JPS6030731A - Oil-pressure circuit for oil-pressure shovel - Google Patents

Abstract

PURPOSE:To switch travelling and joining by only one lever by a method in which the first logic valve and the second logic valve are provided to the upstream and most downstream of the first and second multiple valves, and the bilateral travelling valve of each multiple valve and the first logic valve are connected with a switch valve. CONSTITUTION:A control valve 3a for left-side travelling, a control valve 3b for slewing, a control valve 3c for arming, and a control valve 3d for booming are connected in parallel to the first oil-pressure pump 1. A control valve 4a for right-side travelling, a control valve 4b for booming, and a control valve 4c for bucket are connected in parallel to the second oil-pressure pump 2. A switch valve 16 is provided in parallel independently of the bilateral travelling motor between the control valves 3a and 3b for bilateral travelling and the travelling motor. Pressure oil in the upstreams of the first and second multiple valves 3 and 4 is led to the switch valve 16 through the first logic valves 3f and 4e, and the second logic valves 3g and 3f are provided in the most downstream of the neutral pipeline of each multiple valve.

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic circuit for a hydraulic excavator, and its purpose is to: 1) enable straight travel without meandering by operating only one lever or pedal; 2) during the above operation. The objective is to maintain the straight running performance even when other operations such as swing, arm, boom, or packet operations are performed at the same time, thereby increasing the functionality of the hydraulic excavator. Furthermore, the present invention aims to provide a hydraulic circuit that can be used for a variety of purposes, reduce driver fatigue, and improve work efficiency.

FIG. 1 shows a conventionally known hydraulic circuit. Reference numeral 1 is a first oil and ash pump, and reference numeral 2 is a second hydraulic pump, each of which is driven by an engine (not shown). Reference numeral 3 designates a first control valve, which includes a left travel valve 3a, a swing valve 3b, an arm valve 3c, a boom 2nd speed valve 3d, and a main relief valve 3e.

4 is the second controller 1~roll valve, valve 4a for right travel;
It has a boom 1st speed valve 4b, a packet valve 4c, and a main valve 4d.

In this conventional hydraulic circuit, 1) when driving in a straight line, the left and right travel valves 3a and 48 must be constantly turned on and held in the same direction at the same time, which has the disadvantage of increasing driver fatigue. Ta.

2) Also, if other operations are performed while traveling straight, the discharge amount of the hydraulic pump on the operation side will be diverted to other operations, so the speed of the travel motor on the operation side will decrease and the vehicle will meander. There were drawbacks.

The present invention has been made in order to improve the above-mentioned drawbacks, and an embodiment of a hydraulic circuit for a hydraulic excavator according to the present invention shown in FIG. 2 will be described below.

In Fig. 2, 1 is the first hydraulic pump, 2 is the second itl+
Each of the pumps is driven by an engine (not shown).

3 is supplied with pressure oil from the first hydraulic pump 1.

The first control 1-roll valve has a left travel valve 3a, a swing valve 3b, an arm valve 3C, a boom 2nd speed valve 3d, and a main relief valve 3C. The 20th sick valve 3g is installed in the branch passage branched from the upstream neutral passage.
is arranged in the neutral passage downstream of control valve 1.

4 is a second control valve to which pressure oil is supplied from the second hydraulic pump 2, and includes a right travel valve/Ia, a boom 1st speed valve 4b, a packet valve 4C, a main valve 4d, and a 10th sick valve 4e. The 20th branch passage is branched from the neutral passage at the most upstream side of Control 1-Roll Valve 2.
A sick valve 4f is disposed in a neutral passage downstream of the control valve 2.

Reference numeral 5.6 indicates a pipe line for guiding pressure oil from the tenth sick valves 3f and 4e, each of which joins a pipe line 8 connected to a switching valve 16, which will be described later, via a check valve 7.7'.

9 and 17 and IO and 18 are supply pipes for left travel, 11 and 1
Reference numerals 9, 12, and 20 are supply and discharge pipes for right travel. 13 is a first pilot pipe that connects the tenth sick valves 3f and 4C and the switching valve 15; 14 is a second pilot pipe that connects the twentieth sick valves 3g and 4f and the switching valve 15; and 15 is the Thick valve 3f, 4e, 3g, 4f
In the neutral position, the first pilot line 13 is in a blocked state (and since the second pilot line 14 is connected to the tank), the tenth thick valve 3
f, 4e are in a closed state, and the 20th sick valves 3g, 4f are in an open state. Therefore, the pressure oil of the first and second hydraulic pumps 1.2 does not flow to the pipe line 8 side. Also, switching valve 1
5 to the "A" or "Open" position, the above is reversed and the pressure oil of the first and second hydraulic pumps 1 and 2 flows into the pipe line 8.

16 is a parallel/independent switching valve that is switched in conjunction with the switching valve 15, and in the neutral position, the supply/discharge pipe 9 for left travel is connected to the pipe 17.
The pipes 10 are connected to the pipes 18, the right-travel supply/discharge pipe 11 is connected to the pipe 19, and the pipe 12 is connected to the pipe 20. Further, the pipes 8, which are the sum of the pipes 5 and 6, which lead the pressure oil from the tenth sick valves 3f and 4e, are connected to the tank passages, respectively.

When the switching valve 16 is switched to the "A" position, the pipe line 8 is the pipe 'Jl! 17 and 20, pipe 10 is connected to pipe 8, pipe 11 is connected to pipe 19, and other pipes 9 and 12 are blocked.

When the switching valve 16 is switched to the "r" position, the pipe line 8 is connected to the pipe line 18 and the pipe line 19, respectively, and the pipe line 9 is connected to the pipe line 1.
7 and the pipe line 12 are each connected to the pipe line 20, and the other pipes wi10 and the pipe line 11 are blocked. In this way, in the case of a parallel circuit, the supply direction of pressure oil to the left and right motors is switched to enable forward and backward travel.

Fig. 3 shows another embodiment of the internal connection of the switching valve 16 shown in Fig. 2. When the switching valve 16' is switched to the "A" and "Port" positions, The structure is such that everything except the connecting pipes are connected to the tank.

FIG. 4 shows another embodiment of the interlocking method of the switching valve 15 and the switching valve 16, in which the switching valve 15 is used as an auxiliary valve for the switching valve 16 so that it can be directly switched.

In the above embodiment, the pilot pipes connecting the first and 20th thick valves 3f, lle, 3g, and 4f and the switching valve 15 and the pipe connecting the tenth thick valve and the switching valve 16 are merged, respectively. Although the embodiment has been described in which the pilot pipes of the first and 20th sick valves are not merged, they are switched separately by two switching valves 15 linked to the switching valve 16. It goes without saying that modifications can be made without departing from the gist of the present invention, such as connecting the tenth sick valve to the individual bows 1 of the switching valve 16.

The present invention has the following configuration, and its operation will be explained below.

1. In the case of independent straight traveling: A) When the switching valve 16 is switched to the "A" position, the pipe 8 is connected to the pipe 17 and the pipe 20, and the pipe 10 is connected to the pipe 1.
8, the conduits 11 are each connected to conduits 19, and conduits 9 and 12 form a block.

Also, since the switching valve 15 linked to the switching valve 16 is also switched to the "A" position, the first pilot pipe 13 is connected to the tank via the switching valve 15, so the tenth sick valves 3f and 4e are in the open state. Further, the second pilot 1 to the pipe line 14 are isolated from the tank by the switching valve 15, and the 20th pilot valve 3 is connected to the tank.
g and 4f are in the closed state. For this reason, the first hydraulic pump 1
The pressure oil of the second hydraulic pump 2 is supplied to the tenth sick valves 3f and 4e, the pipe line 5 and the pipe line 6, and the check valve 7.
7', flows into the conduit 8, is divided into the conduit 17 and the conduit 20 in equal amounts via the switching valve 16, and flows into the left and right travel motors. Also, the return oil from the left and right travel motors is passed through pipes 18 and 19, and a switching valve 16 to pipe l.
Returns to the tank through O and pipe 11, left travel valve 3a and right travel valve 4a. As described above, the same pressure and the same amount of pressure oil are supplied to the left and right travel motors, so that the left and right travel motors move straight in the forward direction at the same speed.

B) When the switching valve 16 is switched to the "1 port" position, the direction of supply of pressure oil to the travel motors is reversed from the explanation in item A), but in the same way, the left and right travel motors move straight in the reverse direction at the same speed. I will do it.

2. When other operations are performed at the same time while traveling straight: A) If turning is simultaneously performed while traveling straight, switch the switching valve 16 to the "A" (forward) or "1" (reverse) position, and then turn When the switching valve 3b is switched, the switching valve 15, the 10th thick valve 3f, 4e, and the 20th thick valve 3g
, 4f are the same as explained in 1-A) and 1-B) above, and the turning valve 3b is a parallel circuit for the left and right travel motor and the first hydraulic pump 1, and a parallel circuit for the second hydraulic pump 2. It becomes an independent circuit.

This means that at the beginning of turning, the running drive pressure is generally lower, so the turning is accelerated by that pressure, and most of the discharge amount of the first hydraulic pump 1 flows into the left and right moving motors.
The sum of the above-mentioned σ (input amount 10) and the discharge amount of the second pressure pump 2 is divided into the left and right traveling motors.

Note that when the swing speed increases and the swing motor consumes all of the discharge amount of the first hydraulic pump 1, the discharge amount of the first hydraulic pump 1 does not flow to the left and right travel motors at all, and the discharge amount of the second hydraulic pump 2 is reduced. amount is shunted to the left and right travel motors. Furthermore, since the check valve 7 is provided in the conduit 5, the pressure oil of the second hydraulic pump 2 will not flow back to the first pump group side.

Therefore, even if a turning operation is performed while traveling straight, the turning operation can be performed while maintaining straight traveling, and the traveling speed also gradually decreases without suddenly decreasing, and eventually the second hydraulic pump 2
It only decreases by an amount commensurate with the discharge amount, and there is no further decrease.

B) In the case of simultaneous arm operation while traveling straight: 2-A) above
It is possible to operate the arm while driving straight in the same way. Furthermore, if the arm drive pressure becomes higher than the running drive pressure when escaping from a muddy area, the pressure on the first pressure oil pump 1 side may not rise sufficiently and the retracting force of the arm may not be utilized. In this case, if a suitable throttle is installed in the passage corresponding to the conduit 5, the arm retraction pressure will increase and the arm retraction force can be used, which is effective for escaping from muddy areas.

C) In the case of simultaneous boom operation while traveling straight: 2-A) above
, 2-B), and the boom can be operated while maintaining straight travel. Also in this case, as in 2-B), if the boom drive pressure is higher than the running drive pressure, the boom may not be able to be operated, so if an appropriate restrictor is installed in the passage corresponding to pipe 6, the above drawback can be overcome. It disappears.

D) In the case of simultaneous packet operation while traveling straight: 2-C above
), and packet operations are possible while maintaining straight forward travel.

As described above, in the present invention, the switching valve 16 and the switching valve 15 can be easily operated by merging the first and second hydraulic pumps and switching the running direction by operating only one lever or pedal. becomes.

Further, even if other operations are performed during the above operation, the straightness of travel can be maintained, which has the advantage that the hydraulic excavator can be used for multiple purposes.

In addition, when performing the same traveling operation as before, selector valve 15.1
This can be done by operating the left and right travel valves 3a and 4a in the same way as in the past, without operating the valve 6.

Also, in Figure 2, 1. Although the second hydraulic pumps 1 and 2 are shown as fixed capacity pumps, they may be variable capacity pumps, and although the switching valves 15 and 16 are shown as manually operated, they may of course be pilot operated valves or electromagnetic valves. Furthermore, the 10th
Thick valves 3f, 4e and 20th thick valve 3g,
4f is the 1st. Although it is integrated with the second control valves 3 and 4, they may be installed separately.

Although the present invention has been described above with respect to a hydraulic excavator, it goes without saying that it can also be applied to machines whose travel is driven by a hydraulic motor and whose other operations are driven by a hydraulic motor or a hydraulic cylinder, such as a hydraulic crawler crane.

[Brief explanation of the drawing]

FIG. 1 is a conventionally known hydraulic circuit diagram. FIG. 2 is an improved hydraulic circuit diagram according to the present invention. FIG. 3 shows another embodiment of the internal connection of the switching valve. FIG. 4 shows another embodiment of the switching valve interlocking method. In the figure: ■ First hydraulic pump 2 Second hydraulic pump 3 First control valve 3a Left travel valve 3b Swing valve 3c Arm valve 3d Boom 2nd speed valve 3e Main relief valve 3f 10th sick valve 20th sick valve 4 2nd control valve 4a Right travel valve 4b Boom 1st speed valve 4c Packet valve 4d Main valve 4e 10th sick valve 4f 20th sick valve 5.6 Pipe 7.7' Check valve 8 (10th
Pressure oil from the Tsuji valve joins) Pipe 9, +0.17.18 Left travel supply/discharge pipe 11, . 1
2, 19, 20 Right running supply/discharge pipe 13 1st pilot pipe 14 2nd pilot pipe] 5 Switching valve 16 Switching valve and above Applicant Isamu Ohashi, Patent Attorney, Sumitomo Heavy Industries, Ltd.

Claims (1)

[Claims] In the hydraulic circuit of a hydraulic excavator that has two pumps and two control valves, pressure oil is supplied and discharged to the left and right travel motors through a pipe that connects the left and right travel motors with the left and right travel valves of the first and second control valves. A 10th switch valve is provided in each of the pipelines that branch from the most upstream of the first and second controllers 1 to 1 and roll valves and connect to the switching valve, and a 10th switch valve is installed in each of the pipes that connect to the switching valve. A 20th sick valve is provided in each of the 1st and 20th sick valves, and the pilot pipes of the 1st and 20th sick valves are connected to switching valves that are switched in conjunction with the independent/parallel switching operations of the switching valves, so that they are alternately opened and closed. A hydraulic circuit for a hydraulic excavator characterized by: