JP3468470B2 - Engine auto deceleration control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic deceleration control system for an engine, and more particularly to a system for controlling a hydraulic pump after the engine rotation is sufficiently recovered from the deceleration state when the automatic deceleration state is released. The present invention relates to an automatic deceleration release switching control device for controlling the increase of the capacity so that a sudden load does not act on the engine to reduce the noise of the engine and to greatly improve the exhaust color of the engine. 2. Description of the Related Art In a conventionally used automatic deceleration control device for an engine, when at least one of operation levers is operated as shown in FIG. 6, an auto deceleration signal is released and the rotation of the engine is decelerated. At the same time as starting to recover from the state, the torque variable device is controlled to start releasing the torque decrease signal and start increasing the capacity of the hydraulic pump. [0003] However, in the conventional automatic deceleration control device for an engine described above, the capacity of the hydraulic pump starts to increase before the engine completely recovers to high-speed rotation. There is a problem that the engine noise becomes a problem due to the action and the engine exhaust color is reduced. SUMMARY OF THE INVENTION [0004] The present invention has been made to solve the above-mentioned problems in the prior art, and is provided with a variable displacement hydraulic pump driven by an engine and having a capacity reduced by a torque reduction signal. An operating lever for switching an operating valve that controls the amount of pressure oil flowing from the hydraulic pump to the hydraulic actuator, and the operating lever inputs a neutral position and outputs a torque reduction signal when input. In the automatic deceleration control device that outputs a deceleration command for shifting the rotation speed of the engine to a predetermined low value, the output of the deceleration command is released when the operation lever starts to depart from the neutral position, and a predetermined time has elapsed since the release. The control for starting to release the torque reduction signal later is performed . According to the above arrangement, the following operation is performed. Operation
When all of the bars become neutral, a neutral signal is output from each neutral detector to the pump controller, so a torque reduction signal is output from the pump controller to the torque variable device, and the torque variable device is output to the displacement control cylinder of the hydraulic pump. The capacity of the hydraulic pump is reduced to output the capacity reduction signal, and the engine is decelerated to output the fuel reduction signal from the pump controller to the governor driving device via the engine controller. Further, when at least one of the operation levers is operated, a neutral signal output from the neutral detector of the operation lever to the pump controller is cut off, so that a fuel reduction signal output to the governor driving device is output. Is released, and the rotation of the engine starts to recover from the decelerated state. After a lapse of a predetermined time since the neutral signal is interrupted, the torque reduction signal output to the torque variable device starts to be released,
The release of the capacity reduction signal output from the torque variable device to the capacity control cylinder of the hydraulic pump is started, and the capacity of the hydraulic pump starts to increase. Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIGS. 1 to 5 show a case where the automatic deceleration release switching control device of the present invention is applied to a working machine drive device of a hydraulic excavator, and FIG.
FIG. 2 is a diagram showing an automatic deceleration control device for an engine according to an embodiment, FIG. 2 is a diagram showing the aging characteristics at the time of auto deceleration release switching according to the first embodiment of the present invention, and FIG. It is a figure which shows the time characteristic at the time of the auto deceleration release switching in 2nd Example of invention. FIG. 4 is a diagram illustrating matching between the engine torque curve and the absorption torque of the hydraulic pump, and FIG. 5 is a diagram illustrating an equal absorption torque curve of the hydraulic pump. In FIG. 1, 1 is an engine, 2 is a hydraulic pump driven by the engine 1, 2a is a swash plate for controlling the capacity of the hydraulic pump 2, and 3a and 3b are swing motors driven by the hydraulic pump. And boom cylinder,
4a and 4b are the hydraulic pump 2 and the swing motor 3 respectively.
a and a pilot cylinder for operating the operation valve 4b, 6a and 6b are pilot cylinders for operating the operation valve 4b, and 7a and 5b are pilot cylinders for operating the operation valve 4b. 7b is a pilot valve for sending pilot oil pressure to the pilot cylinders 5a, 5b and 6a, 6b, 8a and 8b are operating levers of the pilot valves 7a and 7b, and 9a and 9b are for extracting pilot oil pressure of the pilot valves 7a and 7b, respectively. Valves 10a and 10b for the shuttle valve 9
a, a hydraulic switch for converting the pilot oil pressure of 9b into an electric signal, 11 is a displacement control cylinder of the hydraulic pump 2,
11a is a piston rod of the displacement control cylinder 11, 11
b is a piston, 11c is a rod chamber, 11d is a bottom chamber,
11e is a return spring installed in the rod chamber 11c, 1
2 is a torque variable valve, 12a is a pilot cylinder for operating the torque variable valve 12, 12b is a solenoid, 12c is a spring, 13 is a control pump, 14 is a pressure setting valve, 15 is a pump controller, 16 is a load determiner, 1
7a is a torque decrease signal generator, 17b is a torque increase signal generator, 18a and 18b are solenoids, 19 is an engine controller, 20a is a deceleration signal generator, 20b is a deceleration release signal generator, 21 is a governor drive motor, and 22 is a governor drive motor. Drive lever, 23 is link, 24 is governor lever, 25
Is a governor, 26 is a tank, 27 is a power supply, 28 is a decel switch, and 29a and 29b are switch. The operation of the above configuration will be described. When all the actuators such as the swing motor 3a and the boom cylinder 3b driven by the engine 1 are stopped after the operation of the hydraulic excavator is completed, or the operation levers 8a and 8b operated on one side are operated in opposite directions. When the operating levers 8a and 8b are temporarily set to the neutral state, the pilot pressure is not applied to the hydraulic switches 10a and 10b, so that the hydraulic switches 10a and 10b are output from the hydraulic switches 10a and 10b to the load determiner 16 of the pump controller 15. Is interrupted (a neutral signal is input). Therefore, the solenoid 18a is demagnetized and the changeover switch 29a
Is switched to the A-contact, and when a no-load signal is output from the load determiner 16 to the torque reduction signal generator 17a, which is a function generator, the solenoid 12b of the torque variable valve 12 is output from the torque reduction signal generator 17a. , And starts to output a torque current it. Therefore,
The torque variable valve 12 is at the position b, the bottom chamber 11d of the displacement control cylinder 11 of the hydraulic pump 2 is drained, and the displacement of the hydraulic pump 2 is reduced by the return spring 12e of the rod chamber 12c. At the same time, when the solenoid 18b is demagnetized and the changeover switch 29b is switched to the A contact, a predetermined no-load signal is output from the load determiner 16 to the decel signal generator 20a in the engine controller 19 which is a function generator. After a time, the governor current i output from the decel signal generator 20a to the governor drive motor 21
To shut off g, the governor 25 puts the engine 1 into a decelerated state via the drive lever 22, the link 23, and the governor lever 24. Next, when at least one actuator such as the swing motor 3a or the boom cylinder 3b driven by the engine 1 is operated, the hydraulic pressure switches 10a, 10b are operated by the pilot oil pressure of the shuttle valve 9a or 9b.
An electric signal is output from 10b to the load determiner 16 of the pump controller 15 (the neutral signal is cut off). Therefore, when the load signal is output from the load determiner 16 to the torque increase signal generator 17b, which is a function generator, when the changeover switch 29a is switched to the B contact because the solenoid 18a is excited, after a predetermined time ( After the engine 1 is completely recovered from the decelerated state), the torque increase signal generator 17b
Starts to output a torque current it increasing the pump torque to the solenoid 12b of the torque variable valve 12. Accordingly, the torque variable valve 12 is at the position a, and the hydraulic pump 2
Since the control oil pressure of the control pump 13 is supplied to the bottom chamber 11d of the displacement control cylinder 11, the capacity of the hydraulic pump 2 increases. At the same time, the solenoid 18b is also excited and the changeover switch 29b is switched to the B contact. When the load signal is output from the load determiner 16 to the decelerating signal generator 20b in the engine controller 19 which is a function generator, The governor 25 recovers the rotation of the engine 1 from the decelerated state via the drive lever 22, the link 23, and the governor lever 24 in order to output the governor current ig from the decel release signal generator 20b to the governor drive motor 21. As described above, when none of the actuators such as the swing motor 3a and the boom cylinder 3b are operating, the engine 1 is set to the decelerated state after a predetermined time, and the hydraulic pump 2 is operated at a low capacity. When at least one of the actuators is actuated,
The engine 1 releases the deceleration state, and the hydraulic pump 2 increases the capacity after a predetermined time to perform a required operation. Even when at least one of the actuators such as the swing motor 3a or the boom cylinder 3b is operating, if the decel switch 28 is turned on manually, the power supply 2
7 outputs a deceleration command signal to the engine controller 19, whereby the governor current ig output from the engine controller 19 to the governor drive motor 21 is output.
Is shut off, the engine 1 is de-selled by the governor 25. Next, a first embodiment of the present invention shown in FIG. 2 will be described. When at least one of the operation levers 8a and 8b of the hydraulic excavator is changed from the neutral state to the operation state, the load determiner 1
6, the no-load signal output to the decel signal generator 20a in the engine controller 19 is cut off, and the load signal is output from the load determiner 16 to the decel release signal generator 20b in the engine controller 19. The governor current ig flows from the deceleration release signal generator 20b to the governor drive motor 21 to drive the governor 25 in the fuel increasing direction, and the engine 1 recovers from the deceleration state. Further, a torque increase signal generator 17 in the pump controller 15 is provided.
b changes with time of the torque current it output to the solenoid 12b of the torque variable valve 12 after the load signal is output from the load determiner 16 to the torque increase signal generator 17b.
After the completion of the recovery of the engine 1 from the decelerated state, the engine 1 is controlled so as to start decreasing (the pump torque T increases).
Accordingly, an excessive load does not act on the engine 1, and the engine rotation can be smoothly recovered. As a result, the noise can be reduced and the exhaust color can be significantly improved. Next, a second embodiment of the present invention shown in FIG. 3 will be described. When at least one of the operation levers 8a and 8b of the hydraulic excavator is changed from the neutral state to the operation state, the load determiner 1
6, the no-load signal output to the decel signal generator 20a in the engine controller 19 is cut off, and the load signal is output from the load determiner 16 to the decel release signal generator 20b in the engine controller 19. The governor current ig flows from the deceleration release signal generator 20b to the governor drive motor 21 to drive the governor 25 in the fuel increasing direction, and the engine 1 recovers from the deceleration state. Further, a torque increase signal generator 17 in the pump controller 15 is provided.
The change over time of the torque current it output from b to the solenoid 12b of the torque variable valve 12 is such that the reduction state (the increase state of the pump torque T) is completed after the rotation of the engine 1 has completely recovered from the deceleration state. Controlled. Therefore, since the increase of the hydraulic pump capacity is controlled after the rotation of the engine 1 has completely recovered from the deceleration state, the engine 1 is released from the auto deceleration state with a margin for the engine output. The engine 1 can be controlled, and an excessive load does not act on the engine 1, and the engine rotation can be smoothly recovered. As a result, the noise can be reduced and the exhaust color can be improved. FIG. 4 is a diagram showing the matching between the torque curve of the engine and the absorption torque of the hydraulic pump. Conventionally, an automatic deceleration return line which reaches a rated output point c from an auto deceleration matching point a through a 'is shown. In the first embodiment of the present invention, the auto-decel matching points a to a ′,
After passing through the auto-deceleration return line reaching the rated output point of c via b and b ', the second embodiment of the present invention is characterized in that the auto-deceleration matching point a and the rated output point of c via a' and b ' Pass the auto-decel return line to reach. The return line (aa′-bb′−) according to the first embodiment of the present invention.
The exhaust color in c) is the return line (a
It was confirmed that the color was approximately halved compared to the exhaust color in -a'-c). FIG. 5 is a diagram showing an iso-absorption torque curve of the hydraulic pump for explaining the function of the variable torque valve. When a low constant electric signal is output to the solenoid 12b of the variable torque valve 12, the hydraulic pump 2 When driven by an equal absorption torque curve and outputting a high constant electric signal to the solenoid 12b of the torque variable valve 12, the hydraulic pump 2
Driven by the equal absorption torque curve. According to the present invention, as described in detail above, the following effects can be obtained. ( 1 ) When the decel is released, the operation lever is released from the neutral position.
The pump load is applied after a lapse of a predetermined time from the start. this
As a result, an excessive load does not act until the rotation speed of the engine 1 becomes high , so that noise can be reduced and exhaust color can be significantly improved. (2) The engine speed has recovered when the deceleration is released
Is the time since the operation lever was released from the neutral position.
Just judge. This allows the location to be
Control to increase the pump load without fail after a fixed time
Construction machinery that performs a series of digging and traveling operations
Can move quickly, improve work efficiency and drive well
A feeling is obtained. (3) The engine speed has recovered when the deceleration is released
Is the time since the operation lever was released from the neutral position.
Only with a timer function
Required, requires various sensors such as rotational speed sensor and wiring
And not. This makes it easy to retrofit existing construction machinery
And an inexpensive control device is obtained. [0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an automatic deceleration control device for an engine according to a first embodiment of the present invention. FIG. 2 is a diagram showing a time-dependent characteristic at the time of auto deceleration release switching in the first embodiment of the present invention. FIG. 3 is a diagram showing a time-dependent characteristic at the time of auto deceleration release switching according to a second embodiment of the present invention. FIG. 4 is a diagram showing matching between an engine torque curve and an absorption torque of a hydraulic pump. FIG. 5 is a diagram showing an iso-absorption torque curve of a hydraulic pump for explaining a function of a variable torque valve. FIG. 6 is a diagram showing the aging characteristics at the time of auto decelerating release switching in the prior art. [Description of Signs] 1 Engine 2 Hydraulic pump 3a Swing motor 3b Boom cylinder 4a, 4b Operating valve 5a, 5b Pilot cylinder 6a, 6b Pilot cylinder 7a, 7b Pilot valve 8a, 8b Operating lever 9a, 9b Shuttle valve 10a, 10b Hydraulic pressure Switch 11 Capacity control cylinder 11a Piston rod 11b Piston 11c Rod chamber 11d Bottom chamber 11e Return spring 12 Torque variable valve 12a Pilot cylinder 12b Solenoid 12c Spring 13 Control pressure pump 14 Pressure setting valve 15 Pump controller 16 Load determiner 17a, torque decrease signal Generator 17b Torque increase signal generator 19 Engine controller 20a Decel signal generator 20b Decel release signal generator 21 Governor drive motor 22 Drive lever 23 Link 24 Governor lever 5 governor 26 tank 27 supply 28 deceleration changeover switch 29a, 29b changeover switch

Claims (1)

(57) [Claim 1] A variable displacement hydraulic pump which is driven by an engine and whose capacity is reduced by a torque decrease signal, and an operation for controlling an amount of pressure oil flowing from the hydraulic pump to a hydraulic actuator. An operating lever for switching a valve, wherein the operating lever inputs a neutral position, outputs a torque reduction signal when input, and shifts the engine speed to a predetermined low value. An automatic deceleration control device that outputs a command, wherein an output of the deceleration command is released when the operation lever is released from the neutral position, and control is performed to start releasing the torque reduction signal after a lapse of a predetermined time from the release. Automatic deceleration control device.