JP3097445B2 - Hydropneumatic suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for a vehicle such as an automobile, and more particularly to a hydropneumatic suspension system.

[0002]

2. Description of the Related Art As one of hydropneumatic suspension devices for vehicles such as automobiles, for example, as described in SAE paper 780052 published in February 1978, a cylinder is reciprocally fitted to a cylinder. A damper unit having a piston defining a working chamber in cooperation with a cylinder and a damping force generating mechanism; a gas-liquid spring device communicating with the working chamber; a reservoir; and a connection passage connecting the working chamber to the reservoir. And a pump rod fixed to the cylinder and reciprocally fitted in the cylinder hole and defining a pump chamber in cooperation with the cylinder hole. Having a self-leveling mechanism that connects the reservoir to the working chamber when the vehicle height increases above the standard vehicle height. Pneumatic suspension device is known from the prior art.

According to such a hydropneumatic suspension device, the pump is driven by the expansion and contraction of the damper unit due to the relative displacement between the wheel and the vehicle body, whereby the working liquid is supplied from the reservoir to the gas-liquid spring device. Therefore, even if the load of the vehicle increases, the vehicle height is gradually increased as the vehicle travels, and is automatically set to the standard vehicle height.

[0004]

However, in the conventional suspension device as described above, the pump is driven in synchronization with the expansion and contraction of the damper, and the discharge stroke of the pump is performed simultaneously with the contraction stroke of the damper. At the time of bouncing, both the damping force of the damper unit and the driving reaction force of the pump act on the vehicle body, and therefore, there is a problem that the ride comfort of the vehicle is deteriorated. In addition, the pump performs the discharge stroke by the pump rod entering the cylinder hole, so that the pressure of the working chamber is reduced, and the working liquid is supplied during the extension stroke of the damper unit, which easily supplies the working liquid to the working chamber. Therefore, there is a problem that it takes a long time to adjust the vehicle height.

The present invention has been made in view of the above-mentioned problems in the conventional hydropneumatic suspension system, and a main problem of the present invention is that the working chamber of the damper unit is moved from the piston and the reservoir of the damper unit. Independent of the pump for supplying the working liquid to the pump and providing the pump in the damper unit, it is possible to improve the ride comfort of the vehicle as compared with the conventional case without increasing the size of the hydropneumatic suspension device It is another object of the present invention to efficiently perform a vehicle height adjustment with respect to a change in a loaded weight of a vehicle.

[0006]

According to the present invention, a main object as described above is to provide a structure according to the first aspect, that is, a main body which is reciprocally fitted to a cylinder and the cylinder and cooperates with the cylinder. A damper unit having a piston defining a working chamber and a damping force generating mechanism; a gas-liquid spring device communicating with the main working chamber; a reservoir; and a connecting passage means for connecting the main working chamber to the reservoir. In the hydropneumatic suspension device comprising: an electric pump provided in the damper unit in the middle of the connection passage means and configured to supply the working fluid in the reservoir to the main working chamber. This is achieved by a hydropneumatic suspension device.

According to the present invention, in order to effectively attain the above-mentioned main object, in the structure of the first aspect, the pump includes a pump passage defining a part of the connection passage means. A reciprocating plunger provided therein; and a check valve that allows only the flow of the working liquid from the internal passage toward the main working chamber (the configuration according to claim 2).

According to the present invention, in order to effectively achieve the above-mentioned main object, in the structure of the first or second aspect, the main working chamber is provided with a first partition defined on both sides of the piston. And the second main working chamber, wherein the suspension device further includes a cylinder hole provided in the piston along a reciprocating direction of the piston, and the cylinder fixed to the cylinder and reciprocally fitted in the cylinder hole. An actuator rod that cooperates with a hole to define a sub-operation chamber; a communication unit that connects the sub-operation chamber to the first main operation chamber; and a reservoir provided on the actuator rod and the sub-operation chamber. An internal passage communicating with the chamber, the sub-operating chamber, the communication means, and the internal passage define the connection passage means, and the pump is provided inside the actuator rod inside the actuator rod. It is provided in the middle of the road (claim 3
Configuration).

According to the present invention, in order to effectively achieve the above-mentioned main object, in the structure of claim 3, the actuator rod includes the internal passage means and the second main working chamber. A communication orifice is provided for communication connection, and the communication orifice is configured to be opened and closed by a sliding surface of the cylinder hole with respect to the actuator rod.

According to the present invention, in order to effectively attain the above-mentioned main object, the means for detecting whether or not the ignition switch has been switched from off to on in the structure of claim 3 or 4 is provided. And control means for driving the pump for a predetermined time when it is detected that the ignition switch has been switched from off to on (configuration of claim 5).

According to the present invention, in order to effectively achieve the above-mentioned main object, the actuator rod according to any one of claims 1 to 5, wherein the actuator rod has a tapered shape, and When the amount of entry of the actuator rod is equal to or greater than a predetermined value, the distance between the opening end of the communication means and the wall surface of the actuator rod gradually decreases as the amount of entry increases, whereby the auxiliary working chamber and the first Is configured so that the degree of communication with the main working chamber gradually decreases.

According to the present invention, in order to achieve the above-mentioned main object effectively, the vehicle height detecting means and the vehicle height may be set to the first predetermined value. Control means for driving the pump when the value is equal to or less than a predetermined value, and stopping the pump when the vehicle height is equal to or more than a second predetermined value higher than the first predetermined value. 7).

[0013]

According to the first aspect of the present invention, the electric pump for supplying the working liquid in the reservoir to the main working chamber is provided, and the pump is not driven by expansion and contraction of the damper unit. Since it is electrically driven independently of the operation state of the damper unit, it is possible to reduce the pressurizing reaction force of the pump as compared with the conventional structure,
The pressure reaction force of the pump is prevented from being transmitted to the vehicle body via the damper unit in synchronization with the input from the road surface, thereby improving the riding comfort of the vehicle and the damper unit being in the extension stroke and the main operation The working liquid can be supplied to the main working chamber even when the pressure in the room is relatively low, so that the vehicle height can be adjusted more efficiently with respect to the change in the loaded weight of the vehicle than in the conventional structure. It becomes possible.
Further, since the pump is provided in the damper unit in the middle of the connection passage means, the size of the suspension device can be reduced as compared with the case where the pump is provided outside the damper unit.

According to the second aspect of the present invention, the pump includes only a reciprocating plunger having a pump internal passage defining a part of the connection passage means, and a flow of the working liquid from the internal passage toward the main working chamber. Therefore, it is possible to reduce the size of the pump itself and to simplify the configuration around the pump.

According to the third aspect of the present invention, the main working chamber includes first and second main working chambers defined on both sides of the piston, and the suspension device further moves the piston along the reciprocating direction of the piston. An actuator rod fixed to the cylinder, fixed to the cylinder, reciprocally fitted into the cylinder hole, and cooperating with the cylinder hole to define a sub-operation chamber;
A communication means for communicating and connecting the sub-working chamber and the first main working chamber; and an internal passage provided in the actuator rod for communicating and connecting the reservoir and the sub-working chamber. The passage defines the connecting passage means, and the pump is provided in the actuator rod in the middle of the internal passage, so that the suspension device is provided as compared with the case where the pump is provided outside the actuator rod even in the damper unit. Can be further reduced in size.

According to the fourth aspect of the present invention, the actuator rod has a communication orifice that connects the internal passage means and the second main working chamber, and the communication orifice is a sliding surface of the cylinder hole with respect to the actuator rod. When the vehicle height is gradually increased by driving the pump, the communication orifice is opened by the sliding surface of the cylinder hole, and the internal passage means and the second main working chamber are opened and closed. Are connected by the communication orifice, and the pressures in the first and second main working chambers and the reservoir are equalized, and the vehicle height is reduced. Therefore, the self-leveling function is exhibited with the position where the communication orifice is opened and closed by the sliding surface of the cylinder hole as the standard vehicle height, and the vehicle height can be reliably controlled to the standard vehicle height without the need for a vehicle height sensor. Become.

According to the above configuration, the means for detecting whether the ignition switch has been switched from off to on, and the pump when the ignition switch has been switched from on to off are detected. Control means for driving for a predetermined time, so that when the ignition switch is switched from off to on, the pump is supplied with working fluid from the reservoir to the second working chamber, whereby the vehicle height is gradually increased, The self-leveling function automatically sets the vehicle height to the standard vehicle height, so that the vehicle height at the start of traveling of the vehicle can be controlled to the standard vehicle height.

According to the above construction, the actuator rod has a tapered shape, and when the amount of entry of the actuator rod into the cylinder hole is equal to or larger than a predetermined value, the opening end of the communicating means and the actuator rod are increased as the amount of entry increases. Is gradually reduced, whereby the degree of communication between the sub-working chamber and the first main working chamber is configured to be gradually reduced.Therefore, as the bounce amount of the wheel increases, that is, the damper unit As the contraction stroke increases, the damping force generated by the communication means increases, and thus, the impact given to the vehicle body when the wheel suddenly bounces significantly is reduced.

According to the above construction, the vehicle height detecting means and the pump are driven when the vehicle height is equal to or less than the first predetermined value, and the vehicle height is higher than the first predetermined value. A control means for stopping the pump when the value exceeds the second predetermined value, so that the vehicle height is set to a value between the first predetermined value and the second predetermined value regardless of the operating state of the damper unit. Is reliably controlled.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 1 is a longitudinal sectional view showing a first embodiment of a hydropneumatic suspension device according to the present invention in which a gas-liquid spring device and a reservoir are integrally formed with a damper unit, and FIG. 2 is a first embodiment. And FIG. 3 is an enlarged vertical sectional view showing the pump of the first embodiment.

In FIG. 1, reference numeral 10 denotes a substantially cylindrical housing extending along an axis 12, and reference numeral 14 denotes a damper unit disposed in the housing 10 and also extending along the axis 12. Is shown. Damper unit 1
Reference numeral 4 denotes a cylinder 16 fixed at the upper end to the end cap 10A of the housing 10 and fixed at the lower end to the end cap 10B of the housing. It has a piston 22 that defines the upper chamber 18 and the lower chamber 20. The piston 22 includes a piston body 24 and a piston rod 26 integrally fixed to the piston body. The piston main body 24 is provided with a well-known damping force generating mechanism 28 for a contraction stroke and a damping force generating mechanism 30 for an extension stroke.

A partition member 32 is disposed between the housing 10 and the cylinder 16 at the center in the longitudinal direction thereof and is fixed to the housing and the cylinder.
Is the housing 10, the cylinder 16, the end cap 10
In cooperation with B, a gas-liquid spring device 34 is defined. The gas-liquid spring device 34 has a liquid chamber 38 and a gas chamber 40 separated from each other by a substantially cylindrical diaphragm 36 extending in the vertical direction. The liquid chamber 38 is provided at the lower end of the cylinder 16. The lower chamber 20 is connected to the lower chamber 20 through the communication hole 16A. The partition member 32 defines an oil reservoir 42 in cooperation with the housing 10, the cylinder 16, and the end cap 10A.

The piston rod 26 is formed by a hollow pipe having a cylinder hole 44 extending along the axis 12. The upper end of the actuator rod 46 is fixed to the end cap 10A together with the end cap 16B of the cylinder 16, and the actuator rod 46 extends along the axis 12 so as to reciprocately fit into the cylinder hole 44. A central chamber 50 as a sub-operating chamber is defined in cooperation with a seal member 48 fixed to a lower end of the central chamber 50. The central chamber 50 is connected to the lower chamber 20 through a plurality of communication holes 52 provided in the piston rod 26.

As shown, the upper chamber 18, the lower chamber 20, the liquid chamber 38 of the gas-liquid spring device 34, a part of the reservoir 42, and the central chamber 50 are filled with oil as a working liquid. The remaining part of the gas chamber 40 and the reservoir 42 is filled with compressed air. The pressure in the gas chamber 40 is set to be higher than the pressure in the reservoir 42 by a predetermined value when the vehicle is in the standard loaded state.

The actuator rod 46 includes a central chamber 50.
An internal passage 54 is provided for communicating and connecting the end cap 16 with the reservoir 42.
B is connected to the upper end of the conduit 56 fixed to B, and the conduit 5
The lower end of 6 is located at a position sufficiently lower than the level of the oil filled in the reservoir 42. An electric pump 58 is provided in the actuator rod 46 in the middle of the internal passage 54. Furthermore, the pump 58 in the internal passage 54
The inner end of a communication orifice 60 extending in the radial direction is connected to a portion closer to the reservoir 42, and the outer end of the communication orifice 60 is open to the wall surface of the actuator rod 46.

As shown in detail in FIG. 2, above the communication orifice 60, the O-ring seal 6 cooperating with the wall of the cylinder bore 44 is provided on the wall of the actuator rod 46.
2 is fixed. The diameter of the region from the upper end of the actuator rod 46 to a portion slightly below the communication orifice 60 is substantially constant, and the clearance a between the wall surface of the region and the wall surface of the cylinder hole 44 is substantially zero. However, the region below the region has a tapered shape, and the clearance between the wall surface of this tapered region and the wall surface of the cylinder hole 44 is set to gradually increase from b to c.

The communication orifice 60 and the O-ring seal 62 have the damper unit 14 in the neutral position when the upper end of the piston 22 is substantially aligned with the seal 62, and the height of the corresponding wheel is the standard vehicle. At a raised position, and thus, as shown in FIG.
When the upper end of the piston 22 is above the seal 62, the vehicle height is lower than the standard vehicle height. Conversely, when the upper end of the piston is below the seal 62, the vehicle height is higher than the standard vehicle height.

The pump 58 in this embodiment is configured as a solenoid actuator type plunger pump as shown in detail in FIG.
4 has a plunger 66 arranged reciprocally along the axis 12. The plunger 66 has an in-pump passage 68 extending as a through hole from the upper end to the lower end, and a core 70 is integrally fixed to the plunger and is disposed in the enlarged portion of the inner passage 54. A stopper member 72 is disposed at the enlarged diameter portion of the internal passage 54 and is fixed to the actuator rod 46. A stopper ring 74 fixed to the upper end of the plunger 66 and a stopper member 7
A compression coil spring 76 for urging the plunger 66 upward as viewed in FIG.

The plunger 66 is provided below the inner passage 54.
The pump chamber 78 which forms a part of the pump chamber 7 is defined.
A check valve 80 that allows only the flow of oil from the pump internal passage 68 toward the pump chamber is provided in the inside 8. A check valve 82 is provided below the check valve 80 to allow only the oil flow from the pump chamber 78 toward the central chamber 50. The plunger is the core 70 in the actuator rod.
Is reciprocated along the axis 12 by a solenoid 84 disposed around the pump, so that the pump 58 discharges oil in the internal passage 54 above it to the central chamber 50.

Although not shown in FIG.
0 is connected to the vehicle body via a rubber bush 90 by a connecting member 88 fixed to the end cap 10A,
The lower end of the piston rod 26 is connected to a suspension member via a rubber bush 94 by a connecting member 92, so that the illustrated suspension device is incorporated independently into the suspension of each wheel.

As shown in FIG. 1, the pump 58 is controlled by an electronic control unit 98 via a harness 96. The electronic control unit 98 includes an ignition switch 10
0, a signal indicating whether or not the switch is on is input, and the electronic control unit supplies a drive current to the solenoid 84 for a certain time when the ignition switch is switched from off to on. It is driven for a predetermined time. In this case, the pump 58
During the predetermined time during which the vehicle is driven, even if the vehicle changes from the minimum loading state to the maximum loading state at the start of traveling, oil in the reservoir 42 is supplied to the damper unit 14 by the pump 58 as described below to reduce the vehicle height. It is set to a time sufficient to ensure the standard vehicle height.

Therefore, in the first embodiment, the damper unit 14 is compressed as shown in FIG. 1, for example, as shown in FIG. Also, oil in the reservoir 42 is supplied to the central chamber 50 through the conduit 56 and the internal passage 54 by the pump 58, and is supplied from the central chamber 50 to the lower chamber 20 through the communication hole 52. A part of the oil in the lower chamber 20 is supplied to the liquid chamber 38 of the gas-liquid spring device 34 through the communication hole 16A to pressurize the gas chamber 40, but a part of the oil in the lower chamber 20 is supplied to the damping force generating mechanism 30. Flows into the upper chamber 18 through this, whereby the piston 22 is displaced downward relative to the cylinder 16 and the damper unit 14 is extended.

Thus, the piston 22 is displaced downward and its upper end is displaced to a position below the seal 62, and the upper chamber 18 is displaced.
And the communication orifice 60, the oil flowing from the lower chamber 20 through the damping force generating mechanism 30 to the upper chamber 18 and the oil flowing from the upper chamber through the communication orifice 60 into the internal passage 54 are balanced. Since oil is no longer supplied from the reservoir 42, the damper 14 does not extend further even when the pump 58 is driven, and the vehicle height is controlled to the standard vehicle height.

Conversely, in the first embodiment, when the damper unit 14 extends beyond the neutral position due to a decrease in the number of occupants or a reduction in the load immediately before the vehicle starts traveling, the orifice communicating with the upper chamber 18 is formed. 60 communicates. In this case, since the pressure in the damper unit 14 and the gas-liquid spring device 34 is higher than the pressure in the reservoir 42, even if the pump 58 is driven, part of the oil flowing from the upper chamber 18 into the communication orifice 60 And reservoir 4 via conduit 56
2, the amount of oil in the damper unit and the gas-liquid spring device decreases, and the vehicle height decreases.

When the upper end of the piston 22 is aligned with the seal 62 due to the decrease in the vehicle height, the upper chamber 1
Since the communication between the communication orifice 8 and the communication orifice 60 is cut off, the vehicle height does not decrease further, and if the pump 58 is in a driving state at that time, the oil in the reservoir 42 is supplied to the damper unit 14. As a result, the vehicle height slightly increases, and the upper chamber 18 and the communication orifice 60 communicate again. However, the pressure drop between the upper chamber 18 and the communication orifice 62 and at the communication orifice causes the upper chamber and the internal passage 54 to have a lower pressure. The piston 22 does not descend until the pressure difference becomes equal to or less than
Finally, the upper end of the piston is aligned with the seal 62, and the vehicle height is controlled to the standard vehicle height.

When the number of occupants is reduced or the load is reduced at the end of traveling of the vehicle, the load acting on the damper unit 14 is reduced, so that the damper unit is extended.
The upper chamber 18 and the communication orifice 60 communicate with each other, and the oil in the damper unit and the gas-liquid spring device flows out to the reservoir 42, whereby the communication between the upper chamber and the communication orifice is interrupted. The height gradually decreases, and also in this case, the vehicle height is finally controlled to the standard vehicle height.

Therefore, according to the first embodiment, even if the load of the vehicle changes and the vehicle height changes to a vehicle height other than the standard vehicle height, the wheels do not need to repeatedly bounce and rebound. The self-leveling function of the communication orifice 60 allows the vehicle height to be automatically controlled to the standard vehicle height, and does not require a vehicle height sensor or an advanced control device. , The structure of the hydropneumatic suspension device can be simplified and the cost can be reduced.

In this embodiment, when the vehicle bounces and rebounds as the vehicle travels, the oil in the upper chamber 18 and the lower chamber 20 circulates through the damping force generating mechanisms 28 and 30 to each other. A damping force is generated. In particular, when the wheels bounce, the upper end of the piston 22 is located above the seal 62, and the upper chamber 18 and the communication orifice 60 are in a state of being cut off from each other, so that the oil in the upper chamber does not flow out to the communication orifice 60. . Even when the pump 58 is driven when the wheels bounce, the pressure applied by the pump acts on the pressure in the damper unit 14 and the gas-liquid spring device 34 before the wheels bounce. Is relatively small, so that a high load due to the pump in addition to the input from the road surface is transmitted to the vehicle body in an impact manner, and the ride comfort of the vehicle due to this is not deteriorated.

When the wheels rebound, the piston 22
Is located below the seal 62, and the upper chamber 18 and the communication orifice 60 communicate with each other, but the pressure in the upper chamber is lower than when the piston 22 is in the neutral position, and the pressure drop is reduced by the communication orifice 60. Since the oil is generated, the oil in the upper chamber 18 does not flow out to the reservoir 42 through the communication orifice 60 or the like as long as the piston speed is equal to or higher than the predetermined value. When the wheel rebounds, the pump 5
When the piston 8 is driven, the pressure in the damper unit 14 and the gas-liquid spring device 34 is lower than when the piston is in the neutral position, so that the oil in the reservoir 42 is efficiently supplied to the damper unit. Thus, the increase in the vehicle height up to the standard vehicle height at the start of running of the vehicle is efficiently adjusted.

Further, according to the illustrated embodiment, when the wheel bounce amount exceeds a predetermined value, the actuator rod 46 overlaps the communication hole 52, and as the bounce amount increases, the center chamber 50 and the lower chamber 20 are connected to each other. Is reduced, and the flow resistance when oil passes through the communication hole 52 increases, so that the damping force generated by the entire damper unit gradually increases. Accordingly, the damping force of the damping force generating mechanism 28 is set to a low value to improve the ride comfort of the vehicle when the stroke of the wheel is small, and the steering stability of the vehicle is effectively suppressed by effectively suppressing the high bound stroke of the wheel. Can be improved.

FIG. 4 is an enlarged vertical sectional view showing another example of an electric pump which may be used in the hydropneumatic suspension device according to the present invention. In FIG. 4, FIG.
The same reference numerals as in FIG. 3 denote parts corresponding to the parts shown in FIG.

The pump 58 shown in FIG. 4 is configured as a piezo actuator pump, and has a piezo actuator 102, a displacement enlarging mechanism 104, and a reciprocating pump section 106. Piezo actuator 10
2 has a piezo stack 108 and an output member 110,
The displacement enlarging mechanism 104 is connected to the inner housing 112 by the axis 1.
A piston 116 and a disc spring 118 are fitted so as to be able to reciprocate along 2, and the piston 116 is pressed against the tip of the output member 110 by the disc spring 118. The piezo stack 108 reciprocates the output member 110 when a control current is applied thereto, and cooperates with the disc spring 118 to reciprocate the piston 116 along the axis 12.

The reciprocating pump section 106 has a pump piston 120 fitted to the inner housing 112 so as to reciprocate along the axis 12. The piston 120 cooperates with the inner housing 112 to define a suction chamber 122. A discharge chamber 126 is defined in cooperation with a discharge valve assembly 124 fixed to a lower end of the inner housing. A disc spring 128 is disposed in the discharge chamber 126, and the piston 120 is urged upward in the figure by the disc spring. The piston 120
Is integrally formed with a plunger 130 extending along the axis 12, and the plunger 130 is reciprocally fitted in a bore 132 provided in the inner housing.

An annular groove is formed on the outer peripheral surface of the inner housing 112, and the annular groove cooperates with the actuator rod 46 to define an annular chamber 132. Annular chamber 1
Numeral 32 is connected to the suction chamber 122 by an internal passage 134 provided in the inner housing, and is provided with an axial groove 136 provided along the axis 12 on the inner peripheral surface of the inner housing 112, the pump 58, and the actuator rod 46. Is connected to the internal passage 54 through the space between the two.

The inner housing 112 is fixed in the actuator rod 46 by a lock nut 138, and the lock nut 138 defines a discharge port 140. The discharge port 140 communicates with the central chamber 50 and is located below the discharge valve assembly 124.
The valve chamber 142 is connected to an internal space 146 in the discharge valve assembly 124 by a communication hole 144. The pump piston 120 is provided with a check valve 148 that substantially allows only the flow of oil from the suction chamber 122 to the discharge chamber 126, and the discharge valve assembly 124 is substantially separated from the discharge chamber 126 by the internal space 146. A check valve 150 is provided which allows only the flow of oil toward the outlet.

Thus, in the case of the pump of this embodiment,
When a control current is applied to the piezo stack 108 of the piezo actuator 102 and the output member 110 reciprocates,
The reciprocating displacement is caused by the displacement of the piston 11 by the displacement enlarging mechanism 104.
6 and is transmitted to the pump piston 120 at a ratio corresponding to the cross-sectional area ratio of the plunger 130, whereby the oil in the internal passage 54 above the pump 58 is passed through the axial groove 136 and the annular chamber 132 to the inside of the pump. And is discharged to the central chamber 50 through the discharge port 140.

Therefore, even when the pump 58 in the first embodiment is a piezo-actuator type pump shown in FIG. 4, the hydropneumatic suspension device operates in the same manner as in the first embodiment. As in the case of the plunger pump of the solenoid actuator type shown in FIG. 3, the pump is incorporated in the actuator rod 46, and the gas-liquid spring device and the reservoir are integrally formed with the damper unit. The pneumatic suspension device is compact.

FIG. 5 is a schematic structural view showing a second embodiment of the hydropneumatic suspension device according to the present invention in which the gas-liquid spring device and the reservoir are formed independently of the damper unit. In FIG. 5, parts corresponding to the parts shown in FIG. 1 are denoted by the same reference numerals as in FIG.

In the second embodiment, the damper unit 14 is connected to the vehicle body 156 at the upper end of the piston rod 26 of the piston 22 by the upper support 154, and the wheel carrier is mounted at the lower end of the cylinder 16 by the bracket 158. 160 are integrally connected. Piston 22
Cooperates with the cylinder 16 to define one cylinder chamber 162 as a main working chamber, and corresponds to the damping force generating mechanism 28 and the damping force generating mechanism 30 in the first embodiment. It has no mechanism.

A gas-liquid spring device 34 is provided at the lower end of the cylinder 16.
Are fixed integrally. The gas-liquid spring device 34 in this embodiment has a substantially cylindrical tank 164 and a free piston 166 disposed in the tank, and the free piston cooperates with the tank to form the liquid chamber 38 and the gas. Room 40
Has been demarcated. The liquid chamber 38 is connected to a lower end of the cylinder chamber by a passage 170 provided in the connecting portion 168. A damping force generating mechanism 28 for the contraction stroke and a damping force generating mechanism 30 for the extension stroke are provided in the middle of the passage 170.

The reservoir 42 is disposed above the upper support 154 and is supported by the upper support. The reservoir 42 in this embodiment has a substantially spherical tank 172 and a diaphragm 174 secured within the tank, the diaphragm cooperating with the tank to define a liquid chamber 176 and a gas chamber 178. ing. The liquid chamber 176 is connected to the upper end of the internal passage 54 provided in the piston rod 26 by a passage 180. In the piston rod 26, the pump 5
8 are provided. The pump 58 may have the configuration shown in FIG. 3 or FIG.

A suspension arm 182 is pivotally supported at the inner end by a joint 184 to the vehicle body 156 and is pivotally mounted at an outer end to a lower end of the wheel carrier 160 by a ball joint 186. Is provided with a vehicle height sensor 188. In the illustrated embodiment, a compression coil spring 194 functioning as an auxiliary suspension spring is elastically mounted between an upper seat 190 provided on the upper support 154 and a lower seat 192 fixed to the cylinder 16. ing.

The pump 58 is controlled by an electronic control unit 98 via a harness 96 based on the detection result of the vehicle height sensor 188. The electronic control unit 98 of this embodiment includes a microcomputer 196 and a driving circuit 198.
The microcomputer 196 includes a CPU, ROM, and RA connected to each other by a bidirectional common bus.
M and an input / output port device. The ROM stores a control program corresponding to the flowchart shown in FIG. 6, and control of the pump 58 based on the control program is started by closing an ignition switch,
Further, for example, the processing is executed in the order of the front left wheel, the front right wheel, the rear left wheel, and the rear right wheel.

First, in step 10, the vehicle height sensor 18
The vehicle height H detected by step 8 is read, and in step 20, the vehicle height H is subjected to low-pass filtering using, for example, 1 Hz as a cutoff frequency to calculate the vehicle height Ha after low-pass filtering. In step 30, it is determined whether or not the vehicle height Ha after the low-pass filter processing is equal to or less than the first reference value H1.

If an affirmative determination is made in step 30, the pump is driven when the pump 58 is not in the driving state in step 40, and the pump is maintained as it is when the pump is in the driving state. If a negative determination is made in step 50, the vehicle height Ha after the low-pass filter processing in step 50 is equal to the second reference value H2 (> H).
1) It is determined whether or not the above is the case. When a negative determination is made, the process returns to step 10, and when an affirmative determination is made, the pump 58 is stopped in step 60.

Thus, according to the second embodiment, the pump 58 is driven when the vehicle height Ha becomes equal to or less than the first reference value H1 as long as the ignition switch is on.
The oil in the reservoir 42 is supplied to the cylinder chamber 162 to increase the vehicle height. When the vehicle height Ha becomes equal to or higher than the second reference value H2, the pump is stopped. Further, regardless of the running condition of the vehicle, the vehicle height is reliably controlled to a standard vehicle height range of H1 or more and H2 or less.

Also in this embodiment, even if the pump 58 is driven when the wheels bounce, the pressure in the damper unit 14 and the gas-liquid spring device 34 is controlled by the pump before the wheels bounce. Since the pressing force is acting and the pressing force is relatively small, a high load by the pump in addition to the input from the road surface is transmitted to the vehicle body in a shocking manner, and the riding comfort of the vehicle caused by this is transmitted. No deterioration occurs.

In this embodiment, the vehicle height is set to the second reference value H by reducing the number of occupants and the load.
When the pressure exceeds 2, the oil in the cylinder chamber 162 flows through the internal passage 54 and the passage 180 due to oil leakage in the pump 58, and the liquid in the liquid chamber 1 of the reservoir 42.
The vehicle height is brought to the standard vehicle height range by being discharged little by little to 76.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described first embodiment, the predetermined time during which the pump 58 is driven is a fixed time from the time when the ignition switch is switched from off to on. It may be driven without interruption as long as it is in the ON state. In the first embodiment, the self-leveling function of the communication orifice 60 automatically controls the vehicle height to the standard vehicle height. However, the communication orifice 60 is omitted, and the pump 58 is replaced by a pump 58. The control may be performed in the same manner as the control in the second embodiment.

Further, in the second embodiment, the damping force generating mechanisms 28 and 30 include the cylinder chamber 162 and the gas-liquid spring device 34.
Although it is provided in the middle of the passage 170 which connects the liquid chambers 38, the pistons may be provided with oil in the upper and lower cylinder chambers and a damping force generating mechanism. In the second embodiment, a compression coil spring 194 functioning as an auxiliary suspension spring is used.
However, an auxiliary suspension spring may be omitted, and the function of the suspension spring may be exhibited only by the gas-liquid spring device 34.

Further, in the first and second embodiments, the pump 58 has the specific structure shown in FIG. 3 or FIG. 4, but is different from the hydropneumatic suspension device of the present invention. The pump can be electrically driven to supply working liquid from the reservoir to the main working chamber of the damper unit.
Any structure may be used as long as it can be incorporated into the damper unit, such as inside the piston rod 26.

[0064]

As is apparent from the above description, according to the first aspect of the present invention, the pump is electrically connected independently of the operating state of the damper unit, and therefore irrespective of the bounding or rebounding of the wheels. The pressure reaction force of the pump can be reduced as compared with the past, and the pressure reaction force of the pump is transmitted to the vehicle body through the damper unit in synchronization with the input from the road surface Can be avoided, the ride comfort of the vehicle can be improved as compared with the conventional structure, and the pressure in the main working chamber is relatively low when the damper unit is on the extension stroke. In this case, the working liquid can be supplied to the main working chamber, so that the vehicle height can be adjusted more efficiently with respect to the change in the loaded weight of the vehicle than in the case of the conventional structure. It is possible to reduce the size of the suspension system in comparison with the case provided outside damper unit.

Further, according to the structure of the second aspect of the present invention, the size of the pump itself can be reduced and the structure around the pump can be simplified. The suspension device can be further downsized even if it is provided inside the unit but outside the actuator rod.

According to the configuration of claim 4 of the present invention, the self-leveling function is exhibited by setting the position where the communication orifice is opened and closed by the sliding surface of the cylinder hole as the standard vehicle height, so that the vehicle height is automatically adjusted. The vehicle is controlled to the standard vehicle height, so the vehicle height can be reliably controlled to the standard vehicle height without using a vehicle height sensor or advanced control device, simplifying the structure of the hydropneumatic suspension device and reducing costs Can be reduced.

According to the configuration of claim 5 of the present invention, when the ignition switch is switched from off to on, the pump is supplied with working fluid from the reservoir to the second working chamber, so that the vehicle height is gradually increased. Since the self-leveling function automatically sets the vehicle height to the standard vehicle height, the vehicle height at the start of traveling of the vehicle can be easily and reliably controlled to the standard vehicle height.

According to the structure of claim 6 of the present invention, the damping force generated by the communication means increases as the bounce amount of the wheel increases, that is, as the contraction stroke of the damper unit increases, so that the road surface projections and the like are increased. Accordingly, even when the wheels suddenly and largely bounce, the impact given to the vehicle body can be effectively reduced, and the occupant of the vehicle can be reliably prevented from feeling a shock.

According to the seventh aspect of the present invention, when the vehicle height becomes equal to or less than the first predetermined value, the pump is driven, and the vehicle height becomes higher than the first predetermined value. At this time, the pump is stopped, so that the vehicle height can be reliably controlled to a value between the first predetermined value and the second predetermined value regardless of the operating state of the damper unit.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a hydropneumatic suspension device according to the present invention in which a gas-liquid spring device and a reservoir are integrally formed with a damper unit.

FIG. 2 is an enlarged partial longitudinal sectional view showing a main part of the first embodiment.

FIG. 3 is an enlarged vertical sectional view showing the pump of the first embodiment.

FIG. 4 is an enlarged vertical sectional view showing another example of the electric pump that may be used in the hydropneumatic suspension device according to the present invention.

FIG. 5 is a schematic configuration diagram showing a second embodiment of a hydropneumatic suspension device according to the present invention in which a gas-liquid spring device and a reservoir are configured independently of a damper unit.

FIG. 6 is a flowchart showing a control routine of the electric pump in the second embodiment.

[Explanation of symbols]

 14 damper unit 16 cylinder 18 upper chamber 20 lower chamber 22 piston 28, 30 damping force generating mechanism 34 gas-liquid spring device 42 reservoir 44 cylinder hole 46 actuator rod 50 central chamber 54 inside Passage 58 Pump 60 Communication orifice 102 Piezo actuator 104 Displacement expansion mechanism 106 Reciprocating pump section

Claims (7)

(57) [Claims] A damper unit having a cylinder, a piston for reciprocatingly engaging with the cylinder and cooperating with the cylinder to define a main working chamber, and a damping force generating mechanism; and a communication with the main working chamber. A liquid / pneumatic spring device, a reservoir, and a connection passage means for communicating and connecting the main working chamber and the reservoir, in the damper unit, in the middle of the connection passage means. A hydraulic pneumatic suspension device provided with a motor-driven pump provided to the main working chamber to supply the working liquid in the reservoir to the main working chamber. 2. The hydropneumatic suspension device according to claim 1, wherein the pump includes a reciprocating plunger having a passage in the pump defining a part of the connection passage means, and the main operation is performed by the internal passage. A hydropneumatic suspension device having a check valve that allows only the flow of the working liquid toward the chamber. 3. The hydropneumatic suspension device according to claim 1, wherein the main working chamber comprises first and second main working chambers defined on both sides of the piston. A cylinder hole provided in the piston along a reciprocating direction thereof, and an actuator fixed to the cylinder so as to reciprocate in the cylinder hole and cooperate with the cylinder hole to define a sub-operation chamber. A rod, a communication means for communicating and connecting the sub-working chamber and the first main working chamber, and an internal passage provided in the actuator rod for communicating and connecting the reservoir and the sub-working chamber, The auxiliary working chamber, the communication means, and the internal passage define the connection passage means, and the pump is provided in the actuator rod in the middle of the internal passage. Hydropneumatic suspension device according to claim Rukoto. 4. The hydropneumatic suspension device according to claim 3, wherein the actuator rod has a communication orifice for connecting and connecting the internal passage means and the second main working chamber, and the communication orifice is provided with the communication orifice. A hydropneumatic suspension device configured to be opened and closed by a sliding surface of the cylinder hole with respect to an actuator rod. 5. A hydropneumatic suspension device according to claim 3, wherein means for detecting whether an ignition switch has been switched from off to on,
Control means for driving the pump for a predetermined time when it is detected that the ignition switch has been switched from off to on, a hydropneumatic suspension device. 6. The hydropneumatic suspension device according to claim 3, wherein the actuator rod has a tapered shape, and when the amount of entry of the actuator rod into the cylinder hole is equal to or more than a predetermined value, the approach is performed. The distance between the open end of the communication means and the wall surface of the actuator rod gradually decreases as the amount increases, whereby the degree of communication between the sub-working chamber and the first main working chamber gradually decreases. A hydropneumatic suspension device characterized in that: 7. The vehicle according to claim 1, wherein the vehicle height detecting means includes:
Control means for driving the pump when the vehicle height is equal to or less than a first predetermined value, and stopping the pump when the vehicle height is equal to or more than a second predetermined value higher than the first predetermined value; A hydropneumatic suspension device.