JPH061804U - Front damping circuit of hydraulic excavator - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hydraulic circuit for operating the front part with a vibration damping circuit for damping the vibration generated immediately after the operation of the front part of the hydraulic excavator is stopped. [Structure] Pipe lines 13a, 13b and 14a, 14b from a flow rate adjusting valve 23 for supplying pressure oil to two boom cylinders 4, 4'for operating a front equivalent load 25.
Is an independent circuit, and a switching valve 30 operated by the pilot pressure of the operating lever 24 is provided between these independent circuits. The switching valve 30 has a vibration damping device that connects the extension side oil chamber 4 ′ a of the boom cylinder 4 ′ and the contraction side oil chamber 4 b of the other boom cylinder 4 via the throttle valves 31 and 32. The throttle valves 31 and 32 have a front equivalent load 25.
The oil flow is damped by the vibration when the air operation is stopped, and the vibrations in the boom cylinders 4 and 4'are also damped.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a front damping circuit for a hydraulic excavator, and more particularly to a damping circuit having a damping device provided in an operating circuit of a work machine such as a wheel loader.

[0002]

[Prior art]

 As shown in FIG. 3, a conventional hydraulic excavator can be roughly divided into a front portion, a machine body 9, a cab 10, and a traveling device 11 when the constituent parts are roughly divided. In the front part, the boom 1, the arm 2 and the bucket 3 are sequentially pin-connected from the machine body 9, and the boom cylinders 4 and 4 ′ between the machine body 9 and the boom 1 and the boom 1 and the arm 2 are connected. An arm cylinder 5 between them, a bucket cylinder 6 between the arm 2 and the bucket 3, and a strap 7 and a rod 8 are provided, and these constituent members are pin-connected to each other.

Among these cylinders, as shown in FIG. 2, the cylinders 4 and 4 ′ are provided so as to be parallel to the front relative load portion 25, and the extension-side oil chambers 4 a and 4 b. It has pistons 4c, 4'c connected to the front load part 25 by piston rods 4d, 4'd so as to divide the oil chambers 4'a, 4'b on the contracted side. The extension-side oil chambers 4a and 4'a and the compression-side oil chambers 4b and 4'b of the cylinders 4 and 4'are connected in parallel to the flow rate adjusting valve 23 by the pipes 13 and 14, respectively. Has been done. The flow rate adjusting valve 23 includes a pump 21 for supplying pressure oil and a drain tank 22 in parallel with the extension side oil chambers 4a, 4'a and the contraction side oil chambers 4b, 4'b of the boom cylinders 4, 4 '. Pilot pressure is sent by the operation of the operation lever 24 so that the connection can be established.

The excavation and loading operation by the hydraulic excavator having such a configuration is performed by expanding and contracting the three types of cylinders 4, 4 ′, 5, 6 by the lever operation of the operator inside the cab 10. At that time, in order to move the bucket 3 to a desired place and perform work, the cylinders for operating the respective members must be expanded and contracted. However, in the work process from excavation to loading of excavated soil, the cylinder It was necessary to make the pressure oil flow into the oil chamber or to discharge the pressure oil from the oil chamber, which often caused large vibrations. However, the operator had to endure such vibration and continue working, and an urgent improvement was required from the viewpoint of occupational health. This has been studied to improve the working environment such as eliminating the harsh labor and improving difficult work, and enabling anyone to work, but construction machinery such as hydraulic excavators etc. There was not enough research in terms of operation.

[0005]

[Problems to be solved by the device]

 Under such circumstances, the conventional hydraulic circuits of the boom cylinders 4 and 4'have no vibration countermeasures as shown in FIG. 2, and as a result, as shown in FIG. When the arm cylinder 5 and the bucket cylinder 6 are fixed and the lengths of the boom cylinders 4 and 4'are changed to stop, the boom portion around the boom foot pin 12 which is very large due to its long front portion. Vibration of the entire front is also induced by the oily spring based on the moment of inertia and the compressibility of the oil in the closed oil chambers of the boom cylinders 4 and 4 ', and the body 9 and the cab 10 are also vibrated. The ride comfort of the operator is significantly impaired.

In the hydraulic circuit shown in FIG. 2, the operation lever 24 is operated to supply the pilot pressure through the pipe line 20 to open / close the flow rate adjusting valve 23. Oil flows in to expand and contract the cylinders 4 and 4 ', but at that time, vibration is generated especially at the time of stopping, and the vibration of the front portion is caused in the oil chambers 4a and 4b and the oil chambers 4'a and 4'b. It is based on the natural vibration determined by the spring property of the oil itself and the front equivalent load 25. In order to damp the vibration, it may be possible to increase the damping performance by inserting an orifice such as an orifice into the pistons 4c and 4'c. However, it is necessary to support the load on the front part due to gravity, including the hydraulic cylinders. Even if an orifice is installed on the pistons 4c and 4'c, the entire front part will fall naturally, and due to the nature of the hydraulic excavator, no drop is allowed. , Is not suitable as a product.

The present invention has been made in view of the above-mentioned problems of the related art, and makes it possible to obtain a rapid damping of front vibration and to easily mount the conventional vibration. It is an object of the present invention to provide a vibration damping circuit for a hydraulic excavator that is made possible.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the damping circuit of the hydraulic excavator of the present invention is such that, in the hydraulic circuit for the two boom cylinders at the front part of the hydraulic shovel, the circuit for each boom cylinder is an independent circuit, and The pipeline to the extension side oil chamber of the boom cylinder and the pipeline to the contraction side oil chamber of the other boom cylinder are connected by a throttle valve that forms a damping device and a pipeline that has a switching valve. It is characterized in that the oil chambers of the boom cylinders are communicated with each other through the throttle valve when the stop of the above.

The damping device provided in such a damping circuit, when the communication of the throttle valve is interrupted by the switching valve during the normal operation, causes the pressure from the flow rate adjusting valve to be the same as the conventional hydraulic excavator. The feature is that oil can be supplied to each boom cylinder.

[0010]

[Action]

 In the vibration control circuit of the hydraulic excavator, when the operator operates the operation lever to operate the flow rate adjusting valve, at the same time, the switching valve is operated to cut off the communication via the throttle valve, and the vibration control device does not work. Therefore, the hydraulic pressure from the flow control valve can be supplied to the expansion side or the contraction side oil chamber of the boom cylinder through an independent circuit, and it can be operated continuously, and the normal hydraulic excavator work can be continuously performed.

Next, when the operator tries to stop the operation of the front part by returning the operation lever to the neutral position, the cylinder vibrates at the same time, but the action of pilot pressure disappears and the return valve of the switch valve causes the switch valve to operate. By switching, the extension side oil chamber of one boom cylinder and the contraction side oil chamber of the other boom cylinder are directly connected by a pipe line via a throttle valve. When directly connected in this way, when the piston vibrates when stopped, oil vibrates in and out through the throttle valve. At that time, the flow of the pressure oil passing through the throttle is attenuated, the vibrational flow is also attenuated, and the vibration of the airframe is simultaneously suppressed.

[0012]

【Example】

 Embodiments will be described below with reference to the drawings. A damping circuit for a hydraulic excavator, which is an embodiment of the present invention, will be described with reference to FIG. The same components as those shown in FIGS. 2 and 3 described as the prior art are designated by the same reference numerals, and the details thereof will be omitted.

In the hydraulic circuit for operating the front equivalent load 25 of the hydraulic excavator, the two boom cylinders 4, 4 ′ are provided with pipe lines 13 a, 14 a and 13 b for supplying pressure oil from the flow rate adjusting valve 23. , 14b are connected. These pairs of conduits 13a, 14a and 13b, 14b form an independent circuit. The boom cylinders 4 and 4'include the extension side oil chambers 4a and 4'a of the piston rods 4d and 4'd and the compression side oil chambers 4b and 4'b on the other side of the pistons 4c and 4'c. It is divided into The switching valve 30 and the throttle valve are connected to the pipe line 14b connected to the contraction side oil chamber 4b of the boom cylinder 4 and the expansion line oil chamber 4'a of the other boom cylinder 4 '. It is provided with valves 31 and 32. The throttle valve 31 is provided between the switching valve 30 and the conduit 13a of the extension side oil chamber 4'a of the other boom cylinder 4 ', and the throttle valve 32 is provided with the switching valve 30 and one boom cylinder 4'. Is provided between the contraction side oil chamber 4'b and the conduit 14b.

The switching valve 30 is provided with a communication part and a cutoff part, and from a pilot pressure passage 20 a branched from a pilot pressure passage 20 for supplying pilot pressure to the flow rate adjusting valve 23 in accordance with the operation of the operation lever 24. At the neutral position of the operating lever 24, which is operated by the pilot pressure of No. 1 and is not sent, the return spring 30a can establish the communication state via the throttle valves 31 and 32 as shown in the figure, and one boom cylinder 4 The extension-side oil chamber 4'a and the contraction-side oil chamber 4b of the other boom cylinder 4 are connected in a communicating state via a communicating portion. In this way, the damping device for the front damping circuit is provided. During normal operation, the switching valve 30 shuts off the conduits 13a and 14b by the shut-off portion by the pilot pressure from the operating lever 24 via the pilot pressure conduit 20a.

In the hydraulic circuit configured as described above, when an ordinary operator operates the operation lever 24, the flow rate adjusting valve 23 uses the pilot pressure via the pilot pressure passage 20 to pump the pressure oil from the pump 21. The oil is supplied to the contraction side oil chambers 4b and 4'b of the boom cylinders 4 and 4'through the passages 14a and 14b, and the extension side oil chambers 4a and 4'a of the boom cylinders 4 and 4'are connected to the conduit 13a. , 13b to the flow rate adjusting valve 23, the front equivalent load 25 can operate normally from the past.

Further, this hydraulic circuit operates as a vibration damping circuit because when the operator returns the operation lever 24 to the neutral state in an attempt to stop the front operation, the pilot pressure stops acting and the return spring 30b switches the operation. The valve 30 is positioned as shown. The pipe line 14b of the compression side oil chamber 4b of one boom cylinder 4 and the pipe line 13a of the extension side oil chamber 4'a of the other boom cylinder 4'communicate via the communication portion of the switching valve 30. Is set to the connected position. In this case, at the moment when the switching valve 30 is returned by the return spring 30b, the boom cylinders 4 and 4'vibrate, but the oil chambers 4b and 4'a are in communication with each other by the pipe lines 13a and 14b. When the pistons 4c and 4'c vibrate when stopped, oil vibrates out and flows in through the throttle valves 31 and 32. At that time, the oil flow is damped in the throttles 31, 32, and accordingly, the motions of the pistons 4c, 4'c of the boom cylinders 4, 4'are damped, and the vibrations are damped. Vibration is also suppressed at the same time.

The vibration damping circuit having such a configuration can be easily applied to a conventional hydraulic excavator that does not include the vibration damping circuit simply by connecting it in the middle of the pipeline in the hydraulic circuit between the flow rate adjusting valve and the boom cylinder. can do.

[0018]

[Effect of device]

 Since the present invention is configured as described above, the damping circuit of the hydraulic excavator having the above configuration has the following effects. While the front of the hydraulic excavator is operating in the air, the throttle valve and the switching valve are connected to the pipeline between the expansion side oil chamber of one boom cylinder and the compression side oil chamber of the other boom cylinder. The unpleasant airframe vibration can be rapidly attenuated by damping the oil flow caused by the front vibration generated by the communication of the switching valve through the throttle valve, improving the ride comfort of the operator and working environment. This is extremely preferable from the viewpoint of occupational hygiene, since even an inexperienced operator can operate with less vibration.

Further, by applying the damping circuit as described above to the hydraulic cylinder at the front part of the conventional hydraulic excavator, the pressure oil supply circuit to each cylinder is made into an independent circuit, and the throttle valve and the switching valve. The front vibration caused by oily springs in the oil chamber when such cylinder operation is stopped can be rapidly attenuated by the easy installation of the connection of the cylinders, resulting in a comfortable working environment and working conditions for the operator. It has an excellent effect of being able to efficiently proceed with the smell.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a vibration damping circuit for a hydraulic excavator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a hydraulic circuit of a conventional hydraulic excavator.

FIG. 3 is a side view of the entire hydraulic excavator according to the present invention.

[Explanation of symbols]

 1 Boom 2 Arm 3 Bucket 4, 4'Boom Cylinder 4a, 4'a Extension Side Oil Chamber 4b, 4'b Contraction Side Oil Chamber 4c, 4'c Piston 5 Arm Cylinder 6 Bucket Cylinder 9 Body 10 Cab 11 Traveling Device 13a , 13b Pipe line 14, 14 'Pipe line 14a, 14b Pipe line 20, 20a Pilot pressure line 23 Flow rate adjusting valve 24 Operation lever 25 Front equivalent load 30 Switching valve 30a Return spring 31, 32 Throttle valve

Claims (2)

[Scope of utility model registration request] 1. At least two boom cylinders for operating the front of a hydraulic excavator, a pipeline for supplying pressure oil to the boom cylinder, a flow rate adjusting valve provided in the pipeline for adjusting the supply of pressure oil, etc. In the hydraulic circuit to the front of the hydraulic excavator having a The connected pipeline and the pipeline connected to the compression side oil chamber of the other boom cylinder are connected by a pipeline having a throttle valve and a switching valve,
Further, the switching valve is operated by pilot pressure for operating the flow rate adjusting valve, and is operated so as to allow the throttle valve to communicate with each other when the boom cylinder is stopped. circuit. 2. The front damping circuit for a hydraulic excavator according to claim 1, wherein the switching valve blocks communication of the throttle valve when the boom cylinder operates. circuit.