JP2019077408A - Suspension system - Google Patents

Abstract

To enable vehicle height increase adjustment in a short time and to hinder increase in load on a pump motor.SOLUTION: A master valve unit 100 is provided in a common plumbing passage 54 that supplies hydraulic oil to a hydraulic cylinder from a pump device 71. The master valve unit 100 comprises: a master valve 100a, which is an electromagnetic opening/closing valve; and a check valve 100b. This check valve 100b is realized by a cup seal 170. The cup seal 170 is provided in a cylindrical communication passage 160 provided outside a passage where hydraulic oil flows in the master valve 100a. In a case where a vehicle height is adjusted in an increasing direction, the cylindrical communication passage 160 is opened to cause hydraulic oil to flow. In a case where the vehicle height is adjusted in a decreasing direction, the cylindrical communication passage 160 is closed to block flow of hydraulic oil.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a suspension system having a vehicle height adjustment function of adjusting a vehicle height by hydraulic pressure of a hydraulic cylinder provided between a vehicle body and a wheel holding member.

  Conventionally, for example, as proposed in Patent Document 1, a suspension system that adjusts the vehicle height by controlling the hydraulic pressure of a hydraulic cylinder (shock absorber) provided between the vehicle body and the four wheel holding members is disclosed. Are known. The hydraulic cylinder of each wheel is connected to the hydraulic oil supply and discharge device via an individual control passage. In this suspension system, an individual control valve for opening and closing an individual control passage and a hydraulic oil supply / discharge device are controlled to raise the vehicle height by supplying hydraulic oil to each hydraulic cylinder, and hydraulic oil is supplied from each hydraulic cylinder. Lower the vehicle height by discharging it.

  Further, each hydraulic cylinder communicates with a high pressure accumulator having a large spring constant and a low pressure accumulator having a small spring constant. A passage that communicates the hydraulic cylinder with the low pressure accumulator is provided with a spring switching valve that can be switched between a state in which both communication is permitted and a state in which the communication is shut off. Therefore, the wheel rate can be switched by opening and closing the spring switching valve.

  In this suspension system, during normal travel, the high pressure accumulator and the low pressure accumulator are communicated with the hydraulic cylinder (spring switching valve: open) and the wheel rate is set to be small (soft). Further, at the time of rapid turning and rapid acceleration / deceleration, the communication between the hydraulic cylinder and the low pressure accumulator is cut off (spring switching valve: closed) and the wheel rate is set to be large (hard). The wheel rate is the spring constant at the wheel position, and the ratio of the change in the ground contact load of the wheel to the change in the vertical distance between the vehicle body and the wheel center (wheel travel) at the wheel, ie, unit wheel travel It represents the amount of change in the contact load of the wheel required to cause it.

JP, 2008-168861, A

  In the above-described system, when raising the vehicle height, the hydraulic pressure in the hydraulic cylinder is increased by operating the pump of the hydraulic oil supply and discharge device to supply hydraulic oil to the hydraulic cylinder to raise the piston rod. At the same time, hydraulic oil is simultaneously supplied to the low pressure accumulator and the high pressure accumulator. For this reason, the amount of hydraulic oil required to raise the vehicle height is large, and accordingly, the time required to raise the vehicle height becomes long.

  Therefore, the applicant of the present invention has considered a new suspension system that can independently perform the supply and discharge of hydraulic oil of the hydraulic cylinder and the supply and discharge of hydraulic oil of the low pressure accumulator. The new suspension system includes a bypass passage that bypasses the individual control valve and the spring switching valve to communicate the low pressure accumulator with the hydraulic fluid supply and discharge device, and a bypass valve that opens and closes the bypass passage. Therefore, by closing the bypass valve and the spring switching valve and supplying the hydraulic oil from the hydraulic oil supply and discharge device (pump) to the hydraulic cylinder, the vehicle height is increased without supplying the hydraulic oil to the low pressure accumulator. It can be done.

  When the spring switching valve is opened from the state where the vehicle height is raised in this way, the hydraulic cylinder and the low pressure accumulator communicate with each other, and the differential pressure between them causes the hydraulic oil to move between them, causing the vehicle height to fluctuate. Resulting in. However, in this new system, after the height elevation is completed, the bypass valve is opened with the individual control valve and the spring switching valve closed, so that the low pressure accumulator from the hydraulic oil supply and discharge device (pump) It can only supply hydraulic fluid. Therefore, by raising the hydraulic pressure of the low pressure accumulator until it becomes equal to the hydraulic pressure of the hydraulic cylinder, it is possible to prevent the vehicle height from changing even if the spring switching valve is opened thereafter.

  In such a system, it is necessary to individually measure the hydraulic pressure of the hydraulic cylinder and the low pressure accumulator. For this purpose, a main valve is provided in the supply / discharge source passage, which is a common passage for supplying the hydraulic oil to the hydraulic cylinders of the respective wheels from the hydraulic oil supply / discharge device (pump). If the device is considered upstream, a hydraulic sensor is provided.

  However, when the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil increases, so the pressure difference ΔP between the upstream side and the downstream side of the main valve becomes large. FIG. 6 (a) is a graph showing the relationship between the pump discharge flow rate Q and the pressure difference ΔP between the upstream side and the downstream side of the main valve for each temperature of the hydraulic oil. As can be seen from this graph, the pressure difference ΔP increases as the temperature of the hydraulic oil decreases and as the pump discharge flow rate Q increases.

  An increase in the pressure difference ΔP leads to an increase in the discharge pressure of the pump, resulting in an increase in the motor current of the pump. FIG. 6B is a graph showing the relationship between the pump discharge flow rate Q and the motor current increase amount for each temperature of the hydraulic oil. As can be seen from this graph, even if the pump discharge flow rate is within the range of use in the hydraulic system, the motor current may exceed the limit value when the hydraulic oil becomes low temperature. Therefore, the durability of the pump motor may be reduced.

  The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a suspension system capable of performing height adjustment in a short time and suppressing an increase in load on a pump motor. .

In order to achieve the above object, the features of the present invention are:
A hydraulic cylinder (20) provided between the wheel holding member and the vehicle body in each of the left and right front and rear wheels of the vehicle, which accommodates hydraulic oil and expands and contracts in accordance with a change in distance between the wheel holding member and the vehicle body ,
A first gas spring (31) provided corresponding to each hydraulic cylinder of the left, right, front and rear wheels and communicating with the hydraulic cylinder to function as a spring of a hydraulic system; and a second gas spring (32)
A spring switching valve (62) provided corresponding to each hydraulic cylinder and switchable between a state allowing communication between the hydraulic cylinder and the second gas spring and a state blocking it;
A pump for supplying and discharging hydraulic oil to and from each of the hydraulic cylinders, and a hydraulic oil supply and discharge device (70) having a reservoir tank;
A supply / discharge hydraulic pressure control circuit (54, 100) having a supply / discharge source passage connected to the hydraulic fluid supply / discharge device and serving as a passage through which the hydraulic fluid flows, and a source valve unit for opening and closing the supply / discharge source passage;
A passage for adjusting the vehicle height, which is provided corresponding to each of the hydraulic cylinders and is a passage of hydraulic oil for communicating each of the hydraulic cylinders with the supply / discharge source passage, and opens / closes the passage for adjusting the vehicle height A hydraulic control circuit (51, 61) for height adjustment having a valve for height adjustment;
A hydraulic oil passage provided corresponding to each of the hydraulic cylinders and bypassing the spring switching valve and the vehicle height adjusting valve to communicate each of the second gas springs with the supply / discharge source passage. A second gas spring hydraulic control circuit (53, 63) having a bypass passage and a bypass valve for opening and closing the bypass passage;
Provided in the hydraulic oil passage on the hydraulic cylinder side with respect to the original valve unit and in the original valve unit side with respect to the bypass valve and on the original valve unit side with respect to the vehicle height adjustment valve An oil pressure sensor (90) for detecting the oil pressure in the passage,
In the case of adjusting the vehicle height in the upward direction, the vehicle height is controlled in the state where the spring switching valve and the bypass valve of the vehicle height adjustment target wheel are closed while controlling the original valve unit in the valve opening state. The vehicle height adjustment valve of the vehicle height adjustment target wheel is controlled to the open state until the vehicle height is reached, the hydraulic fluid is supplied from the hydraulic fluid supply and discharge device to the hydraulic cylinder, and the vehicle height reaches the target vehicle height. The hydraulic pressure detected by the hydraulic pressure sensor at the time of having been stored is stored, and the second gas of the vehicle height adjustment target wheel is closed with the spring switching valve of the vehicle height adjustment target wheel and the vehicle height adjustment valve closed. And a vehicle height control means (200, S11 to S19) for controlling the bypass valve in the open state until the hydraulic pressure of the spring becomes equal to the stored hydraulic pressure.
The former valve unit
A solenoid on-off valve (100a) for opening and closing the supply / discharge source passage;
By bypassing the in-valve passage (133) which is a passage through which the hydraulic oil flows in the electromagnetic on-off valve, the supply and discharge source passage on the hydraulic oil supply and discharge device side with respect to the electromagnetic on-off valve and the hydraulic cylinder A hydraulic fluid passage communicating with the supply and discharge source passage, and a cylindrical communication passage (160) formed around the cylindrical outer wall (130) forming the in-valve passage;
It is provided in the cylindrical communication passage, and allows the flow of hydraulic oil from the hydraulic oil supply and discharge device side to the hydraulic cylinder side in the cylindrical communication passage, and the hydraulic oil supply and discharge device side from the hydraulic cylinder side And a cup seal (170) for blocking the flow of hydraulic fluid to the

  In the present invention, hydraulic cylinders are provided between the wheel holding member and the vehicle body in each of the left and right front and rear wheels of the vehicle. The hydraulic cylinder accommodates hydraulic oil and expands and contracts in accordance with a change in distance between the wheel holding member and the vehicle body.

  A first gas spring and a second gas spring, which communicate with the hydraulic cylinder and function as a spring of a hydraulic system, are provided in the respective hydraulic cylinders of the left and right front and rear wheels. The first gas spring has, for example, a first gas chamber and a first oil chamber in communication with the hydraulic cylinder, and the amount of hydraulic oil accommodated in the first oil chamber according to the hydraulic pressure of the hydraulic cylinder is It changes and functions as a hydraulic system spring. The second gas spring has, for example, a second gas chamber and a second oil chamber communicating with the hydraulic cylinder, and the amount of hydraulic oil accommodated in the second oil chamber according to the hydraulic pressure of the hydraulic cylinder is It changes and functions as a hydraulic system spring.

  The second gas spring is switched by the spring switching valve between a state in which communication with the hydraulic cylinder is permitted and a state in which communication with the hydraulic cylinder is shut off. Therefore, when the spring switching valve is opened, the hydraulic cylinder is in a state in which it is in communication with both the first gas spring and the second gas spring, that is, the wheel rate is set small (soft). Further, by closing the spring switching valve, the hydraulic cylinder communicates with only the first gas spring among the first gas spring and the second gas spring, that is, the state where the wheel rate is set high (Hard)

  By adjusting the pressure of the hydraulic fluid accommodated in the hydraulic cylinder, it is possible to adjust the vehicle height of the wheel position where the hydraulic cylinder is provided. In each hydraulic cylinder, hydraulic oil is supplied and discharged by the hydraulic oil supply and discharge device and the supply and discharge hydraulic pressure control circuit, whereby the vehicle height is adjusted. The hydraulic oil supply and discharge device has a pump (high pressure source) for supplying the hydraulic oil to the hydraulic cylinder, and a reservoir tank (low pressure source) for discharging the hydraulic oil from the hydraulic cylinder.

  The supply and discharge hydraulic pressure control circuit has a supply and discharge source passage connected to the hydraulic fluid supply and discharge device and serving as a passage through which the hydraulic fluid flows, and a source valve unit for opening and closing the supply and discharge source passage.

  The suspension system includes a vehicle height adjustment hydraulic control circuit and a second gas spring hydraulic control circuit, which are provided corresponding to the respective hydraulic cylinders. The vehicle height adjustment hydraulic control circuit is a passage for adjusting the vehicle height, which is a passage for hydraulic oil that connects each hydraulic cylinder to the supply / discharge source passage, and a valve for adjusting the vehicle height adjustment for opening / closing the vehicle height adjustment passage. Have. Therefore, the hydraulic pressure of the hydraulic cylinder of the wheel whose height is to be adjusted can be adjusted to adjust the vehicle height by opening the valve for height adjustment of the original valve unit and the wheel whose height is to be adjusted.

  The second gas spring hydraulic control circuit bypasses the spring switching valve and the vehicle height adjustment valve, and is a bypass passage that is a hydraulic oil passage that causes each of the second gas spring to communicate with the supply and discharge source passage, A bypass valve is provided to open and close the bypass passage. Therefore, with the spring switching valve and the height adjustment valve closed, the hydraulic pressure of any second gas spring is independently adjusted by opening the original valve unit and the optional bypass valve. Can.

  When adjusting the oil pressure of any second gas spring independently, if the oil pressure of the oil pressure cylinder and the second gas spring oil pressure are the same pressure, then the height of the vehicle is increased even if the spring switching valve is opened and closed. The wheel rate can be switched without changing the. For that purpose, a hydraulic pressure sensor is provided. The hydraulic pressure sensor is provided in a hydraulic oil passage on the hydraulic cylinder side with respect to the original valve unit, on the original valve unit side with respect to the bypass valve, and on the original valve unit side with respect to the vehicle height adjustment valve. The hydraulic pressure of the passage is detected. In this case, if the original valve unit and the spring switching valve are closed, the hydraulic pressure of the hydraulic cylinder can be detected by opening the height adjustment valve, and the bypass valve is opened. The oil pressure of the gas spring can be detected.

  The vehicle height control means controls the original valve unit in the open state when adjusting the vehicle height in the upward direction, and closes the spring switching valve and the bypass valve of the vehicle height adjustment target wheel. The valve for height adjustment of the wheel to be height-adjusted is controlled to the open state until the height reaches the target vehicle height, and the hydraulic oil is supplied from the hydraulic oil supply and discharge device to the hydraulic cylinder. In this case, since the supply of hydraulic oil to the second gas spring is not involved, the vehicle height can be adjusted to the target vehicle height in a short time (with a small amount of oil).

  Furthermore, the vehicle height control means stores the hydraulic pressure detected by the hydraulic pressure sensor when the vehicle height reaches the target vehicle height. The stored hydraulic pressure is equal to the hydraulic pressure of the hydraulic cylinder when the vehicle height reaches the target vehicle height. Therefore, if the hydraulic pressure of the second gas spring is set to the stored hydraulic pressure after the vehicle height reaches the target vehicle height, even if the spring switching valve is in the open state, the hydraulic cylinder causes pressure fluctuation. The wheel rate can be reduced (without causing a height fluctuation shock). Therefore, the vehicle height control means makes the hydraulic pressure of the second gas spring of the vehicle height adjustment target wheel equal to the stored oil pressure with the spring switching valve of the vehicle height adjustment target wheel and the valve for the vehicle height adjustment closed. The bypass valve is controlled to open. As a result, it is possible to switch the wheel rate thereafter without causing a vehicle height fluctuation shock.

  When adjusting the vehicle height in the downward direction, the hydraulic oil of the hydraulic cylinder can be returned to the hydraulic oil supply and discharge device by the force by which the hydraulic cylinder is contracted by the weight of the vehicle, so the vehicle height can be increased in a short time It can be adjusted. Therefore, when adjusting the vehicle height in the downward direction, it is not necessary to interrupt the communication between the hydraulic cylinder and the second gas spring, as in the case of adjusting the vehicle height in the upward direction. The main valve unit and the height adjustment valve may be opened, and the hydraulic oil of the hydraulic cylinder may be returned to the hydraulic oil supply and discharge device.

  Since the viscosity of the hydraulic oil increases as the temperature decreases, the pressure difference between the upstream side (the hydraulic oil supply and discharge device side) and the downstream side (the hydraulic cylinder side) of the main valve unit becomes large, and the vehicle height is adjusted upward The motor current of the pump in the case is increased. Therefore, the load on the pump motor may be excessive, which may lead to a decrease in the durability of the pump motor.

  Then, the original valve unit of the present invention is provided with the electromagnetic on-off valve, the cylindrical communication passage, and the cup seal. The solenoid on-off valve opens and closes the supply and discharge source passage. The cylindrical communication passage bypasses the in-valve passage, which is a passage through which the hydraulic fluid flows in the solenoid on-off valve, and supplies and discharges the hydraulic fluid on the hydraulic oil supply and discharge device side with respect to the solenoid on-off valve and the hydraulic cylinder side. A passage for hydraulic fluid that communicates with the source passage, and is formed around a cylindrical outer wall that forms an in-valve passage. The cup seal is provided in the cylindrical communication passage, and allows the flow of the hydraulic fluid from the hydraulic fluid supply / discharge device side to the hydraulic cylinder side in the cylindrical communication passage, and from the hydraulic cylinder side to the hydraulic fluid supply / discharge device side Shut off the flow of hydraulic oil.

  The cup seal is formed of an elastic material, and for example, a cylindrical fixing portion fixed to the outer periphery of the cylindrical outer wall forming the in-valve passage, and an upstream end (a hydraulic oil supply / discharge device side end) of the cylindrical fixing portion The lip section has a ring plate-like lip portion that is obliquely bent in the downstream direction in a V-shaped cross section, and the lip portion is elastically deformed by the pressure of the hydraulic fluid to open and close the cylindrical communication passage. In this case, when the hydraulic pressure on the hydraulic fluid supply / discharge device side in the feed / discharge source passage is higher than the hydraulic pressure on the hydraulic cylinder side, the lip portion opens the cylindrical communication passage and the hydraulic pressure on the hydraulic cylinder side in the feed / discharge source passage If it is higher than the hydraulic pressure on the hydraulic fluid supply and discharge device side, the lip portion closes the cylindrical communication passage. Therefore, the cup seal can be used to obtain the function of the check valve (check valve, one-way valve).

  As a result, when the vehicle height is adjusted in the upward direction, the hydraulic oil supplied from the pump to the hydraulic cylinder flows not only in the in-valve passage of the solenoid on-off valve but also in the cylindrical communication passage. The passage resistance is reduced, and the pressure difference generated in the original valve unit can be reduced. As a result, the load on the pump motor can be suppressed, and the durability of the pump motor can be improved.

  When the vehicle height is adjusted in the downward direction, the solenoid on-off valve may be opened to return the hydraulic oil of the hydraulic cylinder to the reservoir tank without operating the pump, but in this case, Since the cup seal shuts off the cylindrical communication passage, it is possible to suppress the flow rate of the hydraulic oil flowing to the original valve unit. Therefore, the vehicle height adjustment time can be prevented from becoming too short, and the vehicle height adjustment can be performed with high accuracy. In addition, it is possible to prevent the vehicle height adjustment speed from becoming too fast, and it is possible to suppress the occurrence of an impact or abnormal noise.

  Also, since the original valve unit incorporates a cup seal into the solenoid on-off valve and this cup seal functions as a check valve, the number of parts is reduced compared to when the solenoid on-off valve and the check valve are separately provided. And so on.

  In the above description, in order to facilitate understanding of the invention, the constituent elements of the invention corresponding to the embodiment are attached with the reference numerals used in the embodiment in parentheses, but each constituent element of the invention It is not limited to the embodiment defined by

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows the outline of the suspension system which concerns on this embodiment. It is a flowchart showing a vehicle height rise control routine. It is a sectional view of a former valve unit. It is sectional drawing explaining the flow of the hydraulic fluid in a former valve unit. It is a graph showing the relationship between the pump discharge flow rate and the pressure difference according to the present embodiment, and the relationship between the pump discharge flow rate and the motor current increase amount. When a check valve is not provided (comparative example), it is a graph showing the relation between pump discharge flow and pressure difference, and relation between pump discharge flow and motor current increase.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration view showing an outline of a suspension system 1 of the present embodiment.

  Suspension system 1 includes suspension devices 10FL, 10FR, 10RL, and 10RR that connect each of left and right front and rear wheels WFL, WFR, WRL, and WRR to the vehicle body so as to be able to move away from each other. , 10RL, 10RR, and a hydraulic control circuit provided between the hydraulic fluid supply and discharge device 70 for supplying and discharging the hydraulic fluid, and the suspension devices 10FL, 10FR, 10RL, 10RR and the hydraulic fluid supply and discharge device 70 And an electronic control unit 200 (called an ECU 200) that controls the operation of the entire system.

  Hereinafter, with respect to the symbols attached at the end of the reference numeral, FL is a member provided corresponding to the left front wheel, FR is a member provided corresponding to the right front wheel, and RL is provided corresponding to the left rear wheel Although it is a member that can be used, and RR is a member provided corresponding to the right rear wheel, in the specification, the tail symbol is omitted if it is not necessary to specify the corresponding wheel.

  The suspension device 10 includes wheel holding members 11 (for example, lower arms) for holding the left and right front and rear wheels W, and hydraulic cylinders 20 provided between the wheel holding members 11 and the vehicle body. Although not shown, suspension springs (coil springs) are provided in parallel with the hydraulic cylinders 20 between the wheel holding members 11 and the vehicle body. The hydraulic cylinder 20 functions as a shock absorber, and expands and contracts in accordance with a change in distance between the wheel holding member 11 and the vehicle body.

  The hydraulic cylinders 20 have the same structure, and include a housing 21, a piston 22 fitted inside the housing 21 so as to be movable relative to the housing 21, and a piston 22 to the outside of the housing 21. And an extending piston rod 23. The housing 21 is connected to the wheel holding member 11, and the piston rod 23 is connected to the vehicle body. The housing 21 is divided into two oil chambers 24 a and 24 b by a piston 22. The piston 22 has a communication passage 25 communicating the oil chambers 24a and 24b, and the communication passage 25 has a throttle (not shown). The throttling generates a damping force corresponding to the relative movement speed of the piston 22 with respect to the housing 21.

  Each oil chamber 24 a of each hydraulic cylinder 20 is connected to an individual supply and discharge passage 51 which is a passage through which hydraulic fluid flows. The hydraulic cylinder 20 generates a force in a direction to separate the wheel holding member 11 from the vehicle body by the pressure of the hydraulic oil supplied from the individual supply and discharge passage 51. Therefore, the hydraulic cylinder 20 increases the distance between the wheel holding member 11 and the vehicle body and raises the vehicle height as the pressure of the hydraulic oil supplied from the individual supply and discharge passage 51 increases.

  A main accumulator 31 and a leveling valve 61 are connected to the individual supply and discharge passages 51 in order from the side closer to the hydraulic cylinder 20. The main accumulator 31 functions as a hydraulic gas spring provided separately from the suspension spring (coil spring).

  The individual supply and discharge passage 51 corresponds to the vehicle height adjustment passage of the present invention. The main accumulator 31 corresponds to the first gas spring of the present invention. The leveling valve 61 corresponds to the vehicle height adjusting valve of the present invention. Therefore, the configuration including the individual supply and discharge passage 51 and the leveling valve 61 corresponds to the vehicle height adjustment hydraulic control circuit of the present invention.

  The main accumulator 31 includes a housing 31a and a partition member 31b that divides the inside of the housing 31a into two volume change chambers, and an individual supply and discharge passage to the oil chamber 31c which is one volume change chamber partitioned by the partition member 31b. A gas chamber 31d, which is the other volume change chamber, is filled with a gas (for example, nitrogen gas), which is an elastic body, and is configured. In the main accumulator 31, the volume of the gas chamber 31d decreases due to the increase of the volume of the oil chamber 31c. Therefore, the main accumulator 31 functions as a hydraulic gas spring that generates an elastic force for the expansion and contraction operation of the hydraulic cylinder 20 with the amount of hydraulic fluid stored in the oil chamber 31 c changing according to the hydraulic pressure of the hydraulic cylinder 20 Do. The oil chamber 31 c of the main accumulator 31 always communicates with the oil chamber 24 a of the hydraulic cylinder 20.

  The leveling valve 61 is a normally closed electromagnetic on-off valve that operates at the time of adjusting the vehicle height and opens and closes the individual supply and discharge passage 51.

  An individual rate switching passage 52 is branched and connected to each individual supply and discharge passage 51 at a position between the leveling valve 61 and the hydraulic cylinder 20. The spring switching valve 62 and the auxiliary accumulator 32 are connected to the individual rate switching passage 52 in order from the side closer to the connection position with the individual supply and discharge passage 51.

  The auxiliary accumulator 32 corresponds to the second gas spring of the present invention.

  The auxiliary accumulator 32 includes a housing 32a and a partition member 32b that divides the inside of the housing 32a into two volume change chambers, and separate rate switching passage to the oil chamber 32c which is one volume change chamber partitioned by the partition member 32b. A gas chamber 32d, which is in communication with the other volume change chamber 52, is filled with a gas (for example, nitrogen gas), which is an elastic body. In the auxiliary accumulator 32, the volume of the gas chamber 32d decreases due to the increase of the volume of the oil chamber 32c. Therefore, the auxiliary accumulator 32 functions as a hydraulic gas spring that generates an elastic force in the expansion and contraction operation of the hydraulic cylinder 20 when the amount of hydraulic fluid stored in the oil chamber 32 c changes according to the hydraulic pressure of the hydraulic cylinder 20. Do.

  The auxiliary accumulator 32 has a smaller spring constant than the main accumulator 31. The main accumulator 31 and the auxiliary accumulator 32 may be of any type such as a bellows type, a bladder type, and a piston type. In the present embodiment, a metal bellows type accumulator excellent in gas permeation resistance at high compression pressure is adopted as the main accumulator 31. Further, as the auxiliary accumulator 32, a bladder type accumulator with a resin film is adopted, which can secure a relatively large capacity and is excellent in gas permeation resistance.

  The spring switching valve 62 is a normally open electromagnetic switching valve that operates when switching the wheel rate. When the spring switching valve 62 is open, the main accumulator 31 and the auxiliary accumulator 32 are connected in parallel to the hydraulic cylinder 20, and when the spring switching valve 62 is closed, the hydraulic cylinder is opened. 20 and communication with the secondary accumulator 32 are shut off (It can also be expressed that communication between the main accumulator 31 and the secondary accumulator 32 is shut off). Hereinafter, the main accumulator 31 is referred to as a high gas spring 31, and the sub accumulator 32 is referred to as a low gas spring 32.

  As described above, the suspension device 10 includes the wheel holding member 11, the hydraulic cylinder 20, and the high gas spring 61 and the low gas spring 62 connected in parallel to the hydraulic cylinder 20.

  Each individual supply and discharge passage 51 is connected to the common supply and discharge passage 54, respectively. The common supply and discharge passage 54 is connected to the hydraulic oil supply and discharge device 70 and is also a passage for supplying the hydraulic oil from the hydraulic oil supply and discharge device 70 to each individual supply and discharge passage 51. It is also a passage for returning the oil to the hydraulic oil supply and discharge device 70.

  The hydraulic control circuit 50 is provided with an individual bypass passage 53 that allows the low gas spring 32 to communicate with the common supply and discharge passage 54 by bypassing the leveling valve 61 and the spring switching valve 62. Each individual bypass passage 53 is provided with a bypass valve 63. The bypass valve 63 is a normally closed solenoid valve. Therefore, in the state where the bypass valve 63 is opened, the low gas spring 32 communicates with the common supply and discharge passage 54 regardless of the states of the leveling valve 61 and the spring switching valve 62. The configuration including the individual bypass passage 53 and the bypass valve 63 corresponds to the second gas spring hydraulic control circuit of the present invention.

  In the common supply and discharge passage 54, a main valve unit 100 is provided. The source valve unit 100 is an assembly in which a source valve 100a, which is a normally closed solenoid valve, and a check valve 100b provided in parallel with the source valve 100a are incorporated in a common housing. The check valve 100b is provided in a communication passage 100c that connects the upstream passage of the source valve 100a and the downstream passage of the source valve 100a, bypassing the source valve 100a, and the pressure P1 on the upstream side of the source valve 100a is sourced. When the pressure is higher than the pressure P2 on the downstream side of the valve 100a, the valve is opened by the force due to the pressure difference ΔP (P1-P2), hydraulic fluid flows in the downstream direction of the communication passage, and the pressure P1 on the upstream side is downstream When the pressure is lower than the pressure P2 on the side, the valve closed state is maintained by the force due to the pressure difference .DELTA.P (P2-P1), and the one-way valve (reverse Stop valve). The upstream side of the main valve 100a represents the hydraulic oil supply and discharge device 70 side, and the downstream side represents the hydraulic cylinder 20 side.

  Details of the former valve unit 100 will be described after the entire description of the suspension system 1.

  In FIG. 1, the common supply and discharge passage 54 is a passage connected to the separate supply and discharge passages 51FL and 51FR of the left and right front wheels on the downstream side of the original valve unit 100, and the separate supply and discharge passage 51RL, and the left and right rear wheels. It branches into a passage communicating with 51RR, but it is not necessary to branch in this way. For example, each individual supply and discharge passage 51FL, 51FR, 51RL, 51RR is directly communicated with the common supply and discharge passage 54 common to four wheels, etc. The passageways (i.e. the common supply and discharge passageways 54) can be configured arbitrarily.

  The common supply and discharge passage 54 corresponds to the supply and discharge source passage of the present invention. The configuration including the common supply and discharge passage 54 and the original valve unit 100 corresponds to the supply and discharge hydraulic pressure control circuit of the present invention.

  The hydraulic oil supply and discharge device 70 includes a pump device 71 as a high pressure source and a reservoir tank 72 as a low pressure source. The pump device 71 includes a pump 71a and a pump motor 71b that drives the pump 71a. The pump device 71 pumps up the hydraulic oil of the reservoir tank 72 and supplies it to the common supply and discharge passage 54. The hydraulic fluid supply and discharge device 70 includes a check valve 73 (one-way valve) and a return valve 74 in parallel in the common supply and discharge passage 54 on the downstream side (discharge side) of the pump device 71.

  The return valve 74 is a valve that switches between the supply of hydraulic fluid from the pump device 71 to the main valve unit 100 and the discharge of hydraulic fluid from the main valve unit 10 to the reservoir tank 72. Normally, the return valve 74 is in a state in which the passage between the original valve unit 100 and the reservoir tank 72 is opened by the force of a spring, and when the pump device 71 is driven, the discharge pressure and the common supply / discharge passage The valve body is pushed by the differential pressure with the hydraulic pressure of 54 to close the passage between the original valve unit 100 and the reservoir tank 72. As a result, the check valve 73 is opened, and the hydraulic oil discharged from the pump device 71 flows to the original valve unit 100.

  Note that the hydraulic fluid supply and discharge device 70 of the present embodiment does not include an accumulator for accumulating pressure that accumulates the hydraulic pressure pressurized by the pump device 71 in order to reduce the weight.

  Further, the common supply and discharge passage 54 is provided with a hydraulic pressure sensor 90 for detecting the hydraulic pressure on the downstream side of the original valve unit 100. The hydraulic pressure sensor 90 may be provided anywhere in the hydraulic oil passage surrounded by the original valve unit 100, the four leveling valves 61, and the four bypass valves 63. That is, the hydraulic pressure sensor 90 is on the hydraulic cylinder 20 side with respect to the original valve unit 100, is the original valve unit 100 side with respect to the four bypass valves 63, and is the original valve unit 100 with respect to the leveling valve 61. It should just be provided in the passage of hydraulic fluid. Therefore, according to the hydraulic pressure sensor 90, when the leveling valve 61 of any wheel is opened while the original valve unit 100 is closed, the hydraulic pressure of the hydraulic cylinder 20 of the wheel can be detected. When the bypass valve 63 of any wheel is opened, the hydraulic pressure of the low gas spring 32 of that wheel can be detected.

  Thus, the hydraulic control circuit 50 includes the common supply and discharge passage 54, the original valve unit 100, the individual supply and discharge passage 51, the leveling valve 61, the individual rate switching passage 52, the spring switching valve 62, and the individual bypass. A passage 53 and a bypass valve 63 are provided.

  The ECU 200 mainly includes a microcomputer and a drive circuit (a motor drive circuit and a solenoid valve drive circuit). In the present specification, a microcomputer includes a CPU and storage devices such as a ROM and a RAM, and the CPU implements various functions by executing instructions (programs) stored in the ROM.

  The ECU 200 includes various solenoid valves (leveling valve 61, spring switching valve 62, bypass valve 63, and source valve 100a) provided in the hydraulic control circuit 50, and a pump motor provided in the hydraulic oil supply and discharge device 70. 71 b and the hydraulic pressure sensor 90 are connected. Furthermore, a motion detection sensor 210 for detecting a vehicle motion state and an operation detection sensor 220 for detecting an operation of a driver are connected to the ECU 200.

  As the motion detection sensor 210, for example, a vehicle speed sensor that detects a vehicle speed, a vehicle height sensor that detects a vehicle height for each front, rear, left and right wheel position, a vertical acceleration sensor that detects an acceleration in the vertical direction of the vehicle, a yaw rate of the vehicle The yaw rate sensor, and the horizontal acceleration sensor that detects the acceleration in the front, rear, left, and right directions of the vehicle body. The vehicle height sensor detects, for example, the distance between the wheel holding member 11 holding the wheels W and the vehicle body at the wheel position as the vehicle height.

  The operation detection sensor 220 includes a stroke sensor that detects a depression stroke of a brake pedal, a steering angle sensor that detects a steering angle of steering, and a transfer sensor that detects a range state of a transfer. The ECU 200 does not need to directly connect the motion detection sensor 210 and the operation detection sensor 220, and other on-vehicle ECUs (for example, an engine ECU, a brake ECU, and a steering) that connect those sensors. A detection signal may be input from an ECU or the like. In addition, the ECU 200 connects a vehicle height selection switch as the operation detection sensor 220 and a vehicle height adjustment off switch.

  The vehicle height selection switch is a switch for selecting a target vehicle height among the normal vehicle height, the low vehicle height, and the high vehicle height according to the operation of the driver. The vehicle height adjustment off switch is a switch for prohibiting the vehicle height control by the operation of the driver.

  The ECU 200 performs wheel rate switching control and vehicle height control based on detection signals detected by the motion detection sensor 210 and the operation detection sensor 220.

<Wheel rate switching control>
First, wheel rate switching control will be described. In the suspension system of the present embodiment, the wheel rate of the wheel W can be switched by switching the communication and blocking between the low gas spring 32 and the hydraulic cylinder 20 at the wheel position for each wheel W. That is, by the opening / closing control of the spring switching valve 62, the hydraulic cylinder 20 and the low gas spring 32 are in the communication state / the blocking state (can be expressed as the communication state / the blocking state between the high gas spring 31 and the low gas spring 32). By switching, the wheel rate can be switched to small (soft) / large (hard).

  For example, the ECU 200 basically sets the wheel rate to be small (soft) to maintain the ride comfort by maintaining the spring switching valve 62 of the four wheels W in the open state. Further, ECU 200 changes its posture when motion change sensor 210 and operation detection sensor 220 detect (or predict) a posture change of the vehicle body such as a roll motion at the time of turning of the vehicle or a pitch motion at the time of vehicle braking. By closing the spring switching valve 62 of the wheel W (for example, left and right front wheels) according to the situation, the low gas spring 32 is separated from the hydraulic cylinder 20 of the wheel W to increase the wheel rate (hard). Thereby, roll motion and pitch motion (posture change of the vehicle body) of the vehicle body can be suppressed.

<Height control>
Next, vehicle height control will be described. The ECU 200 controls the hydraulic oil supply and discharge device 70 and various solenoid valves 61, 62, 63, 100a based on the vehicle height selected by the vehicle height selection switch and the signals detected by the motion detection sensor 210 and the operation detection sensor 220. The control of the vehicle height switches the supply, discharge, and holding of the hydraulic oil of the hydraulic cylinders 20 of the front and rear left and right wheels W to adjust the vehicle height.

  For example, the ECU 200 performs auto leveling control to maintain the vehicle height selected by the driver regardless of load conditions such as the number of occupants and the load amount. Further, the ECU 200 has a function of setting an optimal target vehicle height according to the vehicle speed. For example, when the low vehicle height and the high vehicle height are selected by the driver's switch operation, the ECU 200 cancels the driver's selected vehicle height and sets the target vehicle when the vehicle speed increases above a preset threshold. Change the height to normal. Further, when traveling at high speed, the ECU 200 cancels the driver's selected vehicle height and changes the target vehicle height to a preset high vehicle speed low vehicle height. Further, when the transfer setting detected by the transfer sensor is in the L4 range (off road traveling range), the ECU 200 switches the target vehicle height to the high vehicle height when the vehicle speed becomes equal to or higher than the preset vehicle speed. .

  The ECU 200 controls the hydraulic oil supply and discharge device 70, the leveling valve 61, the spring switching valve 62, the bypass valve 63, and the main valve 100a so that the vehicle height (actual vehicle height) detected by the vehicle height sensor matches the target vehicle height. Drive control. When the states of the leveling valve 61, the switching valve 62, the bypass valve 63, and the source valve 100a are switched, the ECU 200 outputs a valve opening command or a valve closing command to these valves. The valve opening command is a drive signal for opening the valve, and represents an output ON of the drive signal for the normally closed solenoid valve (NC), and a drive for the normally open solenoid valve (NO). Indicates that the output of the signal is off. Further, the valve closing command is a drive signal for closing the valve, and indicates that the output of the drive signal is off for the normally closed solenoid valve, and the output of the drive signal is on for the normally open solenoid valve. Represents

<Vehicle height increase control>
When it is necessary to change the vehicle height, the ECU 200 adjusts the vehicle height as follows. First, control when raising the vehicle height will be described. Here, vehicle height control for one wheel will be described. FIG. 2 shows a vehicle height increase control routine implemented by the ECU 200. When a vehicle height increase request occurs, ECU 200 starts a vehicle height increase control routine. A vehicle height increase request occurs, for example, when a deviation (L0−Lx) between a vehicle height Lx (hereinafter referred to as actual vehicle height Lx) detected by a vehicle height sensor and a target vehicle height L0 exceeds an allowable value. .

  When the vehicle height increase control routine is started, in step S11, the ECU 200 switches the main valve 100a and the leveling valve 61 from the valve closing state to the valve opening state while maintaining the bypass valve 63 in the valve closing state. The switching valve 62 is switched from the open state to the closed state.

  Subsequently, the ECU 200 activates the pump device 71 in step S12. Thus, the hydraulic oil accumulated in the reservoir tank 72 is supplied to the hydraulic cylinder 20 and the high gas spring 31 via the hydraulic control circuit 50. As a result, the height of the wheel W is increased. In this case, since the low gas spring 32 is not supplied with the hydraulic oil, the vehicle height can be quickly raised with a small amount of oil.

  In step S13, the ECU 200 stands by until the actual vehicle height Lx detected by the vehicle height sensor reaches the target vehicle height L0, and when the actual vehicle height Lx reaches the target vehicle height L0 (S13: Yes), the process proceeds to step S14. The detected value of the hydraulic pressure sensor 90 at the time is stored as the vehicle height adjustment completion pressure P0. The vehicle height adjustment completion pressure P0 is equal to the hydraulic pressure of the hydraulic cylinder 20 and the high gas spring 31 of the vehicle height adjustment target wheel.

  Subsequently, in step S15, the ECU 200 outputs a valve closing command to the leveling valve 61 to maintain the valve opening state of the spring switching valve 62 while keeping the valve opening state of the source valve 100a. While switching to the valve closing state, the valve opening command is output to the bypass valve 63 to switch the bypass valve 63 from the valve closing state to the valve opening state. As a result, the hydraulic oil accumulated in the reservoir tank 72 is supplied to the low gas spring 32 by the operation of the pump device 71 while the hydraulic pressure of the hydraulic cylinder 20 and the high gas spring 31 is held.

  Subsequently, in step S16, the ECU 200 stands by until the detection value Px (referred to as actual hydraulic pressure Px) of the hydraulic pressure sensor 90 reaches the vehicle height adjustment completion pressure P0. That is, the oil pressure of the low gas spring 32 stands by until the oil pressure of the hydraulic cylinder 20 of the wheel W and the oil pressure of the high gas spring 31 become equal.

  When the actual hydraulic pressure Px reaches the vehicle height adjustment completion pressure P0 (S16: Yes), the ECU 200 instructs the bypass valve 63 to close, the spring switching valve 62 to open, and the source valve 100a to close. , And outputs a stop command to the pump device 71. As a result, the pump 71a is stopped, the bypass valve 63 and the original valve 100a are switched from the open state to the closed state, and the spring switching valve 62 is switched from the closed state to the open state. Thus, the hydraulic cylinder 20, the high gas spring 31, and the low gas spring 32 are in communication with one another. When the process of step S17 is performed, the ECU 200 ends the vehicle height increase control routine.

  According to the vehicle height increase control routine, when raising the vehicle height, no hydraulic oil is supplied to the low gas spring 32, and the hydraulic oil is supplied to the low gas spring 32 after the vehicle height rises to the target vehicle height. Therefore, the amount of oil required to raise the vehicle height can be minimized. In addition, the vehicle height can be quickly raised to the target vehicle height. In addition, since the low gas spring 32 is supplied with hydraulic fluid so that the low gas spring 32 and the high gas spring 31 have the same pressure after the vehicle height rises to the target vehicle height, the spring switching valve 62 is opened. It is possible to prevent the vehicle height fluctuation due to the valve operation.

  When there are a plurality of wheels (target wheels) for which the vehicle height is to be increased, the ECU 200 simultaneously starts the processing of step S11 for all the target wheels (common to the valve opening operation of the original valve 100a) After that, when the actual vehicle height Lx reaches the target vehicle height L0 for each target wheel, the vehicle height adjustment completion pressure P0 is stored, and the leveling valve 61 of the wheel is closed. Then, the ECU 200 starts the hydraulic pressure adjustment of the low gas spring 32 at the timing when the vehicle height adjustment of the last target wheel is completed. In this case, the ECU 200 switches the bypass valve 63 of the target wheel one valve at a time while keeping the pump device 71 in operation, the main valve 100a in the valve opening state, and the spring switching valve 62 in the valve closing state. The bypass valve 63 is closed at the timing when the actual hydraulic pressure Px reaches the vehicle height adjustment completion pressure P0, and at this timing, the bypass valve 63 of the next target wheel is opened. The ECU 200 closes the main valve 100 a at the timing at which the hydraulic pressure adjustment of the low gas spring 32 of the last target wheel is completed (at the timing of closing the bypass valve 63 of the last target wheel). The valve is opened and the pump device 71 is stopped.

<Vehicle height descent control>
Next, control when lowering the vehicle height will be described. The ECU 200 executes the vehicle height lowering control when the deviation (Lx−L0) between the actual vehicle height Lx detected by the vehicle height sensor and the target vehicle height L0 exceeds the allowable value. For example, the ECU 200 switches the leveling valve 61 and the main valve 100a from the closed state to the open state in a state where the operation of the pump device 71 is stopped. In this case, when the spring switching valve 62 is closed, the spring switching valve 62 is also switched to the open state. Further, the bypass valve 63 is maintained in the closed state.

  Accordingly, the hydraulic oil of the hydraulic cylinder 20 is discharged to the reservoir tank 72 via the hydraulic control circuit 50. Therefore, the hydraulic cylinder 20 contracts and the height of the wheel W is reduced. The ECU 200 stands by until the actual vehicle height Lx decreases to the target vehicle height L0, and switches the leveling valve 61 and the main valve 100a from the open state to the closed state when the actual vehicle height Lx reaches the target vehicle height L0 or less. Thus, the vehicle height can be reduced to the target vehicle height L0.

  In this case, as in the case of the vehicle height increase control, the low gas spring 32 may be separated from the hydraulic cylinder 20 (with the spring switching valve 62 closed), and the hydraulic oil may be discharged from the hydraulic cylinder 20 As described above, the hydraulic oil may be discharged from the hydraulic cylinder 20 while the hydraulic cylinder 20 and the low gas spring are in communication with each other. In the former case, it is necessary to discharge the hydraulic oil from the low gas spring 32 to adjust the hydraulic pressure after the end of the vehicle height control, but in the latter case, it is necessary to perform the hydraulic adjustment of the low gas spring 32 There is not.

<Original valve unit>
Next, the main valve unit 100 will be described. Since the main valve unit 100 only needs to have the function of opening and closing the common supply and discharge passage 54, basically, only the main valve 100a which is a solenoid on-off valve may be provided. However, the viscosity of the hydraulic oil used in the hydraulic control circuit 50 increases as the temperature decreases. Therefore, at the time of operation of the pump 71a, the pressure difference ΔP (P1-P2), which is the difference between the pressure P1 on the upstream side of the main valve 100a and the pressure P2 on the downstream side, increases. As a result, the discharge pressure of the pump 71a is increased, so the motor load may be increased and the motor current may exceed the limit value.

  Therefore, as shown in FIG. 1, the original valve unit 100 of the present embodiment is provided with a communication passage 100c for communicating the upstream passage of the original valve 100a with the downstream passage of the original valve 100a, and check the communication passage 100c. By providing the valve 100b, the hydraulic oil supplied from the pump 71a flows not only to the main valve 100a but also to the check valve 100b. As a result, the passage resistance in the original valve unit 100 is reduced, and the pressure difference ΔP generated in the original valve unit 100 with respect to the discharge flow rate of the pump 71a can be reduced.

  In the case of lowering the vehicle height, the hydraulic oil of the hydraulic cylinder 20 is returned to the reservoir tank 72 via the original valve unit 100 while the pump 71a is stopped. In this case, the check valve 100b is closed by the pressure difference ΔP (P2-P1) between the pressure P2 on the downstream side and the pressure P1 on the upstream side.

  When the vehicle height is adjusted in the downward direction, the high pressure hydraulic oil accumulated in the hydraulic cylinder 20 is returned to the reservoir tank 72 by the force (vehicle weight) acting in the direction to contract the hydraulic cylinder 20. The height of the vehicle changes in a short time as compared with the case of adjusting in the upward direction. Also, if the vehicle height adjustment time is too short, it will be difficult to perform accurate vehicle height adjustment. In the original valve unit 100 of the present embodiment, when the hydraulic oil is returned to the reservoir tank 72, the check valve 100b is closed. Therefore, in the source valve unit 100, the hydraulic oil passes only the source valve 100a and is returned to the reservoir tank 72. Thus, the vehicle height adjustment can be performed at an appropriate speed that can ensure predetermined vehicle height control performance.

  For example, the problem of an increase in motor load when raising the vehicle height by the operation of the pump 71a can be solved by increasing the opening area of the main valve 100a to reduce the passage resistance. However, if this is done, the size of the main valve 100a is increased. Along with this, the mass of the valve housing and the new cost of cost increase. In addition, when adjusting in the direction of lowering the vehicle height, the flow rate of hydraulic oil increases, so the vehicle height adjustment time becomes too short, the vehicle height adjustment speed becomes too fast, and shocks and noises occur. There is a risk of getting bigger.

  So, in the former valve unit 100 of this embodiment, such a subject is solved by the check valve 100b.

  Furthermore, in the original valve unit 100 according to the present embodiment, the check valve 100b is incorporated into the original valve 100a, thereby reducing the number of parts as compared to the case where the original valve 100a and the check valve 100b are separately provided. The number of machining can be reduced.

  FIG. 3 shows a cross section of the original valve unit 100 of the present embodiment. In FIG. 3, a member indicated by reference numeral 170 corresponds to the check valve 100b, and a passage indicated by reference numeral 160 corresponds to the communication passage 100c. Since the check valve 100 b is realized by a cup seal, the check valve 100 b is hereinafter referred to as a cup seal 170. Further, since the communication passage indicated by reference numeral 160 in FIG. 3 is formed in a cylindrical shape, the communication passage is hereinafter referred to as a cylindrical communication passage 160. About other members, it is a member which constitutes former valve 100a. Therefore, the original valve unit 100 includes the original valve 100a, the cylindrical communication passage 160, and the cup seal 170 provided on the cylindrical communication passage 160 and functioning as a check valve.

  The main valve 100 a includes a solenoid 110, a spherical valve body 120, a valve seat member 130, and a valve casing 140, and is fixed to the housing 150. The solenoid 110 includes a coil 111, a yoke 112 forming a magnetic path outside the coil 111, a stator 113, and a mover 114. The stator 113 is cylindrically formed of a magnetic material, and is inserted into and fixed to one end of a cylindrical sleeve 115 formed of a nonmagnetic material. The mover 114 is made of a magnetic material and formed in a cylindrical shape with a two-step diameter consisting of a small diameter portion 114a and a large diameter portion 114b, and the large diameter portion 114b is inserted into the sleeve 115 so as to be axially movable back and forth. A spring 116 is provided between the mover 114 and the stator 113 in a compressed state. As a result, the mover 114 is biased by the force of the spring 116 in the direction away from the stator 113 (downward in FIG. 3).

  The valve casing 140 is formed in a substantially cylindrical shape. The housing 150 is formed with a valve mounting hole 151 for housing and fixing the valve casing 140. The valve casing 140 is inserted into the valve mounting hole 151 and fixed by a fixing member or the like (not shown). The housing 150 is formed with an upstream passage 161 and a downstream passage 162 communicating with the valve mounting hole 151. The upstream passage 161 is a common supply / discharge passage 54 closer to the pump 71a than the main valve 100a, and the downstream passage 162 is a common supply / discharge passage 54 closer to the hydraulic cylinder 20 than the main valve 100a. The downstream side passage 162 is formed to extend from the valve mounting hole 151 along the axial direction (downward in FIG. 3) of the valve casing 140. On the other hand, the upstream side passage 161 is formed extending from the valve mounting hole 151 along an arbitrary radial direction (right direction in FIG. 3) of the valve casing 140.

  The tip end of one side (the upper side in the drawing) of the valve casing 140 is fitted in the sleeve 115 and positioned and fixed. Thus, in the space enclosed by the cylindrical wall of the valve casing 140, the small diameter portion 114a of the mover 114 is disposed on one side in the axial direction so as to be able to advance and retract. Further, in the valve casing 140, a cylindrical valve seed member 130 is fixed on the other side in the axial direction (the lower side in the drawing). As a result, the mover 114 and the valve seat member 130 are arranged coaxially with each other with their tips facing each other.

  A spherical valve body 120 is fixedly provided at the axial center position of the tip of the mover 114 (the tip of the small diameter portion 114 a). The tip of the valve seat member 130 facing the spherical valve body 120 is formed in a tapered shape, and the tip portion thereof is a valve seat 131. The valve seat 131 is formed in a ring shape surrounding the opening 132 of a perfect circle. The inner diameter of the opening 132 of the valve seat 131 is slightly smaller than the outer diameter of the spherical valve body 120.

  The mover 114 is biased toward the valve seat member 130 by a spring 116. For this reason, in a state where the coil 111 is not energized, the spherical valve body 120 abuts on the valve seat 131 to close the opening 132 of the valve seat 131. That is, the main valve 100a is closed.

  Further, coil 111 is connected to a drive circuit (not shown) provided in ECU 200, and generates an electromagnetic force when a drive current flows from the drive circuit, and the biasing force of spring 116 is generated by the electromagnetic force. The mover 114 is pulled up in the direction of arrow a in FIG. As a result, the spherical valve body 120 is separated from the valve seat 131, and the main valve 100a is opened.

  The valve casing 140 communicates with the valve seat 131 of the valve seat member 130 and the upstream side passage 161, and an in-casing passage 141 which is a passage through which the hydraulic fluid flows is formed.

  The valve seat member 130 is provided with an opening end 132 opposite to the valve seat 131 in the axial direction facing the downstream side passage 162. In the valve seat member 130, a space surrounded by a cylindrical wall is formed between the valve seat 131 and the opening end 132, and this space forms a passage through which hydraulic fluid flows. This passage is referred to as a valve seat passage 133.

  Therefore, when the main valve 100 a is opened, the upstream passage 161 and the downstream passage 162 are communicated via the in-casing passage 141 and the in-valve-seat passage 133.

  The outer peripheral surface of the valve casing 140 on the other side in the axial direction (the lower side in the drawing and the side on which the valve seed member 130 is fixed) is formed in a cylindrical surface shape. This outer peripheral surface is called a casing cylindrical outer peripheral surface 142. Further, in the housing 150, a gap which is opened by a predetermined dimension in the radial direction from the casing cylindrical outer peripheral surface 142 is formed. That is, in the housing 150, a space surrounded by the housing cylindrical inner circumferential surface 152 larger in diameter than the casing cylindrical outer circumferential surface 142 is formed coaxially with the casing cylindrical outer circumferential surface 142 as a part of the valve mounting hole 151 There is. Therefore, a cylindrical space is formed between the casing cylindrical outer peripheral surface 142 and the housing cylindrical inner peripheral surface 152. One end of the cylindrical space communicates with the upstream passage 161, and the other end communicates with the downstream passage 162 to function as a passage through which hydraulic fluid flows. Therefore, this cylindrical space constitutes a cylindrical communication passage 160 which bypasses the main valve 100 a and causes the upstream passage 161 and the downstream passage 162 to communicate with each other.

  The housing cylindrical inner circumferential surface 152 is in series with the inner circumferential surface of the downstream side passage 162. That is, the inner diameter of the downstream side passage 162 formed in the housing 150 is the same as the inner diameter of the housing cylinder inner circumferential surface 152.

  The downstream end of the valve seat member 130 is provided to project further downstream than the downstream end of the valve casing 140. Therefore, the cylindrical communication passage 160 is extended not only to the outer periphery of the casing cylindrical outer peripheral surface 142 but also to the outer peripheral portion of the valve seat member 130.

  The downstream end of the valve seat member 130 is formed with a flange portion 134 extending radially outward. Since the outer diameter of the collar portion 134 is smaller than the inner diameter of the downstream side passage 162 (= the inner diameter of the housing cylinder inner circumferential surface 152), the flange portion 134 does not disturb the flow of hydraulic fluid in the cylindrical communication passage 160.

  A cup seal 170 is fixedly provided between the collar 134 and the other axial end of the valve casing 140.

  The cup seal 170 is an integrally formed product made of an elastic material such as synthetic rubber, and is provided on the cylindrical outer peripheral surface of the valve seat member 130 in a cylindrical cylindrical fixing portion 171 and the upstream end of the cylindrical fixing portion 171. It is composed of a ring plate-like lip 172 extending obliquely outward in the downstream direction (radial direction) in a V-shaped cross section, and the cut surface cut along the axial direction is formed in a cup shape ing.

  The outer diameter of the cup seal 170 is slightly larger than the outer diameter of the cylindrical communication passage 160, that is, the inner diameter of the housing cylindrical inner circumferential surface 152. Accordingly, the outer peripheral edge of the lip portion 172 is in contact with the housing cylindrical inner peripheral surface 152.

  When the pressure P1 of the hydraulic fluid in the upstream side passage 161 is higher than the pressure P2 of the hydraulic fluid in the downstream side passage 162, as shown in FIG. The force by P2) causes the lip portion 172 to be elastically deformed in the direction of reducing the outer diameter, and a gap in which the working oil flows between the outer peripheral edge of the lip portion 172 and the housing cylindrical inner peripheral surface 152 is generated. When the vehicle height is adjusted in the upward direction, the leveling valve 61 and the main valve 100a are opened, and the pump 71a is driven. Therefore, the hydraulic oil in the upstream passage 161 on the high pressure side flows not only to the main valve 100 a but also to the cylindrical communication passage 160 and is sent to the downstream passage 162.

  Conversely, as shown in FIG. 4B, when the pressure P2 of the hydraulic fluid in the downstream passage 162 is higher than the pressure P1 of the hydraulic fluid in the upstream passage 161, the pressure difference ΔP (P2-P1) The outer peripheral edge of the lip portion 172 is in close contact with the housing cylindrical inner peripheral surface 152 by the force of the above, and the cylindrical communication passage 160 is held in the closed state. Therefore, no hydraulic fluid flows in the cylindrical communication passage 160. When the vehicle height is adjusted in the downward direction, the leveling valve 61 and the main valve 100a are opened while the pump 71a is stopped. As a result, the hydraulic oil in the downstream passage 162 on the high pressure side flows only through the main valve 100 a and is sent to the upstream passage 161.

  Thus, the cup seal 170 is provided in the cylindrical communication passage 160 provided outside the passage through which the hydraulic oil flows in the main valve 100a, and the flow of the hydraulic oil in the cylindrical communication passage 160 is allowed only in one direction. Function as a check valve (check valve, one-way valve).

  Therefore, according to the original valve unit 100, when adjusting the vehicle height in the upward direction, since the cup seal 170 opens the cylindrical communication passage 160, the pressure difference between the upstream side and the downstream side of the original valve unit 100 It can be suppressed. Further, when the vehicle height is adjusted in the downward direction, the cup seal 170 shuts off the cylindrical communication passage 160, so that the flow rate of the hydraulic oil flowing to the main valve unit 100 can be suppressed.

  According to the suspension system 1 of the present embodiment described above, since the individual bypass passage 53 and the bypass valve 63 are provided, supply / discharge of hydraulic oil to the hydraulic cylinder 20 and the high gas spring 31 and the low gas spring 32 The supply / discharge of hydraulic fluid to and from can be performed independently of each other. Thus, the vehicle height can be adjusted using the hydraulic system excluding the low gas spring 32, so that the vehicle height can be quickly raised with a small amount of oil.

  Along with this, the necessary supply flow rate of the hydraulic oil in the hydraulic oil supply and discharge device 70 can be reduced, so that the configuration can be simplified. For example, the discharge flow rate of the pump 71a can be reduced. In addition, it is not necessary to provide an accumulator or the like for compensating the discharge flow rate of the pump as in the conventional device. As a result of these, the weight reduction of the hydraulic oil supply and discharge device 70 can be achieved.

  In addition, since the hydraulic pressure of the low gas spring 32 is adjusted to be equal to the hydraulic pressure of the hydraulic cylinder 20 after the adjustment for raising the vehicle height, the spring switching valve 62 is opened to change the vehicle height even when the wheel rate is switched. It can not be done.

  Further, the original valve unit 100 is configured to include a check valve 100b in parallel with the original valve 100a, and when the vehicle height is adjusted in the upward direction, the check valve 100b is opened, so as shown in FIG. As shown, the pressure difference ΔP generated in the source valve unit 100 with respect to the discharge flow rate of the pump 71a can be reduced. As a result, as shown in FIG. 5B, the motor current can be prevented from exceeding the limit value. Therefore, the load increase of the pump motor 71b can be suppressed, and the durability can be improved.

  In addition, when adjusting the vehicle height in the downward direction, the check valve 100b is closed, so the vehicle height adjustment time can be prevented from becoming too short, and vehicle height adjustment with high accuracy can be performed. it can. In addition, it is possible to prevent the vehicle height adjustment speed from becoming too fast, and it is possible to suppress the occurrence of an impact or abnormal noise.

  Further, a cup seal 170 is provided in the cylindrical communication passage 160 provided outside the passage through which the hydraulic fluid flows in the main valve 100a, and this cup seal 170 functions as a check valve, so the original valve 100a and the check valve 100b The number of parts can be reduced and the number of machining can be reduced, as compared with the case where these are separately provided.

  As mentioned above, although the suspension system concerning this embodiment was described, the present invention is not limited to the above-mentioned embodiment, and various change is possible unless it deviates from the object of the present invention.

  For example, in the present embodiment, the number of gas springs provided corresponding to the hydraulic cylinder 20 of each wheel W is two (high gas spring 31 and low gas spring 32), but another gas spring is It may be provided. For example, the configuration may be such that a relief gas spring for releasing the pressure when the pressure in the hydraulic circuit abnormally rises is always in communication with the hydraulic cylinder 20.

  Further, in the present embodiment, when the vehicle height is adjusted in the upward direction, the hydraulic cylinder 20 and the low gas spring 32 are separated and the hydraulic oil is supplied to the hydraulic cylinder 20 first, but it is not always the case. It is not necessary to make the configuration as such, but only in certain situations. For example, when the driver operates the vehicle height selection switch, when it is necessary to raise the vehicle height at the time of the operation, the vehicle height needs to be raised quickly to meet the driver's request. In that case, the hydraulic cylinder 20 and the low gas spring 32 are separated to supply the hydraulic oil to the hydraulic cylinder 20, that is, the vehicle height increase control routine of the embodiment is performed, otherwise The hydraulic oil may be supplied to both the hydraulic cylinder 20 and the low gas spring 32 in communication with each other.

  DESCRIPTION OF SYMBOLS 1 ... Suspension system, 10 ... Suspension apparatus, 11 ... Wheel holding member, 20 ... Hydraulic cylinder, 31 ... Main accumulator (high gas spring), 32 ... Secondary accumulator (low gas spring), 50 ... Hydraulic control circuit, 51 ... Individually Supply / discharge passage, 52: Individual rate switching passage, 53: Individual bypass passage, 54: Common supply / discharge passage, 61: Leveling valve, 62: Spring switching valve, 63: Bypass valve, 70: Working oil supply / discharge device, 71 ... Pump device, 71a: pump, 71b: pump motor, 72: reservoir tank, 90: hydraulic sensor, 100: original valve unit, 100a: original valve, 100b: check valve, 110: solenoid, 114: mover, 120: spherical Valve body, 130: valve seat member, 131: valve seat, 133: valve seat Passage, 134: collar portion, 140: valve casing, 141: passage in the casing, 142: casing cylindrical outer peripheral surface, 150: housing, 151: valve mounting hole, 152: housing cylindrical inner peripheral surface, 160: cylindrical communication passage, 161 ... upstream passage, 162 ... downstream passage, 170 ... cup seal, 200 ... electronic control unit (ECU), 210 ... motion detection sensor, 220 ... operation detection sensor, W ... wheel.

Claims (1)

A hydraulic cylinder provided between the wheel holding member and the vehicle body in each of the left and right front and rear wheels of the vehicle, containing hydraulic oil and expanding and contracting according to a change in distance between the wheel holding member and the vehicle body;
A first gas spring provided corresponding to each of the left and right front and rear hydraulic cylinders and communicating with the hydraulic cylinder to function as a hydraulic system spring, and a second gas spring;
A spring switching valve provided corresponding to each of the hydraulic cylinders and switchable between a state in which communication between the hydraulic cylinder and the second gas spring is permitted and a state in which communication between the hydraulic cylinder and the second gas spring is shut off;
A pump for supplying and discharging hydraulic oil to and from each of the hydraulic cylinders, and a hydraulic oil supply and discharge device having a reservoir tank;
A supply / discharge hydraulic pressure control circuit having a supply / discharge source passage connected to the hydraulic fluid supply / discharge device and serving as a passage through which the hydraulic fluid flows, and a source valve unit for opening and closing the supply / discharge source passage;
A passage for adjusting the vehicle height, which is provided corresponding to each of the hydraulic cylinders and is a passage of hydraulic oil for communicating each of the hydraulic cylinders with the supply / discharge source passage, and opens / closes the passage for adjusting the vehicle height A hydraulic control circuit for height adjustment having a valve for height adjustment;
A hydraulic oil passage provided corresponding to each of the hydraulic cylinders and bypassing the spring switching valve and the vehicle height adjusting valve to communicate each of the second gas springs with the supply / discharge source passage. A second gas spring hydraulic control circuit having a bypass passage and a bypass valve for opening and closing the bypass passage;
Provided in the hydraulic oil passage on the hydraulic cylinder side with respect to the original valve unit and in the original valve unit side with respect to the bypass valve and on the original valve unit side with respect to the vehicle height adjustment valve A hydraulic pressure sensor that detects the hydraulic pressure of the passage,
In the case of adjusting the vehicle height in the upward direction, the vehicle height is controlled in the state where the spring switching valve and the bypass valve of the vehicle height adjustment target wheel are closed while controlling the original valve unit in the valve opening state. The vehicle height adjustment valve of the vehicle height adjustment target wheel is controlled to the open state until the vehicle height is reached, the hydraulic fluid is supplied from the hydraulic fluid supply and discharge device to the hydraulic cylinder, and the vehicle height reaches the target vehicle height. The hydraulic pressure detected by the hydraulic pressure sensor at the time of having been stored is stored, and the second gas of the vehicle height adjustment target wheel is closed with the spring switching valve of the vehicle height adjustment target wheel and the vehicle height adjustment valve closed. Vehicle height control means for controlling the bypass valve in the open state until the hydraulic pressure of the spring becomes equal to the stored hydraulic pressure;
The former valve unit
A solenoid on-off valve for opening and closing the supply and discharge source passage;
The in-valve passage, which is a passage through which the hydraulic oil flows in the electromagnetic on-off valve, is bypassed, and the supply and discharge source passage on the hydraulic oil supply and discharge device side and the supply and discharge on the hydraulic cylinder side with respect to the electromagnetic on-off valve A hydraulic fluid passage communicating with the source passage, and a cylindrical communication passage formed around a cylindrical outer wall forming the in-valve passage;
It is provided in the cylindrical communication passage, and allows the flow of hydraulic oil from the hydraulic oil supply and discharge device side to the hydraulic cylinder side in the cylindrical communication passage, and the hydraulic oil supply and discharge device side from the hydraulic cylinder side Suspension system with a cup seal that shuts off the flow of hydraulic fluid to the

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