JP2842104B2 - Braking energy regeneration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pump which is driven by a drive shaft of a vehicle during braking to store hydraulic energy.
The present invention relates to a braking energy regenerating device that can be used as a driving force of a vehicle by driving a motor with hydraulic energy during starting or acceleration.

[0002]

2. Description of the Related Art Braking energy regenerating devices have been developed for large vehicles, especially for route buses. Generally, in the operation of a route bus, starting and braking are repeatedly performed frequently because the distance between the bus stops is short, and each time the bus stops at the bus stop, that is, every time the braking is performed, frictional heat generated on a brake drum or the like is generated. That is, the kinetic energy of the vehicle released into the atmosphere as heat energy also increases. for that reason,
The energy released during braking was stored as other reusable hydraulic energy, and the braking energy was developed to reduce the stored hydraulic energy to the driving force of the vehicle when starting and accelerating. It is a regenerative device.

[0003] This braking energy regenerating device (hereinafter simply referred to as "device") is mainly composed of an accumulator, a hydraulic oil tank, a hydraulic pump / motor, and each operating valve, and the accumulator is connected via a hydraulic pump / motor. ,
The hydraulic pump is connected to the hydraulic oil tank, and the pump / motor shaft of the hydraulic pump / motor is connected to the drive shaft of the vehicle. According to this device, at the time of braking, the hydraulic pump / motor is operated as a pump by the drive shaft of the vehicle, and the hydraulic oil supplied from the hydraulic oil tank to the hydraulic pump / motor through the hydraulic fluid line is supplied to the hydraulic pump / motor. And pressurized to the accumulator to accumulate the pressure as compression energy of the nitrogen gas sealed in the accumulator.

On the other hand, at the time of starting and accelerating, the hydraulic oil stored in the accumulator is discharged to the hydraulic oil tank through the hydraulic pump / motor and the hydraulic line.
The hydraulic pump / motor works as a motor to assist the driving force of the drive shaft of the vehicle. An air tank is connected to the hydraulic oil tank, and the air tank supplies air pressure to the hydraulic oil tank to keep the hydraulic oil level in the hydraulic oil tank constantly pressurized. The reason for this is that when the hydraulic pump / motor works as a pump during braking, it supplies a somewhat pressurized hydraulic oil to the pump suction port to improve the suction performance of the pump. The air pressure of the air tank is used for braking a vehicle, opening and closing a lifting door, and operating various air cylinders.

[0005] In this device, the hydraulic oil passed between the hydraulic pump / motor and the hydraulic oil tank is used for energy transmission between the hydraulic pump / motor and the lubricating and sliding parts (rotation) in the hydraulic pump / motor. Part). Therefore, when the hydraulic pump / motor is rotating, an appropriate amount of hydraulic oil used for lubrication and cooling is supplied to the inside of the hydraulic pump / motor, and the supplied hydraulic oil is collected in the drain tank and re-operated. It is returned to the tank and circulated.

[0006]

However, when the operation of the device is stopped, the hydraulic pump
The operation of the motor is also stopped, and at this time, if the air pressure from the air tank is constantly supplied to the hydraulic oil tank under pressure, a small amount of hydraulic oil flows to the drain tank through the hydraulic pump / motor due to the pressure difference. Will be leaked. However, when the hydraulic pump / motor is stopped, there is no need to discharge the hydraulic oil, that is, to lubricate the sliding portion with the hydraulic oil. It is necessary to reduce the air pressure. However, if the air pressure in the hydraulic oil tank is reduced, a large amount of air pressure in the air tank is consumed only for the hydraulic oil tank when the start of the device is restarted. After that, the air pressure in the air tank is replenished, but it takes time for the air pressure to reach the predetermined usable air pressure, during which time the air pressure cannot be used for opening and closing the lift door, etc. There is a problem.

The present invention has been made in consideration of the above circumstances, and has as its object to prevent the hydraulic oil from flowing out of the hydraulic pump / motor to the drain tank when the braking energy regenerating device is not operating. An object of the present invention is to provide a braking energy regenerating device that can prevent a decrease in air pressure of an air tank when starting is restarted.

[0008]

In order to achieve the above object, the present invention provides a hydraulic pressure accumulator which presses hydraulic fluid from a hydraulic fluid tank to a hydraulic accumulator through a hydraulic fluid line when the vehicle is being braked. While supplying and accumulating pressure,
When starting and accelerating, the hydraulic fluid accumulated in the hydraulic accumulator is discharged to the hydraulic fluid tank through the hydraulic fluid line to function as a motor, and a hydraulic pump / motor that assists the driving force of the drive shaft of the vehicle. A main air tank connected to the hydraulic fluid tank and storing a predetermined air pressure;
A braking energy regenerating device provided between the main air tank and the hydraulic fluid tank and having an air supply valve for controlling the supply of air pressure from the main air tank to the hydraulic fluid tank; A sub-air tank separate from the main air tank; a communication valve provided between the sub-air tank and the hydraulic fluid tank; and an opening valve for opening the hydraulic fluid tank to the atmosphere.

[0009]

According to the braking energy regenerating device of the present invention, when the device is not operating, the communication valve and the air supply valve are closed, while the open valve is opened, and the air in the hydraulic fluid tank is opened. When the pressure is reduced and the operation of the device is resumed, the opening valve is closed, the communication valve and the air supply valve are opened, and the air pressure from the main and sub tanks is applied to the hydraulic fluid tank. Supplied.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to FIG. Braking energy regeneration device (hereinafter simply referred to as "device")
) Is mainly a piston type accumulator device,
It comprises a hydraulic pump / motor 16, a hydraulic oil tank 17, a gear box 18 with a clutch, and a control unit 25.

The accumulator device includes a pair of accumulators 10, and these accumulators 10
It consists of a hydraulic cylinder having two pressure chambers 12, 13 via a piston 11. These accumulators 1
In the case of 0, one pressure chamber 12 is filled with a predetermined pressure of nitrogen gas, and the other pressure chamber 13 is capable of accumulating hydraulic pressure. The pressure chambers 13 are connected to each other via a high-pressure pipe 14 and an electromagnetic switching valve 15.
The switching valve 15 is connected to the hydraulic pump / motor 1 via a pipe P1.
6 is connected to the first port 16a. In addition, the code | symbol 10a in FIG. 1 shows a bottom cap, and the stroke sensor 11a is provided in the bottom cap 10a of one accumulator 10. FIG. The stroke sensor 11a is electrically connected to the control unit 25. When the piston 11 in the accumulator 10 moves to the bottom cap 11a side, the stroke sensor 11a detects that the piston 11 hits, and outputs this detection signal to the control unit 25. To supply.

The switching valve 15 includes a control unit 25.
And is normally in a first switching position that allows only the flow of hydraulic oil from the hydraulic pump / motor 16 to the accumulator 10, and operates the hydraulic pump / motor to start and When accelerating, it is switched to the second switching position that allows the flow of hydraulic oil from accumulator 10 to hydraulic pump / motor 16.

The hydraulic pump / motor 16 is a swash plate type axial plunger type pump, and its rotation direction is always constant. The hydraulic pump / motor 16 is controlled by a control unit 25 via a hydraulic pump (not shown) provided separately with a swash plate, and operates as a pump during braking, and as a motor during starting and acceleration. Operate. The hydraulic pump / motor 16 operates in a neutral state between the pump and the motor when the vehicle is stopped and the vehicle runs normally.

The second port 16b of the hydraulic pump / motor 16 is connected to a hydraulic oil tank 17 via a pipe P2. The hydraulic oil tank 17 is a tank having a predetermined capacity, and a predetermined amount of hydraulic oil is stored in this tank. The hydraulic oil tank 17 is connected to the main air tank 1 via a first switching valve 28 and a pressure reducing valve 29 at two positions in three directions.
9 is connected. The first switching valve 28 is electrically connected to the control unit 25, and its opening and closing are controlled. Therefore, when the operation of the device is stopped, the first switching valve 28
9 and the hydraulic oil tank 17 are closed, and at the same time, the hydraulic oil tank 17 is switched to the first switching position to be opened to the atmosphere side. A second connection for connecting the oil tank 17 and simultaneously shutting off the connection between the hydraulic oil tank 17 and the atmosphere.
The position is switched to the switching position. Therefore, the first switching valve 2
Numeral 8 is a combination of an air supply valve and an opening valve in this embodiment. Note that the pressure reducing valve 29 adjusts the air pressure supplied from the main air tank 19 to a predetermined pressure.

A sub air tank 20 is connected to the hydraulic oil tank 17 via a second switching valve 30 at two positions in two directions as a communication valve. The second switching valve 30 is electrically connected to the control unit 25, and its opening and closing are controlled. Specifically, the second switching valve 30
When the operation of the device is stopped, the space between the sub air tank 20 and the hydraulic oil tank 17 is closed, the position is switched to the first switching position, and when the operation of the device is resumed, The second switching position is opened to open between the air tank 20 and the hydraulic oil tank 17.

Therefore, when the operation of the device is stopped, the first and second switching valves 28, 30 are both set to the first switching positions 28a, 30a, and the hydraulic oil tank 17
The supply of the air pressure from the main and sub air tanks 19 and 20 is cut off, and the air pressure in the hydraulic oil tank 17 is released to the atmosphere and reduced. As a result, the hydraulic pump
The pressurization of hydraulic oil to the second port 16b of the motor 16, that is, the pump suction port is prevented, and the hydraulic oil from the hydraulic pump / motor 16 to the drain tank is prevented from flowing out. When the operation of the device is stopped, the air pressure in the hydraulic oil tank 17 at that time is accumulated in the sub air tank 20 as it is.

On the other hand, when the operation of the device is resumed, the first and second switching valves 28, 30 are both set to the second switching positions 28b, 30b, and the hydraulic oil tank 17 is moved from the main and sub air tanks 19, 20 to Is supplied, and the liquid level of the hydraulic oil in the hydraulic oil tank 17 is always kept in a pressurized state. Accordingly, when the hydraulic pump / motor 16 operates as a pump, the hydraulic oil to the second port 16b, that is, the pump suction port is also pressurized, so that the pump suction performance of the hydraulic pump / motor 16 is improved. In addition, the occurrence of cavitation can be prevented.

A relief pipe P3 is connected between the hydraulic oil tank 17 and the switching valve 15. Actually, when the hydraulic pressure of the hydraulic oil in the accumulator 10 reaches a predetermined pressure by the relief valve provided inside the switching valve 15, the high-pressure hydraulic oil flows from the switching valve 15 to the hydraulic oil tank 17 through the relief pipe line P <b> 3. Will be returned. The drain port 16c of the hydraulic pump / motor 16 is connected to the drain tank 2
1 and a hydraulic pump 32 connected to the hydraulic oil tank 17. Excess hydraulic oil lubricated inside the hydraulic pump / motor 16 is discharged to the drain tank 21. Further, when the hydraulic oil in the hydraulic oil tank 17 becomes equal to or less than the set capacity, or when the hydraulic oil in the drain tank 21 becomes equal to or more than the allowable level, the hydraulic pump 32 operates to transfer the hydraulic oil from the drain tank 21 to the hydraulic oil tank 17. Hydraulic oil is supplied.

As shown in FIG. 1, the pump / motor shaft of the hydraulic pump / motor 16 is connectable to a connecting shaft J1 via a clutch-equipped gear box 18. The connecting shaft J1 is It is connected to the axle of the drive wheel of the vehicle via a differential gear 22. Note that the differential gear 22 is a propeller shaft J2.
Is connected to the output shaft of the transmission 23 of the engine 24 via the.

The clutch of the gearbox 18 is electrically connected to the control unit 25. When an ON signal is supplied from the control unit 25 and the clutch is turned on, the pump shaft of the hydraulic pump / motor 16 and its Connecting the gear train, i.e. the drive axle of the vehicle,
Conversely, when an off signal is supplied from the control unit 25 and the clutch is turned off, the pump shaft of the hydraulic pump / motor 16 is disconnected from the drive axle of the vehicle.

The clutch is normally connected, and is disengaged during high-speed running. On the other hand, the control unit 25 is composed of a microcomputer or the like. The control unit 25 includes various types of sensors in addition to the switching valve 15, the clutch of the gear box 18 and the hydraulic pump for switching the mode of the hydraulic pump / motor 16. Is connected. That is, the brake sensor 26 and the accelerator sensor 27 are electrically connected to the control unit 25, respectively.

When the brake pedal is operated, the brake sensor 26 supplies a sensor signal to the control unit 25. When the accelerator pedal is operated, the accelerator sensor 27 supplies a sensor signal to the control unit 25. Next, the accumulator 10
The main and sub air tanks 19,
The operation of the above-described braking energy regenerating device will be described on the assumption that the air pressure is accumulated in the braking device 20.

First, when the ignition key is turned on and the engine is operated, the control of the control unit 25 is started, and at the same time, the operation of the regenerative energy regeneration device (hereinafter simply referred to as "device") is started. When the operation of the device is started, the control unit 25 sets the first and second switching valves 28 and 30 together in the second switching position 28b,
Switching to 30b, the air pressure from the main and sub air tanks 19 and 20 is supplied to the hydraulic oil tank 17 so that the hydraulic oil in the hydraulic oil tank 17 is always kept pressurized.

When the accelerator pedal is operated at the time of starting and accelerating and a sensor signal is supplied from the accelerator sensor 27 to the control unit 25, the control unit 25 determines that it is at the time of starting or accelerating, and the accumulator 10 The switching valve 15 is switched to the second switching position, while the hydraulic pump / motor 16 is switched to the motor mode. At this time, the hydraulic oil accumulated in the accumulator 10 is discharged to the hydraulic oil tank 17 through the hydraulic pump / motor 16 and the pipeline P2.
The motor 16 generates a torque which is transmitted via a gearbox 18 to the drive axle of the vehicle. As a result, the driving force of the vehicle is assisted by the torque of the hydraulic pump / motor 16, so that the vehicle can smoothly start and accelerate.

At this time, the control unit 25 detects that the piston has hit the stroke sensor 11a, switches the switching valve 15 to the first switching position, and stops the discharge of the hydraulic oil from the accumulator 100. Therefore,
The vehicle travels only with the driving force of the engine 24 as in a normal vehicle. At this time, the angle of the swash plate is inclined to zero (zero), and the hydraulic pump / motor 16 is driven in a neutral state between the pump and the motor.

At the time of braking, when the brake pedal is operated and a sensor signal is supplied from the brake sensor 26 to the control unit 25, the control unit 25
When it is determined that braking is being performed, the switching valve 15 of the accumulator 10 is switched to the first switching position.
The motor 16 is switched to the pump mode. At this time, the driving force of the vehicle is transmitted from the driving axle to the pump shaft of the hydraulic pump / motor 16 via the gear box 18, and the hydraulic pump / motor 16 supplies the hydraulic oil from the hydraulic oil tank 17 through the pipelines P <b> 2 and P <b> 1. The pressure is fed to the accumulator 10 to accumulate the hydraulic pressure. When the hydraulic pressure is accumulated in the accumulator 10 to a predetermined pressure, the high-pressure hydraulic oil is returned to the hydraulic oil tank 17 via the relief pipe P3.
At this time, the nitrogen gas in the accumulator 10 is compressed,
The driving force of the vehicle, that is, the kinetic energy, is stored in the accumulator 10 as the static pressure energy of the nitrogen gas.
In this way, the accumulated pressure energy stored in accumulator 10 is used again when starting and accelerating.

When the ignition key is turned off and the operation of the engine is stopped, the control unit 25
The operation of the device is stopped. In the process of stopping the operation of the device, the control unit 25
The first and second switching valves 28 and 30 are both set to the first switching position 2
8a and 30a, the supply of air pressure from the main and sub air tanks 19 and 20 to the hydraulic oil tank 17 is cut off, and the air pressure in the hydraulic oil tank 17 is released to the atmosphere to reduce the pressure. At this time, the air pressure before being released to the atmosphere is accumulated in the sub air tank 20 as it is, and this air pressure is used when the operation of the device is restarted.

According to the braking energy regenerating apparatus described above,
When the operation of this device is stopped, since the air pressure in the hydraulic oil tank 17 is reduced, the hydraulic pump
The hydraulic oil is not pressurized toward the second port 16 b of the motor 16, that is, the pump suction port, and the hydraulic oil is prevented from flowing out from the hydraulic pump / motor 16 to the drain tank 21.
On the other hand, when the operation of the device is resumed, the air pressure is supplied from the main air tank 19 to the hydraulic oil tank 17, but the air pressure is also supplied from the sub air tank 20. Since a large amount of consumption is suppressed and a decrease in the air pressure in the main air tank 19 is stopped within an allowable range, a state where the air pressure in the main air tank 19 can always be used can be ensured. Further, even when the decrease in the air pressure of the main air tank 19 exceeds the allowable range, the supply of the air pressure in the main air tank 19 can be completed in a very short time.

Further, during the operation of the device, the air volume of the hydraulic oil tank 17 is substantially increased by the sub air tank 20, so that the air pressure fluctuation in the hydraulic oil tank accompanying the operation of the device is increased. Can be obtained. The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible.

For example, the accumulator device is a pair of accumulators 10, but may be a single accumulator as long as the accumulator capacity can be secured. FIG.
The air pump 30 and the sub air tank 20 are connected to each other so that the air pressure from the air pump 31 can be supplied to the sub air tank 20 in the same manner as the main air tank 19, as shown by the dashed line. Alternatively, the air pressure stored in the sub air tank 20 may be controlled.

[0031]

As described above, the braking energy regenerating apparatus according to the present invention comprises a sub-air tank separate from the main air tank provided in connection with the hydraulic fluid tank, and a sub-air tank and a hydraulic fluid tank. And a release valve that allows the hydraulic fluid tank to be open to the atmosphere, so that when the device is not operating, the communication valve and the air supply valve are closed while the open Since the valve is opened and the air pressure in the hydraulic fluid tank is reduced, the hydraulic oil is not pressurized to the suction port of the hydraulic pump / motor pump,
It is possible to prevent the hydraulic oil from flowing from the hydraulic pump / motor to the drain tank. Further, when the operation of the device is resumed, the opening valve is closed, the communication valve and the air supply valve are opened, and the hydraulic fluid tank is supplied with air pressure from the main air tank. Since the air pressure is also supplied from the sub air tank and the large consumption of air pressure in the main air tank is suppressed, the reduction of the air pressure in the main air tank is stopped within an allowable range, and the air pressure in the main air tank is always available. Can be secured. Also,
Even if the decrease in the air pressure exceeds the allowable range, the supply of the air pressure in the main air tank can be completed in a very short time. Furthermore, by connecting the sub air tank to the hydraulic fluid tank, the air volume in the hydraulic fluid tank is increased by the amount of the sub air tank, so that the air pressure fluctuation in the hydraulic fluid tank during operation of the device is reduced. An effect such as being able to be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic system configuration diagram of a braking energy regeneration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Accumulator 15 Switching valve 16 Hydraulic pump / motor 17 Hydraulic oil tank 18 Gear box 19 Main air tank 20 Sub air tank 21 Drain tank 25 Control unit 28 First switching valve 30 Second switching valve 31 Air pump P1, P2, P3 Pipe line

Claims (1)

(57) [Claims] At the time of braking, a hydraulic fluid acts as a pump by a drive shaft of a vehicle, and supplies hydraulic fluid from a hydraulic fluid tank to a hydraulic accumulator through a hydraulic fluid line to accumulate pressure. The hydraulic fluid stored in the hydraulic fluid tank is discharged to the hydraulic fluid tank through the hydraulic fluid conduit, and serves as a motor, and is connected to the hydraulic fluid tank and the hydraulic fluid pump / motor that assists the driving force of the drive shaft of the vehicle. Is provided between the main air tank and the hydraulic fluid tank to store a predetermined air pressure, and controls the supply of air pressure from the main air tank to the hydraulic fluid tank to increase the hydraulic fluid level of the hydraulic fluid tank. A braking energy regenerating device having an air supply valve for pressurizing, a sub air tank provided in connection with the hydraulic fluid tank, the sub air tank being separate from the main air tank, A communication valve provided between the tank and the hydraulic fluid tank; and an opening valve that allows the air pressure of the hydraulic fluid tank to be released to the atmosphere. When the device is not operated, the communication valve and the air supply valve are provided. Is closed, the open valve is opened, the air pressure in the hydraulic fluid tank is reduced, and when the operation of the device is resumed, the open valve is closed and the communication valve is closed. And an air supply valve is opened to supply air pressure from the main and sub air tanks to the hydraulic fluid tank.