JPH07144619A - Brake energy regenerating device - Google Patents

Abstract

PURPOSE:To suppress the generation of graphite by controlling the motor torque output for the manipulated variable of an accelerator pedal to a large value, when the car speed is lower, as for the constitution where the energy in the brake application of a vehicle is recovered and utilized on start or in acceleration. CONSTITUTION:A brake energy regenerating device mounted on a vehicle such as a city bus is equipped with a hydraulic pump/motor 40 connected with the driving system member of the vehicle through a clutch, and is pump-operated in brake application, and accumulates the brake energy in an accumulator 20, while on start/acceleration, the motor is operated, and the accumulated hydraulic energy is utilized as the start/acceleration energy. In this case, a car speed sensor, engine revolution speed sensor, and an accelerator opening degree sensor are provided. If the car speed or the number of engine revolution is lower on the start in an ECU, the motor torque output for the manipulated variable of an accelerator pedal is controlled to a large value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation type braking energy regenerator that utilizes the braking energy of a vehicle as starting / accelerating energy using hydraulic oil as an energy transmission medium.

[0002]

2. Description of the Related Art Conventionally, a braking energy regenerator, which is mounted on a vehicle such as a city bus, collects energy at the time of braking and utilizes it at the time of starting or accelerating, for example, Japanese Patent Publication No. 5-11.
No. 68 publication. This braking energy regeneration device operates a pump / motor as a pump when the vehicle is being braked, pumps hydraulic oil in a low-pressure tank to an accumulator, and stores braking energy therein. When the vehicle starts or accelerates (these are also simply referred to as start / acceleration), the high-pressure hydraulic oil of the accumulator is supplied to the pump / motor to operate the pump / motor as a motor to drive the vehicle drive wheels. Is driven by a pump / motor, which reuses the braking energy.

The adjustment of the output torque of the motor at the time of starting / accelerating the vehicle equipped with the braking energy regenerating device is as follows.
Although the accelerator pedal, which is an output control device for the engine, is shared, the output torque of the engine is limited while the motor is operating, such as when starting / accelerating, while the output of the motor is changed according to the accelerator pedal operation amount. The torque is adjusted, and the output torque of the motor is set to increase in response to an increase in the operation amount of the accelerator pedal.

[0004]

As in the conventional case, when the motor operation amount of the pump / motor is simply set by the operation amount of the accelerator pedal regardless of whether the vehicle is starting or accelerating, as in the case of high speed acceleration, Even when a very large drive torque is not required, operating the accelerator pedal will generate a motor output torque that is similar to that at start-up, and an excessive drive torque exceeding the amount required for acceleration will be applied to the drive wheels. Will be supplied to.

A vehicle equipped with an engine having a large displacement, such as the above-mentioned city bus, emits a large amount of black smoke when operating at a low vehicle speed (low engine speed) such as at the time of starting acceleration and under high load. Since there is a possibility that it will occur, the pump / motor is operated to drive the motor and the regenerated energy is used as the driving force to reduce the engine load at low vehicle speeds, mainly for the purpose of reducing this black smoke during start-up acceleration. Is desirable.

Further, when the motor output torque of the pump / motor is large, the amount of hydraulic oil discharged per rotation increases, and when the vehicle speed is high and the pump / motor is rotating at high speed, such as during acceleration, Since the amount of discharge increases in proportion to the number of revolutions, the higher the speed, the larger the amount of hydraulic oil stored in the accumulator, and the more regenerative energy required during high-speed acceleration. Originally, the amount of regenerative energy allocated at the time of starting to be most desired may decrease, and the regenerative energy accumulated for effective use is wasted.

Therefore, the present invention suppresses the generation of black smoke when the vehicle speed or engine speed is low, such as when the vehicle starts.
It is an object of the present invention to provide a braking energy regeneration device that effectively utilizes regenerated energy.

[0008]

In order to achieve the above-mentioned object, the braking energy regenerating device of the present invention is provided in a pipe line between a low pressure tank for storing hydraulic oil and an accumulator for accumulating hydraulic energy. , A hydraulic pump / motor connected to a vehicle drive system member via a clutch is operated during braking, the braking energy is converted into hydraulic energy and accumulated in the accumulator, while the motor is operated during start / acceleration. In a braking energy regenerative device that utilizes hydraulic energy accumulated in an accumulator as start / acceleration energy, vehicle speed detecting means for detecting vehicle speed, engine speed detecting means for detecting engine speed, and operation amount of accelerator pedal are detected. And an accelerator operation amount detecting means for controlling the motor torque of the hydraulic pump / motor at the time of starting / accelerating. The control means is configured to largely control the output of the motor torque with respect to the operation amount of the accelerator pedal when the vehicle speed or the engine speed is low compared to when the vehicle speed or engine speed is high. .

[0009]

When the vehicle speed or the engine speed is low, such as when the vehicle starts, the output torque of the motor with respect to the operation amount of the accelerator pedal becomes large, and the regenerative energy is effectively used.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The energy regeneration device shown in FIGS. 1, 2 and 3 includes a transmission 3 having a plurality of selectable shift speeds,
Engine 1 for driving drive wheels via clutch 2
Applied to a vehicle equipped with a piston type accumulator 2
0, a low pressure hydraulic oil tank 30, a swash plate type variable displacement piston type pump / motor 40, a gear box 50, a control unit 60 (hereinafter referred to as an ECU), and the like.

First, the structure of the vehicle to which the energy regeneration device is applied will be described. The output shaft of the engine 1 is connected to the transmission 3 via the clutch 2, and the output shaft 13 of the transmission 3 is the rear wheel drive shaft 10. It is connected to a differential device (through shaft type). The energy regeneration device is connected to the above-described differential device via the drive shaft 12.

The accumulator 20 is connected to the first port 40a of the swash plate type variable displacement piston type pump / motor 40 through the high pressure oil pipe line P1.
The second port 40b of 0 is connected to the hydraulic oil tank 30 via the low pressure oil pipe P2. Accumulator 20
Is divided into a gas chamber 22 and a hydraulic oil chamber 23 by a piston 21, and the gas chamber 22 is filled with nitrogen gas at a predetermined pressure.
Hydraulic pressure can be stored in the hydraulic oil chamber 23.

An accumulator 20 is installed in the high pressure oil line P1.
A shutoff valve 24 and an unload valve (normally open) 25 are arranged in this order from the side. The shutoff valve 24 is an electromagnetic pilot operated valve and normally functions as a check valve that allows the flow of the hydraulic oil from the pump / motor 40 to the accumulator 20 and blocks the flow in the opposite direction.
When the shutoff valve signal D2 from 60 is input, the flow of hydraulic oil from the accumulator 20 side to the pump / motor 40 side is allowed. The electromagnetic unload valve 25 is operated by the unload valve signal D3 from the ECU 60, short-circuits the high-pressure oil pipeline P1 and the low-pressure oil pipeline P2 via the pipeline P4, and the residual pressure trapped in the high-pressure oil pipeline P1. Can be released to the low-pressure oil pipe line P2.

Between the high pressure oil line P1 and the low pressure oil line P2,
A check valve 46 is provided, and the check valve 46 has a low-pressure oil line P.
The hydraulic oil can flow into the high-pressure oil pipeline P1 from 2 to prevent damage to the device or the like caused by running out of hydraulic oil in the high-pressure oil pipeline P1. Further, the high pressure oil pipe P1 on the pump / motor 40 side from the shutoff valve 24 is branched to connect the pipe P3 to the hydraulic oil tank 30, and the discharge pressure of the pump / motor 40 is set to this pipe P3 by the set pressure ( For example, 3
A relief valve 26 is provided for releasing high-pressure oil to the hydraulic oil tank 30 when the pressure exceeds 50 kgf / cm ² ).

The high-pressure oil line P1 is provided with a discharge pressure sensor 89 for knowing the pipe pressure on the pump / motor 40 side from the shutoff valve 24, and supplies a discharge pressure signal PHY to the ECU. When the piston 21 moves to a predetermined position (referred to as the immediately preceding position) slightly before the maximum expansion position of the hydraulic oil chamber 23 due to the expansion of the nitrogen gas, the accumulator 20 detects this and detects the piston position signal (OFF signal). LP
Is provided, and a pressure accumulation sensor 88 that detects the hydraulic pressure in the hydraulic oil chamber 23 and outputs a pressure accumulation signal PAC is provided.
The P and the pressure accumulation signal PAC are supplied to the ECU 60.

The pump / motor 40 includes a gearbox 50.
The driving shaft 12 is connected to the drive shaft 12 via the gearbox 50.
Is transmitted to the pump / motor 40 via the
The start / acceleration energy of the motor 40 is
Is transmitted to the drive shaft 10 via the drive shaft 12 and the differential device. The gear box 50 is composed of a pair of gears 50a and a dog clutch 51. The pair of gears 50a accelerates the rotation of the drive shaft 12 at a constant gear ratio, and the pump / motor 4
Transmit to 0. The connection between the drive shaft 12 and the pump / motor 40 is connected / disconnected by the dog clutch 51.

The pump / motor 40 has a gearbox 50.
Drive shaft 40e connected to the output shaft of the piston, a piston cylinder 40f that rotates integrally with the drive shaft 40e, a piston 40c fitted in the cylinder 40f, and a swash plate that reciprocates the piston 40c as the drive shaft 40e rotates. 40d, and the pump / motor capacity thereof is set by controlling the angle of the swash plate 40d with respect to the drive shaft 40e, that is, the tilt angle.

The tilt angle of the swash plate 40d depends on the tilt cylinder 41.
Variably controlled by. The tilt cylinder 41 includes a piston 41a connected to a swash plate 40d and a piston 41a.
Chambers 41b and 41 formed on both sides of 1a, respectively.
c, and when one chamber, for example, the chamber 41b, is supplied with a pilot oil pressure from a pilot oil pressure source 43 described later, the swash plate 40d is driven to the pump operating side, and the other chamber 41c is supplied with the pilot oil pressure. And it is designed to be driven to the motor operating side.

The pilot hydraulic pressure source 43 is composed of an oil pump driven by an electric motor or the like and a pressure regulating valve, and generates a pilot hydraulic pressure of a predetermined pressure. A filter 45, an electromagnetic two-port switching valve 44, and a proportional solenoid valve 42 are arranged in this order between the hydraulic power source 43 and the tilt cylinder 41.
These are the pilot hydraulic power source 43 and the tilt cylinder 41.
A pilot hydraulic pressure control circuit for controlling the supply pressure of the pilot hydraulic pressure to the pump is configured. The switching valve 44 is an ECU
The drive signal D1 from the pilot oil passage P5
To connect and disconnect.

When the control signal ELP is supplied to one solenoid of the proportional solenoid valve 42, for example, the solenoid 42a, a pilot hydraulic pressure having a magnitude corresponding to the signal value ELP is supplied to the pump operating side of the tilt cylinder 41 via the proportional solenoid valve 42. When the control signal ELM is supplied to the chamber 41b and the other solenoid 42b is supplied, a pilot hydraulic pressure having a magnitude corresponding to the signal value ELM is supplied to the chamber 41c on the motor operating side.
As a result, the operating position of the piston 41a of the tilt cylinder 41, and by extension, the tilt angle of the swash plate 40d, is variably controlled, and when the pump is operating, the discharge amount is adjusted and when the motor is operating. In that case, the output torque is adjusted.

When the pump of the pump / motor 40 is operating,
The swash plate 40d is driven to the pump operating side by the tilting cylinder 41, and the working oil flows from the working oil tank 30 to the filter 3
8, the check valve 58, the pipe line P2, the pump / motor 40, and the pipe line P1 to the accumulator 20, and when the motor is operating, the swash plate 40d is driven to the motor operating side, and the hydraulic oil is different from that when the pump is operating. In the opposite direction, from accumulator 20 to line P1, pump / motor 40, line P2, check valve 57,
It flows to the hydraulic oil tank 30 via the filter 37.

The hydraulic oil tank 30 is connected to the pressurized air tank 31 via the electromagnetic 2-port switching valve 33, the pressure reducing valve 35, and the air dryer 36, and the electromagnetic 3-port switching valve 34.
Are connected to the sub air tank 32 via the, and these constitute an air pressure supply circuit to the hydraulic oil tank 30. The switching valve 34 is operated by the drive signal D7 from the ECU 60, and the sub air tank 32 and the hydraulic oil tank 30 are operated.
It can be switched to a position that allows communication with. Sub air tank 3
By communicating 2 with the hydraulic oil tank 30, the sub air tank 32 supplies a part of the reserved air to the hydraulic oil tank 30, and also according to the fluctuation of the hydraulic oil amount in the hydraulic oil tank 30. The air pressure in the hydraulic oil tank 30 is stabilized by supplying or absorbing air. On the other hand, ECU
When the drive signal D7 from 60 is cut off, the switching valve 34
It switches to the atmosphere release position, and the pressure in the hydraulic oil tank 30 is released to the atmosphere.

The switching valve 33 is operated by a drive signal D6 from the ECU 60, supplies the high-pressure air in the air tank 31 into the hydraulic oil tank 30, and pressurizes the hydraulic oil in the tank 30 to a predetermined pressure, thereby pumping. / Keep the operation of the motor 40 in a stable state. The hydraulic oil leaking from the pump / motor 40, the fitting portion (oil seal) in the hydraulic path, and the like flows back to the drain tank 39. The drain tank 39 is connected to the hydraulic oil tank 30 via a pump 59, a filter 97, and an electromagnetic two-port switching valve 98. When the hydraulic oil in the drain tank 39 reaches a predetermined amount, the pump 59 is operated. , The ECU 60 outputs a drive signal to the switching valve 98, opens the drive signal, and supplies the insufficient operating oil to the operating oil tank 3
Add to 0.

The hydraulic oil tank 30 is provided with a hydraulic oil level sensor 90 and an oil temperature sensor 91, which supply a hydraulic oil level signal LOIL and an oil temperature signal TOIL to the ECU 60, respectively. The ECU 60 uses these signals to
By monitoring whether or not the hydraulic oil is in a normal state and regulating the operation of the regenerative device, damage to the pump / motor 40 and other devices is prevented.

The dog clutch 51 described above is connected and disconnected by air pressure, and the dog clutch 51 is connected to the air tank 52 via an electromagnetic 3-port switching valve 53 for connecting the clutch and an electromagnetic 3-port switching valve 54 for disconnecting the clutch. Are connected, and these constitute a dog clutch operation control circuit. The switching valve 53 for connecting the clutch is the ECU 6
When activated by the drive signal D8 from 0, the air tank 5
The high pressure air of 2 is supplied to the dog clutch 51, and the dog clutch 51 is engaged. On the other hand, when the clutch disconnection switching valve 54 is actuated by the drive signal D9 from the ECU 60, the dog clutch 51 is disengaged.

The dog clutch 51 is provided with a dog clutch connection / disconnection sensor 92, which detects the connection / disconnection state of the dog clutch 51 and supplies a detection signal DCL to the ECU 60. The pump / motor side output shaft of the dog clutch 51 is provided with a rotation speed sensor 93 for detecting the rotation speed of the pump / motor 40, and supplies a pump rotation speed signal NP to the ECU 60.

The brake power unit 70 connected to a brake pedal (not shown) is for controlling the braking force of the driving wheel WR and the driven wheel WF, and brakes the wheel cylinder (not shown) of each wheel. Supplying air pressure. A brake pressure PBK generated according to the amount of depression of a brake pedal (not shown) is detected by a sensor (not shown), and a brake pressure detection signal PBK is sent to the ECU 60.
Is being supplied. The ECU 60 compares the magnitudes of the discharge pressure PHY and the brake pressure PBK of the pump / motor 40, which are detected by the discharge pressure sensor 89 described above, with their respective predetermined values, thereby accumulating brake by the pump operation of the pump / motor 40. And normal service brake operation switching control.

The engine 1 is provided with a fuel injection device 5, and the governor control unit 67 connected to the fuel injection device 5 performs normal fuel injection control, and at the same time, a rack limit signal R from the ECU 60 described later. Fuel injection limitation (rack limitation). The fuel injection limit (rack limit) is set on the engine side so that the sum of the output by the motor operation of the pump / motor 40 and the output by the engine 1 does not exceed the output corresponding to the maximum drive torque by the normal engine 1 alone. As will be described later in detail, the control is performed to limit the fuel injection amount according to the accumulated pressure amount in the accumulator 20. Further, the governor control unit 67 includes an engine speed sensor 67a as an engine speed detecting means, detects the engine speed NE, and supplies the engine speed signal NE to the ECU 60.

The transmission 3 has a vehicle speed sensor 8
3, T / M reverse sensor 84, T / M neutral sensor 85, and select position sensor 8 for detecting the gear position
6 are provided to supply the vehicle speed signal V, the T / M reverse signal TMR, the T / M neutral signal TMN and the select position signal LTM to the ECU 60, respectively. FIG. 3 shows the configuration of the ECU 60 that controls the operation of the energy regeneration device, and the ECU 60 includes a processor, a memory, an input / output circuit, and the like. On the input side of the ECU 60, a main SW 6 that supplies an ON / OFF state signal of the power source
4, an accelerator opening sensor 61 that works in conjunction with an accelerator pedal (not shown) to detect the amount of depression of the accelerator pedal,
Two clutch sensors (CL1) 6 which are interlocked with a clutch pedal (not shown) and detect engine clutch engagement / disengagement.
2, (CL2) 63, and various sensors including the brake pressure sensor described above are connected. Here, the engine clutch engagement / disengagement sensor (CL1) 62 supplies a signal at the return limit (clutch connection) of the clutch pedal (not shown) to turn on the O signal.
The engine clutch engagement / disengagement sensor (CL2) 63 is set to be ON by supplying a signal when the clutch pedal (not shown) is depressed (clutch disengagement). The half-clutch state can be detected by a combination of the sensor (CL1) 62 and the sensor (CL2) 63.

On the other hand, the above-mentioned various electromagnetic switching valves and various indicators are connected to the output side of the ECU 60. The indicators include the piston position signal LP from the piston sensor 87 of the accumulator and the pressure accumulation sensor 88.
A pressure accumulation indicator 66 that indicates the amount of pressure accumulated by the pressure accumulation signal PAC from the CPU and a regeneration lamp 68 that indicates that the energy regeneration device is operating by a dog clutch engagement / disconnection signal DCL from a dog clutch engagement / disengagement sensor 92, and an error is generated by various error signals. Displayed 6
There is 9.

The pump control and motor control of the braking energy regenerating device constructed as described above will be described below with reference to the flow charts shown in FIGS. 4 to 11. Figure 4,
5 and 6 show a control procedure of pump control during braking, which is executed by the ECU 60. First, the ECU 60 turns on the dog clutch 51 by the dog clutch connection / disconnection signal DCL from the dog clutch connection / disconnection sensor 92 in step S10.
It is determined whether (connection) or OFF (disconnection). The dog clutch 51 is used when the vehicle is in a predetermined operating state (for example, when the vehicle speed is 5
When the vehicle is traveling at a selected position other than the reverse gear (km / h or less), the drive signal D8 is supplied from the ECU 60 to the clutch connecting switching valve 53 to turn it on (connect).
Therefore, at a predetermined vehicle speed (for example, 60 km / h) or more, in order to prevent the allowable capacity of the pump / motor 40 from being exceeded, the disconnection switching valve 54 is supplied with the drive signal D9 and is turned off (disconnected).
Becomes When the dog clutch 51 is brought into the connected state, the pump / motor 40 operates so that the drive shafts 10, 12 and the gear box 50 are connected.
It is driven by the drive wheel WR via.

If the determination result of step S10 is OFF (disconnection), the process proceeds to step S20 of FIG. ECU60
Sets the tilt angle control signal value ELP to the proportional solenoid valve 42 to zero (ELP = 0) in step S20. As a result, the pilot oil pressure from the pilot oil pressure source 43 is held in a cutoff state, and the piston 41a of the tilt angle cylinder 41 is also held in the neutral position. Then, by keeping the tilt angle of the swash plate 40d of the pump / motor 40 at zero, the pump / motor 40 does not function as a pump. Next, in step S21, the drive signal D1 to the switching valve 44 is kept turned off and is set to O.
The FF (closed) state is maintained, and in step S22, the unload valve signal D3 is not output to the unload valve (normally open) 25, and it is turned OFF (open) to set the high pressure oil line P1 and the low pressure oil line P1. It is kept in communication with P2. In step S23, the ECU 60 sets a value 0 (f1 = 0) to the flag f1 which is a program control variable,
As a result, it is stored that the pump control is not executed.

Returning to step S10 in FIG. 4, if the determination result in this step is the ON (connection) state, the process proceeds to step S11. In step S11, the ECU 60 determines from the T / M reverse signal TMR whether or not the selected position of the transmission 3 is the reverse gear stage (reverse position), and the determination result is YES (reverse), that is, the vehicle reverse gear stage. If it is the position, step S20 of FIG. 6 described above.
Execute the following and do not perform pump control. On the other hand, if the determination result is NO, that is, the vehicle forward gear position, step S1
Execute 2.

In step S12, the ECU 60 determines whether or not the vehicle is stopped. This determination is based on the vehicle speed V
Is below a predetermined value XV0 (for example, 1 km / h) by the vehicle speed signal V. If V ≦ XV0 (1 km / h), pump control is not executed. On the other hand, the determination result is V> XV0 (1km
/ h), execute step S13. Step S1
In 3, the ECU 60 determines whether or not the brake pressure PBK is generated by the driver stepping on the brake pedal (not shown).
Judging by BK, PBK <XPB (for example, 0.2 kgf / cm
^{In case of 2} ), it is considered that the brake pedal (not shown) is not depressed and the pump control is not executed. On the other hand, if the determination result is PBK ≧ XPB (0.2 kgf / cm ² ), it is determined that all the operating conditions for regenerating energy are satisfied,
Step S14 is executed.

In step S14, the ECU 60 controls the tilt angle control signal value ELP of the swash plate 40d of the pump / motor 40.
Execute the subroutine that sets. As a method of setting the ELP value, for example, as shown in FIG.
A reference value corresponding to BK is calculated, and this reference value is used as the oil temperature TOIL detected by the oil temperature sensor 91 of the hydraulic oil tank,
Vehicle speed V detected by vehicle speed sensor 83, accumulator 2
It is corrected by the accumulated pressure amount PAC of 0 or the like and set to an appropriate value.

In step S15, the ECU 60 outputs a control signal corresponding to the ELP value set as described above to the proportional solenoid valve 42, and sets the tilt angle of the pump / motor 40 to the angle corresponding to the signal value ELP. Set. Next, in step S16, the drive signal D1 is output to the switching valve 44,
This is turned on (open), and pilot hydraulic pressure is supplied to the tilt angle cylinder 41. Further, in step S17, the unload valve (normally open) 25 between the low-pressure oil pipeline P2 and the high-pressure oil pipeline P1 is turned on by the unload valve signal D3.
(Closed), and the pressure in the high-pressure oil pipeline P1 is cut off so as not to escape to the low-pressure oil pipeline P2. Further, in step S18, the flag f is stored to store that the pump is operating.
Set the value 1 to 1.

In this way, when the tilt angle of the pump / motor 40 is set to the angle corresponding to the control signal value ELP to the proportional solenoid valve 42, the pump / motor 40 operates as a pump and the hydraulic oil tank The hydraulic oil of 30 is sucked and pushed into the hydraulic oil chamber 23 of the accumulator 20 to accumulate pressure. In the above pump control, the tilt angle of the pump / motor 40 is set according to the amount of brake pedal depression by the driver, and the pump / motor 40 performs work according to the amount of brake pedal depression and performs braking. Energy will be recovered.

7 to 10 show a control procedure of motor control at the time of starting and accelerating (starting / accelerating). First, E
Before starting the motor operation, the CU 60 determines whether or not the motor control may be executed in steps S30 to S40. In step S30, it is determined whether or not the driver intends to start the vehicle based on whether or not the brake pressure PBK is smaller than a predetermined value XPB (for example, 0.2 kgf / cm ² ). If the determination result of step S30 is PBK ≧ XPB (0.2 kgf / cm ² ), step S50 and subsequent steps of FIG. 10 described later are executed and motor control is not performed. On the other hand, the discrimination result is PBK <XPB (0.2 kgf / cm
^{If 2} ), the process proceeds to step S31.

In step S31, the ECU 60 determines whether or not pump control is in progress, based on whether the flag f1 indicating that pump control is in progress is 1 (YES) or 0 (NO). When the flag f1 is 1 (YES),
That is, during pump control, step S50 and subsequent steps in FIG. 10 described later are executed and motor control is not performed. On the other hand, when the flag f1 is 0 (NO), that is, when the pump control is not in progress, the process proceeds to step S32.

In step S32, the ECU 60 determines whether the dog clutch engagement / disengagement sensor 92 is ON (connected) or OFF (disengaged) based on the dog clutch engagement / disengagement signal DCL, and O
If it is FF (cut), motor control is not executed. on the other hand,
If the determination result is ON (connection), the process proceeds to step S33. In step S33, the ECU 60 determines from the T / M reverse signal TMR whether or not the selected position of the transmission 3 is the reverse gear stage (reverse position), and the determination result is YES (reverse), that is, the vehicle reverse gear stage. If the position is set, motor control is not executed. On the other hand, if the determination result is NO, that is, the vehicle forward gear position, step S
Proceed to 34.

In step S34, the ECU 60 determines whether or not the selected position of the transmission 3 is neutral by the T / M neutral signal TMN.
If the determination result is YES (neutral), that is, if the select position is neutral, it is determined that the driver has no intention of starting the vehicle, and motor control is not performed. On the other hand, when the determination result is NO, the process proceeds to step S35.

In step S35, the ECU 60 determines whether the clutch 2 is in the engaged state or the disengaged state by the clutch engagement / disengagement signal CL2 of the clutch engagement / disengagement sensor (CL2) 63. If the clutch 2 is in the disengaged state, the selected position of the transmission 3 is selected. The motor control is not performed as in the case where is neutral. On the other hand, in the connected state (including the half-clutch state), the process proceeds to step S36 in FIG.

In step S36, the ECU 60 determines whether the accumulator 20 is filled with hydraulic oil.
It is determined by the piston position signal LP from the piston position sensor 87. When the piston position sensor 87 set to the immediately preceding position of the piston 21 is 0FF, that is, when the hydraulic oil is empty, it means that the hydraulic oil is not accumulated in the accumulator 20. In such a case, the motor control is executed. do not do. On the other hand, the piston position sensor 87 is ON
That is, when the accumulator 20 is filled with hydraulic oil, the process proceeds to step S37.

In step S37, the ECU 60 determines from the vehicle speed signal V whether the vehicle speed V is equal to or lower than a predetermined value XV2 (for example, 65 km / h), and if it is higher than the predetermined value XV2 (65 km / h). In order to prevent the pump / motor 40 from being damaged beyond the allowable capacity, no motor control is performed. On the other hand, if it is less than or equal to the predetermined value XV2 (65 km / h), the process proceeds to step S38.

In step S38, the ECU 60 sets the vehicle speed V to the predetermined value XV1 (for example, 5 km) as in step S37.
/ h), if it is smaller than the XV1 value, step S3
9, the clutch connection / disconnection sensor (CL1) 6 is used to determine whether the clutch 2 is completely engaged or in the half-clutch state.
It is determined by the clutch connection / disconnection signal CL1 of 2. According to the determination in step S38, the vehicle speed V is a predetermined value XV1 (5 km / h)
If it is determined that the clutch 2 is completely engaged even though it is smaller, it is determined that there is some abnormality in the clutch sensors 62, 63, the vehicle speed sensor 83, etc. Motor control is not performed. On the other hand, when the clutch connection / disconnection signal CL1 indicates the OFF state, the clutch 2 is combined with the determination result of step S35 described above.
Means that it is in a half-clutch state, and in such a case, the process proceeds to step S40.

In step S40, the ECU 60 determines from the accelerator opening signal L Aθ whether or not the accelerator opening L Aθ is larger than the motor start opening determination value Xθ1. The above-mentioned discriminant value Xθ1 is set according to the vehicle speed V,
FIG. 13 shows the vehicle speed V and the discriminant value X set by the vehicle speed V.
It shows the relationship with θ1. When the accelerator opening L Aθ is smaller than the discriminant value Xθ1 (L Aθ <Xθ1), it is determined that the vehicle should not be accelerated by the regenerative energy, and the motor is not operated. If the motor control is executed when the load is such that the accelerator opening LAθ is equal to or smaller than the determination value Xθ1, it becomes necessary to greatly reduce the engine output. But,
If the engine output is reduced too much, the fuel consumption characteristics of the engine will deteriorate, which is rather undesirable. On the other hand, if it is larger than the discriminant value Xθ1 (L Aθ ≧ Xθ1), step S4
The process proceeds to 1 to start the motor control.

When the motor control is not executed, the ECU
60 is the proportional solenoid valve 4 in step S50 of FIG.
The tilt angle control signal value ELM for 2 is set to zero (ELM = 0) and is output. As a result, the tilt angle cylinder 4
The first piston 41a is held in the neutral position, the tilt angle of the swash plate 40d of the pump / motor 40 becomes zero, and the pump / motor 40 does not function as a motor. In step S51, the piston 41 of the tilt angle cylinder 41 is
Switching valve 44 for controlling supply / discharge of pilot oil for driving a
Is turned OFF (closed) by cutting off the drive signal D1. In step S52, the shutoff valve 24 that is ON (open) when the motor is operating is turned OFF (closed) by shutting off the shutoff valve signal D2, and the flow of hydraulic oil from the accumulator 20 to the pump / motor 40 is stopped. In step S53, the unload valve (normally open) 25 arranged between the low pressure oil pipeline P2 and the high pressure oil pipeline P1 is turned off (open) by stopping the output of the unload valve signal D3, and the high pressure oil pipeline P1. And low pressure oil line P
Connect two. In step S54, a rack limit signal R, which will be described later, transmitted to the engine 1 when the motor is operating is cut off and turned OFF. Further, in step S55, the rack limit valid signal RE similarly transmitted is cut off.
Let it be F.

On the other hand, when the motor control is started by executing step S41, the ECU 60 controls the pump / motor 4
The tilt angle control signal value ELM of the swash plate 40d of 0 is set by executing the subroutine shown in FIG. EL
As a method of setting the M value, first, in step S70, the ELM reference value is set according to the accelerator opening L Aθ and the vehicle speed V (the engine speed NE may be used instead of the vehicle speed V). FIG. 14 shows an ELM map stored in the storage device of the ECU 60, and the ECU 60 reads out the ELM reference value corresponding to the vehicle speed V and the accelerator opening L Aθ from this map.

The relationship between the operation control of the pump / motor 40 and the operation control of the engine 1 during motor control will now be described. When the amount of accumulated pressure in the accumulator 20 is sufficient (for example, the pressure in the accumulator 20 is 350 kg).
In the case of f / cm ² or more), the engine 1 is controlled along the operating line where the engine 1 obtains the best fuel consumption characteristic. Figure 1
5 shows an equal fuel consumption curve of the engine 1, and shows that the best fuel consumption characteristic can be obtained by controlling the operation of the engine 1 along the operation line shown by the broken line in the figure. Therefore, as described in steps S46 and 47 to be described later, a rack limit signal is supplied to the engine 1 and the fuel injection amount is narrowed down to the axial torque at which substantially the best fuel consumption is obtained. On the other hand, pump / motor 40
Is controlled so as to generate an output that complements the above-mentioned engine-side output.

The ELM map shown in FIG. 14 is set on the basis of the second speed stage because the normal start / acceleration is often performed at the second speed stage of the transmission 3. When the detected accelerator opening L Aθ is a value within the region surrounded by the solid line in FIG. 14 and a constant accelerator opening 100% line, the maximum XM2 value as the ELM reference value (for example, 700 mA). ) Is set. In the area where the maximum value XM2 is set as the ELM reference value, the sum of the engine 1 side output and the pump / motor 40 side output described above is the second value.
The output is substantially equal to the output obtained at the maximum torque of the engine 1 when only the engine 1 is operated and the pump / motor 40 is not operated in the speed stage.

On the other hand, in the region where the detected accelerator opening L Aθ is smaller than the accelerator opening indicated by the broken line in FIG. 14, the ELM reference value is set to 0. In the region where the accelerator opening is small, the pump / motor 40 is not operated as a motor. If the ELM reference value is set to be smaller than the minimum value XM0 set corresponding to the broken line, the output required by the driver (the output corresponding to the detected accelerator opening L Aθ) cannot be obtained, which causes inconvenience. The accelerator opening value indicated by the broken line in FIG. 14 corresponds to the accelerator opening determination value Xθ1 set in FIG.

When the detected accelerator opening L Aθ is the accelerator opening indicated by the one-dot chain line in FIG. 14, the ELM reference value is set to the XM1 value, and the detected accelerator opening L Aθ is set.
Is an intermediate value between the accelerator opening values corresponding to the XM2 value and the XM1 value in FIG. 14, or an intermediate value between the accelerator opening values corresponding to the XM1 value and the minimum value XM0, respectively. , The ELM value is calculated by a known interpolation method.

As described above, by setting the ELM reference value according to the accelerator opening L Aθ, the output required by the driver is obtained from the pump / motor 40, and at the same accelerator opening L Aθ Even so, the ELM reference value set when the vehicle speed V is high is set higher than the ELM reference value set when the vehicle speed V is high,
The effective use of regenerative energy during low-speed acceleration such as when starting the vehicle prevents the generation of black smoke.

In the above embodiment, step S7 in FIG.
At 0, the ELM reference value is the vehicle speed V and the accelerator opening L.
Although it is set by Aθ, it can be set by the engine speed NE and the accelerator opening L Aθ instead of the vehicle speed V. FIG. 18 shows a map for obtaining the ELM reference value from the engine speed NE and the accelerator opening L Aθ, and the map shows the engine speed from the lower one as indicated by the broken line, the alternate long and short dash line, and the solid line. Constant line XN0 (for example, 600 rpm), XN1 (for example, 800 rpm),
XN2 (for example, 1300 rpm) is set, and the ELM reference value can be read from this map by a known interpolation method according to the detected engine speed NE and the accelerator opening L Aθ.

The characteristics of the black smoke at the initial stage of starting / acceleration are better represented by the engine speed parameter than the vehicle speed parameter, and black smoke is easily generated at a low engine speed. It is possible to take measures against black smoke with a finer grain by obtaining it as a variable of the engine speed NE.
In addition, the optimum ELM reference value can be read from one map regardless of the established gear position,
Compared with the case where the ELM reference value is set from the vehicle speed V and the accelerator opening L Aθ, there is an advantage that no complicated adjustment for performance matching is required.

Further, if such a map is prepared for each model of the transmission 3 mounted on the vehicle (different in the number of gears and the gear ratio) and stored in the storage device of the ECU 60, the engine speed The gear ratio is calculated from NE and the vehicle speed V, and the model of the transmission 3 installed can be identified from the calculated gear ratio. A map corresponding to the identified model of the transmission 3 is selected,
It is also possible to obtain the ELM reference value by the method described above.

Next, in step S71, a correction coefficient K2 corresponding to the oil temperature TOIL of the hydraulic oil tank 30 detected by the oil temperature sensor 91 is obtained, and this is multiplied by the ELM reference value to obtain the optimum tilt angle. The control signal ELM value (= ELM reference value × K2) is calculated. FIG. 16 shows the relationship between the oil temperature TOIL and the correction coefficient K2. The oil temperature TOI of the hydraulic oil tank 30 is shown in FIG.
The correction by L is that the oil temperature TOIL is XTOIL (eg 70
C)) does not require ELM value correction, but oil temperature T
When the OIL is 70 ° C. or higher, the tilt angle control signal value ELM is corrected so as to decrease. When the temperature is high, the viscosity of the hydraulic oil is reduced, and the pump / motor 40 may be burnt. Therefore, this is prevented by reducing the motor capacity.

In step S72, the ECU 60 controls the tilt angle control signal value EL for each gear of the transmission 3.
The maximum value of M (ELMmax) is calculated, and the pump / motor 4
Limit output torque due to zero motor operation. When the braking energy is regenerated through the speed reducer (gear box) 50 different from the transmission 3, as described above, the sum of the output of the motor operation of the pump / motor 40 and the output of the engine 1 side is a normal value. It is required that the output value corresponding to the maximum drive torque (normally maximum drive torque) by the engine 1 alone is not exceeded. Since the ELM reference value set based on FIG. 14 is set based on the second speed, the gears on the higher speed side than the second speed depend on the motor operation of the pump / motor 40. A limit value is set for the output torque for each shift speed so that the drive torque does not exceed the maximum allowable torque value.

More specifically, the maximum value ELMmax is
XELM1 value (eg 700m at the 1st and 2nd speed)
A), XELM2 value (eg, 500 mA) at the 3rd speed
At the 4th and 5th speed, the XELM3 value (for example, 400
mA) respectively. Thus the maximum value EL
Mmax is set to a value that limits the output torque of the pump / motor 40 as the speed increases. It should be noted that the established shift speed of the transmission 3 may be detected by the select position sensor 86 as in the embodiment.
It may be estimated from the gear ratio calculated from the engine speed NE and the vehicle speed V.

In step S73, the ECU 60, in steps S70 and S71, the tilt angle control signal value ELM calculated according to the accelerator opening L Aθ, the vehicle speed V (or engine speed NE) and the oil temperature TOIL, The maximum value ELMmax set in step S72 is compared, and when the comparison result is ELM ≧ ELMmax, the tilt angle control signal value ELM is set to the maximum value ELM in step S75.
Reset to max. The comparison result is ELM <ELMmax
When, the ELM value is not limited.

As described above, by limiting the ELM value to the maximum value ELMmax set for each shift speed, the output on the engine 1 side is maintained at a value at which the best fuel consumption characteristic is obtained, and the drive is performed at each shift speed. The torque transmitted to the system can be kept below the maximum torque allowed for it. Returning to the motor control flow, the ECU 60 returns to FIG.
In step S42, the control signal corresponding to the ELM value set as described above is output to the proportional solenoid valve 42, and in step S43, the drive signal D1 is output to turn the switching valve 44 ON (open), Pilot hydraulic pressure is supplied to the tilt angle cylinder 41 via the proportional solenoid valve 42. As a result, the swash plate 40d of the pump / motor 40 is set to a tilt angle corresponding to the ELM value. Next, in step S44, the shut-off valve signal D2 is output to the shut-off valve 26, and this is set to O
At the same time as setting to N (open), in step S45, the unload valve signal D3 is supplied to the unload valve (normally open) 25 to turn it ON (close) so that the pressure in the high pressure oil pipe P1 is low. Shut off to avoid running away. As a result, the pump / motor 40 is driven by the high pressure hydraulic oil accumulated in the accumulator, and its driving force is the drive shaft 40e, the gear box 50, and the drive shaft 1
It is transmitted to the drive wheels WR via 2 and 10 and covers a part of the driving force when starting or accelerating.

In step S46, the ECU 60 supplies a rack limit signal R for limiting the fuel supply of the fuel injection device 5 of the engine 1 to the fuel injection device 5 via the governor control unit 67. As described above, the rack limit signal R serves to limit the output torque on the engine 1 side during motor control, and the output limit amount on the engine 1 side is based on the engine speed NE and the accumulated pressure amount PAC of the accumulator 20. Will be decided.

FIG. 17 shows the relationship between the engine speed NE and the rack limit value R. If a sufficient amount of accumulated pressure (350 kgf / cm ² or more) is secured in the accumulator 20, the rack limit value R is shown. Is set to the value given by the solid line in FIG. 17, and the rack limit signal R set in this way is supplied to the fuel injection device 5, and the maximum fuel injection amount is restricted to a value corresponding to this rack limit value R. Then, the engine 1 is adjusted to a shaft torque that provides the best fuel economy characteristics.

On the other hand, when the pressure accumulation amount in the accumulator 20 is 350 kgf / cm ² or less as described above, when the motor of the pump / motor 40 is operating when a sufficient pressure accumulation amount (350 kgf / cm ² or more) is secured. Compared with the above, the output decreases, and the sum of the output of the engine 1 side and the output of the pump / motor 40 side becomes insufficient with respect to the output required by the driver. Such a shortage of output is relaxed by compensating for the rack limit of the engine 1. In this case, the rack limit value R is set to the value indicated by the solid line when the pressure accumulation amount is 350 kgf / cm ² or more, and to the value indicated by the broken line when the pressure accumulation amount is 200 kgf / cm ² or less. , when the pressure accumulation amount is a value between 350 kgf / cm ² and 200 kgf / cm ² is set by interpolation.

Then, in order to surely execute the output limitation on the engine 1 side supplied to the fuel injection device 5, the rack limitation effective signal RE is output to the governor control unit 67 in step S47, and an error due to noise or the like is generated. It prevents the operation. The present invention is not limited to the embodiment in which the engine 1 and the energy regeneration device are arranged with the through shaft type differential device interposed therebetween, and the energy regeneration device is connected to the PTO output shaft of the transmission 3. It can also be applied to things.

[0066]

As described above, according to the braking energy regeneration device of the present invention, the vehicle speed detecting means for detecting the vehicle speed, the engine speed detecting means for detecting the engine speed, and the operation amount of the accelerator pedal are calculated. An accelerator operation amount detecting means for detecting and a control means for controlling the motor torque of the hydraulic pump / motor at the time of starting / accelerating are provided, and the control means is provided when the vehicle speed or the engine speed is low compared to when the vehicle speed or engine speed is high. Since the output of the motor torque with respect to the operation amount of the accelerator pedal is largely controlled, when the vehicle speed or the engine speed is low, such as when the vehicle is starting, the motor output torque can be maximized and a large amount of regenerative energy can be used. On the other hand, as the vehicle speed or engine speed increases, the motor output torque can be reduced to limit the amount of regenerative energy used, It is possible to effectively utilize the energy pears can significantly suppress the generation of black smoke at the start.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a part of a braking energy regeneration device to which an embodiment of the present invention is applied and a vehicle equipped with the braking energy regeneration device.

FIG. 2 is a hydraulic circuit diagram showing a main configuration of a braking energy regeneration device of the present invention.

FIG. 3 is a block diagram showing a configuration of an electronic control unit (ECU) of the braking energy regeneration device of the present invention.

4 is a part of a flowchart of a pump control routine executed by the ECU 60 of FIG.

5 is a part of a flowchart of a pump control routine that follows the flowchart of FIG.

FIG. 6 is the rest of the flowchart of the pump control routine that follows the flowchart of FIG.

7 is a part of a flowchart of a motor control routine executed by the ECU 60 of FIG.

FIG. 8 is a part of a flowchart of a motor control routine following the flowchart of FIG.

9 is a part of a flowchart of a motor control routine that follows the flowchart of FIG.

10 is the rest of the flowchart of the motor control routine that follows the flowchart of FIG.

FIG. 11 is a flowchart of an ELM reference value setting subroutine during motor control according to the present invention.

FIG. 12 is a graph showing an example of a relationship between a brake pressure PBK during pump control of the braking energy regeneration device and an ELP reference value set accordingly.

FIG. 13 is a graph showing an example of a relationship between a vehicle speed V and a discriminant value Xθ1 (accelerator opening degree) during motor control of the braking energy regeneration device.

FIG. 14 is a graph showing an example of a relationship between a vehicle speed V, an accelerator opening degree, and a tilt angle control signal value ELM corresponding to the vehicle speed V during motor control of the braking energy regeneration device according to the present invention.

FIG. 15 is an isometric fuel consumption map showing the relationship between the shaft torque according to the engine speed and the fuel consumption characteristics of the engine.

FIG. 16 is a graph showing an example of the relationship of the correction coefficient K2 according to the hydraulic oil temperature TOIL during pump / motor control of the braking energy regeneration device.

FIG. 17 is a graph showing an example of a relationship between an engine speed NE, a pressure accumulation amount, and a fuel supply limit value (rack limit value) corresponding to the engine speed NE during motor control of the braking energy regeneration device.

FIG. 18 is a graph showing an example of a relationship between an engine speed NE, an accelerator opening degree, and a tilt angle control signal value ELM corresponding to the engine speed NE during motor control of the braking energy regeneration device according to the present invention.

[Explanation of symbols]

1 Engine 2 Clutch 3 Transmission 10 Rear Wheel Drive Shaft 20 Accumulator 30 Low Pressure Hydraulic Oil Tank 40 Swash Plate Type Variable Capacity Piston Pump / Motor 41 Tilt Cylinder 42 Proportional Solenoid Valve 43 Pilot Hydraulic Source 50 Gearbox 51 Dog Clutch 60 Control Unit (ECU) 61 accelerator opening sensor (accelerator operation amount detecting means) 67a engine speed sensor (engine speed detecting means) 83 vehicle speed sensor (vehicle speed detecting means)

Claims (1)

[Claims] 1. A braking system for a hydraulic pump / motor connected to an oil passage between a low-pressure tank for storing hydraulic oil and an accumulator for storing hydraulic energy and connected to a vehicle drive system member via a clutch. At the time of pumping, the braking energy is converted into hydraulic energy and stored in the accumulator, while at the time of starting / accelerating, the motor is operated to utilize the hydraulic energy stored in the accumulator as starting / accelerating energy. Vehicle speed detecting means for detecting a vehicle speed, engine speed detecting means for detecting an engine speed, accelerator operation amount detecting means for detecting an operation amount of an accelerator pedal, and motor torque of the hydraulic pump / motor during start / acceleration When the vehicle speed or the engine speed is high. The braking energy regeneration device is configured to largely control the output of the motor torque with respect to the operation amount of the accelerator pedal when the braking energy is lower than the above.