JP2885032B2 - 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 pressure-accumulation type braking energy regenerating apparatus that uses a vehicle's braking energy for starting / acceleration energy using hydraulic oil as an energy transmission medium.

[0002]

2. Description of the Related Art Conventionally, a braking energy regenerating apparatus which is mounted on a vehicle such as a city bus and collects energy at the time of braking and uses it at the time of starting or accelerating is disclosed in, for example, Japanese Patent Publication No. 5-11.
No. 68 is known. This braking energy regenerating device operates a pump / motor as a pump during vehicle braking, pumps hydraulic oil from a low-pressure tank to an accumulator, and stores braking energy therein. When the vehicle starts or accelerates (these operations 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 and drive wheels of the vehicle. Is driven by a pump / motor, thereby reusing the braking energy.

In such a braking energy regenerating apparatus, generally, a variable displacement pump / motor is used,
Switching of the pump / motor of the pump / motor and adjustment of the capacity (corresponding to the adjustment of the discharge amount in the case of the pump operation and the adjustment of the output torque in the case of the motor operation)
This is performed by changing the tilt angle of the swash plate in the motor.

In particular, when starting / acceleration is performed by operating a motor, a tilt angle of a swash plate of a pump / motor is set according to various operating conditions such as an accelerator pedal depression amount, a vehicle speed, and an engine speed. The required motor output torque (motor output) is obtained by changing the pump / motor capacity. The tilt angle of the swash plate of this pump / motor changes in conjunction with an actuator (tilt cylinder) connected to the swash plate, and the size of this actuator is in accordance with the supply amount of pilot oil from the pilot hydraulic pressure source. The pilot oil supply amount is set by a valve opening corresponding to the magnitude of the electric signal supplied to the proportional solenoid valve.

[0005]

At the time of switching from deceleration or low-speed running to acceleration or at the time of transmission shifting, the target value of the motor output is set according to, for example, the accelerator pedal depression amount as described above. If the pump / motor is operated at a stroke so as to obtain the set motor output target value, a sudden acceleration sensation may be felt depending on the accelerator pedal depression amount, and there is a problem that the traveling feeling becomes extremely poor.

Therefore, according to the present invention, when performing acceleration by motor operation during traveling, the feeling of acceleration (acceleration feeling) when the accelerator pedal is depressed is as smooth as that of a normal engine. It is an object of the present invention to provide a braking energy regenerating device that improves driving performance.

[0007]

In order to achieve the above-mentioned object, a braking energy regenerating device according to the present invention is provided in an oil passage between a low-pressure tank storing hydraulic oil and an accumulator storing hydraulic energy. A hydraulic pump / motor, which is connected to a drive system member of the vehicle via a clutch, is operated by a pump at the time of braking, and the braking energy is converted into hydraulic energy and stored in the accumulator, while the motor is operated at the time of starting / acceleration. A braking energy regenerating device that uses hydraulic energy accumulated in an accumulator as start / acceleration energy, wherein an acceleration operation state detection means for detecting a parameter value representing an acceleration operation state of the vehicle;
Control means for controlling a motor output torque of the hydraulic pump / motor during acceleration, wherein the control means responds to a parameter value detected by the acceleration operation state detection means when the motor operation of the hydraulic pump / motor is started. A target value of the motor output torque is set, and the motor output torque is gradually increased so as to reach the set target value after a predetermined time from the start of motor operation.

[0008]

The motor output torque is gradually increased after the start of the motor operation, and after a predetermined time, the operation amount of the accelerator pedal, the vehicle speed,
An abrupt generation of the motor output torque is prevented by reaching a target value of the motor output torque set according to a parameter value indicating an acceleration operation state of the vehicle such as an engine speed.

[0009]

An embodiment of the present invention will be described with reference to the drawings. The energy regenerating device shown in FIGS. 1, 2 and 3 is applied to a vehicle including an engine 1 for driving drive wheels via a transmission 3 and a clutch 2, and includes a piston type accumulator 20, a low-pressure hydraulic oil tank 30, Swash plate type variable displacement piston type pump / motor 40, gear box 50, control unit 60 (hereinafter referred to as EC
U).

First, the structure of a vehicle to which the energy regenerating 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 connected to the rear wheel drive shaft 10. It is connected to a differential (through shaft type). The energy regenerating device is connected to the above-described differential device via the drive shaft 12.

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

An accumulator 20 is connected to the high-pressure oil pipeline 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 hydraulic oil from the pump / motor 40 to the accumulator 20 and prevents the flow in the reverse direction.
When the shutoff valve signal D2 from 60 is input, the flow of hydraulic oil from the accumulator 20 to the pump / motor 40 is permitted. The electromagnetic unload valve 25 is activated by an unload valve signal D3 from the ECU 60, short-circuits the high-pressure oil line P1 and the low-pressure oil line P2 via the line P4, and stores the residual pressure trapped in the high-pressure oil line P1. To the low-pressure oil pipeline P2.

[0013] Between the high pressure oil pipeline P1 and the low pressure oil pipeline P2,
A check valve 46 is provided, and the check valve 46 is connected to the low-pressure oil pipe P.
2 allows the hydraulic oil to flow into the high-pressure oil pipeline P1, thereby preventing damage to the device caused by running out of hydraulic oil in the high-pressure oil pipeline P1. Further, a line P3 branches off from the high-pressure oil pipe P1 on the pump / motor 40 side from the shut-off valve 24 and is connected to the hydraulic oil tank 30, and the discharge pressure of the pump / motor 40 is set at the set pressure ( For example, 3
When the pressure exceeds 50 kgf / cm ² ), a relief valve 26 is provided for releasing the high-pressure oil to the hydraulic oil tank 30.

The high-pressure oil pipe P1 is provided with a discharge pressure sensor 89 for detecting the pipe pressure on the pump / motor 40 side from the shut-off valve 24, and supplies a discharge pressure signal PHY to the ECU. The accumulator 20 detects when the piston 21 has moved 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, and detects the piston position signal (off signal). LP
And a pressure accumulating sensor 88 for detecting the operating oil pressure in the hydraulic oil chamber 23 and outputting a pressure accumulating signal PAC, respectively.
P and a pressure accumulation signal PAC are supplied to the ECU 60.

The pump / motor 40 includes a gear box 50
Is connected to the drive shaft 12 described above, and the braking energy of the drive shaft 10 is transmitted between the drive shaft 12 and the gearbox 50.
Is transmitted to the pump / motor 40 via the
The starting / 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 includes a pair of gears 50a and a dog clutch 51. The pair of gears 50a increases the speed of 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 disconnected and connected by a dog clutch 51.

The pump / motor 40 includes a gear box 50
Drive shaft 40e connected to the output shaft, a piston cylinder 40f rotating integrally therewith, a piston 40c fitted to the cylinder 40f, and a swash plate for reciprocating the piston 40c with the rotation of the drive shaft 40e. 40d, and the pump / motor displacement 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 is
Is variably controlled. The tilt cylinder 41 includes a piston 41a connected to a swash plate 40d and a piston 4a.
Chambers 41b and 41 respectively formed on both sides of 1a
When a pilot oil pressure from a pilot oil pressure source 43 described later is supplied to one chamber, for example, the chamber 41b, the swash plate 40d is driven to the pump operation side, and the pilot oil pressure is supplied to the other chamber 41c. And the motor is driven to the operating side.

The pilot hydraulic pressure source 43 is composed of an oil pump or a pressure regulating valve driven by an electric motor or the like, 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 pressure source 43 and the tilt cylinder 41.
These are transmitted from the pilot hydraulic pressure source 43 to the tilt cylinder 41
And a pilot hydraulic control circuit for controlling the supply pressure of the pilot hydraulic pressure to the pilot hydraulic pressure. The switching valve 44 is connected to the ECU
60, the pilot signal P5
Communication and shut off.

When a control signal ELP is supplied to one of the solenoids of the proportional solenoid valve 42, for example, the solenoid 42a, a pilot oil pressure having a magnitude corresponding to the signal value ELP is applied via the proportional solenoid valve 42 to the pump operating side of the tilt cylinder 41. When the control signal ELM is supplied to the chamber 41b and the control signal ELM is supplied to the other solenoid 42b, a pilot oil pressure having a magnitude corresponding to the signal value ELM is applied to the chamber 41c on the motor operation side.
Thus, the operating position of the piston 41a of the tilt cylinder 41 and the tilt angle of the swash plate 40d are variably controlled.

FIG. 12 shows the relationship between the control signal value ELM supplied to the proportional solenoid valve 42 and the motor tilt angle.
The value is from 0 to the minimum value ELMmin (for example, 200 mA)
The following range is the dead band of the pump / motor 40,
The tilt angle becomes the minimum value (0 °), and the pump / motor 40 does not operate. The tilt angle increases in proportion to the increase in the ELM value until the ELM value exceeds the minimum value ELMmin and reaches the maximum value ELMmax. When the ELM value is equal to or more than the maximum value ELMmax, the tilt angle is set to the maximum value.

When the pump / motor 40 operates,
The swash plate 40 d is driven to the pump operation side by the tilt cylinder 41, and the hydraulic oil is supplied from the hydraulic oil tank 30 to the filter 3.
8, flows through the check valve 58, the pipe P2, the pump / motor 40, and the pipe P1 to the accumulator 20, and at the time of motor operation, the swash plate 40d is driven to the motor operating side, and the operating oil is at the time of pump operation. In the opposite direction, from the accumulator 20, the pipe P1, the pump / motor 40, the pipe P2, the check valve 57,
It flows to the hydraulic oil tank 30 via the filter 37.

The hydraulic oil tank 30 is connected to a pressurized air tank 31 via an electromagnetic two-port switching valve 33, a pressure reducing valve 35, and an air dryer 36, and to an electromagnetic three-port switching valve 34.
Are connected to the sub-air tank 32 via the air tank, and these constitute an air pressure supply circuit to the hydraulic oil tank 30. The switching valve 34 is operated by a drive signal D7 from the ECU 60, and the sub air tank 32 and the hydraulic oil tank 30
Is switched to the position where the communication is established. Sub air tank 3
The sub-air tank 32 supplies the partially reserved air to the hydraulic oil tank 30 by communicating the hydraulic oil tank 2 with the hydraulic oil tank 30. Then, air is supplied or absorbed to stabilize the air pressure in the hydraulic oil tank 30. On the other hand, ECU 6
When the drive signal D7 from 0 is cut off, the switching valve 34 switches to the atmosphere release position, and releases the pressure in the hydraulic oil tank 30 to the atmosphere.

The switching valve 33 is actuated by a drive signal D6 from the ECU 60, supplies high-pressure air in the air tank 31 to the hydraulic oil tank 30, and pressurizes the hydraulic oil in the tank 30 to a predetermined pressure. / Keep the operation of the motor 40 stable. Hydraulic oil leaking from the pump / motor 40 or the fitting portion (oil seal) in the hydraulic path returns 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 to open the drive signal and to supply the insufficient hydraulic oil to the hydraulic oil tank 3.
Refill to zero.

The hydraulic oil tank 30 is provided with a hydraulic oil level sensor 90 and an oil temperature sensor 91, and supplies 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 the hydraulic oil is in a normal state and restricting the operation of the regenerative device, damage to the device due to seizure of the pump / motor 40 or the like is prevented.

The dog clutch 51 is actuated by the air pressure. The dog clutch 51 is connected to an air tank 52 via an electromagnetic three-port switching valve 53 for connecting the clutch and an electromagnetic three-port switching valve 54 for disengaging the clutch. Are connected, and these constitute a dog clutch operation control circuit. The switching valve 53 for clutch connection is provided by 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. A rotation speed sensor 93 for detecting the rotation speed of the pump / motor 40 is provided on the pump / motor side output shaft of the dog clutch 51, and supplies a pump rotation speed signal NP to the ECU 60.

A 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 a brake is applied to a 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 supplied to the ECU 60.

The engine 1 is provided with a fuel injection device 5, and a governor control unit 67 connected to the fuel injection device 5 performs a normal fuel injection control and a rack limit signal R from an ECU 60 described later. Fuel limit (rack limit). The fuel injection limit (rack limit) is set so that the sum of the output from the motor operation of the pump / motor 40 and the output from the engine 1 does not exceed the output corresponding to the maximum driving torque of the normal engine 1 alone. The control is performed. The governor control unit 67 has an engine speed sensor 67a, detects the engine speed NE, and supplies an engine speed signal NE to the ECU 60.

The transmission 3 includes a vehicle speed sensor 8
3, a T / M reverse sensor 84, a T / M neutral sensor 85, and a select position sensor 86 are provided, and a vehicle speed signal V, a T / M reverse signal TMR,
The T / M neutral signal TMN and the select position signal LTM are supplied to the ECU 60. FIG. 3 shows a configuration of the ECU 60 for controlling the operation of the energy regenerating apparatus.
The U60 includes a processor, a memory, an input / output circuit, and the like. On the input side of the ECU 60, a main switch 64 for supplying an on / off state signal of the power supply, an accelerator opening sensor 61 for detecting an amount of depression of the accelerator pedal in conjunction with an accelerator pedal (not shown), and a clutch pedal (not shown) ), Two clutch sensors (CL1) 62 and (CL2) 63 for detecting connection and disconnection of the engine clutch, and various sensors including the above-described brake pressure sensor are connected. Here, the engine clutch connection / disconnection sensor (CL1)
62 is set to be ON by supplying a signal at a return limit (clutch connection) of a clutch pedal (not shown),
The engine clutch connection / disconnection sensor (CL2) 63 is set so as to be turned on by supplying a signal when the clutch pedal (not shown) is depressed (clutch disengagement). The sensor (CL1) 62 and the sensor (CL2) CL2) The combination of 63 makes it possible to detect the half-clutch state.

On the other hand, on the output side of the ECU 60, the above-mentioned various electromagnetic switching valves and various indicators are connected. Indicators include a piston position signal LP from a piston sensor 87 of the accumulator and a pressure accumulation sensor 88.
An accumulation indicator 66 for indicating the amount of accumulated pressure in accordance with the accumulated pressure signal PAC from the controller, a regenerative lamp 68 for indicating that the energy regenerating device is operating by the dog clutch connection / disconnection signal DCL from the dog clutch connection / disconnection sensor 92, and an abnormality in the dog clutch 51 system. There is a diagnostic lamp 69 that informs the driver that the vehicle cannot travel.

Hereinafter, the pump control and the motor control of the braking energy regenerating apparatus configured as described above will be described with reference to flowcharts shown in FIGS. FIG.
5 and 6 show a control procedure of the pump control performed by the ECU 60 during braking. First, the ECU 60 turns on the dog clutch 51 in response to the dog clutch connection / disconnection signal DCL from the dog clutch connection / disconnection sensor 92 in step S10.
(Connection) or OFF (Disconnection) is determined. Note that the dog clutch 51 is provided when the vehicle is in a predetermined driving state (for example, when the vehicle speed is 5).
The driving signal D8 is supplied from the ECU 60 to the clutch connection switching valve 53 to be ON (connected) when the vehicle is traveling at a selected position other than the reverse gear at km / h or less).
In order to prevent damage to the pump / motor 40 at a predetermined vehicle speed (for example, 60 km / h) or higher, the disconnection switching valve 5
4 is supplied with the drive signal D9 and turned off (disconnected).
When the dog clutch 51 is engaged, the pump / motor 40 is driven by the drive wheels WR via the drive shafts 10, 12 and the gear box 50.

If the result of the determination in step S10 is OFF (cut), the flow advances to step S20 in 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 cut-off state, and the piston 41a of the tilt angle cylinder 41 is also held at the neutral position. By maintaining 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,
In step S22, the unload valve signal D3 is not output to the unload valve (normally open) 25, but is turned off (open), and the high-pressure oil line P1 and the low-pressure oil line P2 is kept in communication. In step S23, the ECU 60 sets a value 0 (f1 = 0) to a flag f1, which is a program control variable,
Thus, the fact that the pump control is not performed is stored.

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

In step S12, the ECU 60 determines whether the vehicle has stopped. This determination is based on the vehicle speed V
Is less than or equal to a predetermined value XV0 (for example, 1 km / h) based on the vehicle speed signal V, and if V ≦ XV0 (1 km / h), the pump control is not executed. On the other hand, if the determination result is V> XV0 (1 km
If / h), step S13 is executed. Step S1
In step 3, the ECU 60 determines whether or not the driver has depressed the brake pedal (not shown) to generate the brake pressure PBK by the brake pressure signal P from the brake pressure sensor.
Determined by BK, PBK <XPB (for example, 0.2 kgf / cm
^{In the 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 result of the determination is PBK ≧ XPB (0.2 kgf / cm ² ), it is determined that all the operating conditions for regenerating energy have been satisfied,
Step S14 is executed.

In step S14, the ECU 60 determines the tilt angle control signal value ELP of the swash plate 40d of the pump / motor 40.
Is executed. 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 further referred to as an oil temperature TOIL detected by an 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 of FIG.
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 an angle corresponding to the signal value ELP. Next, in step S16, a drive signal D1 is output to the switching valve 44 to turn it on (open), and the tilt angle cylinder 41
Supply pilot hydraulic pressure to In step S17, the unload valve (normally open) 25 between the low-pressure oil pipe P2 and the high-pressure oil pipe P1 is turned on (closed) by the unload valve signal D3, and the pressure of the high-pressure oil pipe P1 is changed to the low-pressure oil pipe P2. Cut off so as not to escape. Further, step S
At 18, the value 1 is set to the flag f1 to store that the pump is operating.

When the tilt angle of the pump / motor 40 is set to an 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 Hydraulic oil 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 driver's brake pedal depression amount and the like, and the pump / motor 40 performs work corresponding to the brake pedal depression amount and the like. And the braking energy is recovered.

7 to 10 show a control procedure of motor control at the time of starting and accelerating (at the time of starting / acceleration). First, E
Before starting the motor operation, the CU 60 determines whether or not to execute the motor control 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 result of the determination in step S30 is PBK ≧ XPB (0.2 kgf / cm ² ), step S50 and subsequent steps in FIG. 10 to be described later are executed, and the motor control is not performed. On the other hand, if the discrimination result is PBK <XPB (0.2 kgf / cm
^{If 2} ), go to step S31.

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

In step S32, the ECU 60 determines whether the dog clutch connection / disconnection sensor 92 is ON (connected) or OFF (disconnected) based on the dog clutch connection / disconnection signal DCL.
If it is FF (cut), the 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 whether or not the selected position of the transmission 3 is in the reverse gear position (reverse position) by the T / M reverse signal TMR, and the determination result is YES (reverse), that is, the vehicle reverse gear position If it is the position, the motor control is not executed. On the other hand, if the determination result is NO, that is, if the vehicle is in the 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 in neutral, based on the T / M neutral signal TMN.
If the determination result is YES (neutral), that is, if the selected position is neutral, it is determined that the driver does not intend to start the vehicle yet, and the motor control is not performed. On the other hand, when the result of the determination is NO, the process proceeds to step S35.

In step S35, the ECU 60 determines whether the clutch 2 is connected or disconnected based on the clutch connection / disconnection signal CL2 of the clutch connection / disconnection sensor (CL2) 63. No motor control is performed as in the case where is neutral. On the other hand, if it is 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 or not the accumulator 20 is filled with hydraulic oil.
The determination is made based on the piston position signal LP from the piston position sensor 87. When the piston position sensor 87 set at the immediately preceding position of the piston 21 is 0FF, that is, when the hydraulic oil is empty, the hydraulic oil is not accumulated in the accumulator 20, and 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 the working oil, the process proceeds to step S37.

In step S37, the ECU 60 determines whether or not the vehicle speed V is equal to or lower than a predetermined value XV2 (for example, 65 km / h) based on the vehicle speed signal V. If the vehicle speed V 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 equal to or less than 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 a predetermined value XV1 (for example, 5 km) as in step S37.
/ h), if the value is smaller than the XV1 value, step S3
9 to determine whether the clutch 2 is completely connected or in a half-clutch state.
The determination is made based on the clutch connection / disconnection signal CL1. By the determination in step S38, the vehicle speed V becomes the predetermined value XV1 (5 km / h).
If it is determined that the clutch 2 is completely connected in spite of being smaller, it is determined that there is some abnormality in the clutch sensors 62 and 63, the vehicle speed sensor 83, etc. No motor control is performed. On the other hand, when the clutch connection / disconnection signal CL1 indicates the OFF state, the clutch 2
Means a half-clutch state, and in such a case, the process proceeds to step S40.

In step S40, the ECU 60 determines whether or not the accelerator opening L Aθ is greater than the motor start opening determination value Xθ1 based on the accelerator opening signal L Aθ. The above-described determination value Xθ1 is set according to the vehicle speed V,
FIG. 15 shows the vehicle speed V and the discrimination value X set thereby.
The relationship with θ1 is shown. If the accelerator opening LAθ is smaller than the discrimination value Xθ1 (LAθ <Xθ1), it is determined that the vehicle is not in a state to be accelerated by regenerative energy, and the motor is not operated. On the other hand, if it is larger than the discrimination value Xθ1 (L Aθ ≧ Xθ1), step S41
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 to 2 is set to zero (ELM = 0) and output. Thereby, the tilt angle cylinder 4
The first piston 41a is held at 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
a switching valve 44 for controlling the supply and discharge of pilot oil for driving a
Is turned off (closed) by rejecting the drive signal D1. In step S52, the shut-off valve 24 that is ON (open) when the motor is operated is turned off (closed) by cutting off the shut-off 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 disposed between the low-pressure oil pipeline P2 and the high-pressure oil pipeline P1 stops outputting the unload valve signal D3, and is turned off (open). And low pressure oil pipeline P
Let 2 communicate. In step S54, a rack limit signal R, which will be described later, transmitted to the engine 1 when the motor is operated is turned off by turning off, and in step S55, the rack limit enable signal RE, which is also transmitted, is turned off and OF is turned off.
F. Finally, in step S56, a value 0 (f2 = 0) is set in a flag f2, which is a program control variable, to store that the motor control is not performed.

On the other hand, when the motor control is started by executing step S41, the ECU 60 sets the pump / motor 4
A subroutine for setting the tilt angle control signal value ELM of the zero swash plate 40d is executed. As a method of setting the ELM value,
First, a reference value is set according to a parameter value representing the acceleration operation state of the vehicle, for example, the accelerator opening LAθ and the vehicle speed V (the engine speed NE may be used instead of the vehicle speed V).
FIG. 16 shows the EL stored in the storage device of the ECU 60.
An M map is shown, and the ECU 60 calculates the vehicle speed V from this map.
ELM reference value (XM
0, XM1, ...). Next, the oil temperature sensor 91
A correction coefficient K2 corresponding to the oil temperature of the hydraulic oil tank 30 detected at step (1) is obtained, and the correction coefficient K2 is multiplied by an ELM reference value to obtain an optimum tilt angle control signal target value ELMset (ELM reference value × ELMset).
K2), and calculates the target value ELMse as described later.
The control signal value ELM is output based on t. Changing the tilt angle control signal value ELM according to the accelerator opening LAθ is equivalent to operating the pump / motor 40 so that a response similar to the accelerator operation response at the time of starting and accelerating only by the normal engine 1 is obtained. Is to change the output torque value. Further, the tilt angle control signal value EL depends on the vehicle speed V (or the engine speed NE).
By changing M, the regenerative energy is effectively used in a low-speed region such as when the vehicle starts, and black smoke is prevented from being generated.

The correction based on the oil temperature of the hydraulic oil tank 30 does not require correction of the ELM value if the oil temperature is lower than 70 ° C., for example, but the tilt angle control signal value ELM if the oil temperature is 70 ° C. or higher.
Is corrected to reduce. At a high temperature, the viscosity of the hydraulic oil decreases, and there is a risk of seizure of the pump / motor 40. This is prevented by reducing the motor capacity.

The parameters for setting the ELM value, which represent the acceleration operation state of the vehicle, are not limited to the above-described accelerator opening LAθ and vehicle speed V, but include the accelerator pedal depression speed, rack position, and fuel injection. It may be an amount or the like. Next, in step S42 in FIG. 9, the ECU 60 outputs a control signal to the proportional solenoid valve 42 based on the ELMset value set as described above. The subroutine of the tilt angle slow-up control is executed. This tilt angle slow-up control is intended to alleviate the acceleration caused by the motor operation to have a sudden acceleration feeling different from the feeling of acceleration in the normal engine 1 and to make the rising at the time of acceleration smooth. Is what you do.

FIG. 11 shows a subroutine according to the present invention.
A procedure for executing the tilt angle slow-up control and outputting the control signal value ELM will be described. As shown in FIG. 13, the tilt angle slow-up control outputs the tilt angle signal value at the motor control start time t0 as the minimum value ELMmin, and outputs the minimum value ELMmin after a predetermined time (t1). -T0
: About 1 second) to reach the target value ELMset
This is to gradually increase along the solid line in the figure.

First, in step S70, it is determined whether or not the tilt angle slow-up control should be executed. The tilt angle slow-up control is effective when the tilt angle control signal value ELM changes abruptly, such as immediately after the start of motor control, and determines whether a program control variable flag f (SU) described later is a value 1 or not. 0
Is used to determine such a situation where the ELM value suddenly changes.
A value of 1 indicates a situation where the slow-up control should be executed, and a value of 0 indicates a situation where the execution is not required.
If the determined result is NO and the value is 0, the process proceeds to a step S90.

Steps S90 and S91 are as follows:
This is a step of determining whether or not the tilt angle slow-up control is being performed. In step S90, first, it is determined whether or not the motor control is being performed and immediately after the motor control has been started. The purpose of the tilt angle slow-up control is to make the acceleration feeling during the motor control smooth. For example, it is determined whether or not the motor control has been started to determine whether or not the ELM value has suddenly changed. ing. If the determination result is NO and the motor control is not immediately started, the tilt angle slow-up control is not performed, so that the ELM value is set to the ELMset value (target value) in step S95, and the step S95 is performed.
Go to 77.

On the other hand, if the decision result in the step S90 is YES.
If it is immediately after the start of the motor control, the process proceeds to step S91, and it is determined whether or not the vehicle speed V has reached a predetermined speed (for example, 10 km / h) at which the tilt angle slow-up control is to be performed. Here, the case where the vehicle speed V is less than the predetermined speed (10 km / h) is a case where a large acceleration force is required such as when starting, and in such a case, the tilt angle slow-up control is performed. ELMset value (target value) without performing
Should be supplied directly. Therefore, if the determination result is NO and the speed is less than the predetermined speed (10 km / h), the tilt angle slow-up control is not performed, and the ELM value is changed to ELM in step S95.
Then, the process proceeds to step S77. On the other hand, when the result of the determination is YES, the vehicle speed V becomes the predetermined speed (10 km / h).
If so, the execution condition is satisfied. Then, the process proceeds to step S92, and the flag f (SU), which is a program control variable, is stored in order to store that the tilt angle slow-up control should be executed. Is set to the value 1. At the same time, in preparation for starting the tilt angle slow-up control,
The counter for counting the number N of executions of the routine is reset (N = 0), and the process proceeds to step S75 to execute the tilt angle slow-up control.

In step S75, EL corresponding to the count value N
This is the step of calculating the M value by the following equation.

[0056]

ELM = ((XN−N) / XN) × ELMmin + (N / XN) × ELMset When this step is executed for the first time (N = 0), E
LMmin (minimum value) is output as the ELM value. Then, in the next execution of the routine, the determination result in the previous step S70 is YES, and in the next step S71, the number N of times the routine has been executed is counted up (N = N + 1). Next, in step S72, it is determined whether or not the count value N has exceeded a predetermined value XN of the total number of times. The predetermined value XN is the time required to gradually increase the ELM value from the minimum value ELMmin to the target value ELMset (the time between time t0 and time t1 in FIG. 13;
(For example, 1 second) (the control cycle is 50 ms, for example)
If ec, the value is set to 20). Step S7
If the determination result of No. 2 is NO and the count value N has not yet reached the predetermined value XN, the process proceeds to step S75 to continue the slow-up control. On the other hand, if the determination result of step S72 is YE
If the count value N exceeds the predetermined value XN in S, the tilting angle slow-up control ends, and step S8 is executed.
The program proceeds to 0, and stores that the flag f (SU) is set to a value of 0, indicating that it is no longer necessary to execute the tilt angle slow-up control. Subsequently, in step S81, the ELM value is set to ELMset.
The value is set to the value (target value), and the process proceeds to step S77.

As described above, step S75 or S8
The ELM value obtained in 1 or S95 is output to the proportional solenoid valve 42 in step S77. Thus, at the time of the slow-up control, the tilt angle of the pump / motor 40 is gradually increased to the target angle according to the ELM value based on the above-described proportional relationship in FIG. Returning to the flow of the motor control, in step S43 of FIG. 9, the drive signal D1 is output, the switching valve 44 is turned on (open), and the pilot hydraulic pressure is supplied to the tilt angle cylinder 41 via the proportional solenoid valve. . Thereby, the swash plate 40d of the pump / motor 40 is
The tilt angle is set to the tilt angle corresponding to the ELM value. Next, in step S44, a shutoff valve signal D2 is output to the shutoff valve 26, which is turned on (open), and in step S45.
In step (2), an unload valve signal D3 is supplied to the unload valve (normally open) 25, which is turned ON (closed) to shut off the pressure of the high-pressure oil pipe P1 so as not to escape to the low-pressure oil pipe P2. Thereby, the pump / motor 40
It is driven by the high-pressure hydraulic oil stored in the accumulator, and its driving force is the drive shaft 40e, the gearbox 5
0, transmitted to the drive wheels WR via the drive shafts 12, 10.
It 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. The rack limit signal R is used to limit the output torque of the engine 1 during motor control.
It is determined based on the engine speed NE and the accumulated pressure PAC of the accumulator 20. Then, in order to reliably execute the output restriction on the engine 1 side supplied to the fuel injection device 5, in step S47, a rack restriction enable signal RE is output to the governor control unit 67 to prevent malfunction due to noise or the like. doing. Finally, step S
At 48, a value of 1 is set to a flag f2, which is a program control variable, thereby storing that the motor is operating.

In the tilt angle slow-up control of this embodiment, the vehicle speed V is equal to or higher than a predetermined speed. However, the vehicle speed V is not limited, and all vehicle speed ranges (low speed range) are not limited. May be implemented).

[0060]

As described above, according to the braking energy regenerating apparatus of the present invention, when the motor operation of the hydraulic pump / motor is started, the target value of the motor output torque is set according to the parameter value indicating the acceleration operation state. Since the motor output torque is gradually increased so as to reach the target value after a predetermined time from the start of the motor operation, the torque generation when performing acceleration by the motor operation during traveling becomes smooth, and the feeling of acceleration (acceleration feeling) is increased. Ring) can be improved.

[Brief description of the drawings]

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

FIG. 4 is a part of a flowchart of a pump control routine executed by an ECU 60 in FIG. 3;

FIG. 5 is a part of a flowchart of a pump control routine that follows the flowchart of FIG. 4;

FIG. 6 is the remaining part of the flowchart of the pump control routine following the flowchart of FIG. 4;

FIG. 7 is a part of a flowchart of a motor control routine executed by an ECU 60 in FIG. 3;

FIG. 8 is a part of a flowchart of a motor control routine following the flowchart of FIG. 7;

FIG. 9 according to the present invention, following the flowchart of FIG. 8;
It is a part of the flowchart of the motor control routine.

FIG. 10 is the remainder of the flowchart of the motor control routine that follows the flowchart of FIG. 8;

FIG. 11 is a flowchart of a tilt angle slow-up control routine during motor control of the braking energy regeneration device according to the present invention.

FIG. 12 is a graph showing a relationship between a signal value ELM during motor control and a motor tilt angle set according to the signal value ELM.

FIG. 13 is a graph showing a state in which the tilt angle gradually increases by the tilt angle slow-up control during motor control according to the present invention.

FIG. 14 is a graph showing an example of a relationship between a brake pressure PBK at the time of pump control of the braking energy regeneration device and an ELP value set accordingly.

FIG. 15 is a graph showing an example of a relationship between a vehicle speed V and a discrimination value Xθ1 (accelerator start opening degree) at the time of motor control of the braking energy regeneration device.

FIG. 16 is a graph showing an example of a relationship between a vehicle speed V, an accelerator opening, and a tilt angle control signal value ELM according to these during a motor control of the braking energy regeneration device.

[Description of Signs] 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 Power Source 50 Gear Box 51 Dog Clutch 52 Air tank 60 Control unit (ECU) 61 Accelerator opening sensor (acceleration operation state detection means) 67a Engine speed sensor (acceleration operation state detection means) 83 Vehicle speed sensor (acceleration operation state detection means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 1/10 B60K 25/00

Claims (1)

(57) [Claims] 1. A hydraulic pump / motor, which is interposed in an oil passage between a low-pressure tank for storing hydraulic oil and an accumulator for accumulating hydraulic energy and is connected to a drive system member of a vehicle via a clutch, is provided with a brake. A brake energy regenerating device that operates a pump at the time to convert braking energy into hydraulic energy and accumulates the energy in the accumulator, while operating at start / acceleration, activates a motor to utilize the hydraulic energy accumulated in the accumulator as start / acceleration energy. An acceleration operation state detection means for detecting a parameter value representing an acceleration operation state of the vehicle; and a control means for controlling a motor output torque of the hydraulic pump / motor at the time of starting / acceleration of the vehicle, wherein the control means At the time of starting the motor operation of the pump / motor, the acceleration / operation state detecting means detects A target value of the motor output torque, and gradually increasing the motor output torque so as to reach the set target value after a predetermined time from the start of the motor operation.