 is opened to
increase the pressure in the pressure chamber of fluid motor 325 to
move rack 324 to the left to decrease the output of pump 316 and
hence to decrease the amount of fluid delivered to the combustion
chamber 26 of power section 12. Again, this will result in a
decrease in the amount that the piston 17 moves to the right and
hence decrease the compression stroke of the power piston 217 of
power section 212.
SUMMARY
It will be seen that I have provided a novel free piston engine in
which the return energy means for the power piston is varied so as
to vary the compression ratio in such a manner as to eliminate any
tendency of the engine to knock. This is accomplished by the use of
a condition responsive means responsive to a condition associated
with possible knocking of the engine and providing controlling
means controlled by this condition responsive means for controlling
the return energy means. The return energy means may either take
the form of a bounce chamber or may be a further power cylinder
that supplies energy for the compression stroke of the power
piston. It will also be seen that I can control the amount of
return energy electrically or this may be done mechanically. (By
the term "mechanically", I include the use of any suitable
mechanical controls including hydraulic controls.) It will also be
seen that I have provided means for limiting the movement of a
movable member driven by the engine in which excess movement of
such movable member also results in a change in the return energy
to vary the compression ratio in such a manner as to reduce the
extent to which such movable member is moved by the power
piston.
While I have shown the use of two vibration sensors where
alternatively acting power pistons are used, it is to be
understood, as pointed out above, that a single sensor can be
employed and can be located at a point where it will detect
incipient knocking in either cylinder. Furthermore, while I have
shown means for reducing the amount of return energy available when
incipient knocking occurs, there may be cases in which it is
desirable to increase the return energy to avoid continued
knocking. This is particularly true in a Diesel engine where
reduction in knocking may be accomplished by increasing the
compression ratio.
In general, while I have shown certain specific embodiments of my
invention, it is to be understood that this is only for purposes of
illustration and that the scope of my invention is limited solely
by the appended claims.
* * * * *