JPH0333804Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a signal generation mechanism for improving the straightness of running of left and right traveling devices in a hydraulic circuit of a construction machine such as a hydraulic power shovel.

[Conventional technology]

The hydraulic circuit shown in FIG. 4 will be explained. 0
1 and 02 are hydraulic pumps that usually have the same maximum discharge volume, 09 and 011 are left and right travel motors, and 01
0,012,013 is another actuator,
Reference numerals 03, 05, 06, 07, and 08 are operating valves for each of the actuators, and 04 is a redundant operating valve that is normally reserved and used when installing special attachments, and its supply ports 04X and 04Y are closed. 03a, b to 08a, b are switching pilot pressure passages of each operating valve, W is an external load, and F is the acting direction of the load force.

The discharge sides of the left and right pumps 01 and 02 each constitute a separate circuit, and the straightness on flat ground is determined by the theoretical volumes of the left and right travel motors 09 and 011 and the left and right pumps 0.
It depends on the uniformity of the discharge amount of 1 and 02. If you operate the corresponding operation valve, for example 08, when you need to operate another actuator while traveling straight, the travel operation valves 06 and 08 are connected in parallel, so especially when the load pressure of actuator 013 is lower than that of travel motor 011. , almost all of the oil discharged from the pump 02 is supplied to the actuator 013 side,
The traveling motor 011 receives only a small amount of pressure oil supply compared to the traveling motor 09, which causes a problem that the vehicle travels through a large turn.

[Problem that the invention attempts to solve]

The present invention is an attempt to solve the problems of the prior art, such as curves, which occur when other actuators are operated in conjunction with each other while the vehicle is traveling straight.

[Means for solving problems]

A signal valve is provided to detect this switching state when the left and right travel motor operation valve is switched and any of the actuator operation valves that are subject to simultaneous operation is switched. The operating valve, which is normally surplus, in the circuit is switched by the output signal pressure of the signal valve, and a pipe line is connected from the surplus operating valve to the discharge line of the other supply pump, so that the discharge oil of both pumps is switched to the surplus operating valve. They are merged and supplied through an operating valve. This makes it possible to supply pressure oil to the left and right travel motors in parallel from an apparently single hydraulic source, thereby maintaining straight travel. Furthermore, if other actuators that are operated simultaneously have a light load, a large amount of oil will be supplied from the above-mentioned apparently one hydraulic source to the other light-loaded actuators, and the traveling motor speed will be extremely reduced. The pressure reduction signal valve, which is switched by the output signal, supplies the switching pilot pressure of the operating valves that are simultaneously operated as a source pressure, and regulates the amount of pressure oil supplied to the actuator to prevent an extreme drop in travel speed.

[Effect]

When the operation valve for the other actuator is switched to the oil supply side while the left and right travel motors are operating, the hydraulic circuits leading to the left and right travel motors merge via the surplus operation valve, and the pressure oil of the left and right hydraulic pumps merge and become parallel. Supplied to the left and right travel motors.

Further, the amount of pressure oil supplied to the actuator operation valve is regulated to prevent a large drop in rotation of the travel motor.

〔Example〕

In Fig. 1, 1 and 2 are hydraulic pumps that usually have equal maximum discharge amounts, 9 and 11 are left and right travel motors, 10, 12, and 13 are other actuators, and 14 and 15 are hydraulic pumps with the same maximum discharge volume. Lines 3, 5, 6, 7, and 8 are operation valves for each of the actuators, and 4 is an extra operation valve that is normally reserved and used when installing special attachments, and its supply port 4X is the discharge line of the hydraulic pump 2. 15
The supply port 4Y is closed. 3
a, b to 8a, b are switching pilot pressure passages of each operating valve, W is an external load, and F is the acting direction of the load force. 20 to 24 are signal valves that are switched by the switching pilot pressure of each operating valve 3, 5, 6, 7, and 8, 25 is an output signal passage of the signal valves 20 to 24, 26 is a throttle for eliminating residual pressure, and 27 is a passage. 25 is a pressure reducing signal valve that switches at pressure; 16 is a confluence supply pipe; 28 is a pilot hydraulic pressure source; and 29 is a passage.

The function of the signal valves 20 to 24 is to increase the switching pilot pressure in the switching pilot pressure passages 3a or 3b and 6a or 6b to switch the operating valves 3 and 6 in order to run straight ahead, and to fully operate the left and right travel motors 9 and 11. During driving, the signal valves 20 and 21 are at the open position at the same time, so pressure from the pilot oil pressure source 28 is generated in the passage 29, and the other actuators 10, 21 are activated while the vehicle is traveling straight.
When it is necessary to simultaneously operate one or more of 12 and 13 and switch the corresponding operation valve, the switching pilot pressure passage 5a or 5b or 7a or 7
Since the signal valve 22, 23, or 24 is in the open position to increase the pilot pressure, the passage 25 is connected to the passage 29, that is, the pilot hydraulic pressure source 2.
Generate a pressure of 8. The situation in which this signal pressure occurs is as shown in the logic circuit diagram of FIG. This passage 25 pressure applies pressure to the passage 4a of the operation valve 4, so the operation valve 4 is switched from the position 4d to the position 4c, and the discharge line 14 of the pump 1 is connected to the function 4c of the operation valve 4. Internal passage and supply port 4X and confluence supply pipe line 1
6, it will be connected to the discharge line 15 of the pump 2. As a result, one hydraulic power source is formed by apparently merging the discharge amounts of the two pumps,
Pressure oil can be supplied to the left and right travel motors in parallel from this oil pressure source, thereby maintaining straight travel. or,
When the operation valve 8 is fully switched to the function 8c in order to extend the cylinder rod 13a according to the acting direction F of the external load W of the actuator (for example, 13 in FIG. 1) that is operated simultaneously, the piston chamber 13b of the actuator 13 is Because of the low pressure,
A large amount of oil is supplied to the piston chamber 13b from the apparently single hydraulic pressure source, and the traveling motor speed is extremely reduced. In order to prevent this, when pressure from the pilot hydraulic pressure source 28 is generated in the passage 25, the pressure reduction signal valve 27 is switched to the function 27b, and the pressure in the switching pilot pressure passage 8a is reduced to the two-stage throttle 27d.
and 27c, the intermediate pressure of the throttle reduced by the action of 27c is introduced into the passage 8a', and as shown in FIG. is regulated, so there is no extreme drop in driving speed. Also, in order to stop the simultaneous operation mentioned above,
The pressure at a is reduced to the tank pressure, and the operating valve 8 is returned to neutral. Since all switching pilot pressures other than running are in a non-increased state, the signal valves 22, 23, and 24 are in a neutral closed state, the residual pressure in the passage 25 flows out from the throttle 26 to the tank passage, and the valve 4 is in the neutral function 4d. and the pressure reduction signal valve 27 returns to the function 27a. In this state, the discharge sides of pumps 1 and 2 are separated and form separate circuits as before.
Straight running is ensured.

[Effect of idea]

According to the present invention, even if other actuators other than driving are simultaneously operated while the vehicle is traveling straight, it is possible to continue traveling straight. Furthermore, it is possible to prevent an extreme drop in travel speed due to simultaneous operations.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the hydraulic circuit of the construction machine of the present invention. 2 is a logic circuit diagram of the signal valve circuit of FIG. 1, and FIG. 3 is a functional explanatory diagram of the pressure reducing signal valve of FIG. 1. FIG. 4 shows a conventional hydraulic circuit. 1, 2... Hydraulic pump, 9, 11... Travel motor, 10, 12, 13... Actuator, 3,
5, 6, 7, 8...actuator operation valve, 4
... Surplus operation valve, 16 ... Merging supply pipe, 20
~24... Signal valve, 27... Pressure reduction signal valve, 28...
...Pilot hydraulic power source.

Claims (1)

[Scope of utility model registration request] In a hydraulic circuit that includes two main hydraulic pumps that hydraulically drive construction machinery, separate right and left travel motors that drive the left and right travel devices, and operation valves for other actuators, there is a hydraulic circuit for left and right travel for straight-ahead travel. A signal valve is provided to detect the switching state when the actuator operating valve is switched together with another actuator operating valve that is operated at the same time. is switched by the output signal pressure of the signal valve, and a pipe line from the surplus operating valve is connected to the discharge side of the other pump to merge the discharge oil of both pumps, thereby supplying pressure oil to the left and right traveling motors in parallel. In addition, the pilot pressure is reduced by a pressure reduction signal valve that is switched by the output signal pressure of the signal valve, and the actuator operation valves that are operated simultaneously are switched. A hydraulic circuit for construction machinery, characterized in that the amount of pressure oil supplied to the actuator is restricted to prevent an extreme drop in travel speed.