JP2005104208A - Suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspension device capable of highly accurately performing the movement of a spool to the neutral position and avoidance of the unstability of a vehicle in the pitch or roll direction in failure. <P>SOLUTION: The suspension device has a first spring 50 for energizing a main spool 41 to a pilot room 46 side, and a second spring 51 for energizing a sub spool 74 to the pilot room 46 side. Using the spring forces of the first and second springs 50 and 51 that are disposed on respective end sides opposite to the abutting side of the main spool 41 and the sub spool 74 and energize them, the main spool 41 is set at the neutral position in a balanced state in failure so as to prevent communication of hydraulic cylinders 2 of the four wheels. Thus, attitude change in the pitch or roll direction is prevented to keep the stability of the vehicle. Since the main spool 41 is set at the neutral position in the balanced state, the main spool 41 at the neutral position can be set certainly and accurately. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a suspension device that performs posture control of a vehicle such as an automobile using a hydraulic system.

  As an example of a conventional suspension device, a pump and an accumulator are connected to a hydraulic cylinder of a suspension unit interposed between a vehicle body side and a wheel side of a vehicle via an electromagnetic supply / discharge switching valve (electromagnetic flow control valve). Is connected to the hydraulic source, and the controller operates the supply / discharge switching valve based on parameters such as the vertical and lateral acceleration of the vehicle body detected by various sensors, and the hydraulic fluid is supplied to the hydraulic cylinder according to the running state of the vehicle. In some cases, the posture of the vehicle body is controlled by supplying and discharging. This suspension device is provided with a pilot type check valve between the reservoir tank and the four-wheel supply / discharge switching valve in order to prevent the oil in the hydraulic cylinder from returning to the reservoir tank side at the time of failure.

  This suspension device has a problem that the four-wheel hydraulic cylinder is in communication because the supply / discharge switching valve is in an oil discharge state at the time of failure, and the vehicle becomes unstable in the pitch and roll directions. This problem can be solved, for example, by setting the supply / discharge switching valve to the neutral position at the time of failure. An example of a suspension device that sets the supply / discharge switching valve to the neutral position at the time of failure is disclosed in Patent Document 1.

  In this suspension device, the supply / discharge switching valve has an oil supply position that communicates with the oil supply path according to an energization current to the solenoid, an oil discharge position that communicates with the oil discharge path, and a neutral position (valve closed position) provided therebetween. ), A spring disposed on one side of the spool so as to bias the spool in a direction opposite to the biasing direction by energization of the solenoid, and one end of the spring that supports one end A pressure chamber into which the pressure of the oil supply passage is guided is formed on the surface side, and a first position where the spring is biased with respect to the spool by an increase in pressure in the pressure chamber and a decrease in pressure in the pressure chamber And a piston provided so as to be movable between a second position where the bias is released from the spool.

In this suspension device, a fail-safe valve is provided in a pipe branched from the oil supply passage and connected to the reservoir tank. This fail-safe valve is opened when the suspension device is not operating, energized and closed in a normal operating state, and opened when the supply / discharge switching valve is de-energized due to an abnormality. It comes to speak.
A pilot type check valve is provided in the oil drain passage. This pilot type check valve operates with the oil pressure of the oil supply passage as a pilot pressure, and is always opened when the oil pressure of the oil supply passage is greater than a predetermined value, that is, when the suspension device is operating normally, and is smaller than the predetermined pressure. In this case, it acts as a check valve that prevents the flow of oil from the supply / discharge switching valve side to the reservoir tank side.

When the supply / discharge switching valve is de-energized due to disconnection of the solenoid of the supply / discharge switching valve (when failing), the suspension device opens the failsafe valve to reduce the pressure in the oil supply passage. By reducing the pressure, the spool is automatically moved to the neutral position (valve closing position) by the fluid force. For this reason, even if a pilot-type check valve malfunctions, the hydraulic cylinder supply and exhaust oil is stopped to prevent sudden changes in vehicle height (and thus the vehicle becoming unstable in the pitch and roll directions). Like to do.
JP-A-7-32847

  By the way, in the suspension device of Patent Document 1 described above, the spool of the supply / discharge switching valve is set to the neutral position by the balance between the spring force of the spring disposed on one side of the spool and the hydraulic pressure. For this reason, there is a possibility that the spool moves due to minute fluctuations in the fluid pressure and the position accuracy decreases.

  The present invention has been made in view of the above circumstances, and provides a suspension device that can accurately move a spool to a neutral position, and thus avoid instability of the vehicle in the pitch and roll directions during a failure. With the goal.

  The present invention provides an oil supply that is connected to a hydraulic source via a supply / discharge switching valve that can be controlled by an electromagnetic pilot control valve in a hydraulic cylinder interposed between a vehicle body side and each wheel side of the vehicle. A suspension device that controls a posture of a vehicle by connecting a path and an oil discharge path connected to a reservoir tank, and controlling the supply / discharge switching valve to supply and discharge oil to and from each hydraulic cylinder. The exhaust switching valve is disposed on the switching valve main body having a hollow portion for housing the main spool and the sub spool so as to be slidable and in contact with each other, and on each end side opposite to the contact side of the main spool and the sub spool. And a first spring for biasing the two in a contacting direction, the main spool having an oil supply position for connecting the oil supply path to the hydraulic cylinder, and the oil discharge path for the hydraulic cylinder. Connected exhaust The position is switched selectively to a neutral position that shuts off the hydraulic cylinder with respect to the oil supply passage and the oil discharge passage, and when the suspension device is not controlled, the biasing force of the first spring and the sub spool are used. The second spring is moved to the neutral position in response to the biasing force of the second spring.

  According to the suspension device of the present invention, the spring force of the first and second springs that are arranged at the non-contact side end portions of the main spool and the sub spool and bias the both in the contact direction is used. The main spool can be set to the neutral position in a balanced state so that the four-wheel hydraulic cylinders do not communicate with each other. For this reason, the attitude | position change of a roll and a pitch direction can be prevented, and stability of a vehicle can be maintained. Furthermore, the neutral position of the main spool can be set reliably and accurately by setting the main spool to the neutral position with the first and second spring forces balanced regardless of the pressure in the oil supply passage or the oil discharge passage. Can do.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a hydraulic circuit of the suspension device 1. In FIG. 1, reference numeral 2 denotes a hydraulic cylinder interposed between each wheel of the vehicle and the vehicle body. In the hydraulic cylinder 2, an accumulator 3 as a spring element is passed through a throttle valve 4 as a damping element. Connected. The suspension unit including the hydraulic cylinder 2, the accumulator 3, and the throttle valve 4 is connected to a main accumulator 6 and a reservoir via a pilot-type supply / discharge switching valve 36 that can be controlled by a pilot control valve (electromagnetic pressure control valve) 16. (Reservoir tank) 7 is connected to the main accumulator 6, and a hydraulic pump 9 driven by the engine 8 is connected to the main accumulator 6.
As shown in FIGS. 1 and 2, the supply / discharge switching valve 36 has a pump port 39 (described later) connected to the pump 9 via an oil supply path 60, and a tank port 40 (described later) connected to an oil discharge path 61. It is connected to the reservoir 7 via. In FIG. 1, for convenience, the pump port 39 and the tank port 40 are shown in only one of the four supply / discharge switching valves 36. 2 to 5 show only one of the four supply / discharge switching valves 36 as a representative.

  Check valves 10 and 11 for preventing backflow are provided between the supply / discharge switching valve 36 and the main accumulator 6 and between the main accumulator 6 and the hydraulic pump 9 in the oil supply passage 60, respectively. Further, a pilot check valve 12 is provided between the supply / discharge switching valve 36 and the reservoir 7 in the oil discharge passage 61. The pilot check valve 12 closes when the system is stopped when the pilot pressure is not applied (when the engine is stopped), shuts off the flow of oil from the supply / discharge switching valve 36 to the reservoir 7, and operates when the system is operating (engine operation). ), The valve is opened under the pilot pressure in the pilot passage 13 (described later) so that the oil can be discharged from the supply / discharge switching valve 36 to the reservoir 7.

The upstream side of the check valve 11 on the discharge side of the hydraulic pump 9 is connected to the reservoir 7 side (oil drain passage 61) by an unload passage 22, and a pilot type unload valve 23 is connected to the unload passage 22. Is provided. A portion of the oil supply passage 60 between the check valves 10 and 11 (and thus the main accumulator 6) is connected to the reservoir 7 side (oil discharge passage 61) by a fail safe passage 24 and a pilot passage 13. The fail safe passage 24 is provided with a pilot type fail safe valve 25. The pilot passage 13 is provided with an orifice 26 on the upstream side, and an electromagnetic pilot control valve 27 is provided on the downstream side. The pilot check valve uses the pressure upstream of the orifice 26 in the pilot passage 13 as the pilot pressure. Supplied to 12. Further, the pilot control valve 27 transmits the pilot pressure to the unload valve 23 and the fail safe valve 25 through the pilot pipe 63.
1, reference numerals 14 and 15 are pressure sensors, 17 is a relief valve, 18 is a filter, 19 is an oil cooler, and 21 is an accumulator that absorbs oil hammer when the pilot check valve 12 is opened. The pressure sensor 14 detects the pressure (cylinder pressure) Pc of the hydraulic cylinder 2, and the pressure sensor 15 detects the system pressure (drive pressure source pressure) P.

  As shown in FIGS. 2 to 5, the supply / discharge switching valve 36 is a 3-port 3-position pilot type spool valve, and includes a barrel (switching valve main body) 37 having a hollow portion 70 extending in the longitudinal direction. Thus, the pilot control valve 16 is provided. In the hollow portion 70, the main spool 41 and the sub spool 74 are accommodated so as to be slidable and abuttable.

The hollow portion 70 includes a small-diameter hollow portion 71 and a large-diameter hollow portion 73 that is connected to the small-diameter hollow portion 71 with a stepped portion 72 and connected to the pilot control valve 16 through the pilot passage 49. The large-diameter hollow portion 73 in the stepped portion 72 communicates with the oil supply passage 60, and the pressure receiving surface A0 of the sub-spool 74 is disposed in this portion (the large-diameter hollow portion 73 in the stepped portion 72). Then, the pressure of the main accumulator 6 (hydraulic power source) acts on the pressure receiving surface A0, and the sub spool 74 is pushed in the left direction in FIG.
The small-diameter hollow portion 71 is provided with a cylinder port 38 connected to the hydraulic cylinder 2 side, a pump port 39 connected to the main accumulator 6 side (pump 9 side), and a tank port 40 connected to the reservoir 7 side. A main spool 41 is slidably fitted in the small-diameter hollow portion 71. Depending on the position of the main spool 41, the cylinder port 38 communicates with the pump port 39 or the tank port 40 or is cut off from these. It is supposed to be.

In the present embodiment, the main spool 41 is in the center position (neutral position) shown in FIGS. 2 and 4 [hereinafter, referred to as neutral state as appropriate. ], The cylinder port 38 is disconnected from both the pump port 39 and the tank port 40, and the main spool 41 is in the left position (oil drain position) shown in FIG. . ], The cylinder port 38 is disconnected from the pump port 39 and communicates with the tank port 40, and is in the right position (oil supply position) shown in FIG. ], Each port and land are arranged so that the cylinder port 38 is disconnected from the tank port 40 and communicates with the pump port 39.
In the main spool 41, notches 41a are formed at predetermined intervals in the circumferential direction. When the notches 41a communicate with each port, the notch 41a first faces each port, so that a sudden change in the communication passage area occurs. As a result, it is possible to prevent the ride comfort from being deteriorated due to the rapid supply / discharge of the fluid to / from the hydraulic cylinder 2.

  A sub-spool 74 is slidably fitted to the large-diameter hollow portion 73 side portion of the large-diameter hollow portion 73 and the small-diameter hollow portion 71. The sub-spool 74 is slidably fitted into the large-diameter hollow portion 73 and is slidably fitted into the small-diameter hollow portion 71 connected to the sub-spool main body 74a with a stepped portion 74b. And a sub-spool extension 74c. The front end portion of the sub-spool extension 74c faces the main spool 41 so as to be able to come into contact therewith. The sub spool 74 is formed with a large diameter hole 75 and a small diameter hole 76 substantially corresponding to the sub spool main body 74a and the sub spool extension 74c.

A drain chamber 44 is formed between one end of the main spool 41 and one side wall (right side in FIG. 2) of the hollow portion 70, and a pilot chamber 46 is formed between the sub-spool extension 74 c and the main spool 41. ing. The pilot chamber 46 is connected to the pilot control valve 16 through a small diameter hole 76, a large diameter hole 75 and a pilot passage 49.
A first spring 50 is provided in the drain chamber 44 to urge the main spool 41 toward the pilot chamber 46 (leftward in FIG. 2). Between the bottom of the large-diameter hole 75 of the sub spool 74 and the other end side wall (left side in FIG. 2) of the hollow portion 70, the second is urged toward the pilot chamber 46 side (right direction in FIG. 2). The spring 51 is interposed. As will be described later, when the engine is stopped, the pressure before and after the main spool 41 is the same, and the main spool 41 is brought into contact with the sub spool 74 and receives the urging force of the first and second springs 50 and 51, as shown in FIG. As shown in FIG.

Further, a pressure receiving surface A0 is configured by a stepped portion 74b provided in the sub spool 74. The pressure receiving surface A0 is disposed in the large-diameter hollow portion 73 in the stepped portion 72 as described above. In the sub spool 74, the pressure receiving surface A0 applies a force in the opposite direction (force in the left direction in FIG. 2) from the biasing force (force in the right direction in FIG. 2) of the second spring 51 from the main accumulator 6 (hydraulic power source). To receive.
The sub spool 74 moves the main spool 41 to the neutral position when a solenoid 62 (described later) of the pilot control valve 16 is not energized. For example, when a failure such as a disconnection occurs, the controller 35 stops energizing the solenoid 62 in response to this (in this embodiment, this state is the “when the suspension device is not controlled” of the present invention). The pressure before and after the main spool 41 is made equal, and the supply / discharge switching valve 36 is made neutral by the urging forces of the first and second springs 50 and 51.
Further, after the system is started, the sub spool 74 receives the pressure of the main accumulator 6 (hydraulic power source), and as shown in FIG. 4, the sub spool 74 compresses the second spring 51 and strokes it to the left. A space (pilot chamber 46) is formed between the main spool 41 and the main spool 41 so that it can stroke in the left direction in FIG.

  The pilot control valve 16 includes the solenoid 62 as shown in FIGS. The pilot control valve 16 is driven when the command current from the controller 35 is supplied to the solenoid 62, and the pilot pressure Pp corresponding to the command current is output to the pilot chamber 46 through the pilot passage 49, and the pressure received by the pressure receiving surface A0. The position of the main spool 41 is adjusted in cooperation with the urging forces of the first and second springs 50 and 51.

  In this suspension apparatus 1, the controller 35 inputs detection signals of the sensors including the pressure sensors 14 and 15, executes calculations, and supplies and discharges the pressure of the main accumulator 6 and the hydraulic fluid of the hydraulic cylinders 2 of the wheels. (Supply / discharge oil amount) is controlled to adjust the posture of the vehicle body.

When the engine 8 is stopped, the controller 35 does not output a control signal, and the pilot control valve 27 and the pilot control valve 16 are open. When the pilot control valve 27 is open, no pilot pressure is generated on the unload valve 23, the fail safe valve 25, and the pilot check valve 12, so the unload valve 23 is closed, the fail safe valve 25 is opened, and the pilot reverse valve is opened. The stop valve 12 is closed. The four-wheel hydraulic cylinder 2 is sealed by the check valve 10 and the pilot check valve 12 so that the internal pressure thereof is the same. At this time, since the main accumulator 6 is connected to the reservoir 7 side via the fail-safe valve 25, the pressure is not accumulated.
Further, when the engine 8 is stopped, the supply / discharge switching valve 36 has the same pressure on the supply / discharge side in the hydraulic circuit. The spool 41 is disposed at the neutral position in FIG.

  When the engine 8 is started, discharge of the pressure oil by the hydraulic pump 9 is started, while the unload valve 23 is closed and the fail-safe valve is controlled by the pilot pressure controlled by the controller 35 via the pilot control valve 27. Close valve 25 to turn it on-load. In this on-road state, the oil supply passage 60 and the oil discharge passage 61 are not in communication, so that the discharge flow rate of the hydraulic pump 9 is supplied to the main accumulator 6 and each hydraulic cylinder 2. Further, as the system pressure P increases, the pilot check valve 12 using the pressure as the pilot pressure opens, and the supply / discharge switching valve 36 communicates with the reservoir 7 via the oil discharge passage 61 to allow oil drainage. .

When the oil is discharged during normal control, the main spring 41 is pushed to the left in FIG. 2 by the first spring 50 by lowering the pilot pressure Pp. As shown in FIG. 3, the tank port 40 and the cylinder port Communicate 38.
When the pilot pressure is increased, the pilot pressure Pp is received through the large diameter hole 75 and the small diameter hole 76 of the sub spool 74, and the main spool 41 strokes to the right side in FIG. 3 and reaches the neutral position as shown in FIG. Further, by increasing the pilot pressure Pp, the main spool 41 strokes to the right side, and can be brought to the oil supply position as shown in FIG.
When the controller 35 detects any abnormality (failure), the control signal to the pilot control valve 27 is stopped (“when the suspension device is not controlled” in the present invention), and the pilot pressure is set to zero. For this reason, the unload valve 23 is closed and the fail safe valve 25 is opened. As a result, the oil supply passage 60 and the oil discharge passage 61 are communicated with each other by the fail-safe valve 25, so that the system pressure P of the main accumulator 6 is lowered and the pilot check valve 12 is closed.

Also, the command current to the four-wheel pilot control valve 16 is also stopped, whereby the pressure in the supply / discharge switching valve 36 becomes constant, and the pressures before and after the main spool 41 and the sub spool 74 become equal. Therefore, the sub spool 74 is pushed back by the force of the second spring 51, and the four-wheel supply / discharge switching valve 36 is in the neutral state shown in FIG. As a result, the four-wheel hydraulic cylinder 2 is prevented from communicating, and the stability of the vehicle is maintained.
With this configuration, the state of the main spool 41 of the supply / discharge switching valve 36 can be determined by the force acting on the pressure receiving surface A0, the pilot pressure Pp, and the force of the first and second springs 50 and 51. As described above, when setting the neutral state of the supply / discharge switching valve 36 at the time of failure (moving to the neutral position of the main spool 41), the main spool 41 is pushed from both sides by using the first and second springs 50 and 51. Thus, the neutral position of the main spool 41 can be set reliably and accurately.
Further, as described above, the supply / exhaust switching valve 36 is set to the neutral state during the failure so that the four-wheel hydraulic cylinder 2 does not communicate with each other, thereby preventing the posture change in the roll and pitch directions and maintaining the stability of the vehicle. be able to.

It is a figure which shows the hydraulic circuit of the suspension apparatus which concerns on one embodiment of this invention. FIG. 2 is a cross-sectional view schematically showing a neutral state of the supply / discharge switching valve of FIG. 1 (when the engine is stopped or when a failure such as disconnection occurs). It is sectional drawing which shows typically the oil-discharge state of the supply / discharge switching valve of FIG. FIG. 2 is a cross-sectional view schematically showing a neutral state of the supply / discharge switching valve of FIG. It is sectional drawing which shows typically the oil supply state of the supply / discharge switching valve of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Suspension apparatus, 2 ... Hydraulic cylinder, 16 ... Pilot control valve, 36 ... Supply / discharge switching valve, 41 ... Main spool, 46 ... Pilot chamber, 50, 51 ... First and second springs, 74 ... Sub spool.

Claims (1)

An oil supply path and a reservoir tank connected to a hydraulic source via a supply / discharge switching valve that can be controlled by an electromagnetic pilot control valve in a hydraulic cylinder interposed between the vehicle body side and each wheel side of the vehicle In the suspension device for controlling the posture of the vehicle by connecting the oil discharge passage connected to the vehicle, and controlling the supply / discharge switching valve to supply / discharge oil liquid to / from each hydraulic cylinder,
The supply / discharge switching valve includes a switching valve main body having a hollow portion that slidably and slidably accommodates the main spool and the sub spool.
A first spring and a second spring arranged on each end side opposite to the abutting side of the main spool and the sub spool and biasing them in the abutting direction;
The main spool shuts off the hydraulic cylinder with respect to the oil supply position for connecting the oil supply path to the hydraulic cylinder, the oil discharge position for connecting the oil discharge path to the hydraulic cylinder, and the oil supply path and the oil discharge path. Selectively switching to the neutral position, and when the suspension device is not controlled, the suspension device receives the urging force of the first spring and the urging force of the second spring via the sub spool, and moves to the neutral position. Suspension device characterized.

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