JPH02120145A - Brake energy regenerater for vehicle - Google Patents

Abstract

PURPOSE:To keep off any premature actuation of a hydraulic circuit as well as to make improvements in reliability by judging it to be operation completion of a circuit valve when the absolute value of an output difference between pressure sensors at both sides of this circuit valve is less than the extent of pipeline internal resistance, in the case where the circuit valve is controlled for energy regeneration or recovery. CONSTITUTION:When a changeover control command for energy recovery is given to a circuit selector valve 4 constituting a hydraulic circuit together with both high and low pressure accumulators 5, 6 and a pump-motor 3 from a microprocessing unit 15, an electromagnetic clutch 2 is set to a connected state, controlling a tilting angle of the pump-motor 3 conformed to an operated variable of a brake pedal. At this time, the absolute value of each pressure differential in two pressure sensors 11, 12; 13, 14 at both sides of the circuit selector valve 4 along a flow of oil is found out, and whether the absolute value is higher than constant pipeline resistance pressure in a pipeline of the hydraulic circuit or not is judged. Only when it is lower than the pipeline resistance pressure, a tilting angle control permitting signal of the pump-motor 3 is generated, by way of example.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brake energy regeneration device for a vehicle that recovers deceleration energy of a vehicle and uses it as starting/acceleration energy.

[Conventional technology]

Of the kinetic energy lost when the vehicle decelerates, the amount that is mainly dissipated as heat (brakes, engine) is recovered as hydraulic pressure and stored in an accumulator, and this stored energy is used as starting energy and acceleration energy for the vehicle. PTO (Power-take-o)
ff) A deceleration energy recovery device for a vehicle equipped with an axle equipped with an output device or a transfer has been known for a long time, and the oldest one was developed in the UK in 1976 by C.J.
It was announced that Lawrence was developing a bus using British Leyland's bus, and since then various research and developments have been carried out in Europe and the United States, and recently,
It is disclosed in JP-A No. 2-15128, JP-A-62-37215, JP-A-62-39327, and the like.

The latter devices both include a countershaft driven via an engine clutch, a main shaft connected to a wheel drive system, and a transmission (hereinafter referred to as "transmission") having a multi-stage gear train mechanism that changes speed and transmits the rotation of the countershaft to the main shaft. , abbreviated as T/M), a countershaft PTO gear is mounted on the countershaft so that it can be traversed via a countershaft PTO gear synchronizer, and a gear coupled to this PTO gear is connected to the main shaft so that it can be traversed via a main shaft PTO gear synchronizer. a multi-speed PTO device, PT, having a main shaft PTO gear mounted thereon and a PTO output shaft driven via a drive gear coupled to the main shaft PTO gear;
A pump/motor connected to the O-axis, a hydraulic circuit that connects the accumulator and oil tank via this pump/motor, an electromagnetic clutch that enables this hydraulic circuit to cross the PTO axis, and a pump/motor that controls the electromagnetic clutch. Accumulator and pump connected to motor and high pressure oil circuit
The motor functions as either a pump or a motor depending on the driving state of the vehicle (i.e., it functions as a pump during deceleration, and the rotational force of the wheels causes hydraulic oil to accumulate in an accumulator via the PTO device, thereby mainly acting as a brake. , a motor that recovers the kinetic energy (hereinafter referred to as brake energy) lost as engine heat and generates rotational force using the hydraulic fluid stored in the accumulator during start/acceleration to drive the wheels through the PTO device. ) system to function as a system? ■It is constructed with the means as the main part.

The control means of such a deceleration energy recovery device is as follows: - At the time of starting, when the hydraulic pressure in the accumulator is sufficient, the capacity of the variable displacement motor (tilt angle of the swash plate or slant shaft) is adjusted according to the amount of depression of the accelerator pedal. At the same time, the electromagnetic clutch is connected and the hydraulic circuit starts using hydraulic pressure.During this time, when the vehicle speed exceeds the set speed corresponding to the gear selected by the driver, the engine clutch is connected and the engine starts driving. At the same time, the system controls the speed change of the PTO device, turns off the countershaft synchronizer that was on, turns on the main shaft synchronizer, and then applies hydraulic pressure according to the amount of depression of the accelerator pedal only when the amount of depression is large at that time. I do.

■When braking, the electromagnetic clutch is connected and a tilt angle control signal (pump capacity control signal) corresponding to the depression of the brake pedal is applied to the pump motor to operate the pump.
At the same time, control is performed to disengage the engine clutch.

In this case, the control means, based on the control program, recovers the part of the braking energy consumed by engine braking, and also disconnects the engine from the wheel drive system when driving by motor, so that the clutch of the engine is "disengaged". It is controlled so that the motor and engine are used together, or when starting/accelerating with the engine alone, it is controlled so that it is "contact".

[Problem to be solved by the invention]

In the case of such conventional technology, when recovering/regenerating brake energy using hydraulic pressure, the circuit valve (shutoff valve) in the hydraulic circuit is controlled in an open loop, and the circuit valve (shutoff valve) in the hydraulic circuit is controlled in an open loop. Since the hydraulic circuit is operated without confirming whether the hydraulic circuit has reached a normal state, there is a problem in that cavitation occurs in the pump motor in the hydraulic circuit due to a delay in the response of the circuit valve.

Therefore, an object of the present invention is to provide a brake energy regeneration device for a vehicle that prevents the pump motor from causing cavitation by checking the operation of the circuit valve used in the hydraulic circuit during control to prevent close-off control. shall be.

[Means to solve the problem]

In order to achieve the above object, the brake energy regeneration device for a vehicle according to the present invention includes a hydraulic circuit, a pressure sensor provided at each of the four inlets and outlets of the circuit valve constituting the hydraulic circuit, and a hydraulic circuit installed in the circuit valve. When controlled for oil regeneration or recovery, when the absolute value of the output difference between the pressure sensors on both sides of the circuit valve along the oil flow is less than or equal to the paper resistance pressure in the pipe of the hydraulic circuit, the circuit a control means for determining that the operation of the valve is completed;
It is equipped with

Further, in the present invention, when the circuit valve is controlled to close, when the absolute value of the output difference of the pressure sensor of the pump/motor is substantially equal to the line resistance pressure within the pump/motor, the control means It can also be determined that the closing operation of the circuit valve has been completed.

[Function] In the present invention, when the control means controls the circuit valve provided in the hydraulic circuit for energy regeneration or recovery, oil is transferred from the high pressure side accumulator to the low pressure side accumulator or from the low pressure side accumulator. The oil flows to the accumulator on the high pressure side, and along the flow of this oil, the absolute value of the pressure difference between the two pressure sensors on both sides of the circuit valve, that is, the circuit valve is sandwiched, is determined.

If the absolute values of the pressure differences between two of the four pressure sensors are both below a certain pipe resistance pressure of the hydraulic circuit,
It can be determined that oil is flowing normally in this hydraulic circuit, and it can be confirmed that the predetermined operation for energy recovery/regeneration of the circuit valve has been completed.

Based on this, the control means 1 controls the tilting of the pump and motor of the hydraulic circuit as usual, connects this hydraulic circuit and the PTO device via an electromagnetic clutch, and transfers brake energy from the wheels or drive energy to the wheels. introduce.

Further, in the present invention, when the circuit valve is closed and the absolute value of the output difference between the pressure sensors on the pump and motor side is substantially equal to the line resistance pressure in the pump motor, the control means closes the circuit valve. It is possible to determine that the shutoff operation of the hydraulic circuit has been completed, and it is possible to confirm the control n for prohibiting hydraulic control and maintain the hydraulic circuit in an inactive state, for example.

〔Example〕

FIG. 1 is a configuration diagram of an embodiment of a brake energy regeneration device for a vehicle to which the present invention is applied, and
0 is a PTO device which extracts the driving force of the wheels 21 as hydraulic braking force via 0, an electromagnetic clutch 2 is used to communicate the driving force transmission between the PTO device 1 and the pump/motor 3 that performs pump operation during braking; 4 is a circuit switching valve as a circuit valve; 5 is a high-pressure accumulator; 6 is a low-pressure accumulator that constitutes a hydraulic circuit together with the pump/motor 3, the circuit switching valve 4, and the high-pressure accumulator 5.

Also, between the high pressure accumulator 5 and the circuit switching valve 6, between the circuit switching valve 6 and the pump/motor 3, between the pump/motor 3 and the circuit switching valve 4, and between the circuit switching valve 4 and the low pressure accumulator 6. Pressure sensors 11 to 14 are installed between them, and the hydraulic pressure value of each part is controlled by M as a control means.
It is sent to PU15. And this MPU 15 is
It performs fψ rotation angle (capacity) control of the pump/motor 3, switching/cutoff control of the circuit switching valve 4, and opening/closing control of the electromagnetic clutch 2. In addition, 22 is a PTO device and is connected to an engine (not shown) by an automatically controlled engine clutch 23. (T/M), but in the case of a fluid-controlled transmission, the engine can be disconnected during energy recovery/regeneration by setting it in the neutral position.

The general operation of such a brake energy regeneration device will first be explained.

■Energy recovery mode Now, when the driver depresses the brake pedal (not shown) and an energy recovery mode command is given to the MPU 15, the MPU 15 first controls the electromagnetic clutch 2 to the connected state and switches the circuit. The valve 4 is switched and controlled as shown by the solid line, and the tilt angle (capacity) of the pump/motor 3 is controlled according to the amount of depression of the brake pedal.

As a result, the oil in the low pressure accumulator 6 is accumulated in the high pressure accumulator 5 through the route of circuit switching valve 4 → pump/motor 3 → circuit switching valve 4 → high pressure accumulator 5.

■Energy regeneration mode As mentioned above, the hydraulic energy stored in the high-pressure Akiemulator 5 is activated when the driver depresses the accelerator pedal (not shown), and the energy regeneration mode command is activated.
The MPU 15 first controls the electromagnetic clutch 2 to the connected state, controls the circuit switching valve 4 as shown by the broken line, and then changes the tilt angle of the pump/motor 3 to the amount by which the accelerator pedal is depressed. Control accordingly.

Incidentally, in the hydraulic circuit operations of (1) and (2) above, the engine clutch 22 is normally automatically disengaged by a control signal from the MPU 15. In the case of a normal automatic transmission vehicle that does not use an automatic clutch, the gear position is controlled to 2-toral.

■゛Constant brake control mode In addition to this, there is a mode that does not use the hydraulic circuit at all. In this case, the tilt angle of the pump motor 3 is set to 0 (capacity O).
to prevent the pump/motor 3 from rotating even if pressure is applied to the pump/motor 3, and completely turn off the circuit switching valve 4 (section B) to cut off the hydraulic circuit.
Turn off the electromagnetic clutch 2 and set the pump motor 3 to PT.
The hydraulic brake force is completely cut off from the wheel 21 by disconnecting it from the O device 1 and the wheel 21.

In this way, the MPU 15 controls the circuit switching valve 4 in either mode, but as described above, if the next control is performed before the control operation of the circuit switching valve 4 is completed, the pump in the hydraulic circuit - Cavitation occurs in motor 3.

Therefore, in the present invention, completion of the control operation of the circuit switching valve 4 is confirmed in each of the above modes as follows.

■Operation check in energy recovery mode (Figure 2) First,
When a switching control command is given from the MPU 15 to the circuit switching valve 4 for energy recovery (step S in FIG.
l), in steps S2 and S3, the absolute value 1p, -p of the pressure difference between the two pressure sensors on both sides of the circuit switching valve 4 along the oil flow, the Uchi sensors 11 and 12, and the sensors 13 and 14; , tl Ip, , -p, , 1 is determined, and its absolute value is a constant pipe resistance pressure P in the piping of the hydraulic circuit.

Determine whether it is higher or lower.

Then, in both steps S2 and S3, only when the pipe resistance pressure P is lower, for example, a tilt angle control permission signal for the pump motor 3 is generated (step S4).

In this case, typically P ++ > P 12. P+s＞
Although P la is taken as an absolute value, for example, if there is a slight oil leak between the high pressure accumulator 5 and the circuit switching valve 4, a relationship such as P, <P, □ may occur. It is. However, if a pressure difference greater than or equal to the pipe resistance pressure Pa exists, it is considered that the circuit switching valve 4 has not yet completed switching, so the next control does not proceed and the MPU 15 returns to step S2 in the next processing cycle. , S3 will be checked.

■Operation confirmation in energy regeneration mode (Figure 3) MPU
15 gives a switching control command for energy regeneration to the circuit switching valve 4 (step 511 in FIG. 3),
In steps 312 and S13, two pressure sensors on both sides of the circuit switching valve 4 along the oil flow, that is, sensor 1
1 and 13 and the absolute value of the pressure difference between sensors 12 and 14, P1. -P1311PI! - PI41 is determined, and its absolute value is a constant pipe resistance pressure P in the piping of the hydraulic circuit.

Determine whether it is higher or lower.

Then, in both steps S12 and 313, the pipe line resistance pressure P,
Only when it is lower, for example, a tilt angle control signal for the pump motor 3 is generated (step 514).

In this case as well, the completion of the switching operation of the circuit switching valve 4 is determined by taking the absolute value.

■Operation confirmation in normal brake control mode (Fig. 4) MP
Control B is performed from U15 to the circuit switching valve 4 to bring it into the closed state as a normal brake control mode command (
Step 521 in FIG. 4). After this, the absolute MIP, 2P, 1 of the pressure difference between the pressure sensors 12 and 13 on the pump/motor side of the circuit switching valve 4 is determined, and this absolute value is determined as the constant pipe resistance pressure inside the pump/motor 3. It is determined whether P and I are higher or lower than each other (step 522).

When 1P1z P+zl is substantially equal to the pipe line resistance pressure P, it shows that the oil pressure difference across the pump motor 2 is equal to the paper resistance pressure in the pipe line of the pump motor 2 itself, and this This indicates that the circuit switching valve 4 has completed the cutoff state.

Therefore, in such a case, for example, a hydraulic circuit open state signal is generated (step 523).

In this way, the operation of the circuit switching valve in each control mode is confirmed.

In the above embodiment, when each confirmation operation is completed, the pump/motor 3 may be controlled to tilt immediately, or this state may be stored as a flag or the like as described above, and it may be used later. Control may be performed by taking this flag into consideration together with other flags.

Furthermore, although the electromagnetic clutch is not shown in Figures 2 to 4, the electromagnetic clutch is controlled to be connected before controlling the circuit valve, and a certain load is applied to the pump/motor. The trick is to give.

Moreover, although a circuit switching valve has been described as a circuit valve, depending on the type of pump/motor, a simple circuit cutoff valve that does not require switching the hydraulic circuit may be used in the same manner.

〔Effect of the invention〕

As described above, in the brake energy regeneration device for m vehicles according to the present invention, pressure sensors are provided at each of the four inlets and outlets of the circuit valve provided in the hydraulic circuit,
(1) During the energy recovery/regeneration control of the circuit valve, when the absolute value of the output difference of the pressure sensors on both sides of the circuit valve along the oil flow is less than or equal to the paper resistance pressure in the pipe of the hydraulic circuit, (2
) When the circuit valve is controlled to close and the absolute value of the output difference of the pressure sensor on the pump/motor side is substantially equal to the line resistance pressure within the pump/motor, the respective circuit valve has completed its prescribed operation. Since the configuration is configured to perform hydraulic travel, hydraulic brake operation, or normal brake operation after determining that The situation can be avoided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an embodiment to which the brake energy regeneration device for a mission-driven vehicle according to the present invention is applied, and Fig. 2 is a confirmation of the circuit valve switching operation in the energy recovery mode according to the present invention. FIG. 3 is a flowchart showing the operation of the circuit valve switching operation in the energy regeneration mode according to the present invention. In Fig. 1, 3 is a pump motor, 4 is a circuit switching valve, 5 is a high pressure accumulator, 6 is a low pressure accumulator,
15 each indicates an MPU.

Claims (2)

[Claims] (1) A hydraulic circuit, a pressure sensor installed at each of the four inlets and outlets of a circuit valve constituting the hydraulic circuit, and a pressure sensor installed along the oil flow when the circuit valve is controlled for energy regeneration or recovery. A vehicle characterized by comprising: control means that determines that the operation of the circuit valve is complete when the absolute values of the output differences of pressure sensors on both sides of the circuit valve are both equal to or less than the resistance pressure in the pipeline of the hydraulic circuit. brake energy regeneration device. (2) When the circuit valve is controlled to close, and the absolute value of the output difference of the pressure sensor on the pump/motor side is substantially equal to the line resistance pressure within the pump/motor, the control means closes the circuit valve. The brake energy regeneration device for a vehicle according to claim 1, wherein the device determines that the closing operation of the valve is completed.