JPH0621973Y2 - Hydraulic circuit of hydraulic shovel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic circuit of a hydraulic excavator capable of adjusting relative speeds during combined operations of boom raising and turning.

2. Description of the Related Art FIG. 2 is a hydraulic circuit diagram of a conventional art of a hydraulic excavator. In the figure, 1 is a first switching valve for boom (hereinafter referred to as boom 1st valve), 2 is a second switching valve for boom (hereinafter referred to as boom 2nd valve), 3 is a swing valve, 4 is a swing motor, 5
Is a boom cylinder, 6 is a first pump, 7 is a second pump,
Reference numeral 8 is a pilot pump, 9 is a remote control valve for turning, 10 is a remote control valve for boom, and 10 is a remote control valve for boom. The switching valves for controlling various hydraulic actuators are divided into two groups A and B, the swing valve 3 and the boom second valve 2 are provided in parallel in the group 4, and the boom first valve 1 is provided in the group B. The first pump 6 and the second pump 7 are provided as the pressure oil supply sources of the groups A and B, respectively. Next, the case where the boom raising and the turning are simultaneously operated will be described. First, boom remote control valve 10
When the operation lever 11 of is operated from the neutral position to the a position, the pressure oil discharged from the pilot pump 8 is supplied to the oil passages 12, 13,
It passes through the pilot valve 14 and the pilot oil passage 15, and branches there. One acts on the pilot pressure receiving portion 17 of the boom first valve 1 via the pilot oil passage 16, and the other acts from the pilot oil passage 15 It acts on the pilot pressure receiving portion 19 of the boom second valve 2 via the pilot oil passage 18. Therefore, the boom first valve 1 and the boom second valve 2 are
Since it switches from the neutral position to the b position and the c position respectively,
The pressure oil discharged from the second pump 7 is supplied to the oil passages 20, 21, 2
2, check valve 23, position of boom first valve 1 and oil passage 2
4, through the check valve 25 and the throttle portion 26, the oil is sent to the oil chamber on the base end side of the boom cylinder 5, and the pressure oil discharged from the first pump 6 is supplied to the oil passages 27, 28, 29 and the check valve. After passing through 30, the boom position of the second boom valve, and the oil passage 31, they are joined to the oil passage 24. As a result, the boom cylinder 5 is extended and the boom is raised. On the other hand, turning remote control valve 9
When the operation lever 32 of is operated to the two-position or the e-position, the pressure oil discharged from the pilot pump 8 is supplied to the oil passages 12, 33,
It acts on the pilot pressure receiving portion 38 or 39 of the turning valve 3 via the pilot valve 34 or 35 and the pilot oil passage 36 or 37. Therefore, since the swirl valve 3 is switched from the neutral position to the high position or the high position, the discharge pressure oil from the first pump 6 is moved to the oil passages 27, 28, 40, 41, the check valve 42, and the swirl valve 3 to the high position. Alternatively, the oil is fed to the turning motor 4 through the position G. As a result, the turning motor 4 is rotationally operated in either the left or right direction.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the hydraulic circuit of the related art, the relationship between the boom rising speed and the swing speed at the time of performing a combined operation of boom rise and swing is
At the time of circuit design, the load pressure characteristics of the boom cylinder and the swing motor under standard working conditions were calculated and set in advance.

As a result, the hydraulic excavator did not cause any hindrance when performing normal work such as normal excavation work.
However, when the hydraulic excavator operates under conditions different from normal work, for example, when performing simultaneous operation of the swing motor and boom cylinder, when performing a swing while raising the boom by applying a large load to the boom, or when performing deep digging (deep digging). In some cases, the boom did not rise reliably when performing work. Therefore, the driver operates the boom raising operation lever and the turning operation lever while making fine adjustments. This operation requires skill and also reduces workability. The present invention aims to solve the above problems.

Means for solving the problems a. In the hydraulic circuit of the present invention, pressure oil from a pilot pump is supplied to a remote control valve, and various hydraulic actuator control switching valves that operate by pilot pressure obtained by the remote control valve are configured in two groups. In the group of, there is a swing switching valve and a boom second switching valve.
The first switching valve for booms is provided in the other groups, an independent pump is arranged as a pressure oil supply source to each group, and the operation circuit of the swing motor is divided into an oil passage with a throttle part and an open oil passage. In the hydraulic circuit of the hydraulic excavator to be switched, In the middle of the pressure oil supply oil passage for the swing motor, a throttle valve is installed to switch the internal oil passage to an oil passage with a throttle when the pilot pressure acts on the pressure receiver, and the boom of the pressure receiver of the throttle valve and the remote control valve rises. Connect the side pilot pressure circuit with the pilot oil passage, and A solenoid valve is provided in the middle of the pilot oil passage, and a switch for operating the solenoid valve is provided near the driver.

Action a. According to the present invention, when the swing motor and the boom cylinder are simultaneously operated, the operation circuit of the swing motor can be switched to the oil passage with the throttle portion or the open oil passage as required.

B. When the load applied to the boom is large when the swing motor and the boom cylinder are simultaneously operated, the driver judges and turns on the switch. Since the throttle valve provided in the operation circuit of the swing motor switches to the oil passage position with the throttle portion, the amount of pressure oil supplied to the swing motor is slightly reduced. However, since the reduced amount is added to the amount of pressure oil supplied to the boom cylinder, it is possible to turn while raising the boom having a large load without hindrance.

C. Further, even when the throttle valve is switched to the oil passage position with the throttle portion, since the return oil passage of the turning operation circuit is not throttled, back pressure is not applied to the return oil passage, so that the turning start can be efficiently performed.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of the present invention. In the drawing, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numeral 41 is a pressure oil supply oil passage for the swing motor 4, 43 is a throttle valve, 45 is a solenoid valve which is a valve that can open and close the internal oil passage as required, and 47 is a switch. Next, the configuration of the hydraulic circuit of the present invention will be described with reference to FIG. In the hydraulic circuit of the present invention, the throttle valve 43 is arranged in the middle of the pressure oil supply oil passage 41 for the swing motor 4 so that the internal oil passage is switched to the oil passage with the throttle when the pilot pressure acts on the pressure receiving portion.
And a pilot pressure receiving portion 44 of the throttle valve 43,
The boom remote control valve 10 and the boom raising pilot pressure circuit are connected by a pilot oil passage, a solenoid valve 45 is provided in the middle of the pilot oil passage, and a switch 47 for operating the solenoid valve 45 is provided near the driver. It has been configured in the. Therefore, the throttle valve 4 provided in the pressure oil supply oil passage 41 for the swing motor 4
3 is adapted to switch from the open oil passage position to the throttled oil passage position by applying a pilot pressure to the pilot pressure receiving portion 44. Further, the throttle opening degree of the throttle portion in the oil passage position with throttle portion is set for the combined operation of boom raising and turning.

Next, the operation of the hydraulic circuit will be described. First, the case of a boom raising independent operation will be described. In the case of a single operation, it does not matter whether the switch 47 is on or off, so the switch 47 is kept off. Operating lever 11 for boom remote control valve 10
When is operated from the neutral position to the a position, the boom first valve 1 and the boom second valve 2 are switched to the low position and the high position, respectively, and the boom cylinder 5 is extended so that the boom is raised. At this time, since the swing is not operating, the throttle valve 43 provided in the pressure oil supply oil passage 41 for the swing motor 4 is not relevant. Further, in the case of a single turning operation, the operating lever 32 of the turning remote control valve 9 is operated from the neutral position to either the left or right. Then, the swing valve 3 is switched, and the swing motor 4 rotates in either the left or right direction. However, in this case, since the pilot pressure of the boom remote control valve 10 is not derived, the pilot pressure does not act on the pilot pressure receiving portion 44 of the throttle valve 43. Therefore, the throttle valve 43 is
It remains in the open oilway position.

Next, the case of combined operation of boom raising and turning will be described. The switch 47 is turned on. Since the exciting coil 46 of the solenoid valve 45 is energized, the solenoid valve 45 is switched from the tank communication oil passage position to the open oil passage position. When a load is applied to the boom and the operation lever 11 of the boom remote control valve 10 is moved to the a position, the boom cylinder 5 is extended,
The boom rises. At the same time, the pilot pressure derived from the pilot valve 14 of the boom remote control valve 10 passes through the pilot oil passages 15, 16, 49, the reposition of the solenoid valve 45, the pilot oil passage 50, and the pilot pressure received by the throttle valve 43. It acts on the part 44. Therefore, the throttle valve 43
Switch from the open oil passage position to the oil passage position with throttle. When the turning remote control valve 9 is operated in such a state, the turning valve 3 is switched, so that the pressure oil discharged from the first pump 6 is supplied to the oil passages 27, 28, 40, 41 and the throttle valve 43.
The oil is fed to the turning motor 4 via the oil passage position with the throttle portion, the check valve 42, and the turning valve 3. In this case, since the pressure oil supply oil passage 41 of the swing motor 4 is throttled at the throttle portion-equipped oil passage position of the throttle valve 43, the pressure oil supply amount to the swing motor 4 is slightly reduced. However, since the reduced amount is added to the amount of pressure oil supplied to the boom cylinder 5, it is possible to turn while raising the boom having a large load without hindrance. Further, even when the throttle valve 43 is switched to the throttle-equipped oil passage position, the return oil passage (outward passage) of the turning operation circuit is not throttled. Therefore, back pressure is not applied to the return oil passage and the turning operation is started. Can be done efficiently.

Effect of the Invention In the hydraulic circuit of the present invention, a throttle valve is provided in the middle of the pressure oil supply oil passage for the swing motor so that the internal oil passage is switched to the oil passage with the throttle when the pilot pressure acts on the pressure receiving portion. The pressure receiving part of the valve and the boom rising side pilot pressure circuit of the remote control valve are connected by a pilot oil passage, a solenoid valve is provided in the middle of the pilot oil passage, and a switch for operating the solenoid valve is provided near the driver. Provided and configured. As a result, when the hydraulic excavator performs normal work, for example, normal excavation work, the switch for the solenoid valve is turned off at the discretion of the driver.
Since the throttle valve is at the open oil passage position, the above-mentioned normal work can be performed without any trouble. Also, when the hydraulic excavator performs work under conditions different from normal work, for example, when performing simultaneous operation of the swing motor and boom cylinder, when performing a swing while raising the boom by applying a large load to the boom, or when performing deep digging (deep hole When you want to reliably raise the boom, such as when performing work (including digging) (when the boom load is heavy)
When it is desired to give priority (deep hole digging), the driver judges and turns on the switch. Since the solenoid valve is switched, the throttle valve is switched to the throttle oil passage position. Although the amount of pressure oil supplied to the swing motor is slightly reduced, the reduced amount is added to the amount of pressure oil supplied to the boom cylinder.
It is possible to make a turn while raising a boom with a large load without hindrance. Therefore, the hydraulic circuit of the present invention has a simple circuit configuration and can be manufactured at low cost, and a hydraulic excavator equipped with this circuit can easily perform a combined boom raising and turning operation by one-touch switch operation.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of the hydraulic excavator of the present invention, and FIG. 2 is a hydraulic circuit diagram of the prior art. 1 ... Boom first switching valve 2 ... Boom second switching valve 3 ... Swing valve 4 ... Swing motor 5 ... Boom cylinder 9,10 ... Remote control valve 14 ... Boom raising pilot valve 43 ... … Throttle valve 45 …… Solenoid valve

Claims (1)

[Scope of utility model registration request] 1. A switching valve for controlling various hydraulic actuators, which supplies pressure oil from a pilot pump to a remote control valve and operates by pilot pressure obtained by the remote control valve, is composed of two groups, and at least one group A swivel switching valve and a boom second switching valve are provided inside, and a boom first switching valve is provided in the other group, and an independent pump is arranged as a pressure oil supply source to each group. In the hydraulic circuit of a hydraulic excavator in which the motor operating circuit is switched between an oil passage with a throttle and an open oil passage, internal oil will flow when pilot pressure acts on the pressure receiving part in the middle of the pressure oil supply oil passage for the swing motor. A throttle valve is provided so that the passage switches to an oil passage with a throttle portion, and the pressure receiving portion of the throttle valve and the boom rising side pilot pressure circuit of the remote control valve are connected by a pilot oil passage,
A hydraulic circuit for a hydraulic excavator, wherein a solenoid valve is provided in the middle of the pilot oil passage, and a switch for operating the solenoid valve is provided near a driver.