JP2016217397A - Pump system and control method of pump system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump system and a control method of the pump system, which can improve fuel economy while securing a discharge rate in a pump part in which the inherent discharge rate is changed.SOLUTION: A pump system 1 comprises: a pump part 4 having a first pump 41 and a second pump 42 which are provided in parallel to each other and are connected to a line pressure oil passage 11, and driven by an engine 2; a selector valve 12 which is provided between the line pressure oil passage 11 and the second pump 42 and changes a discharge mode of the second pump 42 between when the second pump 42 discharges into the line pressure oil passage 11 and when unloading the second pump 42; and a pilot check valve 13 which is provided between the line pressure oil passage 11 and the second pump 42 and changes the degree of communication between the second pump 42 and the line pressure oil passage 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pump system and a pump system control method.

  Patent Document 1 discloses a pumping unit in which two pumps are normally connected in series to an oil passage so that one becomes the other boost pump. When the discharge amount is insufficient, the pumping unit switches the connection state to parallel connection and uses the total discharge amount of each pump as the discharge amount.

JP 10-89430 A

  In the above pumping unit, the discharge amount becomes excessive in the parallel connection, but in the scene where the discharge amount is insufficient in the serial connection, as a result of performing the parallel connection so that the discharge amount is not insufficient, an excessive pump load is generated and the fuel consumption is increased. There is a risk of damage.

  The present invention has been made in view of such technical problems, and a pump system capable of improving fuel efficiency while ensuring a discharge amount in a pump unit in which the switching of the specific discharge amount is performed, and control of the pump system It aims to provide a method.

  A pump system according to an aspect of the present invention includes a first pump unit and a second pump unit that are provided in parallel with each other and connected to an oil passage, and are driven by a power source, the oil passage, and the first oil passage. The second pump part is switched between the case where the second pump part is discharged between the oil path and the case where the second pump part is unloaded. A switching unit, and a change unit that is provided between the oil passage and the second pump unit and changes a degree of communication between the second pump unit and the oil passage.

  According to another aspect of the present invention, a pump unit provided in parallel with each other and connected to an oil passage and having a first pump portion and a second pump portion driven by a power source, the oil passage, and the second A switching unit provided between the pump unit and the discharge mode of the second pump unit; and provided between the oil passage and the second pump unit; and communication between the second pump unit and the oil passage. A change unit that changes the degree, and a control method of the pump system, wherein the second pump unit discharges oil into the oil passage, and the second pump unit is unloaded. Switching the discharge mode of the second pump part, and changing the degree of communication between the second pump part and the oil path when the second pump part discharges oil to the oil path. A method for controlling a pump system is provided.

  According to these aspects, by unloading the second pump unit, the specific discharge amount of the pump unit can be made the specific discharge amount of the first pump unit. In addition, by switching the discharge mode of the second pump unit to discharge to the oil passage, the specific discharge amount of the pump unit is set to the total value of the specific discharge amount of the first pump unit and the specific discharge amount of the second pump unit. Can do.

  And according to these aspects, when the specific discharge amount of the pump unit is the specific discharge amount of the first pump unit, when the discharge amount is insufficient, the pump unit sets the specific discharge amount of the pump unit to the above total value, The discharge amount of the part can be ensured. Further, in this case, by changing the degree of communication between the second pump unit and the oil passage, it is possible to discharge only the necessary amount from the pump unit. Therefore, it is not necessary to generate an extra load.

  For this reason, according to these aspects, it is possible to improve the fuel efficiency while securing the discharge amount in the pump unit in which the switching of the specific discharge amount is performed.

It is a schematic structure figure of a vehicle carrying a pump system of an embodiment. It is a figure which shows a pilot check valve. It is a figure which shows the valve opening characteristic of a pilot check valve. It is a figure which shows the valve opening characteristic of a switching valve. It is a figure which shows an example of control of embodiment by a flowchart.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a vehicle on which a pump system 1 is mounted. The vehicle includes an engine 2, a torque converter 3, a pump unit 4, a forward / reverse switching mechanism 5, a variator 6, a final reduction mechanism 7, drive wheels 8, a controller 9, and a hydraulic circuit including the pump unit 4. 10. In the vehicle, the pump system 1 includes a controller 9 and a hydraulic circuit 10. With respect to the hydraulic circuit 10, FIG.

  The engine 2 constitutes a power source for the vehicle and the pump unit 4. The output of the engine 2 is transmitted to the drive wheels 8 through the torque converter 3, the forward / reverse switching mechanism 5, the variator 6, and the final reduction mechanism 7. In other words, the torque converter 3, the forward / reverse switching mechanism 5, the variator 6, and the final deceleration mechanism 7 are provided in a power transmission path for transmitting power from the engine 2 to the drive wheels 8.

  The torque converter 3 transmits power through the fluid. In the torque converter 3, the power transmission efficiency can be increased by fastening the lock-up clutch.

  The pump unit 4 includes a first pump 41, a second pump 42, and a drive shaft 43. The first pump 41 constitutes a first pump part of the pump part 4, and the second pump 42 constitutes a second pump part of the pump part 4. The pump unit 4 is driven by the engine 2.

  Specifically, the first pump 41 and the second pump 42 are both driven by driving the drive shaft 43 common to the first pump 41 and the second pump 42 with the engine 2. For example, the pump unit 4 may be provided so as to extract the power of the engine 2 from the pump impeller of the torque converter 3.

  The forward / reverse switching mechanism 5 is provided between the engine 2 and the variator 6, specifically, between the torque converter 3 and the variator 6. The forward / reverse switching mechanism 5 switches the rotation direction of the input rotation between a forward rotation direction corresponding to forward travel and a reverse rotation direction corresponding to reverse travel.

  Specifically, the forward / reverse switching mechanism 5 includes a forward clutch 51 and a reverse brake 52. The forward clutch 51 is connected when the rotation direction is the forward rotation direction. The reverse brake 52 is connected when the rotation direction is the reverse rotation direction. One of the forward clutch 51 and the reverse brake 52 can be configured as a clutch that intermittently rotates between the engine 2 and the variator 6.

  The variator 6 includes a primary pulley 61, a secondary pulley 62, and a belt 63 wound around the primary pulley 61 and the secondary pulley 62. Hereinafter, the primary is also referred to as PRI and the secondary is also referred to as SEC.

  The PRI pulley 61 includes a fixed pulley 61a, a movable pulley 61b, and a PRI chamber 61c. In the PRI pulley 61, the primary pressure is supplied to the PRI chamber 61c.

  The SEC pulley 62 includes a fixed pulley 62a, a movable pulley 62b, and an SEC chamber 62c. In the SEC pulley 62, the secondary pressure is supplied to the SEC chamber 62c.

  The variator 6 constitutes a belt-type continuously variable transmission mechanism that changes speed by changing the winding diameter of the belt 63 by changing the groove widths of the PRI pulley 61 and the SEC pulley 62, respectively.

  In such a variator 6, by controlling the primary pressure, the movable pulley 61 b is operated and the groove width of the PRI pulley 61 is changed. Further, by controlling the secondary pressure, the movable pulley 62b is operated, and the groove width of the SEC pulley 62 is changed.

  The belt 63 has a V-shaped sheave surface formed by the fixed pulley 61a and the movable pulley 61b of the PRI pulley 61, and a V-shape formed by the fixed pulley 62a and the movable pulley 62b of the SEC pulley 62. Wound around the sheave surface.

  The primary pressure and the secondary pressure are generated by the hydraulic circuit 10 using the line pressure PL as a source pressure. The line pressure PL may be applied to one of the primary pressure and the secondary pressure. In this case, the variator 6 can be configured as a univariator variator.

  The final reduction mechanism 7 transmits the output rotation from the variator 6 to the drive wheels 8. The final reduction mechanism 7 has a plurality of gear trains and differential gears. The final reduction mechanism 7 rotates the drive wheel 8 via the axle.

  The hydraulic circuit 10 supplies primary pressure to the PRI pulley 61 and also supplies secondary pressure to the SEC pulley 62. The hydraulic circuit 10 also supplies hydraulic pressure to the forward / reverse switching mechanism 5. In addition to the pump unit 4, the hydraulic circuit 10 includes a line pressure oil passage 11 that constitutes an oil passage of the line pressure PL, a switching valve 12, a pilot check valve 13, a check valve 14, and a hydraulic pressure adjustment valve 15. Including.

  The first pump 41 and the second pump 42 are provided in parallel with each other and connected to the line pressure oil passage 11. Specifically, the discharge port of the first pump 41 is directly connected to the line pressure oil passage 11. Further, the discharge port of the second pump 42 is connected to the line pressure oil passage 11 via the switching valve 12, the pilot check valve 13 and the check valve 14.

  The switching valve 12 switches the connection destination of the discharge port of the second pump 42 between the line pressure oil passage 11 and the oil pan. The switching valve 12 that performs such switching is provided between the line pressure oil passage 11 and the second pump 42, and the second pump 42 discharges oil to the line pressure oil passage 11 and the second pump 42. Is provided as a switching unit for switching the discharge mode of the second pump 42.

  Specifically, the switching valve 12 is a pilot-actuated switching valve that operates at the pilot pressure Psig. The switching valve 12 connects the discharge port of the second pump 42 and the oil pan when the supplied pilot pressure Psig is equal to or less than a predetermined value α. The switching valve 12 connects the discharge port of the second pump 42 and the line pressure oil passage 11 via the pilot check valve 13 and the check valve 14 when the supplied pilot pressure Psig is higher than the predetermined value α. To do. Hereinafter, the state of the former switching valve 12 is also referred to as OFF, and the state of the latter switching valve 12 is also referred to as ON.

  Since the switching valve 12 performs switching as described above, when the pilot pressure Psig supplied to the switching valve 12 is equal to or less than the predetermined value α, the specific discharge amount Qn of the pump unit 4 is equal to the specific discharge amount Qn1 of the first pump 41. Become. When the pilot pressure Psig supplied to the switching valve 12 is higher than the predetermined value α, the specific discharge amount Qn is the sum of the specific discharge amount Qn1 of the first pump 41 and the specific discharge amount Qn2 of the second pump 42. Become. The specific discharge amount Qn1 and the specific discharge amount Qn2 may be the same or different.

  The predetermined value α secures the discharge amount of the pump unit 4 when the discharge amount of the pump unit 4 can be secured even when the specific discharge amount Qn is the specific discharge amount Qn1, and when the specific discharge amount Qn is the specific discharge amount Qn1. It is a value for distinguishing from the case where it cannot be done. The predetermined value α is, for example, 0.5 MPa, and can be set in advance by experiments or the like.

  The pilot check valve 13 is provided between the second pump 42 and the line pressure oil passage 11, specifically, between the switching valve 12 and the line pressure oil passage 11. A pilot pressure Psig is supplied to the pilot check valve 13. In the pilot check valve 13, the opening degree is changed according to the magnitude of the supplied pilot pressure Psig. The pilot check valve 13 whose opening degree is changed in this way is provided between the second pump 42 and the line pressure oil passage 11 and is a change that changes the degree of communication between the second pump 42 and the line pressure oil passage 11. Provided as part.

  The check valve 14 is provided between the second pump 42 and the line pressure oil passage 11, specifically, between the pilot check valve 13 and the line pressure oil passage 11. The check valve 14 is provided so as to allow the flow from the second pump 42 side to the line pressure oil passage 11 side and prevent the flow from the line pressure oil passage 11 side to the second pump 42 side.

  The hydraulic pressure adjusting valve 15 is an electronically controlled hydraulic pressure adjusting valve that adjusts the pilot pressure Psig. Specifically, the hydraulic pressure adjustment valve 15 is a linear solenoid valve, and adjusts the pilot pressure Psig by generating the pilot pressure Psig according to the control current. The hydraulic pressure adjusting valve 15 generates a pilot pressure Psig from the line pressure PL.

  FIG. 2A is a diagram illustrating a specific example of the pilot check valve 13. FIG. 2B is a diagram showing the valve opening characteristics of the pilot check valve 13. FIG. 2C is a diagram illustrating a valve opening characteristic of the switching valve 12.

  As shown in FIG. 2A, the pilot check valve 13 includes a body 131, a rod 132, a first spring 133, a ball 134, and a second spring 135.

  The body 131 includes a rod chamber 131a, a ball chamber 131b, a pilot port 131c, an inlet port 131d, and an outlet port 131e.

  The rod chamber 131a and the ball chamber 131b are provided side by side in the axial direction of the body 131. The rod chamber 131a accommodates the rod 132 and the first spring 133. A pilot port 131c opens in the rod chamber 131a. A pilot pressure Psig is supplied to the pilot port 131c. The pilot pressure Psig acts to push the rod 132 toward the ball chamber 131b in the rod chamber 131a, thereby generating a force pushing the rod 132 in the valve opening direction.

  The ball chamber 131b accommodates the ball 134 and the second spring 135. An inlet port 131d and an outlet port 131e are opened in the ball chamber 131b. The second pump 42 is connected to the inlet port 131d via the switching valve 12. The line pressure oil passage 11 is connected to the outlet port 131e via the check valve 14. The outlet port 131e is provided so that the ball 134 is seated.

  The rod 132 is accommodated in the rod chamber 131a and protrudes into the ball chamber 131b. The rod 132 slides along the axial direction of the body 131. The first spring 133 biases the rod 132 in the valve closing direction by biasing the rod 132 to the opposite side to the ball chamber 131b side.

  The ball 134 changes the degree of communication between the inlet port 131d and the outlet port 131e by opening and closing the outlet port 131e. The second spring 135 biases the ball 134 in the valve closing direction by biasing the ball 134 toward the rod chamber 131a. A rod 132 acts on the ball 134 in the valve opening direction.

  The opening degree of the pilot check valve 13 is determined by the position of the ball 134. The position of the ball 134 is determined by the balance between the force in the valve opening direction, that is, the force generated by the pilot pressure Psig, and the force in the valve closing direction, that is, the biasing force of the spring composed of the first spring 133 and the second spring 135.

  When the pilot pressure Psig is equal to or less than the predetermined value α, the force in the valve opening direction is equal to or less than the force in the valve closing direction. In this case, the ball 134 is seated on the outlet port 131e, and the communication between the inlet port 131d and the outlet port 131e is blocked. As a result, the pilot check valve 13 is closed.

  When the pilot pressure Psig is higher than the predetermined value α, the force in the valve opening direction exceeds the force in the valve closing direction. In this case, the ball 134 is separated from the outlet port 131e and communicates the inlet port 131d and the outlet port 131e. The opening degree of the pilot check valve 13 is determined by the degree of communication between the inlet port 131d and the outlet port 131e communicated by the ball 134.

  As shown in FIG. 2B, the opening degree of the pilot check valve 13 is a fully closed opening degree when the pilot pressure Psig is equal to or less than a predetermined value α. When the pilot pressure Psig is higher than the predetermined value α, the opening of the pilot check valve 13 changes according to the pilot pressure Psig, and increases as the pilot pressure Psig is higher.

  Specifically, the opening degree of the pilot check valve 13 changes in proportion to the pilot pressure Psig. The opening degree of the pilot check valve 13 becomes a fully opened opening degree when the pilot pressure Psig is a predetermined value β. The predetermined value β is larger than the predetermined value α, and is 1 Mpa, for example.

  As shown in FIG. 2C, the switching valve 12 is turned off when the pilot pressure Psig is equal to or lower than the predetermined value α, and is turned on when the pilot pressure Psig is higher than the predetermined value α. The case where the pilot pressure Psig is the predetermined value α may be included when the switching valve 12 is ON and when the opening degree of the pilot check valve 13 changes according to the pilot Psig.

  As described above, both the switching valve 12 and the pilot check valve 13 operate with the pilot pressure Psig adjusted by the electronically controlled hydraulic pressure adjusting valve 15. Therefore, the switching valve 12 is controlled together with the pilot check valve 13 by the same electronic control that controls the hydraulic pressure regulating valve 15.

  Returning to FIG. 1 and continuing the description, the controller 9 is an electronic control unit, and a signal from the sensor / switch group 91 is input to the controller 9.

  The sensor / switch group 91 includes, for example, an accelerator opening sensor that detects the accelerator opening of the vehicle, a brake sensor that detects the brake depression force of the vehicle, a vehicle speed sensor that detects the vehicle speed Vsp, and an engine rotation that detects the rotational speed Ne. Includes speed sensor.

  The sensor switch group 91 further includes, for example, a PRI pressure sensor that detects the PRI pressure, a SEC pressure sensor that detects the SEC pressure, a PRI rotation speed sensor that detects the input side rotation speed of the PRI pulley 61, and the SEC pulley 62. It includes an SEC rotational speed sensor that detects the output side rotational speed and an inhibitor switch that detects the operating position of the shift lever.

  The controller 9 controls the hydraulic circuit 10 including the hydraulic pressure adjustment valve 15 based on a signal from the sensor / switch group 91. The controller 9 is provided as a control unit that controls the discharge amount of the pump unit 4 by controlling the hydraulic circuit 10.

  Next, an example of the control performed by the controller 9 will be described using the flowchart shown in FIG. The controller 9 can repeatedly execute the processing shown in the flowchart of FIG. 3 every minute time. In this flowchart, the controller 9 controls the switching valve 12 and the pilot check valve 13 by controlling the hydraulic pressure adjustment valve 15.

  In step S1, the controller 9 detects the driving state of the vehicle. The driving state of the vehicle includes, for example, the rotational speed Ne. The driving state of the vehicle may include other parameters detected by the sensor / switch group 91.

  In step S2, the controller 9 acquires the required discharge amount Qreq of the pump unit 4. The required discharge amount Qreq can be set in advance by map data or the like according to the driving state of the vehicle.

  In step S3, the controller 9 controls the hydraulic pressure adjustment valve 15 according to the required discharge amount Qreq. The control current of the hydraulic pressure regulating valve 15 can be set in advance so that the pilot pressure Psig changes in proportion to the required discharge amount Qreq.

  Thereby, when the required discharge amount Qreq is equal to or less than the predetermined value Q1, which is the value of the discharge amount corresponding to the predetermined value α, the pilot pressure Psig is equal to or less than the predetermined value α, so the switching valve 12 is turned off. To be controlled. That is, the switching valve 12 is controlled to unload the second pump 42. The pilot check valve 13 is controlled to close.

  When the required discharge amount Qreq is larger than the predetermined value Q1, the pilot pressure Psig is higher than the predetermined value α, so that the switching valve 12 is controlled to be turned on. That is, the switching valve 12 is controlled such that the second pump 42 discharges oil to the line pressure oil passage 11.

  When the required discharge amount Qreq is larger than the predetermined value Q1, the pilot check valve 13 is controlled according to the required discharge amount Qreq. Specifically, the pilot check valve 13 is controlled so that the opening degree increases as the required discharge amount Qreq increases. After step S3, this flowchart is temporarily terminated.

  Next, main effects of the pump system 1 will be described. The pump system 1 includes a first pump 41 and a second pump 42 that are provided in parallel with each other and connected to the line pressure oil passage 11, and are driven by the engine 2, and the line pressure oil passage 11 and the second pressure oil passage 11. A switching valve that is provided between the pump 42 and switches the discharge mode of the second pump 42 when the second pump 42 discharges oil to the line pressure oil passage 11 and when the second pump 42 is unloaded. 12 and a pilot check valve 13 that is provided between the line pressure oil passage 11 and the second pump 42 and changes the degree of communication between the second pump 42 and the line pressure oil passage 11.

  According to the pump system 1 configured as described above, the specific discharge amount Qn of the pump unit 4 can be set to the specific discharge amount Qn1 of the first pump 41 by unloading the second pump 42. Further, by switching the discharge mode of the second pump 42 to discharge to the line pressure oil passage 11, the specific discharge amount Qn of the pump unit 4 is changed to the specific discharge amount Qn 1 of the first pump 41 and the specific discharge amount of the second pump 42. It can be the total value of Qn2.

  According to the pump system 1 configured as described above, when the specific discharge amount Qn is the specific discharge amount Qn1, when the discharge amount is insufficient, the specific discharge amount Qn is set to the above total value, so that the pump unit 4 Can be ensured. Also, in this case, by changing the degree of communication between the second pump 42 and the line pressure oil passage 11 by the pilot check valve 13, it is possible to discharge from the pump unit 4 as much as necessary, so an extra load is applied. It does not have to occur.

  For this reason, according to the pump system 1 configured as described above, it is possible to improve fuel efficiency while securing the discharge amount in the pump unit 4 where the specific discharge amount Qn is switched. Further, according to the pump system 1 configured as described above, the discharge amount of the pump unit 4 can be continuously changed. Therefore, in the hydraulic pressure adjusting valve for the line pressure PL that adjusts the line pressure PL, It is also possible to prevent or suppress vibrations from being induced (effects corresponding to claims 1 and 6).

  In the pump system 1, the pilot check valve 13 as a changing unit constitutes a pilot check valve whose opening degree is changed according to the magnitude of the supplied pilot pressure Psig.

  According to the pump system 1 having such a configuration, the degree of communication between the second pump 42 and the line pressure oil passage 11 can be changed using the low-pressure pilot pressure Psig as a control pressure. (Effect corresponding to claim 2).

  In the pump system 1, the switching valve 12 as a switching unit is configured to be controlled together with the pilot check valve 13 by the same electronic control.

  According to the pump system 1 having such a configuration, the switching of the discharge mode of the second pump 42 and the change of the opening degree of the pilot check valve 13 are performed by the same electronic control, so that rationalization and simplification of the control is achieved. (Effect corresponding to claim 3).

  The pump system 1 further includes an electronically controlled hydraulic pressure adjusting valve 15 that adjusts the pilot pressure Psig. Further, the switching valve 12 as a switching unit constitutes a switching valve that operates with a pilot pressure Psig adjusted by the hydraulic pressure adjustment valve 15.

  According to the pump system 1 having such a configuration, it is possible to control both the switching valve 12 and the pilot check valve 13 by controlling the hydraulic pressure adjustment valve 15, and appropriately rationalize and simplify the control. Yes (effect corresponding to claim 4).

  The pump system 1 further includes a controller 9 that controls the discharge amount of the pump unit 4. The controller 9 controls the switching valve 12 to unload the second pump 42 when the required discharge amount Qreq is smaller than the predetermined value Q1. In addition, the controller 9 controls the switching valve 12 so that the second pump 42 discharges oil to the line pressure oil passage 11 when the required discharge amount Qreq is larger than the predetermined value Q1, and the controller 9 sets the required discharge amount Qreq to Accordingly, the pilot check valve 13 is controlled.

  According to the pump system 1 having such a configuration, it is possible to appropriately ensure the discharge amount and improve the fuel consumption of the pump unit 4 in which the specific discharge amount Qn is switched. Further, in the hydraulic pressure adjusting valve for the line pressure PL, it is possible to appropriately prevent or suppress the hydraulic vibration from being induced (effect corresponding to claim 5).

  The embodiment of the present invention has been described above, but the above embodiment is merely a part of an application example of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  In the above-described embodiment, the case where the controller 9 indirectly controls the switching valve 12 as the switching unit and the pilot check valve 13 as the changing unit by controlling the hydraulic pressure adjusting valve 15 has been described. However, for example, both the switching unit and the changing unit can be configured by electromagnetic valves, and these can be directly controlled individually by the controller 9.

  In the above-described embodiment, the case where the engine 2 constitutes a power source has been described. However, a power source other than the engine 2 such as a motor may be applied to the power source.

DESCRIPTION OF SYMBOLS 1 Pump system 2 Engine 4 Pump part 41 1st pump (1st pump part)
42 Second pump (second pump part)
43 Drive shaft 6 Variator 9 Controller (control unit)
11 Line pressure oil passage (oil passage)
12 Switching valve (switching unit)
13 Pilot check valve (change part)
15 Hydraulic adjustment valve

Claims (6)

A first pump unit and a second pump unit which are provided in parallel to each other and connected to the oil passage, and are driven by a power source;
The second pump is provided between the oil passage and the second pump portion, and the second pump portion discharges oil to the oil passage and unloads the second pump portion. A switching unit for switching the discharge mode of the unit;
A change unit that is provided between the oil passage and the second pump portion, and changes a degree of communication between the second pump portion and the oil passage;
A pump system comprising: The pump system according to claim 1,
The change unit is a pilot check valve whose opening is changed according to the magnitude of the supplied pilot pressure.
A pump system characterized by that. The pump system according to claim 2,
The switching unit is configured to be controlled together with the pilot check valve by the same electronic control.
A pump system characterized by that. The pump system according to claim 3,
An electronically controlled hydraulic adjustment valve that adjusts the pilot pressure supplied to the pilot check valve;
The switching unit is a switching valve that operates with a pilot pressure adjusted by the hydraulic pressure adjustment valve.
A pump system characterized by that. The pump system according to any one of claims 1 to 4,
A control unit for controlling the discharge amount of the pump unit;
The controller is
When the required discharge amount for the pump unit is smaller than a predetermined value, the switching unit is controlled to unload the second pump unit,
When the required discharge amount is larger than the predetermined value, the second pump unit controls the switching unit to discharge oil to the oil passage, and controls the change unit according to the required discharge amount. To
A pump system characterized by that. A pump unit provided in parallel with each other and connected to an oil passage and having a first pump portion and a second pump portion driven by a power source, and provided between the oil passage and the second pump portion. A switching unit that switches the discharge mode of the two pump units, and a changing unit that is provided between the oil passage and the second pump unit and changes the degree of communication between the second pump unit and the oil passage. A control method for a pump system,
Switching the discharge mode of the second pump part between when the second pump part discharges oil into the oil passage and when unloading the second pump part;
Changing the degree of communication between the second pump part and the oil path when the second pump part discharges oil to the oil path;
A control method for a pump system, comprising:

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