JP2007276525A - Hydraulic pressure source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a working liquid from a hydraulic pressure source corresponding to a demand of a suspension cylinder. <P>SOLUTION: In a suspension cylinder 10, a working liquid volume required for raising to the same vehicle height becomes higher when liquid pressure is low than when it is high. Meanwhile, in a pump device 68, when the liquid pressure of an output part 76 is low, a switch valve 66 is located at a first position, so that two pumps 60, 61 are connected with each other in parallel. The working liquid pumped and emitted by two pumps 60, 61 is supplied to the suspension cylinder 10 so as to supply a large flow rate of the working liquid. As a result, a demand for the suspension cylinder 10 can be quickly satisfied. When the liquid pressure of the output part 76 becomes higher than set pressure, the switch valve 66 is switched to a second position, the two pumps 60, 61 are connected with each other in series. A flow rate of the working liquid emitted from the pump device 68 becomes small, while maximum emission pressure can be made high. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic pressure source device connected to a hydraulic actuator.

Patent Document 1 describes a hydraulic pressure source device including a hydraulic pressure source including one pump and a pump motor that drives the pump. When hydraulic fluid is supplied from this hydraulic pressure source device to a suspension cylinder as a hydraulic actuator provided between the wheel holding device that holds the wheel and the vehicle body, corresponding to the wheel of the vehicle, The vehicle height, which is the relative positional relationship between the holding device and the vehicle body, is increased.
JP 2005-88766 A

  An object of the present invention is to make it possible to supply hydraulic fluid in accordance with the requirements of a hydraulic actuator.

  According to the first aspect of the present invention, there is provided a hydraulic pressure source device connected to a hydraulic pressure source device that is provided in a vehicle and connected to a hydraulic pressure actuator that is operated by hydraulic pressure. ) A hydraulic pressure source that includes a plurality of pumps and one or more electric motors that drive the plurality of pumps; and (ii) for two of the plurality of pumps, By changing at least one of the connection state between each of the electric motors corresponding to the pumps and the connection state between the two pumps, the discharge state of the hydraulic fluid from the hydraulic pressure source is at least And a discharge state control device that controls a high-pressure small-volume discharge state in which the flow rate is small and the maximum discharge pressure is high, and a low-pressure large-volume discharge state in which the flow rate is large and the maximum discharge pressure is low.

In the hydraulic pressure source device according to the first aspect, the hydraulic pressure source includes a plurality of pumps. Then, by changing the connection state of the two pumps or changing the connection state between each of the two pumps and the electric motor for two of the plurality of pumps, Controlled to a low pressure and large discharge state.
On the other hand, in a hydraulic actuator, when the operation amount is the same, a larger amount of hydraulic fluid is often required when the hydraulic pressure is low than when the hydraulic pressure is high. In order to operate more quickly than when the hydraulic pressure of the hydraulic actuator is low, supply of hydraulic fluid at a large flow rate is required. Therefore, if the hydraulic pressure of the hydraulic actuator is low, the low pressure and large volume discharge state is set, and if the hydraulic pressure is high, the high pressure and small volume discharge state is set. It becomes possible to supply hydraulic fluid.
The hydraulic pressure source may include two pumps or three or more pumps. The plurality of pumps are driven by an electric motor that is a pump motor. The pump and the electric motor may be provided in one-to-one correspondence or in many-to-one correspondence. Good. Two or more pumps may be driven by a common electric motor. Further, when the pumps and the pump motors are provided in a one-to-one correspondence, the operation capacities of the plurality of pumps may be the same or different. By varying the capacity of the electric motor, the discharge amount of hydraulic fluid per one rotation of the pump, etc., it is possible to vary the maximum discharge pressure or the discharge flow rate among a plurality of pumps.
The discharge state control device has at least one of a connection state between two pumps of the plurality of pumps and a connection state between the pump and the electric motor (hereinafter referred to as a connection state between the two pumps). If two pumps are included in the hydraulic pressure source, the connection state for all the pumps included in the hydraulic pressure source will be controlled, but if more than two pumps are included. In other words, the connection state between the remaining one pump and another pump may or may not be controlled.
The connection state of the two pumps is switched between a parallel connection state and a series connection state. Further, when two pumps are driven by one common electric motor, the connection state between each of the two pumps and the electric motor is transmitted to both of the two pumps. The two driving force transmission states and the one driving force transmission state in which the driving force of the electric motor is transmitted to one but not the other are switched. In one driving force transmission state, when the hydraulic pressure on the output side is the same as in both driving force transmission states, the load applied to the electric motor can be reduced, thereby increasing the maximum amount of hydraulic fluid that can be discharged from the pump. The discharge pressure can be increased.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating understanding of the claimable invention, and is not intended to limit the set of components constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

(1) A hydraulic pressure source device connected to a hydraulic actuator provided in a vehicle and operated by hydraulic pressure,
A hydraulic source including a plurality of pumps and one or more electric motors for driving the plurality of pumps;
Regarding two pumps of the plurality of pumps, at least one of a connection state between each of the two pumps and the electric motor corresponding to the pumps and a connection state between the two pumps By changing the discharge state of the hydraulic fluid from the hydraulic pressure source, at least the high-pressure and small-volume discharge state where the flow rate is small and the maximum discharge pressure is high, and the high-pressure and small-volume discharge state, the flow rate is large and the maximum discharge pressure is low. A hydraulic pressure source device including a discharge state control device that controls the discharge state.
(2) Motor current control in which the hydraulic pressure source control device controls the discharge state by controlling the supply current to the electric motor in at least one of the high pressure and small amount discharge state and the low pressure and large amount discharge state. The hydraulic pressure source device according to item (1), including a portion.
If the supply current to the electric motor is controlled in at least one of the high pressure and small quantity discharge state and the low pressure and large quantity discharge state, it is possible to control the magnitude of the discharge flow rate of the hydraulic fluid in at least one of the states. Thus, the discharge state of the hydraulic fluid from the hydraulic pressure source can be controlled more finely.
(3) The discharge state control device sets the low-pressure and large-volume discharge state by connecting the two pumps in parallel to each other, and connects the two pumps in series to set the high-pressure and small-volume discharge state in parallel. The hydraulic pressure source device according to item (1) or (2), including a serial connection state switching unit (claim 2).
(4) The hydraulic pressure source device according to (3), wherein each of the two pumps is connected to an individual electric motor.
When each of the two pumps is driven by a separate electric motor, if the two pumps are connected in parallel to each other, the maximum discharge pressure is lower than when connected in series. The discharge flow rate increases. Thus, by switching the connection state of the two pumps, it is possible to control the discharge state of the hydraulic fluid from the hydraulic pressure source.
(5) The parallel / series connection state switching unit is provided between the two pumps, and when the discharge pressure of the hydraulic fluid discharged from the hydraulic pressure source becomes higher than a set pressure, the two pumps are parallel to each other. The hydraulic pressure source device according to (3) or (4), which includes one or more pilot-type switching valves that switch from a parallel connection state connected to a serial connection state to a serial connection state connected in series to each other (Claim 3).
As described above, in a hydraulic actuator, when the hydraulic pressure is low, it is normal to supply hydraulic fluid at a large flow rate than when the hydraulic pressure is high. Further, when the hydraulic actuator and the hydraulic pressure source are in communication, the hydraulic pressure of the hydraulic actuator and the output hydraulic pressure of the hydraulic pressure source are the same. Therefore, if the output hydraulic pressure of the hydraulic pressure source (hydraulic pressure of the hydraulic actuator) is lower than the set pressure, the low pressure large quantity discharge state is set. The hydraulic fluid can be supplied to the actuator in accordance with the operation request of the hydraulic actuator.
In this case, the switching valve can be an electromagnetic valve. However, if a pilot valve is used, the energy consumption can be reduced as compared with the case where an electromagnetic valve is used. On the other hand, if the switching valve is an electromagnetic valve, it is possible to switch between the parallel connection state and the series connection state at any time. In addition, there are one switching valve and two or more switching valves. There are a case where two pumps are switched between a parallel connection state and a series connection state by switching one switching valve, and a case where the two pumps are switched between a parallel connection state and a series connection state by switching two or more switching valves. .
In the case where the hydraulic pressure source includes three pumps, when the two pumps are connected in parallel, when the three pumps are connected in parallel to each other, two pumps in parallel with each other and one pump are connected. May be connected in series. When two pumps are connected in series, there are cases where three pumps are directly connected to each other, two pumps in series and one pump are connected in parallel to each other, and the like.
(6) One pump passage provided with one of the two pumps and the other pump passage provided with the other pump are connected in parallel to each other, and the switching valve is connected to the one pump passage. Between the one pump passage and a connecting passage connecting the discharge side portion of the one pump and the suction side portion of the other pump passage of the other pump passage. When the pressure is lower than a predetermined set pressure, the pump is located at a first position where the discharge side of the one pump is cut off from the connection passage and communicated with the output portion of the hydraulic pressure source, and the pilot pressure is higher than the set pressure. In this case, the hydraulic pressure source device according to (5), which switches to the second position where the discharge side of the one pump is cut off from the output portion and communicated with the connection passage.
In the first position of the switching valve, the hydraulic fluid pumped up by the two pumps is discharged through the output unit. This state is a parallel connection state. In the second position of the switching valve, the hydraulic fluid discharged from one pump is pumped up and discharged by the other pump. This state is a serial connection state. A blocking device (open / close valve or check valve) for blocking the flow of hydraulic fluid discharged from one pump to the low pressure side is provided on the low pressure side from the connection passage on the suction side of the other pump.
(7) The parallel / series connection state switching unit connects all of the plurality of pumps in parallel with each other in the low pressure and large volume discharge state, and all the plurality of pumps in series with each other in the high pressure and small volume discharge state. The hydraulic pressure source device according to any one of (3) to (6), which is connected (Claim 4).
In the hydraulic pressure source device described in this section, the connection states of a plurality of pumps included in the hydraulic pressure source are all controlled. In the low pressure and large volume discharge state, all of the plurality of pumps are connected in parallel, and in the high pressure and small volume discharge state, all the pumps are connected in series.
(8) The hydraulic pressure source device according to (1) or (2), wherein the two pumps are connected to one common electric motor.
(9) In the discharge state control device, (i) in the low-pressure and large-volume discharge state, a parallel connection unit that connects the two pumps in parallel with each other; (ii) in the high-pressure and small-volume discharge state, (a) the 2 One of the two pumps and a pump stop that shuts off from the common electric motor; and (b) a circulation that forms a circulation passage for returning one discharge side of the two pumps to the suction side of the one pump. The hydraulic pressure source device according to item (8), including any one of a passage forming portion (claim 5).
The two pumps are connected in parallel with each other. When the two pumps are in the operating state, the hydraulic fluid is pumped up and discharged from the low pressure side in each of the two pumps. The hydraulic fluid discharged from each of these two pumps is output together from the hydraulic pressure source.
The two pumps are driven by one electric motor. However, in the hydraulic pressure source device described in this section, the two-drive transmission state where two pumps are driven by one electric motor, and one pump is It is switched to one drive transmission state where it is driven but the other pumps are not driven. In both drive transmission states, the two pumps in the parallel connection state are driven. In both the drive transmission state and the one drive transmission state, the load applied to the electric motor can be reduced in the case of the one drive transmission state. As a result, the discharge flow rate is reduced, but the maximum discharge pressure can be increased.
For example, a clutch is provided between one electric motor and one of two pumps, and the switching of the clutch can switch the connection / disconnection between the output shaft of the electric motor and the drive shaft of one pump. can do. By keeping the driving force transmission state between the other pump and the electric motor, and switching between the driving force transmission state and the driving force non-transmission state between the one pump and the electric motor, It is possible to switch between both driving force transmission states and one driving force transmission state. The clutch may be provided between one electric motor and each of the two pumps, or may be provided between any one of the pumps. If it is provided between any one of the pumps, the one pump is operated or stopped. If each is provided between two pumps, one of the two pumps is selectively stopped. The clutch may be an electromagnetic clutch or a hydraulic clutch.
In addition, a return passage that connects the discharge side and the suction side is provided for one of the two pumps, and the discharge side of one pump communicates with the output portion between the return passage and the output portion of the hydraulic pressure source. It is possible to provide a switching valve that can be switched between a state to be turned off and a state to be cut off from the output unit and communicated with the return passage. If the discharge side of one pump is connected to the output section by the switching valve, the two pumps are connected in parallel. If the discharge side of one pump is connected to the return passage, the hydraulic fluid discharged by the pump Will be circulated, and the pump will be disabled. Since only the other pump is operated by the electric motor, the load applied to the electric motor can be reduced.
(10) In one of the two pumps connected in parallel to each other, the circulation passage forming portion is between a return passage connecting a discharge side and a suction side and an output portion of the hydraulic pressure source, The hydraulic pressure source includes an output allowable state in which the discharge side of the one pump is cut off from the return passage and communicated with the output portion, and a hydraulic fluid return state in which the discharge side is cut off from the output portion and communicated with the return passage. The hydraulic pressure source device according to item (9), including one or more pilot-type switching valves that are switched by the discharge hydraulic pressure.
(11) The fluid pressure source includes an accumulator for pressure accumulation that stores hydraulic fluid discharged from the two or more pumps in a pressurized state according to any one of items (1) to (10). Hydraulic pressure source device.
When the hydraulic pressure source includes an accumulator for pressure accumulation and the hydraulic pressure source is operated in a communication state between the accumulator for pressure accumulation and the hydraulic pressure source, the hydraulic fluid is supplied to the hydraulic pressure actuator and the accumulator for pressure accumulation is used. The hydraulic fluid is also supplied. In the accumulator for pressure accumulation, as in the case of the hydraulic actuator, in order to increase the hydraulic pressure of the accumulator for pressure accumulation as much as the hydraulic pressure of the accumulator for pressure accumulation is low, a larger amount of hydraulic fluid is required than when it is high, This is the same as the requirement for supplying hydraulic fluid to the suspension cylinder. In that sense as well, it is appropriate to enable the hydraulic fluid discharge state from the hydraulic pressure source to be switched between the low pressure and large amount discharge state and the high pressure and small amount discharge state.
Conversely, there is an advantage that an accumulator for pressure accumulation is not required. For example, when operating a hydraulic actuator, if the accumulator for accumulating pressure is connected to the hydraulic actuator and the hydraulic pressure source is operated, the hydraulic fluid can be supplied to the hydraulic actuator at a large flow rate. This is because, when the working fluid discharge state of the source is set to the low-pressure and large-volume discharge state, the working fluid can be supplied at a large flow rate without providing a pressure accumulator.
(12) The fluid pressure source and the fluid pressure actuator are both provided in any one of the items (1) to (11) provided in one of a plurality of operating devices provided in the vehicle. The fluid pressure source device described.
For example, a plurality of operating devices such as a brake device and a vehicle height adjusting device are provided in the vehicle, and the hydraulic pressure source device is provided in one of these operating devices. When the hydraulic pressure source device is provided in the brake device, the brake cylinder provided corresponding to the plurality of wheels corresponds to the hydraulic pressure actuator, and when the hydraulic pressure source device is provided in the vehicle height adjustment device, A suspension cylinder provided corresponding to a plurality of wheels corresponds to a hydraulic actuator. The actuating device includes a plurality of hydraulic actuators having the same operation (the same type). The hydraulic pressure source device can also be provided in the steering device. In this case, the power steering mechanism corresponds to the hydraulic actuator.
(13) The fluid pressure source is provided in common to two or more of a plurality of actuators provided in the vehicle, and the fluid pressure actuator is used in common with the fluid pressure source. The fluid pressure source device according to any one of items (1) to (11), which is provided in the device.
The said hydraulic pressure source apparatus can be provided in common with a brake device and a vehicle height adjustment apparatus, for example. In this case, the brake cylinder and the suspension cylinder correspond to a hydraulic actuator. For example, when a large amount of hydraulic fluid is required at low pressure in at least one of the suspension cylinder and the brake cylinder, a low-pressure and large-volume discharge state is set. It can be set as a discharge state. The actuator having a common hydraulic pressure source device includes a plurality of hydraulic actuators of different types (four brake cylinders and four suspension cylinders).
(14) The hydraulic actuator is a suspension cylinder provided between a wheel holding device for holding the wheel and a vehicle body corresponding to a wheel of the vehicle, and the hydraulic pressure source device is the suspension cylinder. A hydraulic fluid supply device that supplies hydraulic fluid to the vehicle to increase the vehicle height, which is a relative positional relationship between the wheel and the vehicle body in the vertical direction, is described in any one of items (1) to (13). A hydraulic pressure source device (claim 6).
The hydraulic pressure source device described in this section is applied to a vehicle height adjusting device. The suspension cylinder is provided with a suspension spring between the wheel holding device and the vehicle body. In the suspension cylinder, when the load applied to the wheel is the same, the hydraulic pressure is lower when the vehicle height is small than when it is large. Therefore, when the vehicle height increase amount is the same between the case where the vehicle height is small and the case where the vehicle height is large, a larger amount of hydraulic fluid is required when the vehicle height is small. Therefore, if the vehicle height is small, the low pressure large quantity discharge state is set, and if the vehicle height is large, the high pressure small quantity discharge state is set, the demand for vehicle height adjustment can be satisfactorily satisfied.
In this way, if the hydraulic pressure source includes a plurality of pumps, it is possible to quickly satisfy the hydraulic fluid requirements in the suspension cylinder, and it is possible to eliminate or reduce the pressure accumulator. .

(15) A suspension cylinder provided between the wheel holding device for holding the wheel and the vehicle body corresponding to the wheel of the vehicle;
A vehicle height adjusting device including a hydraulic fluid supply device that supplies hydraulic fluid to the suspension cylinder and increases a vehicle height that is a relative positional relationship between the wheel and the vehicle body in the vertical direction;
The vehicle height adjusting device, wherein the hydraulic fluid supply device includes a plurality of pumps for pumping and discharging hydraulic fluid.
If a plurality of pumps are provided in the hydraulic fluid supply device of the vehicle height adjusting device, it becomes possible to quickly satisfy the operation request in the suspension cylinder.
In addition, the technical features described in any one of the items (1) to (14) can be employed in the vehicle height adjusting device described in this item.
(16) When the hydraulic fluid supply device controls the operating states of the plurality of pumps, the hydraulic fluid of the suspension cylinder is higher than the preset pressure when the hydraulic pressure of the suspension cylinder is lower than the preset preset pressure. The vehicle height adjusting device according to item (15), including a supply flow rate control unit that increases the flow rate of the vehicle.
When the hydraulic pressure of the suspension cylinder is low, supply of hydraulic fluid at a larger flow rate is required than when the hydraulic pressure is high. Therefore, it is reasonable to increase the flow rate when the hydraulic pressure is lower than the set pressure. The flow rate of the hydraulic fluid output from the hydraulic fluid supply device controls the supply current to the pump motor that drives the pump (for example, controlling the magnitude of the supply current or controlling the ON / OFF of the supply current) Control). Further, the flow rate can be switched to three or more stages or can be switched continuously.
When the load applied to the wheels is the same, the hydraulic pressure of the suspension cylinder is larger when the vehicle height is large than when it is small. Therefore, when the vehicle height is smaller than the set value, the hydraulic pressure is higher than the set value. The flow rate can be increased.
(17) A hydraulic pressure source device provided in a vehicle and connected to a hydraulic actuator operated by hydraulic pressure,
A hydraulic source that includes three or more pumps and one or more pump motors that drive the three or more pumps;
A fluid pressure source device comprising: a fluid pressure source control device that controls at least one of a discharge flow rate and a discharge pressure of hydraulic fluid output from the fluid pressure source.
In the hydraulic pressure source, (i) three pumps can be switched to a parallel state, two parallel pumps and one pump are connected in series, and three pumps can be switched to a serial state. Further, (ii) a state where two pumps are stopped, a state where one pump is stopped, and a state where three pumps are operated can be switched. Furthermore, in each state, it is possible to control the rotational speed of the pump by controlling the pump motor. Thereby, it is possible to finely control the supply state of the hydraulic fluid from the hydraulic pressure source to the hydraulic actuator.
The technical features described in any one of the items (1) to (16) can be employed in the hydraulic pressure source device described in this section.

Hereinafter, a vehicle height adjusting device as one embodiment of the present invention will be described in detail with reference to the drawings. The vehicle height adjusting device includes a hydraulic pressure source control device as one embodiment of the present invention.
As shown in FIG. 1, the present suspension device is arranged between the front and rear left and right wheels 4FL, FR, RL, RR between the vehicle body 8 and the wheel holding devices 6FL, FR, RL, RR for holding the wheels 4, respectively. Suspension cylinders 10FL, FR, RL, and RR as hydraulic actuators are provided together with the suspension spring 21. The suspension cylinders 10FL, FR, RL, RR are actuated by hydraulic fluid. Hereinafter, when it is necessary to distinguish the suspension cylinder 10 or the like by the wheel position, it is used with the symbols FL, FR, RL, and RR indicating the wheel position, and when it is not necessary to distinguish, the symbol is not attached. Used in.
The suspension cylinders 10FL, FR, RL, and RR have the same structure, and each includes a housing 11, a piston 12 fitted inside the housing 11 so as to be relatively movable, and a piston rod 14. The rod 14 is connected to the vehicle body 8 and the housing 11 is connected to the wheel holding device 6 so as not to be relatively movable in the vertical direction. The piston 12 is provided with a communication path 20 that communicates the two liquid chambers 16 and 18 partitioned by the piston 12, and the communication path 20 is provided with a throttle. The throttle generates a damping force corresponding to the relative moving speed of the piston 12 with respect to the housing 11 (the flow rate of the working fluid flowing through the throttle). The suspension cylinder 10 functions as a shock absorber.

As shown in FIG. 1, the piston rod 14 is attached to a spring retainer 22 that holds a suspension spring 21 via an elastic member such as rubber, and the spring retainer 22 is attached to the vehicle body 8 so as not to be relatively movable in the vertical direction. Further, a bound side stopper 24 is attached to the spring retainer 22. The movement limit on the bounce side is defined by the outer upper end surface 26 of the cylinder body 11 coming into contact with the bounce side stopper 24.
On the other hand, a rebound side stopper 28 is provided on the side of the piston 12 where the piston rod 14 is provided. When the inner upper end surface 30 of the main body 11 contacts the rebound side stopper 28, the rebound side movement limit is defined.

Individual control passages 32FL, FR, RL, and RR are connected to the liquid chambers 16 of the suspension cylinders 10FL, FR, RL, and RR, respectively.
In each of the individual control passages 32FL, FR, RL, RR, corresponding to each of the suspension cylinders 10FL, FR, RL, RR, accumulators 34FL, FR, RL, RR and accumulators 36FL, FR, RL, RR is connected. Spring constant switching valves 38FL, FR, RL, and RR are provided between the suspension cylinders 10FL, FR, RL, and RR and the accumulators 36FL, FR, RL, and RR, respectively.

Each of these accumulators 34 and 36 has a function as a spring, and includes, for example, a housing and a partition member that partitions the inside of the housing, and the individual control passage 32 is provided in one volume change chamber of the partition member. The other volume change chamber is connected and an elastic body is provided, and the volume of one volume change chamber decreases due to the increase in volume of one volume change chamber, thereby generating elastic force. It can be made to. The accumulators 34 and 36 may be bellows type, bladder type, piston type, or the like.
In this embodiment, the accumulator 34 has a larger spring constant than the accumulator 36. Hereinafter, the accumulator 34 is referred to as a high-pressure accumulator, and the accumulator 36 is referred to as a low-pressure accumulator. The spring constant switching valve 38 is a normally open electromagnetic on-off valve.

  The individual control passages 32FL, FR, RL, RR are provided with variable throttles 40FL, FR, RL, RR, respectively. As described above, the hydraulic fluid flows in and out in the liquid chamber 16 by the vertical movement of the wheel holding device 6 relative to the vehicle body 8. In this case, the flow area of the individual control passage 32 is reduced by the variable throttle 40. By being controlled, the damping force generated in the suspension cylinder 10 is controlled. In the present embodiment, a damping force adjusting mechanism is constituted by the variable diaphragm 40 and the like.

A hydraulic fluid supply / discharge device 50 is connected to the individual control passages 32FL, FR, RL, RR.
The hydraulic fluid supply / discharge device 50 includes a high pressure source 52, a reservoir as the low pressure source 54, an individual control valve device 58, and the like.
The high-pressure source 52 includes two pumps 60, 61, pump motors 63, 64 provided corresponding to the pumps 60, 61, a pump device 68 including a switching valve 66, a pressure accumulator 70, and the like. . The pump device 68, the pressure accumulator 70, and the like are provided in the control passage 71, and the pump device 68 and the pressure accumulator 70 are connected to each other. The hydraulic fluid in the reservoir 54 is pumped up and discharged by the pumps 60 and 61 and stored in a pressurized state in the accumulator 70 for pressure accumulation or supplied to the suspension cylinders 10FR, FL, RR, and RL.
In the pump device 68, the two pumps 60 and 61 are provided in the same state in the pump passages 72 and 73, respectively. The two pump passages 72 and 73 are provided in parallel with each other between the reservoir 54 and the control passage 71, and the two pumps 60 and 61 are connected in parallel with each other. Further, the discharge side portion of the pump 60 in the pump passage 72 and the suction side portion of the pump 61 in the pump passage 73 are connected by a connecting passage 74, and the switching valve 66 is connected between the connecting passage 74 and the pump passage 72. Is provided.
The switching valve 66 communicates the discharge side of the pump 60 with the output portion 76 of the pump device 68 and cuts off the connection passage 74. The switching valve 66 cuts off the discharge side of the pump 60 from the output portion 76 and connects the connection passage 74. This is a pilot-type switching valve that is switched to the second position that is communicated with the valve by the hydraulic pressure of the output unit 76. Further, the hydraulic fluid from the reservoir 54 is allowed to flow out to the portion closer to the reservoir side than the connection portion 77 of the pump passage 73 to the connection passage 74 on the suction side of the pump 61, but the hydraulic fluid flows into the reservoir 54. A check valve 78 is provided for blocking. The check valve 78 prevents the hydraulic fluid discharged from the pump 60 from returning to the reservoir 54 via the connection passage 74 and the pump passage 73, and the hydraulic fluid discharged from the pump 60 in the operating state of the pump 61 is Pumped up by the pump 61 and discharged.

When the hydraulic pressure of the output unit 76 is lower than the predetermined set pressure P 0, the switching valve 66 is in the first position shown in the figure, and the discharge side of the pump 60 is blocked from the connection passage 74. The pump 60 and the pump 61 are connected in parallel, and the pumps 60 and 61 pump up the hydraulic fluid from the reservoir 54 and discharge it. Both the hydraulic fluid discharged from the pump 60 and the hydraulic fluid discharged from the pump 61 are supplied via the output unit 76.
When the hydraulic pressure of the output unit 76 becomes equal to or higher than the set pressure P0, the switching valve 66 is switched to the second position, the discharge side of the pump 60 is shut off from the output unit 76, and is connected to the suction side of the pump 61. The pumps 60 and 61 are connected in series. The hydraulic fluid pumped from the reservoir 54 by the pump 60 and discharged is supplied to the suction side of the pump 61 through the connection passage 74. The hydraulic fluid discharged from the pump 60 is pumped up by the pump 61, pressurized and discharged.
Thus, in the parallel connection state and the series connection state of the two pumps 60 and 61, the flow rate of the hydraulic fluid output from the output unit 76 is larger in the parallel connection state, and the direction in the serial connection state is Maximum discharge pressure increases. The parallel connection state corresponds to the low pressure and large volume discharge state, and the series connection state corresponds to the high pressure and small volume discharge state.
In this embodiment, the pumps 60 and 61 are both gear pumps, and the pumps 60 and 61 and the pump motors 63 and 64 have the same ability. In other words, the two pump motors 63 and 64 have the same rating, and the pumps 60 and 61 have the same discharge amount of hydraulic fluid per one rotation.

The accumulator for pressure accumulation 70 includes a housing and a partition member that partitions the inside of the housing. A control passage 71 is connected to one volume change chamber (referred to as a hydraulic fluid storage chamber) of the partition member, and an elastic body is provided in the other volume change chamber (elastic force generation chamber). The accumulator for pressure accumulation 70 can be, for example, a piston type, but is not limited thereto.
The accumulator 70 for pressure accumulation is connected to the control passage 71 via a pressure accumulation control valve 90 which is a normally closed electromagnetic on-off valve.
The accumulator control valve 90 is a permissible state (corresponding to the open state of the accumulator control valve 90) that allows the inflow / outflow of hydraulic fluid in the accumulator 70 for accumulation, and a blocking that prevents the inflow / outflow of hydraulic fluid in the accumulator 70 for pressure accumulation. It is possible to switch to a state (corresponding to the closed state of the pressure accumulation control valve 90). In the open state, the hydraulic fluid is allowed to flow out of the accumulator for pressure accumulation 70 and the hydraulic fluid is allowed to flow in from the pump device 68. In the closed state, the hydraulic fluid is prevented from flowing out and inflow.
A hydraulic pressure source hydraulic pressure sensor 92 is provided in the control passage 71. The hydraulic pressure source hydraulic pressure sensor 92 detects the discharge hydraulic pressure of the pump device 68 and detects the accumulator hydraulic pressure. Further, the hydraulic pressure detected by the hydraulic pressure source hydraulic pressure sensor 92 is the same as the hydraulic pressure of the suspension cylinder 10 when the suspension cylinder 10 is communicated with the control passage 71.
A check valve 94 and a silencing accumulator 96 are provided on the suspension cylinder side of the output portion 76 of the control passage 71. An outflow passage 104 that connects the high pressure side and the low pressure side of the pump device 68 is provided, and an outflow control valve 106 is provided in the outflow passage 104.
The outflow control valve 106 is a mechanical on-off valve that uses the discharge fluid pressure of the pump device 68 as a pilot pressure. When the pump device 68 is not in operation, it is in a communicating state, but when the pumping device 68 is operated and the discharge fluid pressure becomes high, the pump device 68 is cut off.

The individual control valve device 58 includes individual control valves 110FL, FR, RL, RR as vehicle height adjustment valves provided in the individual control passages 32FL, FR, RL, RR. Also, a left and right communication valve 112 is provided in the front wheel side left and right communication passage 111 connecting the individual control passages 32FL and FR, and a left and right communication valve 114 is provided in the rear wheel side left and right communication passage 113 connecting the individual control passages 32RL and RR. .
These vehicle height adjustment valves 110FL, FR, RL, RR, and left and right communication valves 112, 114 are normally closed electromagnetic on-off valves. When the left and right communication valves 112, 114 are closed, the vehicle height adjustment valves 110FL, FR, RL, By individually controlling RR, in each of the wheels 4FL, FR, RL, RR, the wheel holding device 6FL, FR, RL, RR and the corresponding part of the vehicle body 8 (suspension cylinders 10FL, FR, RL, RR) The vehicle height, which is the distance between the vehicle and the portion corresponding to (1), can be controlled independently.

The vehicle height adjusting device is controlled by a vehicle height adjusting ECU 150 mainly including a computer. The vehicle height adjustment ECU 150 includes an execution unit 154, a storage unit 156, an input / output unit 158, and the like. The input / output unit 158 includes a spring constant switching valve 38, a coil of the variable throttle 40, a hydraulic fluid supply / discharge device 50 (for pressure accumulation). A control valve 90, a vehicle height adjustment valve 110, coils of left and right communication valves 112, 114, pump motors 63, 64, etc.) are connected via a drive circuit (not shown). A vehicle height sensor 160 that detects the vehicle height, a vehicle height adjustment mode selection switch 164, a vehicle height adjustment instruction switch 166, a vehicle height adjustment request presence / absence detection device 168, etc., are provided for each wheel.
The vehicle height adjustment mode selection switch 164 is operated by the driver, and either one of the automatic mode and the manual mode is selected by the operation of the switch 164.
The vehicle height adjustment instruction switch 166 is operated by the driver when the vehicle height is increased or when the vehicle height is decreased.
The vehicle height adjustment request presence / absence detection device 168 detects the traveling state of the vehicle, detects the driver's intention to start, and detects the possibility of passengers getting on and off. The presence / absence of an adjustment request is detected. The vehicle height adjustment request presence / absence detection device 168 includes, for example, an ignition switch, a shift position sensor, a vehicle speed sensor, and the like.
The storage unit 156 stores a plurality of programs such as a vehicle height adjustment program.

The operation of the vehicle height adjusting device configured as described above will be described.
In each of the suspension cylinders 10, the damping characteristic is controlled by controlling the variable throttle 40.
When the flow area of the individual control passage 32 is reduced by the variable throttle 40, the suspension hardness is hard (a state in which the damping force increases when the vertical relative movement speeds of the wheel and the vehicle body are the same). When the flow path area is increased, it becomes soft (a state in which the damping force is reduced when the relative movement speed is the same). The hardness of the suspension is switched in accordance with an operation by a driver of a mode selection switch (not shown), but may be controlled based on the running state of the vehicle.
Further, the spring constant is switched by the control of the spring constant switching valve 38.
When the spring constant switching valve 38 is in the communication state, the two accumulators 34 and 36 are communicated with the liquid chamber 16 so that the spring constant is small, and the spring constant switching valve 38 is shut off. In this case, since the low-pressure accumulator 36 is shut off from the liquid chamber 16 and the high-pressure accumulator 34 is communicated, the spring constant is increased.

The vehicle height corresponding to the four wheels 4FL, FR, RL, RR is controlled by the control of the hydraulic fluid supply / discharge device 50.
When the automatic mode is selected by the vehicle height adjustment mode selection switch 164, when a predetermined condition is satisfied (when the vehicle height adjustment request detection device 168 detects that there is a vehicle height adjustment request), When the vehicle height is changed accordingly and the manual mode is selected, when the vehicle height adjustment instruction switch 166 is operated, the vehicle height is changed according to the instruction. For example, when the automatic mode is selected, if the ignition switch is switched from the ON state to the OFF state after the vehicle stops, it is assumed that the passenger may get off and the vehicle height is reduced. The In addition, when the ignition switch is switched from the OFF state to the ON state and the intention to start such as when the shift position is switched from the parking position to the drive position is detected, the vehicle height is increased, and the height suitable for driving is increased. It is assumed.
The left and right communication valves 112 and 114 and the vehicle height adjusting valve 110 are normally in the illustrated original positions.
For example, when the vehicle height of the left front wheel 4FL is increased, the pump device 68 is operated, the pressure accumulation control valve 90 is brought into a communication state, and the vehicle height adjustment valve 110FL is brought into a communication state. Since the outflow control valve 106 is switched to the closed state by the operation of the pump device 68, the hydraulic fluid discharged from the pump device 68 is supplied to the suspension cylinder 10FL, and the vehicle height increases. The hydraulic fluid is also supplied from the accumulator 70 for pressure accumulation to the suspension cylinder 10FL. When the actual vehicle height reaches the target value for the left front wheel 4FL, the vehicle height adjustment valve 110FL is shut off and the operation of the pump device 68 is stopped.
When the vehicle height is reduced, the vehicle height adjustment valve 110FL is in a communication state. Since the pump device 68 is in a stopped state, the outflow control valve 106 is in a communicating state. The working fluid is caused to flow from the suspension cylinder 10FL to the reservoir 74. When the actual vehicle height reaches the target value, the vehicle height adjustment valve 110FL is turned off.
In the present embodiment, as described above, the suspension cylinder 10 is provided in parallel with the suspension spring 21 between the wheel holding device 6 and the vehicle body 8. Therefore, assuming that the load applied to the wheel 4 is constant, as shown in FIG. 2, when the vehicle height increases, the force (elastic force) received by the suspension spring 21 decreases, so that the hydraulic pressure of the suspension cylinder 10 (Hereinafter simply referred to as cylinder hydraulic pressure) increases. FIG. 2 shows the relationship between the change in hydraulic pressure of the suspension cylinder 10 and the change in vehicle height for one wheel.

Further, when the vehicle height adjustment for increasing the vehicle height is performed, the pressure accumulation control valve 90 is opened. At the beginning of the vehicle height adjustment, the hydraulic fluid is supplied to the suspension cylinder 10 from both the pressure accumulator 70 and the pump device 68, but the hydraulic fluid stored in the pressure accumulator 70 during the vehicle height adjustment is When no longer available, the hydraulic fluid discharged from the pump device 68 is supplied to both the suspension cylinder 10 and the accumulator 70 for pressure accumulation.
As shown in FIG. 3, when the hydraulic fluid is stored in the pressure accumulator 70, the amount of hydraulic fluid required to increase the hydraulic pressure by the same amount is higher when the hydraulic pressure of the pressure accumulator 70 is low than when it is high. Become. The same applies to the suspension cylinder 10. In the vehicle height adjustment for increasing the vehicle height, when the hydraulic pressure of the suspension cylinder 10 is low, the operation necessary to increase the vehicle height by the same amount as when the hydraulic pressure is high. The liquid volume increases. In other words, when the hydraulic pressure of the suspension cylinder 10 is low, the hydraulic fluid is required to be supplied at a large flow rate when the vehicle height adjustment request is satisfied more quickly than when the hydraulic pressure is high.

As described above, in the suspension cylinder 10 and the accumulator 70 for pressure accumulation, as shown by the thin line A [necessary characteristics] in FIG. 4, the hydraulic fluid is required to be supplied at a larger flow rate when the hydraulic pressure is low than when the hydraulic pressure is high. .
In this case, if the pump motor can be rotated at a large rotational speed, or the pump has a large discharge amount per rotation, the working fluid can be discharged at a large flow rate. Further, if the pump motor can output a large torque and the pump has a high strength, the maximum discharge pressure of the hydraulic fluid discharged from the pump can be increased. The characteristic indicated by the long broken line B [in the case of an increase in size of the pump / motor] is obtained. However, if the pump or pump motor can discharge the hydraulic fluid at a large flow rate and the maximum discharge pressure is increased, the cost increases. Moreover, it has an excessive characteristic with respect to the characteristic (necessary characteristic represented by a thin line) required in the vehicle height adjustment.
On the other hand, if two pumps having the characteristic represented by the broken line C [in the case of one pump] having a short solid line portion are provided in the pump device 68 and connected in parallel to each other, the hydraulic fluid can be operated at a large flow rate when the discharge pressure is low The characteristic represented by the alternate long and short dash line D [when two pumps are arranged in parallel] can be obtained. Also, if two pumps having the characteristics of the broken line C are connected in series, a large flow rate cannot be obtained, but it is represented by a two-dot chain line E [in the case of two pumps in series] that can increase the maximum discharge pressure that can be discharged. Characteristics can be obtained. Furthermore, if the two pumps are connected in parallel when the discharge pressure of the pump device 68 is lower than the set pressure P0, and connected in series when the pressure is equal to or higher than the set pressure P0, the thick solid line F [in this embodiment] The characteristics expressed are obtained.

In this embodiment, in the pump device 68, two pumps 60 and 61 are provided, and when the switching valve 66 becomes lower than the set pressure P0 from the state where the pressure of the output unit 76 is lower than the set pressure P0, the first position is changed from the first position. The two pumps 60 and 61 are switched from the parallel connection state to the series connection state.
When the hydraulic pressure of the output unit 76 of the pump device 68 is lower than the set pressure P0, that is, when the hydraulic pressure of the accumulator 70 for accumulation and the suspension cylinder 10 is low, the two pumps 60 and 61 are connected in parallel. Hydraulic fluid is discharged at a large flow rate. When the hydraulic pressure of the output unit 76 is equal to or higher than the set pressure P0, that is, when the hydraulic pressure of the accumulator 70 for accumulation and the suspension cylinder 10 is high, the two pumps 60 and 61 are connected in series, and the flow rate is small. However, the maximum discharge pressure can be increased.
Thus, in this embodiment, the hydraulic fluid can be supplied from the pump device 68 with the characteristic F represented by the thick solid line. Therefore, it is possible to satisfy the requirements in the suspension cylinder 10 and the accumulator 70 for pressure accumulation without providing a control valve or the like that can control the flow rate and hydraulic pressure of the hydraulic fluid discharged from the pump device 68, and the cost is reduced. It is possible to suppress the increase and to approach the required characteristic (requirement) represented by the thin line A.

Further, in the serial connection state of the two pumps 60 and 61, there is an advantage that the output torque of each of the pump motors 63 and 64 can be reduced, and the volumetric efficiency in the pumps 60 and 61 can be improved.
5 (a) and 5 (b), the broken line indicates the operation of the pump and the pump motor when one pump is included in the pump device, and the solid line indicates that the pump device includes two pumps, and The operation of one pump and pump motor when the pumps included in the pump device are connected in series and the hydraulic pressure of the discharged hydraulic fluid is the same is shown. In FIG. 5B, the thin line A indicates the relationship between the supply current and the torque in the pump motor, and the two-dot chain line B indicates the relationship between the torque and the rotational speed.
As shown in FIG. 5 (a), when two pumps are connected in series, the load applied to one pump motor can be reduced when the hydraulic fluid pressure discharged from the pump device is the same. Recognize.
As shown in FIG. 5B, it can be seen that a large current is required to output a large torque in the pump motor. It can also be seen that when the applied voltage is constant, the rotational speed increases when the output torque of the pump motor is small, and the rotational speed decreases when the output torque is large.
5C, the thin line C represents the relationship between the rotational speed N of the pump and the theoretical discharge flow rate Qp, and the alternate long and short dash line D represents the relationship between the rotational speed N and the actual discharge flow rate Qa. An alternate long and short dash line D is a line that represents a result of measuring each of the rotational speed N and the discharge flow rate Qa of the pump driven by the pump motor when the voltage applied to the pump motor is constant. In FIG. 5 (c), the measurement results [revolution speed N1, discharge flow rate Qa1] and [revolution speed N2, discharge flow rate Qa2] are measured for the pump when the pump device includes one pump. As a result, when two pumps connected in series with each other are included, the measurement results for one pump are not shown, but both are the measurement results for one pump. However, these measurement results are respectively the measurement results for the pump when the number of pumps included in the pump device is one [rotation speed N1, discharge flow rate Qa1], and 1 when two pumps are connected in series. It can be considered to correspond to the measurement results [rotation speed N2, discharge flow rate Qa2] for one pump.
According to the measurement results in this example, it can be seen that the difference (Qp−Qa) between the theoretical discharge flow rate Qp and the actual discharge flow rate Qa is substantially the same even if the rotational speed N changes. Since these differences (Qp−Qa) are considered to be mainly caused by leakage in the pump, they can be referred to as leakage amounts. As a result, the leakage amount {(Qp−Qa) / N} per rotation of the pump is smaller when the rotational speed N is large and the torque T is small than when the rotational speed N is small and the torque T is large. . This also shows that the volumetric efficiency η (actual discharge flow rate / theoretical discharge flow rate) is higher when the rotational speed N is large than when it is small.
Specifically, the theoretical discharge flow rate Qp is expressed by the equation Qp = k · N (1)
It can be expressed as Further, according to the measurement result in the present embodiment, the actual discharge flow rate Qa is expressed by the equation Qa = k · (N−N0) (2)
Can be approximated by
From the equations (1) and (2), the volumetric efficiency η1 when the rotational speed is N1 is as follows: η1 = Qa1 / Qp1 = k (N1−N0) / kN1 = 1− (N0 / N1). 3)
The volumetric efficiency η2 when the rotational speed is N2 is expressed by the following equation: η2 = Qa2 / Qp2 = k (N2−N0) / kN2 = 1− (N0 / N2) (4)
It can be expressed as
From Equations (3) and (4), it can be seen that the rotational efficiency N2 is higher than the rotational speed N1, so that the volumetric efficiency η2 at the rotational speed N2 is higher than the volumetric efficiency η1 at the rotational speed N1 (η2 > Η1).
Thus, in the case where there is one pump and in the case where two pumps are connected in series, the case where two pumps are connected in series can be operated with higher volumetric efficiency. .
Furthermore, when the torque applied to the pump is large, a voltage drop is likely to occur, the pump motor speed is reduced, and the pump speed is likely to be reduced. On the other hand, when two pumps are connected in series, the torque applied to the pump motor can be reduced, so that a voltage drop is unlikely to occur, the rotational speed is reduced, and the discharge flow rate is reduced. It can be avoided.
Further, according to the measurement result in the present embodiment, the region where the rotational speed of the pump is smaller than N0 is a region where the hydraulic fluid cannot be discharged even if the pump rotates. For example, the hydraulic pressure on the discharge side of the pump becomes excessive and the torque of the pump motor becomes excessive, so that the hydraulic fluid cannot be discharged. The value of the rotation speed N0 in this case is considered to be determined by the capabilities of the pump and pump motor, the voltage applied to the pump motor, and the like.
As described above, in this embodiment, the discharge state control device is configured by the switching valve 66, the connecting passage 74, and the like. The discharge state control device corresponds to a parallel / series connection state switching unit. Further, a hydraulic pressure source is constituted by the pump device 68 and the like, and a hydraulic pressure source device is constituted by the pump device 68, the switching valve 66, the connecting passage 74 and the like.

In the above-described embodiment, the switching valve 66 is a pilot valve that is switched by the pilot pressure. However, an electromagnetic valve that is switched by ON / OFF of a supply current to the solenoid may be used. In this case, the first position can be set when the hydraulic pressure of the hydraulic pressure source hydraulic pressure sensor 92 is lower than the set pressure P0, and can be switched to the second position when the set pressure P0 or higher is reached. The switching valve can also be switched based on the vehicle height. For example, the first position is set when the value detected by the vehicle height sensor 160 is lower than the set value (value corresponding to the set pressure P0), and the position is switched to the second position when the set value is exceeded.
Furthermore, the structure of the pump device is not limited to that in the above embodiment.
As shown in FIG. 6, in the pump device 200, a connection passage 202 is provided to connect a portion of the pump passage 72 on the discharge side of the pump 60 and a portion of the pump passage 73 on the suction side of the pump 61. The discharge side switching valve 204 is provided between the pump passage 73 and the suction side switching valve 206 at the reservoir side of the connection passage 205 of the connection passage 202 on the suction side of the pump 61 of the pump path 73. The discharge side switching valve 204 and the suction side switching valve 206 are connected and integrated with each other, and the discharge side switching valve 204 and the suction side switching valve 206 constitute a switching valve 210. The switching valve 210 is a pilot-type switching valve that is switched by the hydraulic pressure of the output unit 76 of the pump device 200, as in the above embodiment.
The discharge side switching valve 204 communicates the discharge side of the pump 60 with the output unit 76 and cuts off the connection passage 202 from the first position, and disconnects the discharge side of the pump 60 from the output unit 76 with the connection passage 202. The suction side switching valve 206 is switched to a first position where the suction side of the pump 61 is communicated with the reservoir 54 and a second position where the suction side is shut off from the reservoir 54.
When the hydraulic pressure of the output unit 76 is lower than the set pressure P0, both the discharge side switching valve 204 and the suction side switching valve 206 are in the first position. The discharge side of the pump 60 is communicated with the output unit 76, and the suction side of the pump 61 is communicated with the reservoir 54. The two pumps 60 and 61 both pump up the hydraulic fluid from the reservoir 54 and discharge it. The two pumps 60 and 61 are connected in parallel.
Further, when the hydraulic pressure of the output unit 76 becomes equal to or higher than the set pressure P0, the discharge side switching valve 204 and the suction side switching valve 206 are switched to the second position. The discharge side of the pump 60 is blocked from the output unit 76 and connected to the connecting passage 202, and the suction side of the pump 61 is blocked from the reservoir 54. The discharge side of the pump 60 is connected to the suction side of the pump 61, and the hydraulic fluid discharged from the pump 60 is pumped up by the pump 61 and discharged from the output unit 76. The two pumps 60 and 61 are connected in series.

  In addition, in the said Example, although the discharge side switching valve 204 and the suction side switching valve 206 were provided integrally, these can also be provided separately.

Furthermore, in the above-described embodiment, each of the two pumps 60 and 61 is driven by the individual pump motors 63 and 64. However, the two pumps 60 and 61 are driven by a common pump motor 228. It can also be driven. An example in that case is shown in FIG.
In the present embodiment, in the pump device 230, one common pump motor 228 is provided for the two pumps 60 and 61. Further, a circulation passage (return passage) 232 connecting the discharge side and the suction side of the pump 60 in the pump passage 72 is provided, and a switching valve is provided between the circulation passage 232 and a portion of the pump passage 72 on the discharge side of the pump 60. 234 is provided. The switching valve 234 has a first position where the discharge side of the pump 60 is cut off from the circulation passage 232 and communicated with the output unit 76, and a second position where the discharge side of the pump 60 is cut off from the output unit 76 and communicated with the circulation passage 232. This is a pilot-type switching valve that switches to the position by the hydraulic pressure of the output unit 76.
When the hydraulic pressure of the output unit 76 is lower than the set pressure P0, the switching valve 234 is in the first position and the pumps 60 and 61 are connected in parallel, but the hydraulic pressure of the output unit 76 is equal to or higher than the set pressure P0. When it becomes, it switches to the 2nd position. In the second position, the discharge side and the suction side of the pump 60 are communicated, and the working fluid is circulated (a circulation path is formed). The operation of the pump 60 is invalidated, and from the pump motor 228, the state is the same as in the stopped state. As a result, the load applied to the pump motor 228 can be reduced. Thereby, the maximum discharge pressure of the hydraulic fluid output from the pump device 230 can be increased. When the hydraulic pressure of the suspension cylinder 10 and the accumulator 70 for pressure accumulation is high, the flow rate of the supplied hydraulic fluid may be small, so that the necessity for operating the two pumps is low.
In this embodiment, the switching passage 234, the circulation passage 232, and the like constitute a circulation passage forming portion.

Further, in the above embodiment, the operation of one pump is disabled, but one pump can be stopped. An example in that case is shown in FIG.
In the pump device 250 according to the present embodiment, the two pumps 60 and 61 are driven by one common pump motor 228, but an electromagnetic clutch 254 is provided between the pump 60 and the pump motor 228. The electromagnetic clutch 254 has a driving force transmission state in which the output shaft of the pump motor 228 and the rotation shaft of the pump 60 are coupled, and a driving force non-transmission state in which the output shaft of the pump motor 228 and the rotation shaft of the pump 60 are disconnected. In response to a command from the vehicle height adjustment ECU 150, the operation is switched.
When the hydraulic pressure detected by the hydraulic pressure sensor 92 is smaller than the set pressure P0, the driving force is transmitted. When the hydraulic pressure is higher than the set pressure P0, the driving force is not transmitted. In the driving force transmission state, the output shaft of the pump motor 228 and the rotation shaft of the pump 60 are connected, and the two pumps 60 and 61 are driven by the pump motor 228 in a parallel connection state. In the driving force non-transmission state, the pump 60 is disconnected from the pump motor 228, and the pump 60 is stopped. As a result, the load applied to the pump motor 228 can be reduced, and the maximum discharge pressure of the hydraulic fluid that can be discharged from the pump 61 can be increased. A check valve 256 is provided on the discharge side of the pump 60 to prevent backflow from the output unit 76 to the pump 60, and the hydraulic fluid discharged from the pump 61 flows back to the reservoir 54 when the pump 60 is stopped. Is avoided.
In the present embodiment, the parallel connection portion and the pump stop portion are configured by the electromagnetic clutch 254, the portion that controls the electromagnetic clutch 254 of the vehicle height adjustment ECU 150, and the like.

  A hydraulic clutch that can be switched between a driving force transmission state and a driving force non-transmission state by hydraulic pressure (pilot pressure) can be provided between the pump 60 and the pump motor 228 instead of an electromagnetic clutch. In the hydraulic clutch, when the applied hydraulic pressure becomes lower than the set pressure from the state lower than the set pressure P0, the drive force transmission state is switched to the drive force non-transfer state. In this case, the hydraulic clutch constitutes a parallel connection portion and a pump stop portion.

In each of the above embodiments, the number of pumps included in the pump device is two, but may be three or more. An example in that case is shown in FIG.
In the present embodiment, the pump device 300 is configured by combining the pump device 68 of FIG. 1 and the pump device 250 of FIG. The pump device 300 includes three pumps 312 to 316 respectively provided in pump passages 302 to 306 provided in parallel to each other. The pumps 312 and 314 are driven by a common pump motor 320, but an electromagnetic clutch 322 is provided between the pump 312 and the pump motor 320. A check valve 323 is provided on the discharge side of the pump 312 to prevent backflow to the pump. Also, these two parallel pumps 312 and 314 and one pump 316 are provided in parallel. The pump 316 is driven by a pump motor 324.
The suspension cylinder side portion of the output portions 330 of the pumps 312 and 314 and the suction passage portion of the pump passage 306 from the pump 316 are connected by the connecting passage 332 and the switching valve 334 (the same configuration as the switching valve 66 is formed). Thing) is provided. Further, a check valve 336 is provided in a portion of the pump passage 306 on the suction side of the pump 316.
When the hydraulic pressure of the output section 338 of the pump device 300 is lower than the set pressure P0, the switching valve 334 is in the first position, and two pumps 312 and 314 connected in parallel with each other and one pump 316 are in parallel. It is said. That is, the three pumps 312, 314, and 316 are connected in parallel to each other. As a result, the flow rate of the hydraulic fluid discharged from the pump device 300 can be made larger than when two pumps are in parallel.
When the hydraulic pressure of the output unit 338 becomes equal to or higher than the set pressure P0, the switching valve 334 is switched to the second position. Pumps 312, 314 and pump 316 connected in parallel with each other are connected in series. As a result, the flow rate is smaller than when the three pumps 312 to 316 are connected in parallel to each other, but the maximum discharge pressure is increased.
Further, the pump 312 can be stopped by controlling the electromagnetic clutch 322.
Thus, in this embodiment, (i) a state where three pumps are connected in parallel to each other, (ii) a state where two pumps parallel to each other and one pump are connected in series, iii) When one pump is stopped, the two pumps can be switched between a parallel connection state and a serial connection state.

Further, the pump device 380 shown in FIG. 10 is a combination of the pump device 68 of FIG. 1 and includes pumps 312 to 316 provided respectively in pump passages 302 to 306 provided in parallel to each other. The pump passages 302 to 306 are provided in parallel between the reservoir 54 and the control passage 71, and the pumps 312 to 316 are driven by individual pump motors 382 to 386, respectively.
The discharge side portions of the pumps 312 and 314 in the pump passages 302 and 304 and the suction side portions of the pumps 314 and 316 in the pump passages 304 and 306 are connected by connecting passages 390 and 392, respectively. In addition, switching valves 394 and 396 are provided between the pump passage 302 and the connection passage 390 and between the pump passage 304 and the connection passage 392, respectively. Further, check valves 400 and 402 for preventing the backflow of the hydraulic fluid to the reservoir 54 are provided in portions on the reservoir side of the connection portions of the pump passages 304 and 306 with the connection passages 390 and 392, respectively.
The switching valves 394 and 396 have the same configuration as the switching valve 66 of FIG. 1, and are pilot-type switching valves that are switched between the first position and the second position by the hydraulic pressure of the output unit 410 of the pump device 380. is there. In the first position of the switching valves 394, 396, the three pumps 312, 314, 316 are connected in parallel to each other. When the switching valves 394 and 396 are switched to the second position, the three pumps 312 to 316 are connected to each other in series.
Thus, in this embodiment, the three pumps can be switched between a state where they are connected in parallel to each other and a state where they are connected in series with each other.

  Note that the two switching valves 394 and 396 may be connected to each other so as to be interlocked with each other.

As shown in FIG. 11, the pump device 450 may include pumps 462 to 466 provided in three pump passages 452 to 456 connected in parallel to each other. The three pumps 462 to 466 are driven by individual pump motors 472 to 476, respectively. Check valves 482 to 486 that prevent backflow to the pumps are provided in the discharge side portions of the pumps 462 to 466 of the pump passages 452 to 456, respectively. In the present embodiment, the supply currents to the three pump motors 472 to 476 can be controlled independently of each other, whereby the discharge flow rate from the pump device 450 can be controlled.
If all of the pump motors 462-466 are in operation, three pumps 462-466 are connected in parallel, and if two of the three are in operation, two pumps are in parallel and two are If stopped, hydraulic fluid is discharged from only one pump.
Further, if the supply current to the pump motors 462 to 466 is controlled continuously, the discharge flow rate can be controlled continuously.

In the above embodiment, the plurality of pumps and pump motors included in the hydraulic pressure source have the same capability, but may be different from each other.
Further, the hydraulic pressure source device can be applied to a motive power hydraulic pressure source device capable of supplying hydraulic pressure to a brake cylinder as a hydraulic pressure actuator in the hydraulic brake device.
In addition, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

It is a figure which shows the whole vehicle height adjustment apparatus provided with the hydraulic pressure source apparatus which is one Example of this invention. It is a figure which shows the change state of the hydraulic pressure in the suspension cylinder contained in the said vehicle height adjustment apparatus. It is a figure which shows the relationship between the hydraulic pressure in the accumulator for pressure | pressure accumulation contained in the said hydraulic pressure source apparatus, and the amount of supply liquids. It is a figure which shows the relationship between the discharge pressure and discharge flow rate of the pump apparatus contained in the said hydraulic pressure source apparatus. It is a figure which shows the operating state of the pump apparatus contained in the said hydraulic pressure source apparatus. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention. It is a figure which shows the hydraulic pressure source apparatus which is another one Example of this invention.

Explanation of symbols

60, 61, 312, 314, 316, 462, 464, 466: pump 63, 64, 324, 382, 384, 386, 472, 474, 476: pump motor 66, 334, 394, 396: switching valve 68, 200 , 230, 250, 300, 380, 450: Pump device 74, 332, 390, 392: Connection passage 76, 338, 410, 490: Output part 78, 336, 400, 402: Check valve 323, 482, 484 486: Check valve 202: Connection passage 204: Discharge side switching valve 206: Suction side switching valve 210: Switching valve 228, 320: Pump motor 232: Circulation passage 234: Switching valve 254, 322: Electromagnetic clutch

Claims (6)

A hydraulic pressure source device provided in a vehicle and connected to a hydraulic actuator operated by hydraulic pressure,
A hydraulic source including a plurality of pumps and one or more electric motors for driving the plurality of pumps;
Regarding two pumps of the plurality of pumps, at least one of a connection state between each of the two pumps and the electric motor corresponding to the pumps and a connection state between the two pumps By changing the discharge state of the hydraulic fluid from the hydraulic pressure source, at least the high-pressure and small-volume discharge state where the flow rate is small and the maximum discharge pressure is high, and the high-pressure and small-volume discharge state, the flow rate is large and the maximum discharge pressure is low. A fluid pressure source device comprising: a discharge state control device that controls the discharge state.   Parallel / series connection state in which the discharge state control device makes the low-pressure and large-volume discharge state by connecting the two pumps in parallel to each other, and connects the two pumps in series to make the high-pressure and small-volume discharge state. The hydraulic pressure source device according to claim 1, comprising a switching unit.   The parallel / series connection state switching unit is provided between the two pumps, and when the discharge pressure of the hydraulic fluid discharged from the hydraulic pressure source becomes higher than a set pressure, the two pumps are connected in parallel to each other. 3. The hydraulic pressure source device according to claim 2, further comprising one or more pilot-type switching valves that switch from a parallel connection state to a serial connection state that are connected in series with each other.   The parallel / series connection state switching unit connects all of the plurality of pumps in parallel with each other in the low pressure and large volume discharge state, and connects all of the plurality of pumps in series with each other in the high pressure and small volume discharge state. The hydraulic pressure source device according to claim 2 or 3.   The two pumps are connected to one common electric motor, and the discharge state control device is (i) a parallel connection part for connecting the two pumps in parallel in the low-pressure large-volume discharge state; and (ii) In the high-pressure small-volume discharge state, (a) a pump stop portion that shuts off one of the two pumps from the common electric motor, and (b) one discharge side of the two pumps as one of the two pumps. The hydraulic pressure source device according to claim 1, further comprising any one of a circulation passage forming portion that forms a circulation passage returning to the suction side of the pump. The hydraulic actuator is a suspension cylinder provided between a wheel holding device for holding the wheel and a vehicle body corresponding to a wheel of the vehicle, and the hydraulic pressure source device is operated with hydraulic fluid in the suspension cylinder. The hydraulic pressure source device according to any one of claims 1 to 5, further comprising a hydraulic fluid supply device that increases a vehicle height that is a relative positional relationship in the vertical direction between the wheel and the vehicle body.

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