U.S. patent number RE30,550 [Application Number 06/031,091] was granted by the patent office on 1981-03-24 for automatic trailer sway sensing and brake applying system.
This patent grant is currently assigned to Durrell U. Howard. Invention is credited to Herman A. Reise.
United States Patent |
RE30,550 |
Reise |
March 24, 1981 |
Automatic trailer sway sensing and brake applying system
Abstract
An apparatus for automatically sensing trailer sway and applying
trailer brakes, thereby minimizing or eliminating the sway is
provided. A hydraulic device, similar to a shock absorber with the
addition of a pressure operated switch at each end of the cylinder,
is mounted between the trailer A frame and the hitch head assembly.
A sudden sway in either direction causes one of the switches to
close and apply power to the electric trailer brakes thus
minimizing or eliminating the sway and causing the car and trailer
to "line up". The hydraulic device has an orifice in the piston or
at each end of the cylinder so that normal turns made by the car
and trailer do not cause sufficient pressure build up to cause
either switch to operate. Similar automatic performance can be
realized by the use of a gas filled bellows device.
Inventors: |
Reise; Herman A. (Lakewood,
NJ) |
Assignee: |
Howard; Durrell U. (San
Antonio, TX)
|
Family
ID: |
26706824 |
Appl.
No.: |
06/031,091 |
Filed: |
April 18, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
629603 |
Nov 6, 1975 |
04040507 |
Aug 9, 1977 |
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Current U.S.
Class: |
188/112A;
180/282; 280/455.1; 303/20; 303/7 |
Current CPC
Class: |
B60T
7/20 (20130101); B60T 8/1708 (20130101); B60T
8/248 (20130101); B60T 13/74 (20130101); B60T
8/246 (20130101); B60T 2230/06 (20130101) |
Current International
Class: |
B60T
7/20 (20060101); B60T 13/74 (20060101); B60T
13/00 (20060101); B60T 8/24 (20060101); B60T
8/17 (20060101); B60T 007/20 () |
Field of
Search: |
;303/3,7,20 ;340/53
;180/282 ;188/112R,112A ;280/432,446B,6.1,6H,6R,DIG.1
;91/517,518 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Blix; Trygve M.
Assistant Examiner: Eisenzopf; Reinhard J.
Attorney, Agent or Firm: Pollock, Vande Sande &
Priddy
Claims
I claim:
1. A sway control system for controlling brakes of a towed vehicle
in response to the detection of a sway condition comprising:
a hydraulic unit having first and second ends mounted to coupling
means between the towed vehicle and a towing vehicle, which
hydraulic unit includes first and second fluid passages associated
with said first and second ends of the unit.Iadd., .Iaddend.each
passage including a check valve shunted by a bypass restricted
orifice and a pressure switch, and
an electric brake circuit for applying and releasing the brakes of
the towed vehicle in response to said pressure switches being
opened or closed, said hydraulic unit constituting a sway detection
device for sensing the onset of a sway condition of a towed vehicle
relative to a towing vehicle. .Iadd.
2. A sway control apparatus for controlling the brakes of a towed
vehicle joined to a towing vehicle by a towing connection
permitting turning movement of said towed and towing vehicles
relative to each other about a yaw axis, said apparatus
comprising:
signal generating means connected between said towed and towing
vehicles for providing a signal having a characteristic responsive
to the rate of change of the angle between said vehicles about said
yaw axis; and,
actuator means for actuating said brakes in response to said
signal, said actuator means being effective to actuate said brakes
in response to a single turning movement between said vehicles in
either direction about said yaw axis when said rate of angle change
exceeds a predetermined magnitude. .Iaddend. .Iadd.3. The apparatus
of claim 2 in which said signal generating means includes a first
member, a second member movable relative to said first member,
coupling means mounted on said towed and towing vehicles for
causing said first and second members to move relative to each
other as said towed and towing vehicles turn relative to each other
about said yaw axis, and sensing means for providing a signal in
response to a predetermined rate of said relative movement between
said first and second members. .Iaddend. .Iadd.4. The apparatus of
claim 3 in which said first member is a cylinder, said second
member is a piston slidable in said cylinder, and said coupling
means causes said piston to slide in said cylinder as said towed
and towing vehicles turn relative to
each other about said yaw axis. .Iaddend. .Iadd.5. The apparatus of
claim 4 in which said piston and said cylinder define a chamber for
pressurizing a fluid, and said actuator means includes pressure
responsive means for actuating said towed vehicle brakes in
response to a predetermined fluid pressure in said chamber.
.Iaddend. .Iadd.6. The apparatus of claim 5 in which said sensing
means includes conduit means for conveying said fluid between said
chamber and said pressure responsive means. .Iaddend. .Iadd.7. The
apparatus of claim 6 in which said conduit means includes valves
means for controlling the flow of fluid through said conduit means.
.Iaddend. .Iadd.8. The apparatus of claim 7 in which said valve
means includes a check valve .Iaddend. .Iadd.9. The apparatus of
claim 7 in which said valve means includes an orifice. .Iaddend.
.Iadd.10. The apparatus of claim 7 in which said valve means is
adjustable. .Iaddend. .Iadd.11. The apparatus of claim 6 in which
said conduit means includes a first fluid passage containing a
check valve for permitting free flow from said chamber to said
pressure responsive means while preventing flow from said pressure
responsive means to said chamber, and a second fluid passage
bypassing said check valve and containing an orifice for
restricting flow between said chamber and said pressure responsive
means. .Iaddend. .Iadd.12. The apparatus of claim 2 in which said
signal generating means includes cylinder means having a first
chamber and a second chamber, piston means cooperating with said
cylinder means for pressurizing a fluid in said first chamber and
said second chamber, and coupling means for causing fluid in said
first chamber to be pressurized in response to relative turning
movement between said vehicles in one direction about said yaw axis
and fluid in said second chamber to be pressurized in response to
relative turning movement between said vehicles in the other
direction about said yaw axis, and in which said actuator means
includes pressure responsive means for actuating said towed vehicle
brakes in response to a predetermined fluid pressure in said first
and second chambers. .Iaddend.
Description
GENERAL DESCRIPTION OF THE INVENTION
One of the greatest dangers in towing a trailer is swaying and
jackknifing. This can be caused by quick evasive action by the
driver, gusty winds or air currents caused by other vehicles,
especially large tractor trailers, overtaking and passing the
towing and towed vehicle. When a vehicle overtakes and passes a
towed vehicle.Iadd., .Iaddend.the driver of the towing vehicle
should (1) keep as far away from the passing vehicle as the road
will permit.Iadd., .Iaddend.(2) apply more gas to the towing
vehicle .[.and or.]. .Iadd.and/or .Iaddend.(3) slightly apply the
trailer brakes. Methods (2) and (3) result in greater tension
between the towing and towed .[.vehicle.]. .Iadd.vehicles
.Iaddend.thereby tending to minimize the possibility of swaying.
Method (2), applying more gas, is not desirable under level or
especially down hill road conditions for swaying tendencies and
loss of control are greater under higher speeds and downhill
conditions. All of these methods depend upon proper driver
reactions to the then existing circumstances.
Normally a manual trailer brake control is provided at a convenient
position for the driver. This manual control is also hydraulically
or mechanically coupled to the foot brake of the towing vehicle.
Proper driver reaction and his reaction time to apply the manual
trailer brakes are very important in preventing or minimizing a
sway. An automatic device or system that will sense a sway and
automatically apply the trailer brakes is desirable in that it
detects the beginning of an abnormal sway and immediately applies
the trailer brakes. Such a system must cause the brakes to be
released as soon as the sway is miminized or eliminated. Normal
turns during highway driving or parking of the trailer must not
cause the brakes to be applied. The Automatic Trailer Sway Sensing
and Brake Applying System covered in this patent application does,
as the title implies, meet the sway sensing and brake applying
needs of trailer towing and towed vehicles.
The basic part of this system is a hydraulic unit similar to a
shock absorber except that the forces required to compress or
extend the unit are essentially equal. In addition.Iadd.,
.Iaddend.the unit is manufactured with pressure operated switches
at each end of the hydraulic cylinder. The rubber inserts used on
the shock absorber mounting details must not be used on the
hydraulic sway sensing unit. The presence of such rubber inserts
would result in a delay in the time of application of the brakes as
well as an increase in the amplitude of the sway before the brakes
are applied. A metal universal joint type of connection or mounting
detail with a minimum of bearing clearance must be used. The
hydraulic unit can be small to perform the sway sensing and brake
applying functions only or the pressure operated switches can be
made a part of hydraulic anti-sway devices during manufacture.
SUMMARY
This sway sensing and brake applying system can be used in
conjunction with anti-sway devices that are commercially available.
It automatically senses the beginning of a sway and automatically
applies the trailer brakes. The brakes are automatically released
as soon as the sway is minimized or eliminated. Brakes are not
applied during normal driving turns or parking procedures.
The brake applying pressure operated switches can be made a part of
hydraulic type anti-sway devices during manufacture. Such units
then perform the dual function of an anti-sway device and an
automatic sway sensing and brake applying system.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 This simplified drawing of the hydraulic unit shows, in
block form, a check valve, bypass orifice and pressure operated
switch on each end of the hydraulic cylinder.
FIG. 2 .[.A section.]. .Iadd.Sections .Iaddend.of the towing and
towed .[.vehicle.]. .Iadd.vehicles .Iaddend.and the manner in which
one end of the hydraulic sway sensing unit is mounted to the A
frame and the other end is mounted on the hitch head, a short
distance from the hitch ball, .[.is.]. .Iadd.are
.Iaddend.shown.
FIG. 3 The electrical brake circuit, including the pressure
operated switches for a one or two axle trailer.Iadd., .Iaddend.is
shown.
FIG. 4 In this circuit the pressure operated switches will cause
the brake or brakes on one side or the other only to be applied.
This results in quicker corrective action.
FIG. 5 This figure is used to describe the operation under FIG. 4
conditions.
FIG. 6 A dual braking system, including the sway sensing pressure
operated switches, is shown in this figure.
FIG. 7 The principle of appying the brakes on one side or the other
only, in case of a sway, is shown for the dual braking system in
this figure. In addition.Iadd., .Iaddend.isolation resistors and
diodes are provided to eliminate the possibility of complete
braking failure in case of an electrical short or open circuit in
the overall electrical circuit of the braking system.
FIG. 8 Functionally this circuit is similar to that shown in FIG. 7
except that some of the isolation is provided by using two pole
pressure operated switches.
DETAILED DESCRIPTION OF THE DRAWINGS
The basic unit of the Automatic Sway Sensing and Brake Applying
System is shown in FIG. 1. The hydraulic unit 1 is similar to a
shock absorber except that the fluid escapement orifice .Iadd.1A
.Iaddend.in the piston .Iadd.1B .Iaddend.or at each end of the
cylinder .Iadd.1C .Iaddend.is such that the force required to
elongate the unit is essentially the same as that required to
compress or shorten the unit. Mounting details 2 and 3 must not
have rubber inserts as they normally have in shock absorbers.
Hydraulic check valves 5 and 9 have adjustable bypass valves 6 and
10 in parallel with them. Pressure operated switches 7 and 11 have
either wire or terminal connections represented by 8 and 12. A
universal joint type element 4 is mounted to 2 and 3 by means of a
through bolt. The other ends of the universal elements are then
mounted to the A frame 13 of the towed vehicle 33 and the hitch
head 15 of the towing vehicle 34 as shown in FIG. 2. The universal
joint 4 that is bolted to 2 is in turn mounted on a supporting pin
on the hitch head 15 a short distance from the hitch ball 14. The
purpose of check valves 5 and 9 is to allow free passage of
hydraulic fluid to pressure operated switches 7 and 11. The fluid
must return to the cylinder through adjustable valves 6 and 10. A
slight delay in the opening of switches 7 and 11 has thereby been
introduced to keep the brakes energized for a short period after
the rate of swaying has been reduced. For a given operational
requirement.Iadd., .Iaddend.fixed orifices can be used in place of
valves 6 and 10. The combination of valves 6 and 10 (or fixed
orifices) and check valves 5 and 9 is shown to obtain the ultimate
in sway correction. Considerable, and in most cases adequate.Iadd.,
.Iaddend.sway correction is realized without the use of 5, 6, 9 and
10. In applications where a delay in releasing the brakes is
considered desirable it can also be done by means of electrical
delay circuits.
A schematic of the electrical circuit is shown in FIG. 3. The
towing vehicle battery 24 is connected to the brake control unit 23
which is located in a convenient position for the driver to reach
and operate. Plug and connector 22 provide circuit connection from
the towing vehicle to the towed vehicle. Not shown in the
simplified diagrams are the tail light, stop light, direction
signal light, running lights and inter battery connections normally
provided through connector 22. Electromagnets of the brakes of a
single axle trailer are represented by 16 and 17. In trailers with
two axles.Iadd., .Iaddend.the electromagnets 18 and 19 are shown by
dashed lines. Trailer battery 20 supplies the brake operating
current through adjustable resistor 21 and pressure operated switch
7 or 11. Adjustable resistor 21 is set in accordance with one or
two axle brake requirements.
Quicker sway correction can be realized by using the trailer brake
circuit shown in FIG. 4. This can be described by referring to FIG.
5. If an abnormally fast left turn of the towing vehicle takes
place.Iadd., .Iaddend.pressure switch 7 will close and cause only
the trailer left wheel brake or brakes to be applied. This will
cause the front of the trailer to move to the left and thereby
provide .[.the force required.]. .Iadd.a force tending .Iaddend.to
"line up" the towed and towing vehicles. If the towing vehicle in
effect makes an abnormally fast right turn.Iadd., .Iaddend.pressure
operated switch 11 closes and applies the trailer right wheel brake
or brakes. Diodes 25 and 26 provide the required electrical
isolation when either switch 7 or 11 operate and yet permit current
to flow to all brakes when brake control 23, in the towing vehicle,
is operated.
Present day cars have, for safety reasons, a braking system in
which the front wheel brakes and the associated controls are
isolated from the rear wheel brakes and their associated control
system. Both systems are actuated by the common brake pedal. In
such a system.Iadd., .Iaddend.the chance of simultaneous failures
of both systems is very remote. Therefore if one system fails you
still have the braking capability of the other.
Practicaly all present day tandem axle trailers have a single
electrical braking system. An open circuit in the main line,
connector.[.,.]. .Iadd.or .Iaddend.brake control or a short circuit
anywhere in the electrical braking system will result in the loss
of all brakes. A dual braking system should be used for tandem axle
trailers for the same safety reasons that it is used in a car. Such
a system, in conjunction with a sway sensing system.Iadd.,
.Iaddend.is shown in FIG. 6. Separate trailer front wheel brake
wiring and rear wheel wiring is connected through separate plugs
and connectors 28 and 29 to dual brake control 27. This figure
shows the sway sensing pressure operated switches 7 and 11
connected in such a manner that the operation of either switch will
apply braking power to all trailer brakes through diodes 30 and 31.
When brake control 27 is operated.Iadd., .Iaddend.these diodes
provide electrical isolation between the trailer front and rear
axle brakes. In a case where the sway sensing system is not
used.Iadd., .Iaddend.resistor 32, pressure operated switches 7 and
11, diodes 30 and 31 and the associated wiring are not used.
A dual braking system in which the sway sensing system applies
power to the appropriate left or right trailer brakes only is shown
in FIG. 7. Diodes 39, 40, 41, 42, 43, 44, 45 and 46, and resistors
35, 36, 37 and 38 provide electrical isolation for dual brake
control 27 operation .[.and or.]. .Iadd.and/or .Iaddend.sway
sensing switch 7 or 11 operation in a manner that provides maximum
protection against possible circuit failure such as a short circuit
or open circuit in the braking system.
Some simplification of the circuit shown in FIG. 7 can be realized
by using double pole pressure operated switches 47 and 48 .Iadd.as
.Iaddend.shown in FIG. 8. Basically the same type of electrical
isolation against complete braking system failure in case of open
or short circuit conditions is realized with the circuit shown in
FIG. 8 as in FIG. 7.
* * * * *