GB2238990A

GB2238990A - Vehicle height adjustment device using a plurality of driven cylinders linked to suspension jacks

Info

Publication number: GB2238990A
Application number: GB9023719A
Authority: GB
Inventors: Yoshio Negishi; Eiichi Minowa; Kenichi Nagatsuka
Original assignee: SHOWA Manufacturing; Showa Seisakusho Co Ltd
Current assignee: SHOWA Manufacturing; Showa Corp
Priority date: 1989-10-31
Filing date: 1990-10-31
Publication date: 1991-06-19
Anticipated expiration: 2010-10-31
Also published as: GB9023719D0; GB2238990B

Abstract

A vehicle height adjusting mechanism for adjusting the height of a motor vehicle includes a plurality of jack units 8, 9 associated respectively with dampers 6 interposed between a vehicle body and a plurality of axles 3, 4, a drive source, and a single drive cylinder unit 16 actuatable by the drive source for supplying working oil to and discharging working oil from the jack unit to adjust the height of the motor vehicle. The drive cylinder unit has a plurality of driven cylinders 14a,b, 15a,b connected independently to the jack units, respectively, and a plurality of driven piston assemblies 17a,b 18a,b, slidably disposed in the driven cylinders, respectively, for supplying working oil to and discharging working oil from the jack units, respectively. The drive cylinder unit may be replaced by an electric motor driving a screw (Fig. 7). The driven cylinders may be in line (Fig. 8). <IMAGE>

Description

VEHICLE HEIGHT ADJUSTING MECHANISM The present invention relates to a mechanism for adjusting the height of a motor vehicle.

Recently, more and more general passenger cars, racing cars, and other cars are equipped with active suspensions and vehicle height adjusting mechanisms. One conventional height adjusting mechanism comprises a jack cylinder coupled to a hydraulic damper and the vehicle body of a motor vehicle. The jack cylinder has a slidably fitted jack piston which supports one end of a suspension spring. The height of the motor vehicle can be adjusted when working oil is supplied to or discharged from the jack cylinder by a pump which is actuated by an external motor.

If vehicle height adjusting mechanisms were independently combined with respective suspension dampers of a passenger car or the like, then the entire system of vehicle height adjusting mechanisms would be complex and heavy, and it would be highly difficult to keep the left and right dampers in balance during operation.

One solution to the above problem would be to add a drive cylinder unit mounted onthe vehicle body separately from the left and right dampers, the drive cylinder unit having a single cylinder connected to the jack cylinders which are coupled to the respective left and right dampers.

However, if the pipes interconnecting the cylinder of the drive cylinder unit and the jack cylinders presented different resistances to the flow of working oil through the pipes, then the working oil would be supplied at different rates to the jack cylinders, making it impossible to adjust the height of the motor vehicle equally on the left and right sides thereof.

In view of the aforesaid drawbacks of the conventional vehicle height adjusting mechanisms, it is an object of the present invention to provide a vehicle height adjusting mechanism which is of a relatively small weight and can adjust the height of a motor vehicle smoothly.

According to the present invention, there is provided a vehicle height adjusting mechanism comprising a plurality of jack units associated respectively with dampers interposed between a vehicle body and a plurality of axles, a drive source, and a single drive cylinder unit actuatable by the drive source for supplying working oil to and discharging working oil from the jack units to adjust the height of a motor vehicle, the drive cylinder unit having a plurality of driven cylinders connected independently to the jack units, respectively, and a plurality of driven piston assemblies slidably disposed in the driven cylinders, respectively, for supplying working oil to and discharging working oil from the jack units, respectively.

Some embodiments of the invention will now be described by way of example and with reference to the accompanylng oEawlngs, ln wilch:- FIG. 1 is a schematic front elevational view of a motor vehicle incorporating a vehicle height adjusting mechanism according to a first embodiment of the present invention; FIG. 2 is a schematic plan view of the motor vehicle shown in FIG. 1; FIG. 3 is a diagram showing the manner in which the height of the motor vehicle is varied by the vehicle height adjusting mechanism according to the first embodiment; FIG. 4 is a schematic front elevational view of a motor vehicle incorporating a vehicle height adjusting mechanism according to a second embodiment of the present invention;; FIG. 5 is a diagram showing the manner in which the height of the motor vehicle is varied by the vehicle height adjusting mechanism according to the second embodiment; FIG. 6 is a cross-sectional view of a modified hydraulic damper having a jack function, for use in the vehicle height adjusting mechanisms according to the first and second embodiments: FIG. 7 is a cross-sectional view of a drive cylinder unit according to a first modification for use in the vehicle height adjusting mechanisms according to the first and second embodiments; and FIG. 8 is a fragmentary cross-sectional view of a drive cylinder unit according to a second modification for use in the vehicle height adjusting mechanisms according to the first and second embodiments.

Shown in FIGS. 1 and 2 is a motor vehicle which incorporates a vehicle height adjusting mechanism according to a first embodiment of the present invention. The motor vehicle has left and right front wheels la, 2b and left and right rear wheels ib, 2b, and hydraulic dampers 5 interposed between a vehicle body and axles 3, 4 coupled to the respective wheels la, ib, 2a, 2b. Each of the hydraulic dampers 5 includes a cylinder-6 and a piston rod 7 extending therefrom. The piston rod 7 has a lower end fixed to a piston (not shown) slidably fitted in the cylinder 6, and an upper end connected to a jack cylinder 8 with a jack piston 9 slidably fitted therein. The jack cylinder 8 and the jack piston 9 jointly constitute a jack unit.A suspension spring 11 is disposed between the jack cylinder 9 and a spring seat 10 which is vertically adjustably threaded over the cylinder 6. The height of the motor vehicle can be varied or adjusted when the jack piston 9 is vertically moved.

As shown in FIG. 1, a drive cylinder unit 13 is disposed substantially centrally on the vehicle body. The drive cylinder unit 13 comprises front and rear left driven cylinders 14a, 14b, front and rear right driven cylinders 15a, 15b, and a central drive cylinder 16. The drive cylinder unit 13 also has left driven pistons 17a, 17b slidably fitted in the left driven cylinders 14a, 14b, respectively, right driven pistons 18a, 18b slidably fitted in the right driven cylinders 15a, 15b, respectively, and a drive piston 19 slidably fitted in the central drive cylinder 16.

According to the present embodiment, the pistons 17a, 17b, 18a, 18b, 19 are connected to respective piston rods 21a, 21b, 22a, 22b, 23 which are joined together by a joint plate 24. The left front cylinder 14a is hydraulically connected to the jack cylinder 8 of the hydraulic damper 5 associated with the left front wheel la through an independent pipe or tubular member. The left rear cylinder 14b is hydraulically connected to the jack cylinder 8 of the hydraulic damper 5 associated with the left rear wheel ib through an independent pipe or tubular member. The right front cylinder 15a is hydraulically connected to the jack cylinder 8 of the hydraulic damper 5 associated with the right front wheel 2a through an independent pipe or tubular member.The right rear cylinder 15b is hydraulically connected to the jack cylinder 8 of the hydraulic damper 5 associated with the right rear wheel 2b through an independent pipe or tubular member.

The joint plate 24 is connected to a displacement sensor 26 which produces an output position signal indicative of the amount of displacement of the pistons 17a, 17b, 18a, 18b, 19.

The vehicle height adjusting mechanism shown in FIG. 1 has an accumulator 27 mounted on the vehicle body as a hydraulic pressure source. The accumulator 27 has a piston 29 slidably fitted in a cylinder 28 and dividing the interior of the cylinder 28 into a gas chamber Si and an oil chamber S2. The oil chamber S2 is filled with such an amount of working oil as to be able to operate the jack pistons 9 a predetermined number of times. The gas chamber S1 is filled with a gas which can operate the piston 29 a predetermined number of times.

The chamber in the drive cylinder 16 and the oil chamber S2 of the accumulator 27 are hydraulically connected to each other through an oil supply solenoid-operated valve 31.

The chamber in the drive cylinder 16 is also connected to a reservoir tank 33 through an oil discharge solenoid-operated valve 32.

The vehicle height adjusting mechanism has an upward adjustment switch 35 for producing an indication signal which indicates an increase in the vehicle height and a downward adjustment switch 36 for producing an indication signal which indicates a reduction in the vehicle height, each of the switches 35, 36 serving as a vehicle height adjustment indicating means. When a microcomputer (CPU) 37 which is powered by a battery 38 is supplied with a vehicle height increasing signal from the upward adjustment switch 35, the CPU 37 opens the solenoid-operated valve 31. When the piston 19 is lowered a desired distance as detected by a position signal from the displacement sensor 26, the CPU' 37 closes the solenoid-operated valve 31.When the the CPU 37 is supplied with a vehicle height reducing signal from the downward adjustment switch 36, the CPU 37 opens the solenoid-operated valve 32. When the piston 19 is lifted a desired distance as detected by a position signal from the displacement sensor 26, the CPU 37 closes the solenoidoperated valve 32.

Operation of the vehicle height adjusting mechanism will be described in detail below. When the upward adjustment switch 35 is operated on and produces a vehicle height increasing signal, the solenoid-operated valve 31 is opened in response to a drive signal from the CPU 37. Working oil is supplied from the oil chamber S2 of the accumulator 27 to the chamber in the drive cylinder 16, lowering the drive piston 19. Since the driven pistons 17a, 17b, 18a, 18b are also lowered with the drive piston 19 through the joint plate 24, working oil in the driven cylinders 14a, 14b, 15a, 15b is supplied to the jack cylinders 8 of the hydraulic dampers 5, thereby lowering the jack pistons 9.Therefore, the reactive forces from the suspension springs 11 increase, so that the height of the motor vehicle increases as indicated by the solid-line curve in FIG. 3.

The amount by which the vehicle height has increased is detected as an amount of displacement of the piston 19 which is detected by the displacement sensor 26.

When the piston 19 is lowered a desired distance as detected by the position signal from the displacement sensor 26, the CPU 37 closes the solenoid-operated valve 31. Working oil from the accumulator 27 is no longer supplied to the drive cylinder 16, and the process of increasing the vehicle height comes to an end.

When the downward adjustment switch 36 is operated on and produces a vehicle height reducing signal, the solenoid-operated valve 32 is opened in response to a drive signal from the CPU 37. Under the reactive forces from the suspension springs 11, the jack pistons 9 are elevated to force working oil from the jack cylinders 8 back into the driven cylinders 14a, 14b, 15a, 15b, upwardly moving the driven pistons 17a, 17b, 18a, -18b. Since the drive piston 19 is also moved upwardly with the driven pistons 17a, 17b, 18a, 18b through the joint plate 24, working oil in the drive cylinder 16 flows through the solenoid-operated valve 32 back into the reservoir tank 33. Upon upward movement of the jack pistons 9 of the respective hydraulic dampers 5, the reactive forces of the suspension springs 11 are reduced, thereby reducing the height of the motor vehicle.

The amount by which the vehicle height has decreased is detected as an amount of displacement of the piston 19 which is detected by the displacement sensor 26.

When the piston 19 is lifted a desired distance as detected by the position signal from the displacement sensor 26, the CPU 37 closes the solenoid-operated valve 32. Working oil from the jack cylinders 8 is no longer returned to the drive cylinder 16, and the process of reducing the vehicle height is ended.

In this embodiment, the driven cylinders for supplying working oil to and discharging working oil from the respective jack units are provided independently of each other and are independently connected to the jack cylinders of the jack units. Therefore, even if the pipes interconnecting the drive cylinder unit and the jack cylinders present different resistances to the flow of working oil therethrough for the left and right or front and rear wheels, the height of the motor vehicle can uniformly be varied or adjusted. Since the accumulator is used as a drive source for supplying working oil to and discharging working oil from the drive cylinder unit, any motor and pump are not employed, resulting in a reduction in the weight of the overall vehicle height adjusting mechanism.

FIG. 5 shows a vehicle height adjusting mechanism according to a second embodiment of the present invention.

Those parts shown in FIG. 5 which are identical to those shown in FIGS. 1 and 2 are denoted by identical reference numerals, and will not be described in detail. According to the second embodiment, the vehicle height adjusting mechanism is further reduced in weight as no reservoir tank is included.

Before the vehicle height adjusting mechanism shown in FIG. 5 is activated for height adjustment, it is brought into a setup condition. To achieve the setup condition, a valve 30 connected to the gas chamber S1 of the accumulator 27 is opened to fill the gas chamber S1 with a gas supplied from an external source, and the chamber in the drive cylinder 16 is supplied with working oil from the oil chamber S2 through a check valve 34, thus lowering the drive piston 19.

Since the driven pistons 17a, 17b, 18a, 18b are also lowered with the drive piston 19 through the joint plate 24, working oil in the driven cylinders 14a, 14b, 15a, 15b is supplied to the jack cylinders 8 of the hydraulic dampers 5, thereby lowering the jack pistons 9. Therefore, the reactive forces from the suspension springs 11 increase, so that the height of the motor vehicle increases. After the vehicle height has been set to a predetermined height level, the valve 30 is opened to bleed the gas chamber S1 and hence vent the gas chamber S1 to the atmosphere. The vehicle height adjusting mechanism is now set up.

In order to lower the vehicle height, the downward adjustment switch 36 is operated on to produce a vehicle height reducing signal. The CPU 37 produces a drive signal to open an oil discharge solenoid-operated valve 39. Under the reactive forces from the suspension springs 11, the jack pistons 9 ascend to force working oil from the jack cylinders 8 back into the driven cylinders 14a, 14b, 15a, 15b, thereby moving the drive piston 19 upwardly. Working oil in the drive cylinder 16 now returns through the solenoidoperated valve 39 into the accumulator 27. The upward movement of the jack pistons 9 of-tWe hydraulic dampers 5 reduces the reactive forces of the suspension springs 11, so that the height of the motor vehicle is reduced.

When the piston 19 is lifted a desired distance as indicated by the position signal from the displacement sensor 26, the CPU 37 closes the solenoid-operated valve 39. Working oil from the jack cylinders 8 is no longer returned to the drive cylinder 16, and the process of reducing the vehicle height is ended. Each time the downward adjustment switch 26 is operated on, the vehicle height varies as shown in FIG. 5.

FIG. 6 shows a modified hydraulic damper which may be used in place of each combination of the hydraulic damper 5 and the jack unit in the vehicle height adjusting mecha nisms according to the first and second embodiments of the present invention. The hydraulic damper, generally denoted at 5' in FIG. 6, comprises a damper unit with a jack function, the damper unit being essentially a combination of a hydraulic damper and a jack cylinder mechanism. The damper 5' comprises a cylinder 6 and a hollow piston rod 7' which is connected at its lower end to a piston 7a slidably fitted in the cylinder 6. The piston 7a and a free piston 7b, which is also slidably fitted in the cylinder 6, jointly define an oil chamber S3 therebetween within the cylinder 6, the oil chamber S3 being held in communication with each of the driven cylinders 14a, 14b, 15a, 15b (see FIGS. 1 and 4).

A gas chamber is defined below the free piston 7b in the cylinder 6. The height of the motor vehicle can be adjusted when working oil is directly supplied into and discharged from the oil chamber S3.

FIG. 7 shows a drive cylinder unit 13A according to a first modification for use in the vehicle height adjusting mechanisms according to the first and second embodiments of the present invention. The drive cylinder unit 13A comprises an electric motor 40 serving as a drive source, the electric motor 40 having a rotatable screw shaft 41 extending parallel to the drive piston rods 21a, 21b, 22a, 22b. A nut 42 fixed to the joint plate 24 is threaded over the screw shaft 41. Therefore, when the motor 40 is energized, the joint plate 24 is moved upwardly or downwardly thereby to slidably move the pistons 17a, 17b, 18a, 18b in the respective cylinders 14a, 14b, 15a, 15b.

FIG. 8 shows a drive cylinder unit 13B according to a second modification for use in the vehicle height adjusting mechanisms according to the first and second embodiments of the present invention. While the cylinders 14a, 14b, 15a, 15b are disposed around and parallel to the drive cylinder 16 in the drive cylinder unit 13 shown in FIGS. 1 and 2, the drive cylinder unit 13B according to the second modi fication have a linear array of cylinders. More specifically, the drive cylinder unit 13B has a cylinder 14a connected to an open end of a drive cylinder 16, a cylinder 14b connected to an open end of the cylinder 14a, a cylinder 15a connected to an open end of the cylinder 14b, and a cylinder 15b (not shown) connected to an open end of the cylinder 15a.Pistons 19, 17a, 17b, 18a, 18b are slidably fitted respectively in the cylinders 16, 14a, 14b, 15a, 15b, and have their respective piston rods which are successively threadedly connected to each other. Therefore, when the piston 19 is slidably moved in the cylinder 16, the other pistons 17a, 17b, 18a, 18b are also slidably moved together in the respective cylinders 14a, 14b, 15a, 15b. The arrangement shown in FIG. 8 therefore allows the pistons 17a, 17b, 18a, 18b to move in unison with the piston 19, as with the first modification shown in FIG. 7.

In each of the embodiments described above, all the dampers are operated to effect vehicle height adjustments.

However, only the dampers corresponding to the left and right front wheels or the left and right rear wheels may be operable to adjust the vehicle height. The pistons 17a, 17b, 18a, 18b may not necessarily be required to have the same pressure-bearing areas. Instead, the pressure-bearing area of the pistons 17a, 18a slidably fitted in the front cylinders 14a, 15a may be different from the pressurebearing area of the pistons 17b, 18b slidably fitted in the rear cylinders 14b, 15b for vehicle height adjustments.

Although there have been described what are at present considered to be the preferred embodiments of the present invention, it will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments are therefore to be considered in all aspects as illustrative, and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description.

Claims

Claims:

1. A vehicle height adjusting mechanism comprising a plurality of jack units associated respectively with dampers interposed between a vehicle body and a plurality of axles, a drive source, and a single drive cylinder unit actuatable by the drive source for supplying working oil to and discharging working oil from the jack units to adjust the height of a motor vehicle, said drive cylinder unit having a plurality of driven cylinders connected independently to said jack units, respectively, and a plurality of driven piston assemblies slid ably disposed in said driven cylinders, respectively, for supplying working oil to and discharging working oil from said jack units, respectively.

2. A vehicle height adjusting mechanism according to claim 1, wherein said driven piston assemblies are joined to each other by joint means for slidable movement in unison with each other in said driven cylinders to simultaneously supply working oil to and discharge working oil from the jack units.

3. A vehicle height adjusting mechanism according to claim 1, wherein said driven cylinders are disposed independently parallel to each other, each of said driven piston assemblies having a driven piston slid ably fitted in one of said driven cylinders and a driven piston rod connected to said driven piston, said driven piston rods being joined to each other by a joint element to cause the driven pistons to move in unison with each other in said driven cylinders.

4. A vehicle height adjusting mechanism according to claim 1, wherein said driven cylinders are disposed independently in a linear array, said driven piston assemblies having driven pistons slidably fitted in said driven cylinders, respectively, and driven piston rods interconnecting said driven pistons such that said driven pistons can slidably move in unison with each other.

5. A vehicle height adjusting mechanism according to claim 3, wherein said drive source comprises a hydraulic pressure source, said drive cylinder unit further having a drive cylinder connected to said hydraulic pressure source and disposed parallel to said driven cylinders, and a drive piston slidably fitted in said drive cylinder for slid able movement therein in response to a hydraulic pressure supplied from said hydraulic pressure source, said drive piston being coupled to said joint element for moving said driven piston assemblies in unison therewith.

6. A vehicle height adjusting mechanism according to claim 4, wherein said drive source comprises a hydraulic pressure source, said drive cylinder unit further having a drive cylinder connected to said hydraulic pressure source and connected to an end of said linear array of the driven cylinders, and a drive piston slidably fitted in said drive cylinder for slidable movement therein in response to a hydraulic pressure supplied from said hydraulic pressure source, said drive piston being coupled to an end of said drive piston rods for moving said driven piston assemblies in unison therewith.

7. A vehicle height adjusting mechanism according to claim 3, wherein said drive source comprises an electric motor having a rotatable screw shaft extending parallel to said driven piston rods, said joint element comprising a nut threaded over said screw shaft, whereby said driven piston assemblies can slide in said driven cylinders through threaded engagement between said nut and said screw shaft which is rotated by said electric motor.

8. A vehicle height adjusting mechanism according to claim 3 or 4, wherein the axles include left and right axles, and the jack units include a left jack unit interposed between the vehicle body and the left axle and a right jack unit interposed between the vehicle body and the right axle, and wherein the driven piston slidably fitted in the driven cylinder associated with the left jack unit has a pressure-bearing area which is the same as the pressurebearing area of the driven piston slid ably fitted in the driven cylinder associated with the right jack unit.

9. A vehicle height adjusting mechanism according to claim 1, wherein each of said dampers comprises a hydraulic damper including a cylinder having a lower end supported on one of said axles, and a piston rod inserted in said cylinder and having an upper end supported on said vehicle body, and wherein each of said jack units comprises a jack cylinder mounted on an upper end of said piston rod, a jack piston slidably fitted in said jack cylinder, and a suspension spring disposed between said piston and said cylinder of the hydraulic damper.

10. A vehicle height adjusting mechanism according to claim 1, wherein each of said dampers is combined with one of said jack units, thereby constituting a single damper and jack unit combination, said damper and jack unit combination comprising a cylinder having a lower end supported on said vehicle body, a piston slidably fitted in said cylinder and dividing an interior of the cylinder into first and second oil chambers, said piston having having a valve which provides communication between said first and second oil chambers, and a hollow piston rod connected to said piston for supplying working oil from one of said driven cylinders to and discharging working oil to said one of the driven cylinders from one of said first and second oil chambers.

11. Vehicle height adjusting mechanisms substantially as hereinbefore described with reference to the accompanying drawings.