CN108978771A - Hydraulic slewing system and excavator - Google Patents

Abstract

The present invention relates to an excavator, in order to solve the problem that the existing excavator may have the problem of overspeeding of the slewing motor when working on a slope; it provides an excavator slewing hydraulic system, including a slewing motor, a slewing control main valve, a pilot valve, and a controller , speed sensor, the two connecting oil lines between the pilot valve and the pilot liquid control terminals at both ends of the swing control main valve are equipped with solenoid valves connected to the controller. When the speed of the swing motor exceeds the preset value, the controller will send The solenoid valve outputs a control signal to reduce the pilot pressure transmitted to the pilot liquid control end of the swing control main valve until the rotation speed of the swing motor is lower than the preset value. In the present invention, when the slewing motor is slewing overspeed under the support of the bucket and the load, the pilot pressure transmitted to the pilot liquid control end of the slewing control main valve is reduced, and the speed of the slewing motor is reduced, thereby protecting the slewing motor from Possible damage due to overspeed rotation.

Description

Swing hydraulic system and excavator

technical field

The invention relates to a rotary hydraulic system, more specifically, to a rotary hydraulic system and an excavator.

Background technique

The excavator is composed of a lower traveling mechanism and an upper body slewing and installed on the lower traveling mechanism, and the slewing of the upper body is driven by a slewing motor. When the excavator is working on flat ground, the rotation of the upper body does not cause a change in the height of the center of gravity of the upper body, and the center of gravity of the upper body moves in the horizontal plane. The power to rotate the upper body of the excavator comes from the slewing motor, so the slewing motor will not rotate too fast to cause excessive pressure at the oil discharge end of the slewing motor and air suction at the oil inlet end of the slewing motor.

However, the excavator is known as the king of construction machinery, and it is suitable for various working conditions, among which half-slope operation is a relatively common working condition. Different from the level ground, when the excavator is turning on a half slope, the center of gravity of the upper body moves in a plane with a certain angle with the horizontal plane. If the load of the bucket is heavy or the turning radius of the bucket is large, the body Due to the influence of gravitational potential energy brought by the tilt angle, the moment of inertia of the upper mechanism will also increase. When the excavator bucket rotates from high to low, the speed will increase, and there may be overspeed in the rotation, overpressure and rotation at the oil discharge end of the swing motor Phenomena such as air suction at the oil inlet end of the motor will seriously endanger the service life of the motor.

Contents of the invention

The technical problem to be solved by the present invention is to provide a rotary hydraulic system and an excavator for the problem of overspeeding of the rotary motor that may occur when the existing excavator works on a slope, so as to avoid the excavator working on a slope due to the bucket and When the material rotates from a high place to a low place, its potential energy accelerates the speed of rotation, causing the phenomenon of overspeed, overpressure and air suction of the rotary motor to avoid damage and shortened life of the rotary motor.

The technical solution for realizing the object of the present invention is as follows: a rotary hydraulic system is provided, including a rotary motor, a rotary control main valve connected with the rotary motor for controlling the rotary motor, and pilot liquid control ports at both ends of the rotary control main valve A connected pilot valve and an oil pumping system connected to the main valve for slewing control; it is characterized in that it includes a controller and a speed sensor connected to the controller for measuring the rotational speed of the slewing motor. Solenoid valves are installed on the two connecting oil lines between the pilot liquid control terminals, and the electric control terminals of the solenoid valves are connected to the controller. When the rotation speed of the rotary motor exceeds the preset value, the controller sends The solenoid valve outputs a control signal so that the pilot pressure transmitted to the pilot liquid control end of the main valve of the swing control decreases until the rotation speed of the swing motor is lower than the preset value. In the present invention, when the slewing hydraulic system is applied to the excavator and the excavator is slewing on the slope, when the slewing motor is supported by the bucket and the load to make its speed exceed the design value (preset value), the controller Output the control signal to the solenoid valve, the solenoid valve reduces the pilot pressure transmitted to the pilot liquid control end of the main rotary control valve, and the valve opening of the main rotary control valve decreases, so that the flow entering the rotary motor decreases and the oil return back pressure increases , the rotation speed of the swing motor is reduced so that the rotation speed of the swing motor cannot exceed the preset maximum rotation speed. Therefore, the swing motor is protected from possible damage caused by overspeed rotation of the swing motor.

In the slewing hydraulic system of the excavator, the solenoid valve is an on-off solenoid valve, or a proportional solenoid valve. Proportional solenoid valve is adopted, which can linearly control the back pressure range of the oil outlet of the rotary motor, and the control program is more flexible.

The technical solution of the present invention for realizing its purpose is as follows: an excavator is provided, which has the aforementioned excavator rotary hydraulic system.

Compared with the prior art, the present invention intelligently controls the maximum rotational speed of the rotary motor, avoids the occurrence of excessive rotary speed, overpressure and air suction, and prolongs the service life of the rotary motor.

Description of drawings

Fig. 1 is a schematic diagram of the rotary hydraulic system of the excavator of the present invention.

The names and serial numbers of parts in the figure:

Hydraulic oil tank 1, oil pump 2, slewing control main valve 3, slewing motor 4, pilot valve 5, controller 6, speed sensor 7, solenoid valve 8.

Detailed ways

The specific implementation will be described below in conjunction with the accompanying drawings.

As shown in Figure 1, the rotary hydraulic system in this embodiment is used for excavators, and it includes a rotary motor 4, a rotary control main valve 3 connected to the rotary motor 4 for controlling the rotary motor 4, and a rotary control main valve 3. The pilot valve 5 connected to the pilot hydraulic control end at the end, the oil pumping system connected to the main valve 3 for swing control, the controller 6, and the speed sensor 7 connected to the controller 6 for measuring the speed of the swing motor; the oil pumping system includes an oil pump 2 and The hydraulic oil tank 1 and the oil pump 2 draw hydraulic oil from the hydraulic oil tank 1 and output it from the pump port, and supply oil to the swing motor 4 through the swing control main valve 3 to provide the power required for the upper body of the excavator to swing. The pilot valve 5 outputs different pilot control pressures to control the valve opening of the rotary control main valve to be small, thereby controlling the flow into the rotary motor and realizing the speed control of the rotary motor.

Solenoid valves 8 are arranged on the two connecting oil lines between the pilot valve 5 and the pilot hydraulic control ports at both ends of the rotary control main valve 3, and the solenoid valves 8 can be switch-type solenoid valves or proportional solenoid valves. Proportional solenoid valve is adopted, which can linearly control the back pressure range of the oil outlet of the rotary motor, and the control program is more flexible.

Under the condition that the pilot valve 5 outputs the pilot control pressure of the same magnitude, when the excavator is slewing on flat ground, the rotation speed of the slewing motor will not exceed the speed, and its rotation speed is within its design range. However, when the excavator is slewing on a slope, the rotation speed of the slewing motor 4 may exceed its allowable maximum value under the support of the gravitational potential energy when the bucket and load turn from a high place to a low place. If the rotational speed of the rotary motor 4 exceeds the allowable maximum value (preset value), the rotational speed sensor 7 converts its rotational speed into an electrical signal, and the controller 6 compares the electrical signal with the preset value and determines that the rotational speed of the rotary motor exceeds the preset value. value, the controller 6 outputs a control signal to the solenoid valve, so that the pilot pressure transmitted to the pilot liquid control end of the rotary control main valve decreases, the solenoid valve reduces the pilot pressure transmitted to the pilot liquid control end of the rotary control main valve, and the rotary control main valve The opening of the valve port decreases, so that the flow into the rotary motor decreases, the back pressure of the oil return increases, and the rotational speed of the rotary motor decreases, so that the rotational speed of the rotary motor cannot exceed the preset maximum rotational speed. Therefore, the swing motor is protected from possible damage caused by overspeed rotation of the swing motor. When the rotation speed of the slewing motor is lower than the preset value, the controller outputs a signal to make the solenoid valve return to the initial state, and the pilot pressure signal output by the pilot valve can be transmitted to the pilot liquid control terminal of the slewing control main valve without being affected, so that the driver Control the slewing action of the excavator just like a traditional excavator. The invention intelligently controls the maximum rotational speed of the rotary motor, avoids the occurrence of excessive rotary speed, overpressure and air suction, and prolongs the service life of the rotary motor.

Claims (4)

1. A rotary hydraulic system, including a rotary motor, a rotary control main valve connected to the rotary motor for controlling the rotary motor, a pilot valve connected to the pilot liquid control terminals at both ends of the rotary control main valve, and a rotary control main valve connected An oil pumping system; it is characterized in that it includes a controller, a speed sensor connected to the controller for measuring the speed of the slewing motor, the two-way connecting oil circuit between the pilot valve and the pilot liquid control terminals at both ends of the slewing control main valve Each is provided with a solenoid valve, and the electric control end of the solenoid valve is connected to the controller. When the rotation speed of the slewing motor exceeds a preset value, the controller outputs a control signal to the solenoid valve so that it is transmitted to the slewing control main Pilot pressure at the pilot pilot end of the valve decreases until the swing motor speed is less than the preset value. 2. The rotary hydraulic system according to claim 1, characterized in that the solenoid valve is an on-off solenoid valve. 3. The rotary hydraulic system according to claim 1, characterized in that the solenoid valve is a proportional solenoid valve. 4. An excavator, characterized by comprising the slewing hydraulic system according to any one of claims 1 to 3.