JP2016155408A - Hydraulic hybrid vehicle and control method of hydraulic hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic hybrid vehicle which can omit a charge pump when a hydraulic power supply device is constituted of a swash-plate type axial piston pump, does not need special control, can improve the efficiency of a hydraulic circuit while securing responsiveness at a start of the swash-plate type axial piston pump, and can increase a fuel economy improvement effect, and a control method of the hydraulic hybrid vehicle.SOLUTION: An accumulator 21 is arranged which is connected to a main pump 20a of a swash-plate type axial piston pump 20 via a hydraulic circuit HL, and a branch passage 30 is formed which connects the accumulator 21 and a swash plate control valve 20d for controlling an angle of a swash plate 20c of the swash-plate type axial piston pump 20. By arranging a pressure reduction valve 31 at the branch passage 20, a working fluid of the accumulator 21 is made to flow into the swash plate control valve 20d via the pressure reduction valve 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic hybrid vehicle that uses both an internal combustion engine and a hydraulic power supply device as a power source for driving the vehicle, and a control method for the hydraulic hybrid vehicle.

  In the prior art, there is a hydraulic hybrid vehicle in which both an internal combustion engine such as a diesel engine and a hydraulic power supply device such as a hydraulic pump motor are mounted, and both devices are used as a power source for traveling the vehicle.

  In this hydraulic hybrid vehicle, when the vehicle decelerates, the regenerative power of the wheels is supplied to the hydraulic power supply device via the drive shaft, differential gear, propeller shaft, transmission, etc., and the main pump in the hydraulic power supply device is supplied. By driving and accumulating the accumulator connected to the main pump via a hydraulic circuit, high-pressure hydraulic oil is stored, and the regenerative energy generated by driving the main pump is accumulated using the hydraulic oil flowing through the hydraulic circuit as a medium.

  When the vehicle is accelerated, the high-pressure hydraulic oil stored in the accumulator is caused to flow through the hydraulic circuit, and the energy of the high-pressure hydraulic oil is transmitted to the main pump, that is, driven as a hydraulic motor. Is generated.

  The amount of regenerative energy and travel energy depends on the amount of hydraulic oil discharged by the main pump, but when the hydraulic power supply device is configured with a swash plate type axial piston pump, the amount of hydraulic oil discharged is determined by the piston shoe. It is adjusted by changing the stroke amount of the piston by controlling the angle of the swash plate to be pressed.

  In the prior art, as shown in FIGS. 4 and 5, the main pump 20 a is driven by high-pressure hydraulic oil supplied from the accumulator 21 via the high-pressure hydraulic circuit HL (indicated by a one-dot chain line in FIG. 5). However, the change in the angle of the swash plate 20c of the main pump 20a is caused by changing the hydraulic oil pressure generated by driving the charge pump 20b connected (directly connected) to the main pump 20a to a hydraulic circuit (thick solid line in FIG. 5) CL. Is supplied to a swash plate control valve 20d provided between the charge pump 20b and the swash plate 20c, and the valve opening is controlled. That is, the valve opening degree of the swash plate control valve 20d controls the angle of the swash plate 20c, in other words, the discharge amount of the swash plate type axial piston pump. The charge pump 20b is driven by low-pressure hydraulic oil supplied from the low-pressure tank 22 via a low-pressure hydraulic circuit LL (solid line in FIG. 5).

  However, in the configuration in which the main pump 20a and the charge pump 20b are directly connected as described above, the charge pump 20b operates even when it is not necessary to control the angle of the swash plate 20c. Oil loss from 20e has occurred, and loss due to friction / viscous resistance of the pump body accompanying the operation of the charge pump 20b has also occurred, resulting in a decrease in the efficiency of the hydraulic circuit, resulting in a hybrid There is a problem that the fuel efficiency improvement effect is reduced.

  In this connection, the pressure oil discharged from the hydraulic pump is depressurized by a pressure reducing valve provided on the pressure oil supply line, and is supplied to the swash plate drive mechanism via the pressure oil supply line. A control device for a hydraulic pump that controls the angle of the plate has been proposed (see, for example, Patent Document 1).

  However, in this self-pressure hydraulic assist control that uses the hydraulic oil of the hydraulic pump, the hydraulic pressure for control changes depending on the operation status of the hydraulic pump, and when the hydraulic pump is operating, the angle of the swash plate is controlled. However, when the hydraulic pump starts to operate, the angle of the swash plate cannot be controlled, and the operation starts at the angle of the swash plate when the hydraulic pump is stopped. As a result, there is a problem that it is necessary to perform control in consideration of the operation of the pump.

JP 2000-38991 A

  The present invention has been made in view of the above, and an object of the present invention is to control a hydraulic hybrid vehicle and a hydraulic hybrid vehicle using both the internal combustion engine and the hydraulic power supply device as a power source for running the vehicle. Regarding the method, when the hydraulic power supply device is composed of a swash plate type axial piston pump, the charge pump can be dispensed with and the responsiveness at the start of the swash plate type axial piston pump is ensured without requiring special control. On the other hand, it is an object of the present invention to provide a hydraulic hybrid vehicle and a method for controlling the hydraulic hybrid vehicle that can improve the efficiency of the hydraulic circuit and increase the fuel efficiency improvement effect.

  In order to achieve the above object, a hydraulic hybrid vehicle of the present invention uses both an internal combustion engine and a hydraulic power supply device as a power source for running the vehicle, and the hydraulic power supply device is constituted by a swash plate type axial piston pump. And a swash plate control for controlling an angle between the accumulator and a swash plate of the swash plate type axial piston pump in a hydraulic hybrid vehicle including an accumulator connected to a main pump of the swash plate type axial piston pump through a hydraulic circuit. A branch passage that connects to the valve is provided, and a pressure reducing valve is provided in the branch passage, so that hydraulic oil of the accumulator flows into the swash plate control valve via the pressure reducing valve.

  That is, as in the prior art, a charge pump is connected to the main pump inside the swash plate type axial piston pump, and the charge pump is driven by supplying low pressure oil, and the oil generated by driving the charge pump is Is not supplied to the swash plate control valve to control the angle of the swash plate, but the branch passage that branches from the hydraulic circuit through which high-pressure oil flows between the main pump and the accumulator passes through the pressure reducing valve. The pressure of the oil generated by driving the charge pump of the prior art is provided by connecting to the control valve, flowing a part of the high pressure oil of the accumulator through the branch passage, and the high pressure oil flowing through this branch passage by the pressure reducing valve The pressure of the reduced oil is supplied to the swash plate control valve to control the angle of the swash plate.

  Therefore, according to this configuration, the charge pump becomes unnecessary, and the charge pump does not operate in conjunction with the operation of the main pump. Loss of hydraulic oil from the relief valve connected to the charge pump and loss of friction resistance and viscous resistance of the main pump due to extra operation are eliminated, improving the operation efficiency of the main pump and improving the efficiency of the hydraulic circuit It is possible to improve fuel efficiency.

  In addition, since the swash plate angle is controlled not by the hydraulic oil discharged from the main pump but by the hydraulic oil once stored in the accumulator, it is possible to control the swash plate angle with sufficient hydraulic pressure even when the main pump starts. It is possible to secure responsiveness when starting the hydraulic pump.

  Further, in the hydraulic hybrid vehicle described above, if a relief valve is provided downstream of the pressure reducing valve in the branch passage, it is possible to prevent excessive hydraulic pressure from being supplied to the swash plate control valve.

  In order to achieve the above object, a control method for a hydraulic hybrid vehicle according to the present invention comprises using both an internal combustion engine and a hydraulic power supply device as a power source for running the vehicle, and the hydraulic power supply device is a swash plate type axial. A hydraulic hybrid vehicle control method comprising a piston pump and having an accumulator connected to a main pump inside the swash plate type axial piston pump via a hydraulic circuit, wherein hydraulic oil of the accumulator is passed through the pressure reducing valve Then, the swash plate angle is controlled by supplying to a swash plate control valve for controlling the swash plate angle of the swash plate type axial piston pump. According to this method, the same operational effects as the hydraulic hybrid vehicle can be obtained.

  According to the hydraulic hybrid vehicle and the control method of the hydraulic hybrid vehicle of the present invention, when the hydraulic power supply device is constituted by a swash plate type axial piston pump, the charge pump can be made unnecessary and no special control is required. In addition, the efficiency of the hydraulic circuit can be improved and the fuel efficiency improvement effect can be increased while ensuring the responsiveness at the start of the swash plate type axial piston pump.

1 is a diagram schematically showing a configuration of a hydraulic hybrid vehicle according to an embodiment of the present invention. It is a hydraulic circuit diagram of the hydraulic system of FIG. 1, and is a figure which shows typically the case where a relief valve is not provided. It is a hydraulic circuit diagram of the hydraulic system of FIG. 1, and is a figure which shows typically the case where a relief valve is provided. It is a figure which shows typically an example of a structure of the hydraulic hybrid vehicle which concerns on a prior art. FIG. 5 is a hydraulic circuit diagram of the hydraulic system in FIG. 4.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a hydraulic hybrid vehicle and a control method for a hydraulic hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, a hydraulic hybrid vehicle 1 according to an embodiment of the present invention uses an engine (internal combustion engine) 10 and a swash plate type axial piston pump (hydraulic power supply device) 20 for traveling the vehicle 1. As a power source, the vehicle is provided with an accumulator 21 connected to a main pump 20a inside the swash plate type axial piston pump 20 via a high pressure hydraulic circuit HL through which high pressure hydraulic oil flows.

  In the hydraulic hybrid vehicle 1, when the vehicle 1 is decelerated, the regenerative power of the wheels 50 is supplied to the swash plate type axial piston pump 20 via the drive shaft 51, the differential gear 52, the propeller shaft 53, the transmission 54, etc. The main pump 20a is driven, and high pressure hydraulic oil is stored in the accumulator 21 connected to the main pump 20a via the hydraulic circuit HL, so that the main pump 20a is driven using the hydraulic oil flowing through the hydraulic circuit HL as a medium. Accumulate regenerative energy by.

  When the vehicle 1 is accelerated, the high-pressure hydraulic oil stored in the accumulator 21 is supplied to the hydraulic circuit HL, and the energy of the high-pressure hydraulic oil is transmitted to the main pump 20a so that it is driven as a motor. Is generated.

  Note that a low-pressure hydraulic circuit LL and a three-way valve 23 are also provided for flowing hydraulic oil between the main pump 20 a, the accumulator 21, and the low hydraulic tank 22. Further, in FIG. 1, the passage connecting the accumulator 21 and the low hydraulic tank 22 and the three-way valve 23 are omitted. Further, the low hydraulic tank 22 is provided with an air vent passage 24 for removing the air A flowing into the tank.

  In the present invention, the angle of the swash plate 20c of the swash plate type axial piston pump 20 is controlled by branching from the high pressure hydraulic circuit HL without connecting the charge pump 20b to the main pump 20a as in the prior art. A branch passage 30 connected to the swash plate control valve 20d is provided, and a pressure reducing valve 31 is provided in the branch passage 30.

  In addition, a control device 40 is provided for controlling the opening degrees of the swash plate control valve 20 d and the pressure reducing valve 31 according to the operating state of the vehicle 1. The control device 40 is usually configured to be incorporated in a control unit that controls the overall operation state of the hydraulic system OS including the swash plate type axial piston pump 20, the accumulator 21, the low hydraulic tank 22, and the three-way valve 23.

  And the control method of the hydraulic hybrid vehicle based on the configuration of the hydraulic hybrid vehicle 1 of the present invention is such that the hydraulic oil of the accumulator 21 is supplied to the swash plate 20c of the swash plate type axial piston pump 20 via the pressure reducing valve 31. The method is characterized in that the angle of the swash plate 20c is controlled by supplying the swash plate control valve 20d for controlling the angle. In other words, a part of the hydraulic oil flowing through the high-pressure hydraulic circuit HL is caused to flow through the branch passage 30 and the pressure of the hydraulic oil flowing through the branch passage 30 is reduced to a pressure that can be supplied to the swash plate control valve 20d by the pressure reducing valve 31. Then, this reduced hydraulic oil is supplied to the swash plate control valve 20d to control the angle of the swash plate 20c.

  That is, in the control method for the hydraulic hybrid vehicle 1 and the hydraulic hybrid vehicle according to the present invention, the charge pump 20b is connected to the main pump 20a inside the swash plate type axial piston pump 20 as in the prior art. Instead of supplying low pressure hydraulic oil to the pump 20b and supplying hydraulic oil pressure generated by driving the charge pump 20b to the swash plate control valve 20d, the angle of the swash plate 20c is not controlled. A branch passage 30 is branched from the hydraulic circuit HL through which high-pressure hydraulic fluid flows between the hydraulic pump 20a and the accumulator 21, and is connected to the swash plate control valve 20d via the pressure reducing valve 31. Between the main pump 20a and the accumulator 21, A part of the high-pressure hydraulic fluid that flows through the hydraulic circuit HL flows through the branch passage 30, and the high-pressure hydraulic fluid that flows through the branch passage 30 is reduced by the pressure reducing valve 1, the pressure of the hydraulic oil generated by driving the charge pump 20b of the prior art is reduced to the same level, and the reduced hydraulic oil is supplied to the swash plate control valve 20d to control the angle of the swash plate 20c. .

  Further, in the hydraulic hybrid vehicle 1 of the present invention, as shown in FIG. 3, when the relief valve 20 e is provided in the branch passage 30 downstream from the pressure reducing valve 31, excessive hydraulic pressure is applied to the swash plate control valve 30. It can prevent being supplied.

  2 and 3, the hydraulic circuit between the pressure reducing valve 31 and the swash plate control valve 20d is a circuit CL for supplying a control pressure to the swash plate control valve 20d, and the high pressure hydraulic circuit HL and the low pressure hydraulic circuit. It is distinguished from LL.

  According to the control method of the hydraulic hybrid vehicle 1 and the hydraulic hybrid vehicle described above, when the hydraulic power supply device 20 is constituted by a swash plate type axial piston pump, the charge pump 20b can be made unnecessary and special control is required. Instead, the efficiency of the hydraulic circuit can be improved and the fuel efficiency improvement effect can be increased while ensuring the responsiveness at the start of the swash plate type axial piston pump 20.

1 Hydraulic hybrid vehicle 10 Engine (internal combustion engine)
20 Swash plate type axial piston pump 20a Main pump 20b Charge pump 20c Swash plate 20d Swash plate control valve 20e Relief valve 21 Accumulator 22 Low hydraulic tank 23 Three-way valve 24 Air vent passage 30 Branch passage 31 Pressure reducing valve 40 Controller A Air HL For high pressure Hydraulic circuit LL Low pressure hydraulic circuit CL Control hydraulic circuit

Claims (3)

Both the internal combustion engine and the hydraulic power supply device are used as a driving power source for the vehicle, and the hydraulic power supply device is constituted by a swash plate type axial piston pump, and the main pump of the swash plate type axial piston pump is connected via a hydraulic circuit. In a hydraulic hybrid vehicle with an accumulator to be connected,
A branch passage that connects the accumulator and a swash plate control valve that controls the angle of the swash plate of the swash plate type axial piston pump is provided, and a pressure reducing valve is provided in the branch passage to reduce the operating oil of the accumulator. A hydraulic hybrid vehicle configured to flow into the swash plate control valve via a valve.   The hydraulic hybrid vehicle according to claim 1, wherein a relief valve is provided downstream of the pressure reducing valve in the branch passage. Both the internal combustion engine and the hydraulic power supply device are used as power sources for running the vehicle, and the hydraulic power supply device is constituted by a swash plate type axial piston pump, and a hydraulic circuit is provided in the main pump inside the swash plate type axial piston pump. In a control method of a hydraulic hybrid vehicle provided with an accumulator connected via
The hydraulic oil of the accumulator is supplied to the swash plate control valve that controls the angle of the swash plate of the swash plate type axial piston pump via the pressure reducing valve, and the angle of the swash plate is controlled. Control method of hydraulic hybrid vehicle.

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