CA2058660C - Training vehicle skid simulating mechanism - Google Patents

Abstract

An automotive training vehicle capable of providing controlled simulated skid conditions selectable in either right or left directions by a driving instructor accompanying a student driver. The vehicle has conventional front wheel steer and a pair of rear wheels mounted for simultaneous turn about parallel, substantially vertical axes. A switch which is located in a position accessible to the driving instructor activates a control system to energize a drive cylinder connected to the rear wheels for effecting turn of the rear wheels from a straight ahead position through an infinite number of positions to a maximum steer position in either direction from the straight ahead. The control system when in a non-activated condition places the drive cylinder in a hold position preventing turn of the rear wheels from the selected position. The severity of the simulated skid and its timing are thus fully within the control of the driving instructor.

Description

This invention relates to a training vehicle skid simulating mechanism, and more particularly to a vehicle having a modified rear axle and wheel arrangement which permits controlled steer of the rear wheels so as to provide an opportunity for a driving student to experience the effects of skid-like conditions on the vehicle.
It is known that when a vehicle commences a skid condition, i.e. the rear end of a vehicle slides out to one side or the other from a normal tracking condition behind the front wheels, the driver's reaction is frequently such that the skid condition is worsened, possibly resulting in a serious accident. A skid condition usually develops in a turn or during braking, particularly of the road surface conditions, such as wet or icy roads, or on roads of the type having a non-paved surface. However, a skid can also develop on a normal road surface, such as when the vehicle is negotiating a curve at a speed higher than for which the road was designed.
Knowing the proper reaction, and thus the required steering maneuvers to quickly correct the skid condition, in order to avoid complete loss of control of vehicle, is important. Even experienced drivers, particularly those who have not previously encountered a serious skid condition, are known to panic when first sensing a skid condition, or initially react by purposely steering the vehicle in a direction opposite to that necessary to compensate for the condition and commence to rectify it. The result, particularly if the vehicle is travelling even at moderate speeds, of course, can be fatal.
Accordingly, it has become apparent to those involved in training drivers that it would be extremely advantageous to produce conditions during one's training period to let the driver experience skid or a simulated skid conditions. It is, of course, difficult to develop an area and/or driving condition which would allow the driver to practice in handling the vehicle under true skid conditions. Attempts have therefore been made to develop vehicles which could be manipulated to simulate a skid condition. Canadian Patent No. 1,197,194, issued November 11, 1986, to Bertel Roos, discloses a vehicle the rear wheels of which are pivotable and have a positive caster with a bias mechanism for maintaining the rear wheels in a non-steer condition until the bias force is overcome during travel at a sufficient speed during a turn of the vehicle. Although the disclosed structure shows the options of providing mechanisms for varying the biasing forces and the amount of castor of the rear wheels, the inducement of the skid condition is brought about by the vehicle negotiating a turn and lacks complete control by the driving instructor so as to enable the trainee to be initially introduced to the feel of a skid under otherwise completely favorable conditions.
It is an object of the present invention to provide an automotive training vehicle which allows an instructor to cause the vehicle to undergo a simulated skid condition, the timing of the skid and the severity of it being fully within the control of the instructor.
According to the invention there is provided a training vehicle for providing controlled simulated skid conditions selectable in either right or left directions by a driving instructor accompanying a student driver.
The vehicle has steerable front wheels with a pair of rear wheels mounted for simultaneous turn about parallel, substantially vertical axis. Drive means is connected to the rear wheels and is energizable to turn the rear wheels in either direction from a straight ahead position through an infinite number of positions to a maximum severe skid simulated position. Switch means is provided which is accessible to the driving 2~~~~~0 instructor, and control circuitry means is activatable by the switch means for energizing the drive means. The control circuitry in a non-activated condition places the drive means in a whole condition for preventing the rear wheels from turning from a selected position.
In the accompanying drawings, which show an example of the present invention, Figure 1 is a simplified plan view of the chassis and wheels of a training vehicle of the present invention showing the rear wheels turned to provide a simulated skid condition;
Figure 2 is a rear view of the rear axle and wheel arrangement of a training vehicle in accordance with the present invention;
Figure 3 is a plan view of the arrangement of Figure 2;
Figure 4 which appears on the same sheet as Figure 2, is an enlarged view, partially in cross-section of pivot mounting of one of the rear wheels;
Figure 5 is an electrical and hydraulic schematic of a control system of a training system of the present invention; and Figure 6 is an alternative embodiment of a control system using only hydraulic circuitry.
In Figure 1, the training vehicle 10 of the present invention has a chassis or frame 11, which may be effectively provided in the form of a unit body. The front wheels 12,12 may be provided with a conventional steer system 13 controlled by the driver from a conventional steering wheel 14 for steering from the normal straight-ahead direction indicated by the arrow S. A non-conventional rear axle and wheel arrangement 15 is provided including a steering mechanism, which is described in more detail below, the steering of rear wheels 16,16 being controlled by an internal switch box 17, located within the vehicle passenger compartment in a position readily accessible by the driving instructor, such as near the front passenger seat.
Referring now to Figures 1, 2 and 3, the vehicle 10 is provided with a rear axle 18. The suspension system, which is shown as an example, includes a pair of rigid arms 20,20 (Figure 3) fixed at the rear ends thereof to the axle 18 and being pivotably connected through resilient bushings 21,21 to the chassis (not shown) of the vehicle forward of the rear axle, thus permitting effective upward and downward movement of the axle relative to the vehicle chassis. A pair of shock absorber and spring units 22,22 are connected between the axle 18 and the vehicle body for thereby controlling the resiliency in the upward and downward movement of the axle 18. An anti-swing bar 23 is pivotally connected at a lower end near one end of the axle and extends obliquely upward to a pivot connection to the body at a location on the body towards the side opposite to its connection to the axle. The above-described suspension incorporates one form of rear axle which is used in commercially available vehicles of the front-wheel drive type and in which the rear axle is in fact designed to accomodate flexing during use. This system may be modified or strengthened somewhat to take into account additional forces which are present during steer of the rear wheels. Other types of commercially used axles such as the rigid type may be used, or the steerable rear wheels may be independently mounted in a fashion commonly used for the front wheels of conventional rear-wheel drive vehicles.
Affixed to both outer ends of the axle 18 are suspension or axle knuckles 24,24 in which are mounted king pins 25,25. The upper and lower ends of each king pin 25 extend above and below its respected axle knuckle 24 (Figure 4). A wheel spindle 26 on which wheel 16 is journalled to freely rotate has a spindle knuckle 27 with portions extending above and below axle knuckle 24 and are provided with aligned bores 28. The upper bores 28 has an upper bushing 30 and the lower bore receives a lower flanged bushing 31. The bushings 30,31 receive the upper and lower ends, respectively, of the king pin 25. Thus, the spindle knuckle 27 can pivot about a substantial vertical axis, relative to the axle knuckle 24. Accordingly, the spindle 26 can swing in an arc disposed in a horizontal plane to effect a steering action of each rear wheel 16 as illustrated in Figure 1 and in dashed lines in Figure 3. There is affixed to a lower surface of the spindle knuckle 27 of the left rear wheel 16, as seen in Figures 2 and 3, a steering arm 32 while a similar steering arm 33 is affixed to a low surface of the spindle knuckle of the right rear wheel 16. A tie rod 34 having conventional balljoint connections at opposite ends is connected between outer ends of the two steering arms 32 and 33 so as to accomplish uniform steer of the two rear wheels 16,16 of the vehicle.
A bracket 37 which has a pair of parallel flanges 39 is attached to a rear surface of the rear axle 18 near the left hand end of the axle, and an expandable and contractible drive motor is provided which is shown in the form of a drive cylinder 35 having an apertured lug 38 at one end thereof, commonly referred to as the cap end, projecting between the flanges 39 of the bracket. A pin 29 pivotally connects the apertured lug 38 to the bracket 37. The drive cylinder 35 is a double acting hydraulic cylinder 35 having piston rod 36, projecting from the opposite end, which is commonly referred to as the head end, and an outer end of the piston rod 36 is connected by a pivot connection 19 intermediate the ends of the steering arm 32. Thus on expansion of the drive cylinder 35, as will be described in more detail below, the rear wheels 16,16 are pushed by the drive cylinder to the steering position shown in 2~5~~~0 Figure 3 and on contraction of the drive cylinder the rear wheels are swung to an opposite steer position. As is described in more detail below, any amount of steer can be selectively accomplished by the driving instructor to represent varying severity of skid conditions. When in a neutral or central position of the drive cylinder the rear wheels are locked in a straight ahead position so that the rear wheels perform as normal rear wheels of a front-wheel steer vehicle.
While the illustrated embodiment is shown incorporated in a conventional vehicle having front wheel drive, the invention can also be used in a vehicle having front wheel steer and rear wheel drive. In such an embodiment, the rear drive axle is provided with an inward connection inboard of the steering knuckle which carries the end of the drive axle on which the rear wheel is mounted, not unlike the type of drive axle used in front wheel drive vehicles.
In Figure 5, which shows an electrical and hydraulic schematic of the control system in the present invention, there is provided an electric motor 40. When activated the motor 40 drives a hydraulic pump 41 having an inlet conduit 42 which places a reservoir 43, containing a supply of hydraulic fluid, in communication with the pump 41. An outlet or supply conduit 44 connects an outlet port of pump 40 to an inlet port of a two position control valve 45 which includes a control solenoid 46. A conduit 47 including a relieve valve system 50 is connected between the supply conduit 44 and the reservoir 43 so as to permit hydraulic fluid to bypass directly back to the reservoir 43 in the event the pressure in supply conduit 44 exceeds a predetermined value. Located between the connection of the conduit 47 to the outlet conduit 44 and the valve 45 is a one-way or check valve 51 which permits flow only in a direction away from the pump 40 towards the valve 45.

2o~ssso _ 7 _ The valve 45 has an outlet port in communication with a conduit 52 which serves as a return line from the valve to the reservoir 43. The valve 45 also has two ports connected respectively to conduits 53 and 54.
Conduit 53 is connected to the inner or head end of the drive cylinder 35, while conduit 54 extends to a port of a second two position control valve 55 which includes a control solenoid 56. The valve 55 has a port to which a conduit 57 is connected so as to place the port in communication with the outer cap end of the drive cylinder 35.
When the solenoid 46 of valve 45 is not activated the valve spindle within the valve is spring biased to the position depicted in Figure 5 so that fluid in supply conduit 44 is in communicated with conduit 53, and is therefore in communication with the inner end or head end of the drive cylinder 35. If at the same time, however, the spindle of valve 55 is in the non-activated position, i.e. the solenoid 56 also has not been energized, the fluid of conduit 57 is not in communication with conduit 54 which is otherwise in communication with the return conduit 54 through valve 45. This is due to the fact that in the non-activated position, valve 55 provides a check valve between conduits 57 and 54 allowing flow only from conduit 54 to 57 and not in the opposite direction. Thus, regardless of whether motor 40 is energized, while both of the solenoids 46 and 56 of the valves 45 and 55 remain unenergized, the drive cylinder 35 effectively remains in a locked condition due to isolation of fluid in conduit 57 by the check valve in control valve 55.
If, on the other hand, the solenoid 46 of control valve 45 is activated, while motor 40 is energized to proved pressurized hydraulic fluid to supply conduit 44 while solenoid 56 remains unenergized, the spindle of valve 45 shifts to a position placing supply conduit 44 20~~~60 _8_ in communication with conduit 54 and conduit 53 in communication with return conduit 52. The pressurized fluid from pump 41 thus flows through valve 45 to conduit 54 and then through the check valve of valve 55 to the cap end of the drive cylinder 35 via conduit 57.
At the same time, i.e. while valve 45 is in the activated position, because the conduit 53 is connected to the return conduit 52 through valve 45, the fluid at the inner end of the drive cylinder is forced to the reservoir through conduits 53 and 52 as the piston rod moves toward the extended position.
If the solenoid 56 of control valve 55 is energized while solenoid 46 of valve 56 remains unenergized and motor 40 is energized to provide pressurized fluid to supply conduit 44, the pressurized fluid is free to communicate with conduit 53 through valve 45 and thus be available to the inner end of the drive cylinder 35.
When energized, the solenoid 56 of valve 55 forces the spindle of the valve to a position to allow fluid to pass from conduit 57 to conduit 54, which can pass through non-activated valve 45 to the return line 52.
Accordingly, the pressurized fluid admitted to the inner end of the drive cylinder 35 drives the piston towards the outer or cap end of the drive cylinders, expelling the fluid in the outer end to return conduit 52, and resulting in piston rod 36 of the drive cylinder 35 being driven to a more retracted position.
The electrical portion of the control system includes a remote control switch 60 in the switch box 17 located adjacent the driving instructor. The control switch 60 is shown as being of a type having a pair of push buttons 61,62, preferably interlocked in a manner to allow only one button to be pushed at a time. The electrical system is connected to an electrical source, which may be the 12 volt system of the vehicle. The line is connected to a main supply line 64 which extends to control switch 60 through a three pin connector 65 allowing disconnection of the control switch from the system. The push button arrangement is such that when button 61 is depressed, a line 66, which also extends through the three pin connector, is energized. If button 62 is depressed line 67, which again extends through the line pin connector, is energized.
Lines 66 and 67 are connected to terminals of a solenoid relay 70 so that on depression on button 61, electromagnet 71 of the solenoid relay 70 is activated or if button 62 is activated electromagnet 71 is activated. Associated with each of electromagnets 71 and 72 are two pairs of switch contacts 71a, 71b and 72a, 72b, one contact of each of the two pairs being connected to the main supply line 64. When solenoid 71 is energized by pushing button 61, the switch contacts of the pairs of switch contacts 71a, 71b are closed, thus energizing output lines 73 and 74. When button 62 is pushed to energize line 67 to thereby energize electromagnet 72, the closing of contacts 72a, 72b energized output lines 75 and 76.
When either of output lines 74 or 76 is energized by pushing of either button 61 or 62, motor 40 is energized to drive pump 41 because both of lines 74 and 76 are connected to line 77 which is connected to motor 40. Thus, while the motor would not be normally operating, it is started when either of button 61 or 62 is pushed and becomes de-energized when the pushed button is released.
When button 61 is pushed, and line 73 thus becomes energized, the solenoid 46 of the first control valve, to which line 73 is connected becomes energized, but solenoid 56 does not become energized. Therefore, in this condition fluid from pump 41 is delivered to the outer end of the drive cylinder 35, while the inner end is connected to the return line so that the piston rod 36 moves towards an extended position as described above. The extending movement stops, of course, as soon as the button 61 is released and the piston rod in effect becomes locked in the position it occupies. This happens not only because the motor immediately stops, but the spindle of control valve 45 returns to its nonactivated position and the spindle of control valve 55 remains in its non activated position thereby trapping the fluid in the outer or cap end of the drive cylinder 35.
When button 62 is pushed, the motor is again started and simultaneously the spindle of control valve 55 is moved to permit the flow of fluid from the outer end of the drive cylinder 35 to return to the reservoir, while pressurized fluid enters the inner end of the drive cylinder, thus driving the piston of the drive cylinder 35 to move the piston rod 36 towards a more retracted position. When button 62 is released, the movement stops not only because the motor 40 stops, but because on control valve 55 becomes non-activated, are the spindle thereof returns to a position to again effectively lock the fluid in the outer end of the drive cylinder 35 thereby preventing any movement of the piston.
It will be appreciated that as one alternative to using a combination electrical-hydraulic control system, one which is only electrical may be used. In such an arrangement, the drive motor may be in the form of an electric linear actuator of a type commercially available and consisting of bi-directional DC motor which drives a rod to extend or retract, such as through a worm-gear drive. Thus the switch 60 would be movable to two positions from a neutral position to two energizing positions to provide current from driving the motor in either direction.
Another alternative is shown in Figure 6 which shows a schematic of an entirely hydraulic system. A

2o~s6so hydraulic pump (not shown) which may be in the form of a modified power steering pump can be mounted to be driven directly from the vehicle engine to provide pressurized fluid through a line 44a to a metering type control valve 90. A line 52a is connected to the valve 90 and provides a return from the valve to a reservoir (not shown). In place of the electric switch 60 the valve 90 has control levers 61a and 62a, thus providing switching means, located for easy access to the instructor. The valve 90 has a spool which is moved in one direction by lever 61a and in the opposite direction by lever 62a.
When the spool is in a neutral position as shown in Figure 6, the pressurized fluid in line 44a is returned directly to the fluid reservoir. If movement of lever 61a, for example, moves the spool to the lift, as viewed in Figure 6, the pressurized fluid from the pump, which is continuously driven, is metered to a line 53a connected to the head end of the hydraulic cylinder 35 while the cap end is connected via line 57a and valve 90 to the reservoir through line 52a. Accordingly the cylinder retracts to cause steer of the rear wheels in one direction as described above. When lever 62a is operated to move the spool in the opposite direction, i.e. to the right, pressurized fluid from line 44a is directed to the cap end of the cylinder 35, and line 53a, which is in communication with the head end of the cylinder, is connected to line 52a and thus to the reservoir so that the piston is forced to the left to cause the cylinder to expand. The rear wheels of the vehicle are thus steered in the opposite direction. In this embodiment, it can be seen that when neither of levers 61a and 62a are operated the spool is spring biased to its neutral position in which the fluid on both sides of the piston is blocked from escaping so that the steer position of the rear wheels thus selected is locked in place.

..

As indicated above, the pump may be a continuously driven power steer type pump which has been slightly modified to effect flow control from outside of the pump. As shown in Figure 6, a load sense shuttle valve 91 is placed in a line connected between lines 53a and 57a. Valve 91 is connected via a line 92 to pump so as to control the output and by-pass control valuing within the normal power steering pump.
Accordingly, it can be seen that with the present invention, an instructor can at all times control the position of the rear wheels, and when the rear wheels are located in a straight ahead position the vehicle operates entirely in a conventional manner regardless of what operating conditions the vehicle is experiencing.
If for example, the instructor decides to initiate the student to skid conditions, a location such as an open parking lot can be selected, and with the student driving at a comfortable speed in a straight ahead position, the instructor can cause the rear wheels 16,16 to steer to the right, by pushing button 61 in the embodiment shown in Figure 6, whereby the rear of the vehicle moves in the direction of arrow 80 (Figure 1).
The student then attempts to steer the vehicle by timing steering wheel 14 to compensate for the simulated skid and maintain the direction of travel of the vehicle under control. As the steering of the rear wheels can be moved to an infinite number of steer positions between the straight ahead position and a predetermined amount of steer in either direction, only minor simulated skid conditions may be initiated and tried at various speeds, with more severe skids being simulated as the students experience develops.
While only one'embodiment has been illustrated various modifications within the spirit of the invention as defined in the accompanying claims will be obvious to those skilled in the art.

Claims (19)

1. A training vehicle for providing controlled simulated skid conditions selectable in either right or left directions by a driving instructor accompanying a student driver, said vehicle comprising:
steerable front wheels, a pair of rear wheels mounted for simultaneous turn about parallel, substantially vertical axes, drive means connected to said rear wheels and being energizable to turn said rear wheels about said axes in either direction from a straight ahead position through an infinite number of positions to a maximum sever skid simulated position, switch means accessible to the driving instructor, and control circuitry means activatable by said switch means for energizing said drive means, said control circuitry in a non-activated condition placing said drive means in a hold condition for preventing said rear wheels from turning from a selected position.

2. A training vehicle as defined in claim 1, further comprising suspension means mounting the pair of rear wheels at opposite sides of said vehicle.

3. A training vehicle as defined in claim 2, wherein said mounting means includes suspension knuckle means and cooperating wheel spindle knuckle means connected by king pin means defining said vertical axes.

4. A training vehicle as defined in claim 3, further comprising steering arms affixed one each to said wheel spindle knuckle, and tie rod means connected between said steering arms and providing the simultaneous turn of said rear wheels.

5. A training vehicle as defined in claim 4, wherein said suspension means includes rear axle means, means mounting the pair of rear wheels one each at opposite ends of said axle means.

6. A training vehicle as defined in claim 5, wherein said drive means includes a motor means connected between said axle and one of said steering arms for turning said rear wheels in either direction on energization of said motor means.

7. A training vehicle as defined in claim 6, wherein said motor means is an electric linear actuator for turning said rear wheels in opposite directions on expansion or contraction thereof respectively.

8. A training vehicle as defined in claim 6, wherein said drive motor is a double acting hydraulic cylinder for turning said rear wheels in opposite directions on expansion or contraction thereof respectively.

9. A training vehicle as defined in claim 8, wherein said control circuitry means includes means for providing pressurized fluid from a reservoir means, and fluid conduits connected to opposite ends of said cylinder means for selectively supplying pressurized fluid to one end of said cylinder means while permitting fluid flow to said reservoir from other end of said cylinder means to accomplish the expansion or contraction of said cylinder means.

10. A training vehicle as defined in claim 9, wherein said control circuitry includes valve means for preventing fluid flow from at least one end of said cylinder means in said non-activated condition for placing said drive means in said hold condition.

11. A training vehicle as defined in claim 1 wherein said drive means includes cylinder means for turning said rear wheels in one direction from a straight ahead position on expansion of said cylinder means and for turning said rear wheels in the opposite direction on contraction of said cylinder means.

12. A training vehicle as defined in claim 11 wherein said cylinder means is a double acting cylinder, and said control circuitry includes a hydraulic circuit for selectively directing pressurized fluid to opposite ends of said cylinder for causing a varying amount of said expansion and contraction.

13. A training vehicle as defined in claim 12, wherein said control circuitry includes an electrical circuit connected to an electrical source, said switch means including means for selectively energizing one of two lines on said electrical circuit.

14. A training vehicle as defined in claim 13, wherein said hydraulic circuit includes a source of pressurized fluid and a pair of solenoid controlled valves, one each of said lines being connected to one of said solenoid controlled valves for thereby selectively activating one of said valves at a time.

15. A training vehicle as defined in claim 14, wherein said source of pressurized fluid includes a driven pump connected to receive fluid from a reservoir and having an output connected to a first of said solenoid controlled valve.

16. A training vehicle as defined in claim 14, wherein said first solenoid controlled valves in an activated condition directs flow of pressurized fluid to the second of said solenoid controlled valve while permitting flow of fluid from one end of said cylinder to said reservoir, said second solenoid control valve in a non-activated condition directing the flow of pressurized fluid from the first solenoid controlled valve to the second end of said cylinder.

17. A training vehicle as defined in claim 16, wherein said second solenoid controlled valve include means for preventing flow from said second end of said cylinder to said reservoir when said second solenoid controlled valve is in a non-activated condition.

18. A training vehicle as defined in claim 17, wherein said first solenoid controlled valve in a non-activated condition directs flow from said pump to said one end of said cylinder, and said second solenoid controlled valve in an activated condition permits flow of fluid from said second end of said cylinder to said reservoir.

19. A training vehicle as defined in claim 15, 16, 17 or 18, wherein said pump includes an electric drive motor, said electrical circuit including switching means for energizing a third line connected to said motor, said third line being energized when either of said two lines is energized to thereby start drive of said pump as either of said solenoid controlled valves is activated.