JPH02306817A - Suspension control device - Google Patents

Abstract

PURPOSE:To improve safety in the device in the title for ground clearance adjustment and posture control by branching a release pipeline with a check valve opened when abnormal supply is continued between a flow rate control valve and a hydraulic cylinder, and connecting the pipeline to a reservoir tank. CONSTITUTION:A release pipeline 21 is branched between a pilot check valve 14 and a hydraulic cylinder 11, connected to the combined pipeline part 15A of a pilot pipeline 15 through a release valve 22, and communicated to a reservoir tank 2. The release pipeline 21 is formed of two branched release pipeline parts 21A branched from each supply and discharge pipeline 8 and a combined release pipeline part 21B combining them, and a release valve 22 is provided in the connecting part of the both pipeline parts 21A, 21B. The release valve 22 is formed in such a manner as to release oil pressure in a hydraulic cylinder 11 to the reservoir tank 2 when abnormal supply is contained. According to this constitution, safety can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suspension control device that adjusts vehicle height or controls the attitude of a vehicle body.

[Conventional technology] FIG. 3 shows a prior art suspension control device.

In the figure, l is a hydraulic pump driven by an engine, motor, etc. (not shown), 2 is a reservoir tank in which oil is stored, and the suction side of the hydraulic pump 1 is connected to the reservoir tank 2 via a suction pipe 3. has been done.

Reference numeral 4 denotes a supply pipe provided on the discharge side of the hydraulic pump 1, and the supply pipe 4 includes, in order from the hydraulic pump l side, a check valve 5 for preventing pressure oil from flowing back to the hydraulic pump 1 side, and a hydraulic A main accumulator 6 is provided that temporarily stores pressure oil from the pump 1 and supplies the pressure oil to the hydraulic cylinder 11 in accordance with the operation of a flow rate control valve 7, which will be described later. Further, the supply pipe 4 branches into branch supply pipe parts 4A, 4A in the middle.

7.7. . . . is a flow rate control valve connected to each branch supply piping section 4A, and each flow rate control valve 7 is connected to each branch supply piping section 4A.
Consisting of a three-position electromagnetic proportional control valve, the spool section is displaced by controlling the current flowing through the solenoid section, and the hydraulic cylinder 11, which will be described later, is extended, normally in the neutral position (A). When the oil pressure cylinder 11 is contracted, it is placed in the oil supply position (b), and when the hydraulic cylinder 11 is contracted, it is placed in the oil drain position (c). Furthermore, the flow control valve 7 is configured such that by adjusting the magnitude of the current flowing through the solenoid section, the spool section is continuously displaced according to the magnitude to adjust the valve opening degree and perform feedback control. It has become. Note that, due to the structure of the flow control valve 7 as a spool valve, even if it is in the neutral position (A), leakage is likely to occur between each branch supply piping section 4A and the piping 8 and 9 described later.

8.8. . . . are supply/discharge pipes connecting each flow control valve 7 and a suspension IO to be described later, 9.9.・・・
* indicates a return pipe connecting each flow control valve 7 and the reservoir tank 2, respectively. Note that the return pipe 9 is extended from each of the flow rate control valves 7 and merged into a single merging pipe portion 9A, which extends into the reservoir tank 2.

Reference numeral 10 indicates four suspensions that suspend the vehicle body (in the figure, only the left and right suspensions of the front or rear wheels are shown); 11 indicates a hydraulic cylinder that constitutes the suspension 10; each hydraulic cylinder 11 is a cylindrical cylinder; Part 1
1A, and a piston rod IIB whose one end is fixed to a piston (not shown) slidably inserted into the cylinder section 11A and whose other end projects outside the cylinder section 11A. Each hydraulic cylinder 11 is connected to a hydraulic pump 1 via a supply/discharge pipe 8, and is expanded or contracted by pressure oil supplied and discharged from the hydraulic pump I to adjust the vehicle height or the posture of the vehicle body. It is designed to take control. The hydraulic cylinder 11 is connected to an accumulator 12 and is provided with a damping force valve 13 as a damping force generating mechanism, so that the pressure oil in the hydraulic cylinder 11 is connected to the accumulator 12 and the hydraulic cylinder 11 . A damping force is generated by a damping force valve 13 when moving between the two.

14.14. . . . are pilot check valves as leakage prevention valves installed in the middle of each supply/discharge pipe 8,
Each pilot check valve 14 prevents the pressure oil in each hydraulic cylinder 11 from leaking to the reservoir tank 2 side via the flow rate control valve 7, which tends to leak, and lowering the vehicle height when the vehicle is not driven for a long period of time. When pilot pressure is not applied, it functions as a normal check valve, and when pilot pressure is applied, it opens and pressurized oil can flow freely in both directions. It is now ready for distribution. Reference numeral 15 denotes a pilot pipe whose one end side is connected to each pilot check valve 14, and the pilot pipes 15 are joined together to form one merging pipe portion 15A. 16 is the confluence piping section 15A
The pilot pressure control valve 16 is a 3-bottom, 2-position electromagnetic switching valve,
The merging piping section 15A of each pilot piping 15 is connected to the one branch supply piping section 4A and the return piping 9 via connection piping 17.18, respectively, so that the merging piping section 15A is connected to the branch supply piping section 4A. and the return pipe 9.

Further, an unloading pipe 19 is provided between the supply pipe 4 located between the hydraulic pump l and the check valve 5 and the merging pipe section 9A by connecting them. is provided with an unload valve 20 consisting of a two-bottom, two-position electromagnetic switching valve. The unload valve 20 is normally located at a neutral position (:), and the unload valve 20 is
When the pressure of the pressure oil supplied from the hydraulic pump 1 to the main accumulator 6 reaches a predetermined value, the main accumulator 6 is placed in the communication position (N) so that the pressure oil from the hydraulic pump 1 is returned to the reservoir tank 2.

Each of the flow rate control valves 7. Pilot pressure control valve 16
and the unload valve 20 are each connected to a control device (not shown), and the control device maintains the vehicle height at an optimum state according to the vehicle condition (increase/decrease in number of passengers and loaded baggage, vehicle speed, etc.). are controlled by each. Furthermore, the control device is equipped with a fail-safe function against malfunction of the control valve 7 for each flow 11. In other words, if one of the flow rate control valves 7 malfunctions, the control device may cause the hydraulic cylinder 11 that is controlled by the flow rate control valve 7 to malfunction.
When the internal pressure of the hydraulic cylinder l decreases to the shortest state, the hydraulic cylinder l
A pressure sensor or vehicle height sensor (both not shown) provided on the l side detects this, and other flow rate controls are applied. l valve 7
control oil to bring all the hydraulic cylinders 11 to the shortest possible state, and if one of the flow control valves 7 malfunctions,
When the internal pressure of the hydraulic cylinder 11 controlled by the flow rate control valve 7 rises to the longest state, the sensor detects this,
All hydraulic cylinders 11 by controlling other flow control valves 7
It is equipped with a function that prevents the vehicle body from tilting and controls its posture so that it is always in a horizontal state.

The pilot pressure control well 16 is normally not energized and communicates between the return pipe 9 and the pilot pipe 15, and when the flow control valve 7 is switched to the oil drain position (c), It may be set so that the pilot check valve 14 is opened by energizing the supply pipe 4 and the pilot pipe 15, and the main switch of the vehicle is set to O.
When it is set to N, the supply pipe 4 and the pilot pipe 15 may be communicated with each other, and the pilot check valve 14 may be opened.

In the conventional suspension control device purchased as described above, when the hydraulic pump l is driven by the engine or the like, the pressure oil discharged from the hydraulic pump l flows through the check valve 5.
When the pressure is accumulated in the main accumulator 6 via The pressure oil is returned to the reservoir tank 2, and the internal pressure in the supply pipe 4 is set to a predetermined pressure.

When the vehicle height becomes lower due to an increase in passengers or onboard luggage, the vehicle height sensor detects this, and the control device switches each flow rate control valve 7 from the neutral position (A) to the refueling position (B).
The pressure oil stored in the main engine regulator 6 is supplied to the hydraulic cylinders 11 of each suspension 10 through each pilot check valve 14, and the hydraulic cylinders 11 are extended to raise the vehicle height and maintain a constant level. Maintain vehicle height. At this time, each hydraulic cylinder 11 has a different height depending on the position of the passenger or cargo (the vehicle body may tilt), but each flow control valve 7 that controls each hydraulic cylinder 11 is controlled by a vehicle height sensor. The difference in height is detected, and each flow control valve 7 is selectively positioned at the refueling position (B), and the valve volume is adjusted in the meantime, so that the heights of all hydraulic cylinders 11 are controlled to match. ing.

Furthermore, when the vehicle height increases due to a reduction in the number of passengers and cargo on board, the flow control valve 7 is switched from the neutral position (A) to the oil drain position (C), and the pressure oil in the hydraulic cylinder 11 flows through the return pipe 9. The oil is returned to the reservoir tank 2 via the hydraulic cylinder 11, and the hydraulic cylinder 11 contracts, lowering the vehicle height and maintaining a constant vehicle height. Also at this time, when the vehicle body is tilted, the control device performs the same control as in the above case.

On the other hand, if one of the flow control valves 7 malfunctions while remaining in the oil drain position (c), in this state, the pilot check valve 14 controlled by the pilot pressure control oil well 16 will open. The pressure oil in the hydraulic cylinder 11, which is in a valve state and is controlled by the flow rate control valve 7, is returned to the reservoir tank 2 from the return pipe 9, and the internal pressure of the hydraulic cylinder 11 decreases, causing the hydraulic cylinder 11 to becomes the shortest state. As a result, the vehicle height of the part of the suspension 10 in which the hydraulic cylinder 11 controlled by the flow control valve 7 that has caused the abnormality is incorporated becomes low (and the vehicle body tends to lean, but the control device detects this and , controls the other flow rate control valves 7 to bring all other hydraulic cylinders 11 to the shortest possible position to prevent the vehicle body from tilting.

Also, one of the flow rate control valves 7 is at the refueling position (o
), and a malfunction occurs and the hydraulic cylinder 11 controlled by the flow rate control valve 7 and the main accumulator 6 become in communication, the pressure oil in the accumulator 7 is continuously transferred to the hydraulic cylinder 11. The internal pressure of the hydraulic cylinder 11 increases and the hydraulic cylinder 11 becomes the longest state, and only the vehicle height of the part of the suspension 10 in which the hydraulic cylinder ti is incorporated increases and the vehicle body tends to lean. The control device detects this and controls all other flow rate control valves 7 to the refueling position (B), and all other hydraulic cylinders 11 to the longest position to prevent the vehicle body from tilting.

In addition, in the prior art, pilot pressure control is used as a leakage prevention valve to prevent the pressure oil in each hydraulic cylinder 11 from leaking to the reservoir tank 2 side and lowering the vehicle height when the vehicle is not driven for a long period of time. Although the explanation has been given using the pilot check valve 14 controlled by the well 16 as an example, it is also possible to install a 2-bot, 2-position electromagnetic switching valve controlled by a control device in the middle of the supply/discharge pipe 8. Are known.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, if a malfunction occurs while the flow rate control valve 7 is in the oil supply position (0), an abnormal state occurs in which the pressure oil continues to be supplied (abnormal supply continues).
Since there is no means to discharge the pressure oil in the supply/discharge piping 8 connected to the flow control valve 7 and the hydraulic cylinder 11, it is possible to prevent the vehicle from leaning by setting all the hydraulic cylinders 11 to their maximum length and raising the vehicle height. is prevented. However, as the height of the vehicle increases, there is a problem in that the running stability deteriorates and there is a risk of overturning if the vehicle is not stable.

The present invention was developed in view of the above-mentioned problems of the prior art.The present invention improves safety during driving by constantly controlling the hydraulic cylinder to lower the vehicle height in response to malfunction of the flow control valve, especially abnormal continuous supply. The purpose of the present invention is to provide a suspension control device that ensures the following.

[Means to solve the problem]

The configuration adopted by the present invention in order to solve the above-mentioned problems includes a pair of left and right hydraulic cylinders that are incorporated into a vehicle suspension and control the vehicle height or the attitude of the vehicle body by expanding and contracting, and a pair of left and right hydraulic cylinders that are connected to each of the hydraulic cylinders. , a hydraulic pump that supplies oil stored in a reservoir tank into each hydraulic cylinder, and a hydraulic pump that is provided between the hydraulic pump, the reservoir tank, and each hydraulic cylinder, and that controls the amount of oil supplied to and discharged from each hydraulic cylinder. In a suspension control device having a pair of flow rate control valves to be controlled, a relief pipe is branched from between the flow rate control valve and each hydraulic cylinder and communicates with the reservoir tank, and a relief pipe is provided in the middle or at a branch part of the relief pipe. and a relief valve that releases the pressure oil in the hydraulic cylinder to the reservoir tank when abnormal supply continues from the flow rate control valve.

[Function] With the above configuration, if the flow control valve malfunctions (continuation of abnormal supply) and the hydraulic cylinder side and hydraulic pump side remain in communication and do not change, the relief valve opens and the hydraulic pressure is reduced. Pressure oil in the cylinder is returned directly to the reservoir tank from the relief pipe, preventing the vehicle height from rising abnormally.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2. The overall configuration of the suspension control device of this embodiment is almost the same as the suspension control device of the prior art described above, so the same members are given the same reference numerals and the explanation thereof will be omitted here.

First, a first embodiment of the present invention will be described based on FIG.

Figure 1 shows a pair of left and right suspensions on the front wheel side.The rear wheel side has the same configuration as the front wheel side, except that the pump 1, reservoir tank 2, accumulator 6, etc. are common.
The explanation will be omitted.

In the figure, reference numeral 21 indicates a pair of left and right supply/discharge pipes 8 that are branched off from between the pilot check valve 14 and the hydraulic cylinder 11, and are joined together to connect to the merging pipe section 15A of the pilot pipe 15. The relief piping 21 is a relief piping connected to the reservoir tank 2.
1A, and a merged relief piping section 21B in which the branch relief piping sections 21A are merged into one.

22 is the branch relief piping section 21A and the confluence relief piping section 21
The relief valve 22 is a 2-bottom, 2-position electromagnetic switching valve installed at the connection position with B. The relief valve 22 is a two-bottom, two-position electromagnetic switching valve, and is connected to the control outlet device to connect all the branch relief piping sections 2LA to one another. It can be selectively switched between a relief position (to) connected to the relief piping portion 21B and a neutral position (g).

Then, when one of the flow rate control valves 7 malfunctions and the corresponding hydraulic cylinder 11 is in the longest state or the shortest state, the control device de-energizes the pilot pressure control valve 16 and releases the relief piping. 21 side and the return piping 9 side, the relief valve 22 is energized and placed in the relief position (to), and the pressure oil in each hydraulic cylinder 11 is transferred through the pilot check valve 14 and the flow rate control valve 7. It is set so that the hydraulic cylinder 11 is always contracted to the shortest position and the vehicle height is lowered in the event of any malfunction of the flow rate control valve 7 by directly returning it to the return pipe 9 instead of At the same time, the unload valve 20 is placed in the communication position (N) so that the pressure oil from the hydraulic pump 1 is not supplied to the supply pipe 4.

The present embodiment is configured as described above, and its operation will be explained next. The overall operation of the suspension control device of this embodiment is the same as that of the prior art described above, so the explanation thereof will be omitted here.

However, in this embodiment, if any of the flow control valves 7 malfunctions while being in the force q oil-retaining position (b), the hydraulic cylinder l controlled by that flow control valve 7
The pressure in the hydraulic cylinder 11 increases and the hydraulic cylinder 11 expands, but either the vehicle height sensor detects a vehicle height higher than a predetermined height, or the pressure sensor detects a pressure higher than a predetermined value, and the control device , the relief valve 22 is energized and placed in the relief position (to), and the pilot pressure control valve 16 is de-energized and communicated with the return piping 9, so that the pressure oil in each hydraulic cylinder 11 is transferred to the relief piping 21. ．． Relief valve 22. The pressure is released through the pilot pressure control valves 16 to the return piping 9 and returned to the reservoir tank 2, and the hydraulic cylinder 11 is brought to its shortest position. At the same time, the unload valve 20 is placed in the communication position (N) to allow the pressure oil from the hydraulic pump 1 to flow back to the reservoir tank 2 and prevent it from being supplied to the supply pipe 4. When the pressure oil in the hydraulic cylinder 11 is exhausted, the influence of the pressure oil from the main accumulator 6 side is eliminated, and the pressure oil in the hydraulic cylinder 11 is drained within a short time.

In addition, if each flow rate control valve 7 malfunctions while remaining in the oil drain position (c), the control device controls the relief valve 22 to prevent each hydraulic cylinder from operating in the same manner as described above. The pressure oil in ll is released from the pipe 21. Relief valve 2
2. The pressure is returned to the reservoir tank 2 through the pilot pressure control wells 16, respectively, and each hydraulic cylinder 11 is brought to its shortest position. In this case, the control device may be set in the same manner as in the prior art (in this case, each hydraulic cylinder 11 is brought to its shortest position by the same control action as in the prior art).

As a result, if an abnormality occurs in the flow rate control valve 7, the vehicle height is always lowered, and even when the vehicle is running, it will not suddenly become unstable and roll over, greatly improving safety. .

Further, when replacing the entire suspension 10 or the hydraulic cylinder 11 during maintenance, the internal pressure of the hydraulic cylinder 11 can be relieved by simply opening the relief valve 22, which simplifies the replacement work.

Next, a second embodiment of the present invention will be described.

In this embodiment, instead of the pilot check valve 14, the leakage prevention valve is a two-bottom valve that is controlled by the control device and is open when the control device is in an operating state and closed when the control device is in an inactive state. Two-position electromagnetic switching valves 23 are provided in the middle of the supply/discharge piping 8, respectively. For this reason, the confluence and relief piping section 21B of the relief piping 21 is directly connected to the return piping 9.

The suspension control device of this embodiment is constructed as described above, except that the operation is to control the electromagnetic switching valve 23 instead of controlling the pilot pressure side valve 16. It operates in the same manner as the embodiment and produces the same effects.

In the first and second embodiments, the hydraulic supply systems for the front and rear wheels of the suspension are made independent, and only the pair of left and right hydraulic supply systems on the side that has failed are drained. Alternatively, the four wheels may be provided with the same hydraulic pressure supply system to drain oil from all four wheels at the same time.

Although the branch point of the relief pipe 21 is provided between the leak prevention valve 14.23 and the hydraulic cylinder 11, it may be provided between the leak prevention valve 14.23 and the flow rate control valve 7.

If the flow rate control valve 7 is not a spool valve and is of a type that does not cause leakage during oil supply and drainage, the leakage prevention valves 14 and 23 can be omitted.

In addition, the above-mentioned No. 1. In the second embodiment, only one relief valve 22 is provided in the middle of the relief pipe 21 branched from the supply/discharge pipe 8, but the present invention is not limited to this. Four relief valves 22 may be provided at each branch portion, and each relief valve 22 may be controlled and released by a control device. In this case, the control device controls the flow rate control valve 7.
In case of an abnormality, all the relief valves 22 may be set to be controlled at the same time, or only the relief valve 22 of the flow control valve 7 where the abnormality has occurred is operated, and the rest are controlled by the flow control valve 7. The pressure oil in the cylinder 11 may be released to the reservoir tank 2.

Furthermore, the four relief valves 22 provided at the branch points of each supply/discharge piping 8 and relief piping 21 are composed of three-bottom, two-position electromagnetic switching valves, which also function as leakage prevention valves. You may also do so.

[Effects of the Invention J As described in detail above, according to the present invention, there is a valve installed in the middle or at the branch part of the relief pipe that branches between the flow control valve and the hydraulic cylinder and communicates with the reservoir tank, in the event of an abnormality in the flow control valve. A relief valve is provided to release the pressure oil in the hydraulic cylinder to the reservoir tank, so even if the flow control valve malfunctions and the hydraulic cylinder side and hydraulic pump side remain in communication and do not change, The relief valve opens and releases the pressure oil in the hydraulic cylinder directly from the piping to the reservoir tank, preventing the vehicle height from rising abnormally. As a result, no matter what kind of abnormality occurs in the flow control valve, the vehicle height will always be lowered, and even when the vehicle is running, it will not suddenly become unstable (and roll over), greatly improving safety. .

[Brief explanation of the drawing]

1 and 2 relate to embodiments of the present invention, FIG. 1 is an overall configuration diagram of a suspension control device showing the first embodiment, and FIG. 2 is a diagram of the suspension control device showing the second embodiment. FIG. 3 is an overall configuration diagram of a suspension control device according to the prior art. l...Hydraulic pump, 7...Flow control valve, 10...
Suspension, 11... Hydraulic cylinder, 14...
Pilot check valve (leak prevention valve), 21... relief piping, 22... relief valve, 23... electromagnetic switching valve (leak prevention valve). @Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A pair of left and right hydraulic cylinders that are built into the vehicle suspension and expand and contract to control the vehicle height or posture of the vehicle, and are connected to each hydraulic cylinder to supply oil stored in a reservoir tank into each hydraulic cylinder. In the suspension control device, the suspension control device includes a hydraulic pump, a pair of flow control valves each provided between the hydraulic pump, a reservoir tank, and each hydraulic cylinder, and controlling the amount of oil supplied to and discharged from each hydraulic cylinder. A relief pipe is provided between the flow control valve and each hydraulic cylinder and communicates with the reservoir tank, and a relief pipe is provided in the middle or at a branch part of the relief pipe, and is provided in the hydraulic cylinder when abnormal supply continues from the flow control valve. A suspension control device comprising: a relief valve that releases pressure oil to the reservoir tank.