U.S. patent application number 09/865210 was filed with the patent office on 2002-09-05 for combination starter-generator.
Invention is credited to Henry, Rassem Ragheb.
Application Number | 20020123401 09/865210 |
Document ID | / |
Family ID | 23042890 |
Filed Date | 2002-09-05 |
United States Patent
Application |
20020123401 |
Kind Code |
A1 |
Henry, Rassem Ragheb |
September 5, 2002 |
Combination starter-generator
Abstract
A combination starter-generator system for use in a vehicle is
provided. The vehicle has an internal combustion engine and a
battery. The system includes a starter-generator electrically
coupled to the battery to generate a current and to start the
internal combustion engine. A drive mechanism connects the
starter-generator machine and the internal combustion engine. The
starter-generator machine generates the current by receiving a
charging torque from one side of the drive mechanism and starts the
internal combustion engine by imparting a starting torque to a
different side of the drive mechanism. The charging torque or the
starting torque is a greater torque. A passive tensioning system
cooperates with the drive mechanism to tension the drive mechanism
only at the side of the greater torque.
Inventors: |
Henry, Rassem Ragheb;
(Clinton Township, MI) |
Correspondence
Address: |
MARGARET A. DOBROWITSKY
DELPHI TECHNOLOGIES, INC.
Legal Staff, Mail Code: 480-414-420
P.O. Box 5052
Troy
MI
48007-5052
US
|
Family ID: |
23042890 |
Appl. No.: |
09/865210 |
Filed: |
May 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60273191 |
Mar 2, 2001 |
|
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Current U.S.
Class: |
474/101 ;
474/117; 474/138 |
Current CPC
Class: |
F01L 13/08 20130101;
F01L 1/46 20130101; F16H 2007/0874 20130101; F02N 11/04 20130101;
F02N 19/004 20130101; F16H 2007/0823 20130101; F01L 2800/01
20130101; F16H 2007/0806 20130101; F02D 41/0087 20130101; F16H
2007/0887 20130101; F01L 13/0005 20130101; F02N 15/08 20130101;
F01L 1/34 20130101 |
Class at
Publication: |
474/101 ;
474/117; 474/138 |
International
Class: |
F16H 007/08; F16H
007/22 |
Claims
1. An apparatus for starting an engine, comprising: a starter
generator being configured to provide a rotational starting torque
to a first side of a drive mechanism and receive a rotational
generating torque from a second side of said drive mechanism, said
starter generator generating a current when said drive mechanism
receives said rotational generating torque, said drive mechanism
being configured, dimensioned and positioned to engage said starter
generator and a crankshaft of said engine, said rotational
generating torque or said rotational starting torque being a
greater torque; and a passive tensioning system in cooperation with
said drive mechanism to tension said drive mechanism at only said
first side or said second side, respectively, having said greater
torque.
2. The apparatus as in claim 1, wherein said rotational generating
torque is said greater torque and said passive tensioning system
cooperates with said drive mechanism at said second side.
3. The starter-generator system as in claim 1, wherein said
rotational starting torque is said greater torque and said passive
tensioning system cooperates with said drive mechanism at said
first side.
4. The starter-generator system as in claim 1, wherein said passive
tensioning system comprises an idler pulley biased into operative
engagement with said drive mechanism.
5. The starter-generator system as in claim 4, wherein said idler
pulley is biased into operative engagement with said drive
mechanism by a spring connection mounted on a structure.
6. The starter-generator system of claim 1, wherein said drive
mechanism compensates for differences in said rotational generating
torque and said rotational starting torque with a non-adjusting
gear ratio in a range between 2:1 to 3:1.
7. The starter-generator system of claim 1, wherein said drive
mechanism is selected from the group consisting of a belt driven
system and a chain driven system.
8. The starter-generator system of claim 1, wherein said drive
mechanism connects a pulley of said starter-generator and said
crankshaft of said internal combustion engine at either a
crankshaft pulley of said internal combustion engine or a flywheel
of said internal combustion engine.
9. An apparatus for starting an internal combustion engine,
comprising: a starter-generator being operable in a first direction
for generating a current and a second direction for starting said
internal combustion engine; a drive mechanism connecting said
starter-generator and said internal combustion engine by a
non-adjusting gear ratio in a range between 2:1 to 3:1, said
starter-generator operates in said first direction to generate said
current by receiving a charging torque from said internal
combustion engine imparted to a first side of said drive mechanism
and said starter-generator operates in said second direction to
start said internal combustion engine by imparting a starting
torque to a second side of said drive mechanism; a first tensioning
system cooperating with said drive mechanism to tension said drive
mechanism at said first side during application of said charging
torque; and a second tensioning system cooperating with said drive
mechanism to tension said drive mechanism at said second side
during application of said starting torque.
10. The apparatus of claim 9, wherein said drive mechanism connects
said starter-generator and said internal combustion engine at
either a crankshaft of said internal combustion engine or a
flywheel of said internal combustion engine.
11. The apparatus of claim 9, wherein said drive mechanism is
selected from the group consisting of a belt driven system and a
chain driven system.
12. The apparatus of claim 9, wherein said first tensioning system
is a passive tensioning system and said second tensioning system is
an active tensioning system.
13. The apparatus of claim 12, wherein said passive tensioning
system comprises an idler pulley biased into operative engagement
with said drive mechanism.
14. The apparatus of claim 13, wherein said idler pulley is biased
into operative engagement with said drive mechanism by a spring
connection mounted on a structure.
15. The apparatus of claim 12, wherein said active tensioning
system comprises an idler pulley extendable into operative
engagement with said drive mechanism during application of said
starting torque and retractable out of operative engagement with
said drive mechanism after removal of said starting torque.
16. The apparatus of claim 15, further comprising a solenoid for
extending said idler pulley and a biasing member for retracting
said idler pulley.
17. The apparatus of claim 16, wherein said first tensioning system
is a first active tensioning system and said second tensioning
system is a second active tensioning system.
18. The apparatus of claim 17, wherein said first active tensioning
system comprises a first idler pulley extendable into operative
engagement with said drive mechanism during application of said
starting torque and retractable out of operative engagement with
said drive mechanism after removal of said charging torque, and
said second active tensioning system comprises a second idler
pulley extendable into operative engagement with said drive
mechanism during application of said starting torque and
retractable out of operative engagement with said drive mechanism
after removal of said starting torque.
19. The apparatus of claim 18, further comprising a first solenoid
for extending said first idler pulley, a first biasing member for
retracting said first idler pulley, a second solenoid for extending
said second idler pulley and a second biasing member for retracting
said second idler pulley.
20. An active tensioning system, comprising: a drive mechanism
operable to create a first slack side and a first tight side of
said drive mechanism and operable to create a second slack side and
a second tight side of said drive mechanism, said first slack side
and said second tight side being coincident, said second slack side
and said first tight side being coincident; a guide mountable on a
structure; a first idler sprocket being operatively coupled with
said first slack side of said drive mechanism and being slidable on
said guide; a second idler sprocket being operatively coupled with
said second slack side of said drive mechanism and being slidable
on said guide; and a biasing member connecting said first idler
sprocket and said second idler sprocket and biasing said first
idler sprocket and said second idler sprocket towards one another
such that upon creation of said first slack side and said first
tight side, said first tight side acts upon said second idler
sprocket to slide said first idler sprocket and said second idler
sprocket upon said guide to tension said drive mechanism, and such
that upon creation of said second slack side and said second tight
side, said second tight side acts upon said first idler sprocket to
slide said first idler sprocket and said second idler sprocket upon
said guide to tension said drive mechanism.
21. The active tensioning system of claim 20, wherein said drive
mechanism is selected from the group consisting of a belt driven
system and a chain driven system.
22. A starter-generator system for use in a vehicle, comprising: a
starter-generator being adapted to operate in a charging mode and a
starting mode; a drive mechanism connecting said starter-generator
and an internal combustion engine, said starter-generator operates
in a charging mode by receiving a charging torque from a first side
of said drive mechanism and operates in said starting mode by
imparting a starting torque to a second side of said drive
mechanism, said drive mechanism compensating for differences in
said charging torque and said starting torque with a non-adjusting
gear ratio in a range between 2:1 to 3:1; and an active tensioning
system cooperating with said drive mechanism to tension said drive
mechanism at said first side during application of said charging
torque or at said second side during application of said starting
torque.
23. The starter-generator system of claim 22, wherein said drive
mechanism comprises: a guide mountable on a structure; a first
idler sprocket being operatively coupled with said first side of
said drive mechanism and being slidable on said guide; a second
idler sprocket being operatively coupled with said second side of
said drive mechanism and being slidable on said guide; and a
biasing member connecting said first idler sprocket and said second
idler sprocket and biasing said first idler sprocket and said
second idler sprocket towards one another such that during
application of said charging torque said second side acts upon said
second idler sprocket to slide said first idler sprocket and said
second idler sprocket upon said guide to tension said drive
mechanism, and such that upon creation of said starting torque said
first side acts upon said first idler sprocket to slide said first
idler sprocket and said second idler sprocket upon said guide to
tension said drive mechanism.
24. The starter-generator system of claim 22, wherein said drive
mechanism is selected from the group consisting of a belt driven
system and a chain driven system.
25. The starter-generator system of claim 22, wherein said drive
mechanism connects said starter-generator and said internal
combustion engine at either a crankshaft of said internal
combustion engine or a flywheel of said internal combustion
engine.
26. An apparatus for starting an internal combustion engine,
comprising: a starter-generator being operable in a first direction
for generating a current and a second direction for starting said
internal combustion engine; a drive mechanism connecting said
starter-generator and said internal combustion engine by a
non-adjusting gear ratio in a range between 2:1 to 3:1, said
starter-generator operates in said first direction to generate said
current by receiving a charging torque from said internal
combustion engine imparted to a first side of said drive mechanism
and said starter-generator operates in said second direction to
start said internal combustion engine by imparting a starting
torque to a second side of said drive mechanism; a constant
tensioning system having a first tensioning mechanism and a second
tensioning mechanism, said first tensioning mechanism system
cooperating with said drive mechanism to tension said drive
mechanism at said first side, and said second tensioning mechanism
cooperating with said drive mechanism to tension said drive
mechanism at said second side.
27. The apparatus of claim 26, wherein said first tensioning
mechanism includes a low-friction chain guide biased into operative
engagement with said chain and said second tensioning mechanism
includes an idler sprocket into operative engagement with said
drive mechanism.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is related to provisional application
serial No. 60/273,191 filed on Mar. 2, 2001 and bearing Attorney
Docket No. DP-3021 11, the contents of which are incorporated
herein.
TECHNICAL FIELD
[0002] This application relates generally to vehicles having a
combination starter-generator. More specifically, this application
relates to tensioning systems and drives for combination
starter-generators.
BACKGROUND
[0003] Prior internal combustion engine includes both a starter
machine and a generator or alternator machine (hereinafter
generator). The starter provides an engine-cranking torque to the
flywheel or crankshaft of the engine in order to rotate the
camshaft and facilitate the movement of the pistons during the
ignition of the engine. The generator provides an electrical output
in order to meet the electrical loads of the vehicle, as well as to
charge the vehicle's battery. Generally, a torque is applied to a
pulley of the generator by a belt frictionally engaged with a
pulley of the generator and a pulley of the engine in order to
generate the electrical charge from the generator.
[0004] The concept of using only one machine to do both functions,
namely starting and generating, adds efficiency. Thus,
starter-generators use less space, weigh less, eliminate the cost
of one of the machines and reduce assembly time. However,
starter-generators give rise to issues described below that affect
the cost, complexity, and reliability of such starter-generator
systems. Accordingly, there is a continuing need for inexpensive,
reliable tensioning systems for starter-generators.
SUMMARY
[0005] A combination starter-generator system for use in a vehicle
having an internal combustion engine is provided. A drive mechanism
connects the starter-generator machine and the internal combustion
engine. The starter-generator machine generates a current by
receiving a charging torque from one side of the drive mechanism
and starts the internal combustion engine by imparting a starting
torque to a different side of the drive mechanism. Depending on the
application, the charging torque or the starting torque is a
greater torque. A passive tensioning system cooperates with the
drive mechanism to tension the drive mechanism only at the side of
the greater torque.
[0006] An apparatus for starting an internal combustion engine
having a starter-generator machine is provided. The
starter-generator machine is operable in a first direction for
generating a current and a second direction for starting the
internal combustion engine. A drive mechanism connects the
starter-generator machine and the internal combustion engine by a
non-adjusting gear ratio in a range between 2:1 to 3:1. The
starter-generator machine operates in the first direction to
generate a current by receiving a charging torque from the internal
combustion engine imparted to a first side of the drive mechanism.
The starter-generator machine operates in the second direction to
start the internal combustion engine by imparting a starting torque
to a second side of the drive mechanism. A first tensioning system
cooperates with the drive mechanism to tension the drive mechanism
at the first side during application of the charging torque. A
second tensioning system cooperates with the drive mechanism to
tension the drive mechanism at the second side during application
of the starting torque.
[0007] An active tensioning system for use on a drive mechanism is
provided. The drive mechanism creates a first slack side and a
first tight side of the drive mechanism. The drive mechanism also
creates a second slack side and a second slack side of the drive
mechanism. The first slack side and the second tight side are
coincident. Similarly, the second slack side and the first tight
side are coincident. The active tensioning system has a guide. A
first idler sprocket is operatively coupled with the first slack
side of the drive mechanism and is slidable on the guide. A second
idler sprocket is operatively coupled with the second slack side of
the drive mechanism and is also slidable on the guide. A spring
connects the first idler sprocket and the second idler sprocket.
The spring also biases the first idler sprocket and the second
idler sprocket towards one another such that upon creation of the
first slack side and the first tight side, the first tight side
acts upon the second idler sprocket to slide the first idler
sprocket and the second idler sprocket upon the guide to tension
the drive mechanism, and such that upon creation of the second
slack side and the second tight side, the second tight side acts
upon the first idler sprocket to slide the first idler sprocket and
the second idler sprocket upon the guide to tension the drive
mechanism.
[0008] A combination starter-generator system is provided. The
vehicle has an internal combustion engine and a starter-generator
machine for generating a current and starting the internal
combustion engine. A drive mechanism connects the starter-generator
machine and the internal combustion engine. The starter-generator
machine charges the battery by receiving a charging torque from a
first side of the drive mechanism. The starter-generator machine
starts the internal combustion engine by imparting a starting
torque to a second side of the drive mechanism. The drive mechanism
compensates for differences in the charging torque and the starting
torque with a non-adjusting gear ratio in a range between 2:1 to
3:1. An active tensioning system cooperating with the drive
mechanism to tension the drive mechanism at the first side during
application of the charging torque or at the second side during
application of the starting torque.
[0009] The above-described and other features and advantages of the
present invention will be appreciated and understood by those
skilled in the art from the following detailed description,
drawings, and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a front view of a belt or chain drive
mechanism;
[0011] FIG. 2 is a block diagram of a starter-generator
circuit;
[0012] FIG. 3 is a first step of a control sequence of the circuit
of FIG. 2;
[0013] FIG. 4 is a second step of a control sequence of the circuit
of FIG. 2;
[0014] FIG. 5 is a third step of a control sequence of the circuit
of FIG. 2;
[0015] FIG. 6 is a fourth step of a control sequence of the circuit
of FIG. 2;
[0016] FIG. 7 is a top view of a first embodiment of a
starter-generator system;
[0017] FIG. 8 is a front view of a first embodiment of a tensioning
system for the starter-generator system of FIG. 7;
[0018] FIG. 9 is a front view of second embodiment of a tensioning
system for the starter-generator system of FIG. 7;
[0019] FIG. 10 is a front view of third embodiment of a tensioning
system for the starter-generator system of FIG. 7;
[0020] FIG. 11 is a front view of fourth embodiment of a tensioning
system for the starter-generator system of FIG. 7;
[0021] FIG. 12 is a top view of a second embodiment of a
starter-generator system;
[0022] FIG. 13 is a view of a first embodiment of a tensioning
system on the starter-generator system of FIG. 12, taken along
lines A-A;
[0023] FIG. 14 is a view of a second embodiment of a tensioning
system on the starter-generator system of FIG. 12, taken along
lines A-A;
[0024] FIG. 15 is a top view of a third embodiment of a
starter-generator system; and
[0025] FIG. 16 is a view of a tensioning system for the
starter-generator system of FIG. 15.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Starter-generators give rise to issues that affect the cost,
complexity, and reliability of such systems. First, the drive
mechanism connected to a starter-generator handles power in two
directions, which presents a unique tensioning problem for the
drive mechanism. Second, there is a large gap between torque and
speed requirements for starting an engine versus generating
electricity. The differing torque and speed requirements have
typically been overcome by the use of transmission having a
different ratio for each the starting function and the generating
function. Such transmissions typically required a gearbox and a
switching clutch, which adds cost, complexity, and decreased
reliability of starter-generators.
[0027] Referring to the Figures and particularly to FIG. 1, a belt
or chain drive mechanism 10 is shown handling power transmission in
two directions, and, thus illustrates the unique tensioning problem
for the drive mechanism. Drive mechanism 10 includes a first pulley
or sprocket 12, a second pulley or sprocket 14 and a chain or belt
16. In the instance where first sprocket 12 is the drive sprocket
driving mechanism 10 in the direction of arrow 18, second sprocket
14 becomes the driven sprocket and first sprocket 12 acts on chain
16 such that the chain has a tight-side or pulled-side 20 and a
slack-side or pushed side 22.
[0028] Conversely, in the instance where second sprocket 14 is the
drive sprocket driving mechanism 10 in the direction of arrow 24,
first sprocket 12 becomes the driven sprocket and second sprocket
14 acts on chain 16 such that the chain has a tight-side 26 and a
slack-side 28. In either instance, a chain tensioner is needed on
slack-side 22 and 28 to maintain chain 16 operatively engaged with
drive sprocket 12 and 14, respectively. Thus, where the drive
sprocket and the driven sprocket change place, the tight-side and
slack-side of drive mechanism 10 also change place, giving rise to
a need for more than one tensioner in the drive mechanism. It
should be noted that the belt or chain of drive mechanism 10 does
not change its direction of rotation, rather only the source of
power (i.e., the drive sprocket) changes.
[0029] Embodiments of starter-generator system 100 are illustrated
in FIGS. 7, 12 and 14. Generally, system 100 provides a starting
function to an internal combustion engine 110 and a generating
function to a battery 140. System 100 includes a starter-generator
130 electrically coupled to battery 140 by a lead 141.
Starter-generator 130 is operatively connected to engine 110 by a
belt or chain drive mechanism 10. Thus, starter-generator 130
performs dual functions of starting engine 110 and generating
electrical output to battery 140. Belt or chain drive mechanism 10
is described in this application by way of example as either a belt
drive mechanism or a chain drive mechanism, however both belt and
chain drive mechanisms are considered within the scope of the
present invention.
[0030] Starter-generator 130 is adapted to provide either an
engine-cranking torque 200 to drive mechanism 10 or receive a
generator-cranking torque 300 from the drive mechanism. By way of
example, operation of starter-generator 130 is described with
respect to FIGS. 2 through 6. Starter-generator 130 is a
three-phase rotary machine including a rectifier bridge 30 and a
unit 32 for controlling the rectifier bridge. Starter-generator 130
includes a coil-carrying rotor 34 constituting the primary magnetic
circuit associated with two rings and with two brushes that convey
excitation current (of the order of a few amps); and a stator 36
carrying a plurality of coils constituting the secondary magnetic
circuit, connected in star or delta configuration in the common
case of a three-phase structure and acting, during generating
operation, to deliver converted electrical power to the rectifier
bridge 30 (several tens of amps at a voltage of the same order as
the battery voltage).
[0031] Bridge 30 is connected to the various phases of the stator
36 and is connected between ground and a power supply terminal of a
battery 140. Bridge 30 includes a plurality of diodes 40 forming a
rectifier bridge, and a plurality of switches 42, such as
transistors. Switches 42 are connected in parallel with respective
diodes 40 and control the various phases (e.g., starting and
generating) of starter-generator 130.
[0032] During a starting function, diodes 40 act as freewheel
diodes, whereas in a generating function, the diodes act as a
rectifier bridge. Switches 42 are advantageously MOSFET type
transistors. Switches 42 include a diode between drain and source.
Consequently, the switches 42 enable bridge 30 to be implemented
using transistor components only that then act both as switches and
as freewheel diodes.
[0033] The starting function of starter-generator 130 is achieved
by imposing DC on the primary magnetic circuit rotor 34 and by
delivering signals that are phase-shifted by 120 degrees to the
phases of stator 36, which signals are ideally sinewave signals,
but may optionally be squarewave signals or trapezoidal wave
signals. Referring now to FIGS. 3 through 6, an example of a
control sequence for switches 42 is illustrated. The sequence is
made up of squarewave signals issued by the control unit. The
signals A, B, and C shown in these Figures are control signals for
those of switches 42 in bridge 30 which are connected to ground.
The signals A', B', and C' which control the other transistors,
i.e. those connected to battery 140, are signals that are inverted
relative to the signals A, B, and C, without overlapping them. This
is shown in FIG. 6 where the signal C' is drawn for controlling the
transistor connected to the transistor controlled by the signal C.
With this kind of control, the rotor performs one full revolution
while each of the phases goes through a number of periods equal to
the number of pairs of poles of the rotor (e.g. eight).
[0034] This starting operation is used for driving engine 110 to
start it, thereby making it possible to eliminate the starter and
the associated drive ring, and also the power cabling generally
associated with the starter. To enable engine 110 to be started in
this way, the control signals for switches 42 are advantageously
variable frequency signals, at a frequency that is regulated to be
increasing by unit 32, so as to avoid any slip of the rotor
relative to the rotating magnetic field created by the stator. For
example, frequency regulation may be provided by unit 32 in such a
manner so as to guarantee that the alternator has a speed profile
enabling the engine to be started.
[0035] Control unit 32 includes a means for recognizing a code
signal that authorizes engine starting. This signal is transmitted
to the unit 32 by a code transmitter means inside the vehicle. The
unit 32 switches on the transistors 42 in a manner suitable for
starting the engine only if it receives the code signal.
Consequently, the control unit 32 and the code transmitter means
which transmit the unlocking signal to said unit, constitute a
system for immobilizing the engine.
[0036] After engine 110 has started, unit 32 controls the
transistors 42 so as to operate in a generating mode. Unit 32
controls switches 42 so that all of them are open circuit across
the terminals of all of the diodes. The bridge 32 then reverts to
being a rectifier bridge. In another possible embodiment, the
transistors 42 are controlled so as to short circuit the conductive
diodes. They are caused to be open circuit only across the
terminals of non-conductive diodes. Thus, a current no longer
passes through the conductive diodes, such that the short circuits
made in this way serve to reduce losses. To synchronize control of
transistors 42 relative to the switching from the conductive state
to the non-conductive state of diodes 40, unit 32 is connected to a
means for detecting when diodes 40 pass from one state to another.
By way of example, these means may be constituted by a sensor, such
as a Hall effect sensor, for measuring the angular position of the
rotor relative to the stator. Such a sensor may also be used for
determining the speed of the rotor, e.g. by counting pulses in a
given time window, so as to enable the unit to detect that engine
110 has started and thus switch from operating in starting mode to
operating in generating mode.
[0037] Also, means 44 are provided for regulating voltage so as to
maintain the voltage of battery 140 at a suitable level. Provision
is also made for a switch 46, e.g. another MOSFET type switch,
whose ON or OFF state is controlled by the control unit. Switch 46
is designed to short circuit the regulator in starting mode so that
the secondary magnetic circuit 36 is then directly excited by
battery 140.
[0038] Thus when starter-generator 130 is in the starting mode,
engine-cranking torque 200 is applied by drive mechanism 10 from
the starter-generator to engine 110. Moreover, when
starter-generator 130 is in the generating mode, generator-cranking
torque 300 is applied by drive mechanism from engine 110 to the
starter-generator. It should be recognized that the operation of
starter-generator 130 has been described above by way of example
only and that other starter-generators adapted to provide a
starting function to engine 110 and a generating function to
battery 140 are considered within the scope of the present
invention.
[0039] Starter-generator 130 described above is adapted for use in
the position typically used for either automobile starters or
alternators. Therefore, no complicated design changes to engine 110
are required for implementation of starter-generator 130.
[0040] Referring now to FIG. 7, a tensioning system 100 is
illustrated. System 100 includes engine 110, a starter-generator
130 electrically coupled to battery 140 by a lead 141 and belt or
chain drive mechanism 10. Once started, engine 110 drives a
flywheel 116 operatively connected to a transmission 105 to propel
the vehicle. Drive mechanism 10 has a single belt 150 connected to
engine 110, and starter-generator 130.
[0041] Engine 110 includes a crankshaft 112 having a crank pulley
114 operatively connected thereto. Similarly, starter-generator 130
includes a starter-generator shaft 132 having a starter-generator
pulley 134 operatively connected thereto. Belt 150 is configured to
frictionally engage pulleys 114 and 134. In addition, and if
necessary, belt 150 is configured to drive pulleys of other vehicle
accessory systems, including but not limited to cooling systems,
air conditioning systems and power steering systems. For example, a
pulley 124 is illustrated as driving a water pump 120 of an engine
cooling system. Of course, other systems may or may not be driven
by belt 150. At a minimum, system 100 includes belt 150 and pulleys
114 and 134. Thus, as crank pulley 14 is driven by engine 110, belt
150 rotates pulleys 114 and 134.
[0042] Upon activation by a user, starter-generator 130 draws
energy from battery 140 through lead 141 to rotate
starter-generator shaft 132. Shown in FIG. 8, starter-generator
shaft 132 in turn rotates starter-generator pulley 134 to impart
engine-cranking torque 200 to belt 150. Thus, belt 150 being
operatively connected to crank pulley 114 drives crankshaft 112.
Engine-cranking torque 200 acts on crankshaft 112 to rotate engine
110 as required for engine starting procedures.
[0043] As shown in FIG. 8, during the starting of engine 110, belt
150 has a tight-side 133 and a slack-side 135 created on either
side of starter-generator pulley 134. A passive tensioning system
170 is provided at slack-side 135 of belt 150 to remove the slack,
keeping the belt in operative engagement with starter-generator
pulley 134. Passive tensioning system 170 includes an idler pulley
172 biased into operative engagement with belt 150 so as to remove
the slack from slack-side 135 of the belt. Preferably, pulley 172
is biased into operative engagement with belt 150 by a spring
connection 174 mounted on engine 110 or elsewhere on the vehicle,
such as, but not limited to the transmission, the exhaust manifold,
or the vehicle body.
[0044] After engine 110 has been started, starter-generator 130
generates an electrical output to battery 140 through lead 141.
Shown in FIG. 9, engine 110 rotates crankshaft 112 and crankshaft
pulley 114 to impart a generator-cranking torque 300 to belt 150.
Thus, belt 150 being operatively connected to starter-generator
pulley 134 drives starter-generator shaft 132. Generator-cranking
torque 300 acts on starter-generator shaft 132 to rotate
starter-generator 130, which generates the electrical output to
battery 140 through lead 141. Starter-generator 130 is described by
way of example as receiving electrical energy from and providing
electrical energy to battery 140, however it is considered within
the scope of the present invention for the starter-generator to
receive or provide electrical energy to or from other devices. In
one embodiment, generator-cranking torque 300 also acts to rotate
pump pulley 124 of water pump 120 in order to provide a flow of
cooling fluid to engine 110 as required in engine cooling
systems.
[0045] During the generation of the electrical output to battery by
starter-generator 130 shown in FIG. 9, belt 150 has a tight-side
113 and a slack-side 115 on either side of crankshaft pulley 114.
Passive tensioning system 170 is also provided at slack-side 115 of
belt 150 to remove the slack, keeping the belt in operative
engagement with crankshaft pulley 114. Idler pulley 172 is biased
into operative engagement with belt 150 so as to remove the slack
from slack-side 115 of belt 150. Preferably, pulley 172 is biased
into operative engagement with belt 150 by spring connection 174
mounted on engine 110 or elsewhere on the vehicle, such as, but not
limited to the transmission, the exhaust manifold, or the vehicle
body.
[0046] Accordingly, tensioning system 170 maintains belt 150 in
engagement with pulleys 114 and 134 during the charging and
starting operations, respectively. It has been determined that
drive mechanism 10 having tensioning system 170 only on the
slack-side of the pulley 114 or 134 generating the greater torque
is sufficient for proper operation of starter-generator 130. More
specifically, passive tensioning system 170 is placed at slack side
115 when generator-cranking torque 300 is greater than
engine-cranking torque 200 as shown in FIG. 9. Alternately, passive
tensioning system 170 is placed at slack-side 135 when
engine-cranking torque 200 is greater than generator-cranking
torque 300, as shown in FIG. 8.
[0047] For example, if engine-cranking torque 200 is greater than
generator-cranking torque 300 (e.g., engine 110 is started at very
cold ambient temperatures when oil in the engine is very viscous),
then tensioning system 170 is provided only at slack-side 135.
Oppositely, if engine-cranking torque 200 is lower than
generator-cranking torque 300 (e.g., high electrical load on
battery 140), then tensioning system 170 is provided only at
slack-side 115. The life of belt 150 is typically inversely
proportional to its maximum tension. Thus, placing passive
tensioning system 170 only on one of slacksides 115 and 135
increases the service life of belt 150.
[0048] An alternate embodiment of the tensioning system is
illustrated in FIG. 10. Here, component parts performing similar or
analogous functions are numbered in multiples of one hundred. In
this embodiment, an active tensioning system 270 is provided for
starter-generator pulley 134 and an active tensioning system 370 is
provided for crank pulley 114. Active tensioning systems 270 and
370 actively or automatically engage drive mechanism 10 as needed.
In this embodiment, active tensioning system 270 includes an idler
pulley 272, a spring connection 274, and a solenoid 276. Spring
connection 274 is mounted on engine 110 or elsewhere on the
vehicle, such as, but not limited to the transmission, the exhaust
manifold, or the vehicle body. Solenoid 276 is adapted to extend
idler pulley 272 into operative engagement with slack-side 135, and
spring connection 274 is adapted to retract the idler pulley upon
deactivation of the solenoid. Similarly, active tensioning system
370 includes an idler pulley 372, a spring connection 374 and a
solenoid 376. Spring connection 374 is mounted on engine 110 or
elsewhere on the vehicle, such as, but not limited to the
transmission, the exhaust manifold, or the vehicle body. Solenoid
376 is adapted to extend idler pulley 372 into operative engagement
with slack-side 115, and spring connection 374 is adapted to
retract the idler pulley upon deactivation of the solenoid.
[0049] Thus, during starting when engine-cranking torque 200 is
imparted to belt 150 to create slack-side 135 and tight-side 133
(shown in FIG. 10 in dotted lines), solenoid 276 of active
tensioning system 270 is activated to extend idler pulley 272 into
operative engagement with the slack-side. After engine 110 has been
started and engine-cranking torque 200 is removed from belt 150,
solenoid 276 of active tensioning system 270 is deactivated such
that spring connection 274 retracts idler pulley 272 out of
operative engagement with slack-side 135.
[0050] Similarly, during generation of energy when
generator-cranking torque 300 is imparted to belt 150 to create
slack-side 115 and tight-side 113 (shown in FIG. 10 in solid
lines), solenoid 376 of active tensioning system 370 is activated
to extend idler pulley 372 into operative engagement with the
slack-side. After battery 140 has been charged and
generator-cranking torque 300 is removed from belt 150, solenoid
376 of active tensioning system 370 is deactivated such that spring
connection 374 retracts idler pulley 372 out of operative
engagement with slack-side 115.
[0051] The selective extension and retraction of active tensioning
systems 270 and 370 increases the service life in belt 150 since,
as discussed above, the life of the belt 150 is inversely
proportional to its maximum tension.
[0052] Another embodiment of the tensioning system is provided in
FIG. 11. In this embodiment, passive tensioning system 470 is
provided for crank pulley 114 and active tensioning system 570 is
provided for starter-generator pulley 134. Active tensioning system
570 includes an idler pulley 572, a spring connection 574, and
solenoid 576. Spring connection 574 is mounted on engine 110 or
elsewhere on the vehicle, such as, but not limited to the
transmission, the exhaust manifold, or the vehicle body. Solenoid
576 is adapted to extend idler pulley 572 into operative engagement
with slack-side 135, and spring connection 574 is adapted to
retract the idler pulley upon deactivation of the solenoid. Passive
tensioning system 470 includes idler pulley 472 and spring
connection 474 mounted on engine 110 or elsewhere on the vehicle,
such as, but not limited to the transmission, the exhaust manifold,
or the vehicle body. Spring connection 474 biases idler pulley 472
into operative engagement with slack-side 115. In this embodiment,
spring connection 474 of passive tensioning system 470 biases idler
pulley 472 into operative engagement with slack side 115 regardless
of the state of generator-cranking torque 300.
[0053] Thus, during starting when engine-cranking torque 200 is
imparted to belt 150 to create slack-side 135 and tight-side 133
(shown in FIG. 11 in dotted lines), solenoid 576 of active
tensioning system 570 is activated to extend idler pulley 572 into
operative engagement with the slack-side. After engine 110 has been
started and engine-cranking torque 200 is removed from belt 150,
solenoid 576 of active tensioning system 570 is deactivated such
that spring connection 574 retracts idler pulley 572 out of
operative engagement with slack-side 135.
[0054] The selective extension and retraction of tensioning system
570 increases the service life in belt 150 since, as discussed
above, the life of the belt is typically inversely proportional to
its maximum tension. The inclusion of one active tensioning system
570 and one passive tensioning system 470 decreases complexity and
cost. Active tensioning system 570 has a low power/energy
requirement since solenoid 576 is activated for only used for a
very short time, namely during engine cranking.
[0055] Active tensioning systems 270, 370, and 570 are described
above by way of example as including solenoids 276, 376, and 576
and spring connections 274, 374, and 574. However, alternate
devices for extending and retracting idler pulley 272, 372, and 574
are considered within the scope of the present invention. For
example, alternate embodiments include, but are not limited to,
extension and retraction by an actuator, or a lever.
[0056] An alternate embodiment of starter-generator system 100 is
illustrated in FIGS. 12 through 14. System 100 includes engine 110,
a starter generator 130 electrically coupled to battery 140 by a
lead 141 and belt or chain drive mechanism 10, namely a chain 160.
Once started, engine 110 drives a flywheel 116 operatively
connected to a transmission 105 to propel the vehicle and drives a
crankshaft 112 having a crank pulley 114 operatively connected
thereto.
[0057] Cooling system 120 includes a pump-shaft 122 having a pump
pulley 124 operatively connected thereto and starter-generator 130
includes a starter-generator shaft 132 having a starter-generator
sprocket 134 operatively connected thereto. Accessory belt 150
operatively connects crank pulley 114 and pump pulley 124. A chain
160 operatively connects starter-generator sprocket 134 and
flywheel 116.
[0058] Upon activation by a user, starter-generator 130 draws
energy from battery 140 through lead 141 to rotate
starter-generator shaft 132. Shown in FIG. 13 in dotted lines,
starter-generator shaft 132 in turn rotates starter-generator
sprocket 134 to impart an engine-cranking torque 200 to chain 160.
Thus, engine-cranking torque 200 acts on flywheel 116 to rotate
engine 110 as required for engine starting procedures. During the
starting of engine 110, chain 160 has a tight-side 133 and a
slack-side 135 on either side of starter-generator sprocket 134. A
tensioning system 180 is provided at slack-side 135 of chain 160 to
remove the slack, keeping the chain in operative engagement with
starter-generator sprocket 134.
[0059] After engine 110 has been started, starter-generator 130
generates an electrical output to battery 140 through lead 141.
Engine 110, when running, rotates flywheel 116 and crankshaft
pulley 114. Belt 150 being operatively connected to crankshaft
pulley 114 and cooling system pulley 124, acts to rotate pump-shaft
122 to drive cooling system 120 in order to provide cooling to
engine 110. Simultaneously, flywheel 116 imparts a
generator-cranking torque 300 to chain 160.
[0060] Generator-cranking torque 300 acts on starter-generator
shaft 132 to rotate starter-generator 130, which generates the
electrical output to battery 140 through lead 141. During the
generation of the electrical output to battery 140 by
starter-generator 130, chain 160 has a tight-side 117 and a
slack-side 118 on either side of flywheel 116, shown in FIG. 13 in
solid lines. Tensioning system 180 is also provided at slack-side
118 of chain 160 to remove the slack, keeping the chain in
operative engagement with flywheel 116.
[0061] Tensioning system 180 is an active tensioning system, namely
it actively or automatically tensions chain 160 as needed.
Tensioning system 180 includes a guide 182, a first idler sprocket
184, a second idler sprocket 186, and a spring 188. Guide 182,
preferably a shaft, is mounted on engine 110 or elsewhere on the
vehicle, such as, but not limited to the transmission, the exhaust
manifold, or the vehicle body. First idler sprocket 184 is adapted
to slide or float up and down on guide 182. Similarly, second idler
sprocket 186 is adapted to slide or float up and down on guide 182.
First idler sprocket 184 and second idler sprocket 186 are tied
together by spring 188 such that the spring biases the sprockets
184, 186 towards one another. Thus, the assembly of first idler
sprocket 184, second idler sprocket 186, and spring 188 are
permitted to slide together on guide 182.
[0062] During starting, shown in FIG. 13 in dotted lines, the
tension in tight-side 133 of chain 160 acts on second idler
sprocket 186 to slide tensioning system 180 downwards until first
idler sprocket 184 takes up the slack in slack-side 135. Thus,
tensioning system 180 being in its lower position and being biased
by spring 188 takes up the slack in chain 160. During generating,
shown in solid lines, the tension in tight-side 117 of chain 160
acts on first idler sprocket 184 to slide tensioning system 180
upwards until second idler sprocket 186 takes up the slack in
slack-side 135. Thus, tensioning system 180 being in its upper
position and being biased by spring 188 takes up the stack in chain
160.
[0063] Friction between guide 182 and sprockets 184, 186 acts to
dampen vibrations induced by chain 160 traveling. Alternately, an
active means of damping (not shown) such as, but not limited to a
hydraulic damper attached between guide 182 and sprockets 184, 186
and/or spring 188 is used to further dampen vibrations induced by
traveling of chain 160.
[0064] Referring now to FIG. 14, a tensioning system 280 is
illustrated. During the generation of the electrical output to
battery 140 by starter-generator 130, chain 160 has a tight-side
117 and a slack-side 118 on either side of flywheel 116. During
starting, chain 160 has a tight-side 133 and a slack-side 135 on
either side of starter-generator pulley 134.
[0065] Tensioning system 280 is a constant tensioning system,
namely it provides tension to chain 160 during starting, generating
and static conditions. Tensioning system 280 includes a first or
upper tensioning mechanism 282 and a second or lower tensioning
mechanism 284. Upper tensioning mechanism 282 biases a low-friction
chain guide 286 into operative engagement with chain 160 by a
spring connection 288 mounted on engine 110 or elsewhere on the
vehicle, such as, but not limited to the transmission, the exhaust
manifold, or the vehicle body.
[0066] Lower tensioning mechanism 284 includes an idler sprocket
290 in operative engagement with chain 160. Sprocket 290 is
rotatably mounted by a bracket 292 to engine 110 or elsewhere on
the vehicle, such as, but not limited to the transmission, the
exhaust manifold, or the vehicle body. Bracket 292 is adapted to
mount idler sprocket 290 in operative engagement with chain 160.
For example, bracket 292 includes a take-up system, such as but not
limited to a screw 294 and a slot 296. Accordingly, lower
tensioning mechanism 284 removes any initial slack from belt 160 in
a normal or static state.
[0067] During starting or the application of starting torque 200,
spring connection 288 of upper tensioning mechanism 282 biases
low-friction chain guide 286 towards chain 160 to remove slack from
slack-side 135. During generating or the application of generating
torque 300, idler sprocket 290 continues to tension slack from
slack-side 118 of chain 160, while low-friction chain guide 286 of
upper tensioning mechanism 282 applies a very low drag force on the
chain. Accordingly, during generating upper tensioning mechanism
282 does not affect the performance of chain drive mechanism 10
since the upper tensioning mechanism is not adding additional load
to the chain.
[0068] Yet another embodiment of starter-generator system 100 is
provided in FIGS. 15 and 16. System 100 includes engine 110, a
starter-generator 130 electrically coupled to battery 140 by a lead
141 and belt or chain drive mechanism 10, namely a belt 190. Once
started, engine 110 drives a flywheel 116 operatively connected to
a transmission 105 to propel the vehicle. Engine 110 includes a
crankshaft 112 having an accessory pulley 108 and a crank pulley
114 operatively connected thereto.
[0069] Cooling system 120 includes a pump-shaft 122 having a pump
pulley 124 operatively connected thereto and starter-generator 130
includes a starter-generator shaft 132 having a starter-generator
pulley 134 operatively connected thereto. Accessory belt 150
operatively connects accessory pulley 108 and pump pulley 124. Belt
190 operatively connects starter-generator pulley 134 and crank
pulley 114.
[0070] Upon activation by a user, starter-generator 130 draws
energy from battery 140 through lead 141 to rotate
starter-generator shaft 132. Shown in FIG. 16 in dotted lines,
starter-generator shaft 132 in turn rotates starter-generator
pulley 134 to impart an engine-cranking torque 200 to
starter-generator belt 190. Thus, engine-cranking torque 200 acts
on crank pulley 114 to rotate engine 110 as required for engine
starting procedures. During the starting of engine 110,
starter-generator belt 190 has a tight-side 133 and a slack-side
135 on either side of starter-generator pulley 134. Tensioning
system 180 is provided at slack-side 135 of belt 190 to remove the
slack, keeping the belt in operative engagement with
starter-generator pulley 134.
[0071] After engine 110 has been started, starter-generator 130
generates an electrical output to battery 140 through lead 141.
Engine 110, when running, rotates and crank pulley 114. Accessory
belt 150 being operatively connected to accessory pulley 108 and
cooling system pulley 124, acts to rotate pump-shaft 122 to drive
cooling system 120 in order to provide cooling to engine 110.
Simultaneously, crank pulley 114 imparts a generator-cranking
torque 300 to belt 190.
[0072] Generator-cranking torque 300 acts on starter-generator
shaft 132 to rotate starter-generator 130, which generates the
electrical output to battery 140 through lead 141. During the
generation of the electrical output to battery 140 by
starter-generator 130, belt 190 has a tight-side 117 and a
slack-side 118 on either side of crank pulley 114, as shown in FIG.
16 in solid lines. Tensioning system 180 is also provided at
slack-side 118 of belt 190 to remove the slack, keeping the belt in
operative engagement with crank pulley 114.
[0073] Tensioning system 180 shown in FIG. 16, similar to the
discussion above with respect to FIG. 13, is an active tensioning
system that actively or automatically engages belt 190 as needed.
Tensioning system 180 includes guide 182, first idler pulley 184,
second idler pulley 186, and spring 188. Guide 182, preferably a
shaft, is mounted on engine 110 or elsewhere on the vehicle, such
as, but not limited to the transmission, the exhaust manifold, or
the vehicle body. First idler pulley 184 is adapted to slide or
float up and down on guide 182. Similarly, second idler pulley 186
is adapted to slide or float up and down on guide 182. First idler
pulley 184 and second idler pulley 186 are tied together by spring
188 such that the spring biases the pulley 184, 186 towards one
another. Thus, the assembly of first idler pulley 184, second idler
pulley 186, and spring 188 are permitted to slide together on guide
182.
[0074] During starting, shown in FIG. 16 in dotted lines, the
tension in tight-side 133 of belt 190 acts on second idler pulley
186 b slide tensioning system 180 downwards until first idler
pulley 184 takes up the slack in slack-side 135. Thus, tensioning
system 180 being in its lower position and being biased by spring
188 takes up the slack in belt 190. During generating, shown in
solid lines, the tension in tight-side 117 of belt 190 acts on
first idler pulley 184 to slide tensioning system 180 upwards until
second idler pulley 186 takes up the slack in slack-side 118. Thus,
tensioning system 180 being in its upper position and being biased
by spring 188 takes up the slack in belt 190.
[0075] For purposes of clarity, tensioning system 180 has been
described by way of example as part of a two pulley/sprocket
system. However, it is considered within the scope of the present
invention for use of such tensioning systems 180 with
pulley/sprocket systems having more than two pulleys.
[0076] A difference between torque and speed requirements for
starting an engine versus generating electricity exists. The
tensioning systems described herein ensure that the belt/chain
remains operatively connected to its respective pulleys/sprockets.
Thus, it has been determined that the effect of the torque
difference on starter-generator 130 is minimized by adjusting the
gear ratio of starter-generator pulley 134 with respect to crank
pulley 114 (or flywheel 116).
[0077] Engine-cranking torque 200, namely the torque supplied to
crankshaft 112, is equal to the torque provided by
starter-generator 130 multiplied by the gear ratio of the
starter-generator pulley 134 with respect to the crank pulley 114.
The gear ratio should desirably be between 2:1 and 3:1. For
example, if the gear ratio is 3:1 and engine 110 requires 150
foot-pounds of torque for starting purposes, starter-generator 130
must generate 50 foot-pounds (ignoring losses) to provide the
required 150 foot-pounds at crankshaft 112.
[0078] Additionally, the electrical energy generated by
starter-generator 130 is proportional to the speed of crankshaft
112. Thus, at higher crankshaft 112 speeds more electrical energy
is generated, and, conversely, at lower crankshaft speeds less
electrical energy is generated. Thus, in the example provided above
where the gear ratio is 3:1, if crankshaft 112 has a speed of 1000
rpm, starter-generator shaft 132 has a resulting speed of 3000
rpm.
[0079] Setting the gear ratio at higher than the desired range of
between 2:1 and 3:1, would decrease the amount of torque
starter-generator 130 must generate to provide the required
engine-cranking torque 200. For example, if the gear ratio is 10:1
and engine 110 requires 150 foot-pounds of torque for starting
purposes, starter-generator 130 must generate only 15 foot-pounds
(ignoring losses) to provide the required 150 foot-pounds at
crankshaft 112. Moreover, in this example, if crankshaft 112 has a
speed of 1000 rpm, starter-generator shaft 132 has a resulting
speed of 10,000 rpm. Thus, when the ratio is set such that
starter-generator 130 is required to produce low amounts of torque,
the resulting speed of starter-generator shaft 132 tends to exceed
the maximum rate determined from mechanical and/or electrical
restrictions in high velocity revolution. However, it has been
found that the desired ratio of between 2:1 and 3:1 balances the
speed of starter-generator shaft 132 and the amount of torque
starter-generator 130 must generate.
[0080] Thus, starter-generator system 100 provides a low cost
method for achieving a starter-generator. Drive mechanism 10
includes simple active and passive tensioning systems. Moreover,
starter-generator system 100 eliminates the need for gearboxes and
their switching clutches to compensate for torque and speed
differences during starting and generating.
[0081] While the invention has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *