JPH0526323Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a merging circuit for hydraulic actuators installed in construction machinery.

BACKGROUND ART FIG. 3 is an overall side view of a hydraulic excavator among construction machines. In the figure, 1 is the lower traveling body of the hydraulic excavator, 2 is the upper rotating body, and 3 is the upper rotating body 2.
Work attachment attached to the front part of the 4
is the boom of work attachment 3, 5 is the arm,
6 is a bucket, 7 is a boom cylinder, 8 is an arm cylinder, and 9 is a bucket cylinder. FIG. 4 is a hydraulic circuit diagram of the prior art. In the figure,
10 is a first pump, 11 is a second pump, 12 is a pilot pump, 13 is a remote control valve, 14 is a remote control operating lever, 15 and 16 are respective pilot valves, 17 is a first pilot switching valve, 18, 1
Reference numeral 9 denotes pilot pressure receiving portions on the left and right sides of the first pilot switching valve 17, 20 a spring for a spool (not shown) of the first pilot switching valve 17, and 21
22 is a confluence side pilot pressure receiving part of the second pilot switching valve 21, 23 is a spring for a spool (not shown) of the second pilot switching valve 21, and 24 is a specific hydraulic actuator (for example, the boom cylinder 7). ), 25 is a hydraulic oil tank.

Next, the configuration of a conventional hydraulic circuit will be described with reference to FIGS. 3 and 4. In the conventional hydraulic circuit,
The first pump 10 and the second pump serve as pressure oil supply sources for various hydraulic actuators installed in the hydraulic excavator.
A pump 11 is arranged. Therefore, when a specific operating lever 14 of the remote control operating levers is operated in the merging side direction A, both the first pilot switching valve 17 and the second pilot switching valve 21 are switched, and the first pump 10 and the second The pressure oil discharged from the pump 11 is configured to be combined and supplied to the specific hydraulic actuator 24.

Next, the function of the hydraulic circuit of the prior art will be described. When the remote control operation lever 14 is operated in the confluence side direction A, the pilot pressure oil discharged from the pilot pump 12 passes through the oil passage 26 and the confluence side pilot valve 15, one of which passes through the pilot oil passage 27 and acts on the pilot pressure receiving portion 18 of the first pilot switching valve 17. The other of which branches off from the confluence side pilot valve 15 and flows through the pilot oil passage 28.
The pressure is applied to the pilot pressure receiving portion 22 of the second pilot switching valve 21 through the spool spring 20 of the first pilot switching valve 17.
The spring set loads of the spool spring 23 of the second pilot switching valve 21 are set differently when the spools of the pilot switching valves 17 and 21 are assembled. Therefore, the pilot pressure action related to the stroke operation of the spool is as follows:
The second pilot switching valve 21 is not equal to the first pilot switching valve 17. That is, the second pilot switching valve 21 is switched slightly later than the first pilot switching valve 17. As a result, the first pilot switching valve 17 is first
The first pump 1 is switched from the neutral position to the B position.
The discharge pressure oil from the second pump 11 is fed to the specific hydraulic actuator 24 via the oil passage 29, the B position of the first pilot switching valve 17, and oil passages 30 and 31. The specific hydraulic actuator 24 operates at the first speed. After a slight delay, the second pilot switching valve 21 switches and switches from the neutral position to the C position. The discharge pressure oil from the second pump 11 is fed to the specific hydraulic actuator 24 via the oil passage 29, the B position of the first pilot switching valve 17, and oil passages 30 and 31.
Oil passage 32, second pilot switching valve 21 in position C,
The oil passes through an oil passage 33 and joins an oil passage 31. The specific hydraulic actuator 24 includes a first pump 10 and a second pump 11.
Since the pressure oil discharged from the pump 11 is joined and sent, the operation speed is the second speed which is faster than the first speed.

Problems to be solved by this invention Construction machines engage in various types of work by operating various hydraulic actuators installed in their bodies. At that time, the specified hydraulic actuator having the above-mentioned merging circuit is also operated, but even though the types of work to be performed are different (for example, excavation work, crane work, etc.), the first speed of the specified hydraulic actuator is activated. The timing of operation transition between 2nd speed and 2nd speed was limited to one specification. For this reason, it is not possible to adjust the timing of the second speed earlier or later depending on the work or job content. Even if an attempt was made to adjust the set load of the spring for the spool of the pilot switching valve, it would be difficult for the driver to do so.

The purpose of this invention is to solve the above-mentioned problems and provide a hydraulic circuit for construction machinery that allows the operator to freely change and adjust the timing of the second speed according to the type of work.

Means for Solving the Problems The means of this invention taken to solve the above problems are as follows: (a) Of the various pilot switching valves installed on construction machinery, both the first pilot switching valve and the second pilot switching valve A variable throttle section is provided in the pilot oil passage that communicates the confluence side pilot valve of the remote control remote control valve to be switched and the confluence side pilot pressure receiving section of the second pilot switching valve, The oil passage communicating with the confluence side pilot pressure receiving part of the second pilot switching valve is connected to the hydraulic oil tank via a fixed throttle part.

Operation A: When the remote control lever that operates a specific hydraulic actuator among the various hydraulic actuators installed on construction machinery is operated in the direction of the merging side, the pilot pressure oil discharged from the pilot pump passes through the merging side pilot valve; acts on the pilot pressure receiving portion of the first pilot switching valve.

(b) The other branch is branched from the merging side pilot valve, passes through a variable throttle portion, and acts on the merging side pilot pressure receiving portion of the second pilot switching valve. At this time, a part of the pilot pressure oil flows out into the hydraulic oil tank through the fixed throttle part through the oil passage communicating the variable throttle part and the confluence side pilot pressure receiving part for the second pilot switching valve. As a result, the timing of the switching operation of the second pilot switching valve is slightly delayed from that of the first pilot switching valve.

C. Therefore, by adjusting the throttle opening degree of the variable throttle section in item (B) above, the timing for slightly delaying the switching operation of the second pilot switching valve can be adjusted, so the timing for the second speed of the specific hydraulic actuator can be adjusted freely. Can be adjusted to change.

Embodiments Hereinafter, a hydraulic circuit according to this invention will be explained in detail based on the drawings. FIG. 1 is a hydraulic circuit diagram according to this invention. In the figure, the same reference numerals are given to the same components as in the prior art. 34 is a variable diaphragm section, and 35 is a fixed diaphragm section.

Next, the configuration of the hydraulic circuit according to this invention will be explained in the first part.
Let's talk about the diagram. The merging side pilot valve 15 of the remote control valve 13 for switching both the first pilot switching valve 17 and the second pilot switching valve 21 is communicated with the merging side pilot pressure receiving part 22 of the second pilot switching valve 21. A variable throttle part 34 is provided in the pilot oil passage. At the same time, an oil passage 36 communicating the variable throttle part 34 and the confluence side pilot pressure receiving part 22 of the second pilot switching valve 21 and the hydraulic oil tank 25 are connected via a fixed throttle part 35. did.

Next, the functions of the hydraulic circuit according to this invention will be described. When the remote control operation lever 14 is operated in the merging side direction A, the pressure oil discharged from the pilot pump 12 passes through the merging side pilot valve 15, and one side passes through the pilot pressure receiving part of the first pilot switching valve 17 as in the prior art. Acts on 18. The other branch is branched from the merging side pilot valve 15 and acts on the merging side pilot pressure receiving section 22 of the second pilot switching valve 21 via an oil passage 37, a variable throttle section 34, and an oil passage 36. At that time, some of the pilot pressure oil is transferred to the variable throttle section 34 and the confluence side pilot pressure receiving section 2 for the second pilot switching valve 21.
The oil flows out from the oil passage 36 that communicates with the hydraulic oil tank 25 through the fixed throttle part 35. As a result, the timing of the switching operation of the second pilot switching valve 21 is slightly delayed from that of the first pilot switching valve 17. Therefore, the operator of the construction machine can adjust the timing to slightly delay the switching operation of the second pilot switching valve 21 by adjusting the throttle opening degree of the variable throttle section 34. The timing can be changed and adjusted freely.

FIG. 2 is a diagram of a multi-stage diaphragm section 38 that can be used in place of the variable diaphragm section 34 in FIG. 1 as another embodiment of this invention. Fixed throttle part 39,
40 is the confluence side pilot valve 1 of the remote control valve 13.
5 and the merging side pilot pressure receiving part 22 of the second pilot switching valve 21 are provided in parallel in the pilot oil passage communicating with the confluence side pilot pressure receiving part 22 of the second pilot switching valve 21.
The oil passage on the side is opened and closed by switching operation of the on-off valve 41,
The flow rate of pilot pressure oil can be adjusted in stages.

Note that the variable throttle section 34, fixed throttle section 35, and multi-stage throttle section 38 described above may be structurally built into or assembled into the pilot switching valve. In addition, the hydraulic oil tank 25 is located on the fixed throttle part 35 side.
Therefore, by adjusting the throttle opening degree of the variable throttle section 34, the pressure loss related to the second speed can also be adjusted.

Effects of the invention In the conventional hydraulic circuit for construction machinery equipped with a specific hydraulic actuator in which the second gear operates with a slight delay in timing from the first gear, the conventional hydraulic circuit for the construction machine is equipped with a specific hydraulic actuator that operates with a slight delay in timing from the first gear. Regardless, the timing of operation transition between the first speed and the second speed of the specific hydraulic actuator is limited to one specification.
For this purpose, depending on the work and job content,
It was not possible to adjust the speed timing earlier or later. Even if an attempt was made to adjust the set load of the spring for the spool of the pilot switching valve, it would be difficult for the driver to do so.

However, in the hydraulic circuit according to this invention, the merging side pilot valve of the remote control valve and the second
A variable throttle part is provided in a pilot oil passage that communicates with a merging side pilot pressure receiving part of a pilot switching valve, and an oil passage that communicates the variable throttle part with a merging side pilot pressure receiving part for a second pilot switching valve; It was connected to the hydraulic oil tank via a fixed throttle. Therefore, the operator of the construction machine can adjust the throttle opening degree of the variable throttle section and adjust the timing of the second speed for the specific hydraulic actuator in the merging circuit to be earlier or later. At the same time, the pressure loss associated with the second speed can also be adjusted.

Therefore, in the hydraulic circuit of the construction machine according to this invention, the timing of the second speed of the specific hydraulic actuator for merging can be freely changed and adjusted according to the type of work, thereby improving the work functionality of the construction machine. .

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram according to this invention, Fig. 2 is a diagram of a multi-stage throttle section relating to another embodiment of this invention, Fig. 3 is an overall side view of a hydraulic excavator, and Fig. 4 is a hydraulic circuit diagram of a conventional technology. It is a circuit diagram. 10...first pump, 11...second pump, 1
2...Pilot pump, 13...Remote control valve,
14... Operating lever, 15, 16... Pilot valve, 17... First pilot switching valve, 18, 1
9, 22...Pilot pressure receiving part, 21...Second
Pilot switching valve, 24... Specific hydraulic actuator, 25... Hydraulic oil tank, 34... Variable throttle section, 35, 39, 40... Fixed throttle section.

Claims (1)

[Scope of utility model registration request] A first pump and a second pump are arranged as pressure oil supply sources for various hydraulic actuators installed in construction machinery. In a hydraulic circuit in which two pilot switching valves are both operated to switch, pressure oil discharged from the first pump and the second pump can be combined and supplied to a specific hydraulic actuator, the merging side pilot valve of the remote control valve for remote control, and the above-mentioned A variable throttle part is provided in the pilot oil passage that communicates with the confluence side pilot pressure receiving part of the second pilot switching valve, and
A hydraulic circuit for construction machinery, characterized in that an oil passage communicating the variable throttle section and the pilot pressure receiving section of the second pilot switching valve and a hydraulic oil tank are connected via a fixed throttle section.