JPH0643258Y2 - Small excavator hydraulic circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic circuit of a small excavator equipped with a dozer device.

2. Description of the Related Art FIG. 2 is a side view of a small shovel. In the figure,
1 is a lower traveling body, 2 and 3 are traveling motors mounted on the left and right sides of the lower traveling body 1, 4 is an upper swing body, 5 is a swing motor attached to the upper swing body 4, and 6 is a front of the upper swing body 4. 1 is a work attachment attached to the section, 7 is a boom cylinder, 8 is an arm cylinder, 9 is a bucket cylinder, 10 is a dozer device attached to the front part of the lower traveling body 1, and 11 is a dozer cylinder of the dozer device 10. FIG. 3 is a prior art hydraulic circuit diagram of a small shovel. In the figure, 12 and 13 are first and second pumps respectively, 14 and 15 are left and right traveling valves, 16 is a swing valve, 17 is a dozer valve, 18, 19 and 20 are switching valves for various hydraulic actuators, and 21 , 22 are relief valves, 23, ..., 29 are check valves, and 30 is an oil tank. It should be noted that symbols of various hydraulic actuators are not shown.

Next, the configuration of the conventional hydraulic circuit will be described with reference to FIG. Various hydraulic actuators of the small excavator are divided into two groups A and B, which are operated by the pressure oil discharged from the first and second pumps 12 and 13, respectively. Also, the left and right traveling valves
14 and 15 are provided in the front row of each of groups A and B, and the travel valve 1
4, the switching valves 18, 19 and the traveling valve 15, the swing valve 16, the switching valve 20, the dozer valve 11 are connected in tandem, and the switching valves 18, 19 are swiveled in parallel with the traveling valve 14 and swiveled. The valve 16, the switching valve 20, and the dozer valve 11 are connected to the traveling valve 15 in parallel.

Next, the operation of the hydraulic actuator in the conventional hydraulic circuit will be described. Travel valve 14 and switching valve 1 in group A
When 8 and 19 are switched, the pressure oil discharged from the first pump 12 is sent to the traveling motor 2 and the other hydraulic actuators in group A to operate the hydraulic actuators in group A. On the other hand, when the traveling valve 15, the swing valve 16, the switching valve 20, and the dozer valve 17 in the group B are switched, the pressure oil discharged from the second pump 13 is transferred to the traveling motor 3, the swing motor 5, other hydraulic actuators, Oil is sent to the dozer cylinder 11, and Group B
Operate the internal hydraulic actuator.

Problems to be solved by the invention When the small shovel travels straight ahead, the travel valves 14, 15
Operate simultaneously. The discharge pressure oil from the first pump 12 is supplied to the traveling motor 2 via the traveling valve 14, and the second pump
Since the pressure oil discharged from 13 is supplied to the traveling motor 3 via the traveling valve 15, the small excavator travels straight ahead. However, while traveling straight ahead, any of the switching valves other than the traveling valves 14 and 15,
For example, when the turning valve 16 in the group B is switched, the pressure oil discharged from the second pump 13 is simultaneously sent to both the traveling motor 3 and the turning motor 5. Therefore, the amount of oil supplied from the second pump 13 to the traveling motor 3 is smaller than the amount of oil supplied from the first pump 12 to the traveling motor 2, so that the rotation speed of the traveling motor 3 is equal to that of the traveling motor 2. The number was smaller than the number, and the small shovel sometimes caused meandering. Various hydraulic circuits have been taken into consideration to solve the above problems, but none have been sufficient. An object of the present invention is to provide a hydraulic circuit in which a small shovel equipped with a dozer device is provided with a straight traveling function and independent turning and dozer operating functions.

Means for solving the problems a. In the present invention, among the various hydraulic actuators of the small excavator equipped with the dozer device, the actuators other than the swing motor are divided into two groups A and B.
The pressure oil from the first and second pumps, and the pressure oil from the third pump to the swing motor, and the left and right travel valves are set to the most upstream side of each group A, B. Tandem, and the other actuator control switching valve on the downstream side is arranged in parallel.
In a hydraulic circuit in which pressure oil from one hydraulic pump of the first and second pumps is supplied to the left and right traveling motors, and pressure oil from the other hydraulic pump is supplied to the other actuators. The swing motor and the dozer cylinder are set in the group C, and the pressure oil from the third pump is supplied to the group C. c. In addition, a solenoid valve is provided that switches to the pilot pressure derivation position by inputting the rotation signals of the left and right traveling motors. In addition, each side has a pilot pressure receiving part,
A travel straight valve is provided at the position of a single oil passage during a single travel operation, and a travel straight valve capable of switching to a plurality of oil passage positions having an oil passage with a throttle portion at the same time when a travel motor and an actuator other than group C are simultaneously operated. A single oil passage position side pilot pressure pressure receiving portion of the straight valve is connected to a pressure oil supply circuit for other actuators of groups A and B, and a plurality of oil passage position side pilot pressure receiving portions is connected to the pilot pressure derivation portion of the solenoid valve. To communicate with e. Further, the upstream side of the oil passage with the throttle portion at a plurality of oil passage positions of the traveling straight-travel valve and the pressure oil supply circuit for the traveling motor are made to communicate with each other through the throttle portion and the check valve, and the excess of the oil passage with the throttle portion is provided on the upstream side. It is configured to supply pressure oil to the traveling motor.

Action a. Since a straight traveling valve was installed in the oil passage that connects the left and right traveling valves and other switching valves to the first and second pumps, when the left and right traveling valves are operated simultaneously, a controller or the like is operated based on the switching operation signal. , The signal output switches the traveling straight valve and the switching valve. As a result, the pressure oil discharged from the first pump is supplied to the left and right traveling motors in parallel, so that the small excavator travels straight ahead.

B. On the other hand, since the third pump is provided as a hydraulic power source other than the first and second pumps in the hydraulic circuit of the small shovel, and the swing motor and the dozer cylinder of the hydraulic actuators other than the left and right traveling motors are separated as a group C, Even if the turning motor and the dozer are operated while the vehicle is running straight, the small excavator runs straight.

Embodiment Hereinafter, a hydraulic circuit of a compact shovel according to the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. First
The figure is a hydraulic circuit diagram according to the present invention. In the figure, 31 is a straight traveling valve, 32 is a solenoid valve, 33 is a third pump, 34
Is a relief valve, 35, 36 and 37 are check valves, 38 is a throttle, 39 is a controller, and 40 and 41 are travel valves 14 and 15, respectively.
It is a signal generator provided near the operation lever.

Next, the configuration of the hydraulic circuit of the present invention will be described with reference to FIG. In the present invention, the swing motor 5 and the dozer cylinder 11 are set in the group C, and the third pump 33 is set for the group C.
From the left and right traveling motors 2
Solenoid valve that switches to pilot pressure derivation position B by inputting rotation operation signals of 3 and 3 via controller 39
32 is provided. Further, a plurality of oil passages each having a pilot pressure receiving portion on the left and right sides are provided at a single oil passage position c when the traveling alone is operated, and an oil passage with a throttle portion 51 is provided when the traveling motors 2 and 3 and other actuators other than the group C are simultaneously operated. The traveling straight valve 31 that can be switched to the road position D is provided, and the single pilot oil pressure position of the traveling straight valve 31 on the side of the oil passage position C (not marked) is used to adjust the pressure for other actuators of groups A and B. The pilot pressure receiving portion 45, which is communicated with the oil supply circuit and is located on the second oil passage position D side, is communicated with the pilot pressure derivation portion of the solenoid valve 32. Further, the upstream side of the oil passage with the throttle portion 51 at the plural oil passage positions D of the traveling straight-travel valve 31 and the pressure oil supply circuit for the traveling motors (2 and 3) are connected via the throttle portion 38 and the check valve 37. In fact, the excess pressure oil on the upstream side of the oil passage with the throttle portion 51 is configured to be supplied to the traveling motors 2 and 3.

Next, the operation of the hydraulic circuit of the present invention will be described. In the present invention, the swing motor 5 and the dozer cylinder 11 are set in the group C, and the pressure oil from the third pump 33 is supplied to the group C. When the small shovel performs the dozer work, the dozer cylinder 11 and the swing motor 5 are hardly operated at the same time. Therefore, since the turning can be operated independently, the turning driving force at the time of work can be always ensured. In addition, it can be operated independently, that is, the left and right travel valves
When 14 and 15 are operated simultaneously, the switching operation signal from the signal generators 40 and 41 is input to the controller 39, and acts on the solenoid 42 of the solenoid valve 32 via the controller 39. Therefore, the solenoid valve 32 is switched from the tank communication oil passage position a to the pilot pressure derivation position b.
The pump pressure of the pump 13 passes through the oil passage 43, the position of the solenoid valve 32, and the oil passage 44, and acts on the pilot pressure receiving portion 45 of the straight travel valve 31. However, at this time, the pressure oil supply circuits for the other actuators of the groups A and B are shut off at the neutral positions of the other actuator control switching valves 18, 19 and 20, respectively, and the traveling straight valve 31 is not switched. Since a pressure receiving area difference (not shown) is set in the left and right pilot pressure receiving portions of the traveling straight-travel valve 31, the pilot pressure derived from the pilot pressure deriving position B of the solenoid valve 32 is transmitted through the oil passage 44. Even if it acts on the pressure receiving portion, the traveling straight-ahead valve 31 can be held at the single oil passage position c. Next, in the above state, the switching valve for controlling other actuators in groups A and B,
If at least one of 19, 20 is switched, the hydraulic pressure in the pressure oil supply circuit will drop instantaneously.
Reference numeral 31 switches from a single oil passage position c to a plurality of oil passage positions d having an oil passage with a throttle portion 51. The pressure oil discharged from the first pump 12 passes through the oil passage 46, one of which passes through the oil passage 47 and the traveling valve 14 and is supplied to the traveling motor 2, and the other of which branches off at the oil passage 46.
It is supplied to the traveling motor 3 via 48, the two positions of the traveling straight-travel valve 31, the oil passages 49 and 50, and the traveling valve 15. As a result, the pressure oil discharged from the first pump 12 is supplied in parallel to the left and right traveling motors 2 and 3, and the small excavator travels straight. On the other hand, the pressure oil from the second pump 13 is supplied to the actuators respectively connected to the switching valves 18, 19, 20. Since the throttle portion 51 is provided in the oil passage in the second position of the traveling straight traveling valve 31, when the small excavator is operating any of the other hydraulic actuators 18, 19, 20 during traveling straight traveling, The traveling straight-ahead valve 31 can be held in the two position. At the same time, the surplus pressure oil of the second pump 13 is transferred to the oil passage 5
2. Travel motors 2 and 3 via check valve 37 and throttle 38
Can be reinforced. In the present invention, as described above, the throttle portions 51 are provided at the plural oil passage positions D of the straight travel valve 31, so that the flow rate to other hydraulic actuators is adjusted and the feeling (operation feeling) at the time of valve switching. Can also be improved.

Effect of the Invention In the hydraulic circuit of the present invention, the swing motor and the dozer cylinder are set in the group C, and the pressure oil from the third pump is supplied to the group C, so that the swing or the dozer can be operated independently. It can be carried out. Also, because the oil passages with throttles are provided at the multiple oil passage positions for the traveling straight travel of the traveling straight travel valve,
It is possible to prevent a decrease in traveling speed by replenishing excess pressure oil on the upstream side of the oil passage with a throttle portion to the traveling motor when traveling and simultaneously operating other actuators. At the same time, the flow rate to actuators other than the traveling motors in groups A and B is adjusted by the throttle portion, and the feeling (driving feeling) at the time of valve switching can be improved. Further, in the hydraulic circuit of the present invention, the minimum number of valves, that is, the straight traveling valve and the electromagnetic valve are arranged to surely perform the straight traveling, so that the maintainability and layout of the circuit equipment can be improved. .

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram according to the present invention, FIG. 2 is a side view of a small shovel, and FIG. 3 is a conventional hydraulic circuit diagram. 2,3 Travel motor 5 Swing motor 11 Dozer cylinder 12 First pump 13 Second pump 14,15 Travel valve 16 Swirling valve 17 Dozer valve 18,19, 20 …… Switching valve 31 …… Direct travel valve 32 …… Solenoid valve 33 …… Third pump 39 …… Controller

Claims (1)

[Scope of utility model registration request] 1. Various types of hydraulic actuators of a small excavator equipped with a dozer device are divided into actuators other than a swing motor into two groups A and B, and the first and second pumps for the groups A and B are divided into groups. Pressure oil and pressure oil from the third pump are supplied to the swing motor, and the left and right traveling valves are arranged in tandem on the most upstream side of each group A and B, and the other downstream side When the actuator control switching valves are arranged in parallel and other actuators other than traveling and turning are operated when the traveling motor rotates,
In the hydraulic circuit in which the pressure oil from one hydraulic pump of the second pump is supplied to the left and right traveling motors and the pressure oil from the other hydraulic pump is supplied to the other actuator, the swing motor and the dozer are provided. A solenoid valve that is set to a group C with cylinders, supplies pressure oil from the third pump to the group C, and switches to the pilot pressure derivation position by inputting rotation signals of the left and right traveling motors. Is also provided with pilot pressure receiving parts on the left and right respectively, and in the single oil passage position during traveling alone operation,
When the traveling motor and other actuators other than group C are operated simultaneously, a traveling straight-ahead valve that can switch to a plurality of oil passage positions having an oil passage with a throttle portion is provided, and the pilot pressure on the single oil passage position side of the traveling straight-ahead valve is arranged. The pressure receiving portion is connected to the pressure oil supply circuits for the other actuators of groups A and B, and the pilot pressure receiving portion on the side of the plurality of oil passages is connected to the pilot pressure derivation portion of the solenoid valve. The upstream side of the oil passage with the throttle at the road position and the pressure oil supply circuit for the traveling motor are made to communicate with each other via the throttle and the check valve, and the excess pressure oil on the upstream side of the oil passage with the throttle is replenished to the traveling motor. The hydraulic circuit of a small excavator characterized by doing so.