JPH09137476A - Hydraulic device of construction machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce microseism of drain oil discharged from a hydraulic pump and to reduce vibration and noises of a drain pipe. SOLUTION: The other end side of a drain hose 32 flowing drain oil from a hydraulic pump 32 is mounted so as to intersect with a return pipe 23 at a mounting position 33, and the other end side of a drain hose 34 flowing drain oil from a hydraulic pump 15 is mounted so as to intersect with the return pipe 23 at a mounting position 35. The lengths of the drain hoses 32 and 34 are set in natural number times of approximate 1/4 wave length of hydraulic microseism. By the constitution, microseismic waves moving forward in drain oil inside the drain hoses 32 and 34 are reflected at the mounting positions 33 and 35 to be return pipe 23, and since the reflected waves are interferred with the microseismic waves moving forward to the return pipe 23 from the hydraulic pumps 14 and 15 and are offset each other, hydraulic microseism of drain oil flowing the drain hoses 32 and 34 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device that is installed in a construction machine such as a hydraulic excavator and that supplies and discharges pressure oil to and from an actuator.

[0002]

2. Description of the Related Art Generally, a construction machine such as a hydraulic excavator or a hydraulic crane is equipped with a hydraulic actuator that operates by pressure oil supplied from a hydraulic pump, and a switching valve controls the supply and discharge of the pressure oil from the hydraulic pump. By doing so, the operation of the hydraulic actuator is controlled.

Therefore, a hydraulic system for a construction machine according to this type of conventional technology will be described with reference to FIGS. 4 to 7 as an example in which the hydraulic system is applied to a hydraulic excavator.

In the figure, reference numeral 1 denotes a lower traveling body of a hydraulic excavator, which is a truck frame 2 and
Drive wheels 3 arranged on the rear end side of the track frame 2
And an idler wheel 4 disposed on the front end side, and a crawler belt 5 wound around the idler wheel 4 and the drive wheel 3.

Reference numeral 6 denotes an upper revolving structure which is rotatably provided on the lower traveling structure 1. The upper revolving structure 6 is provided with a revolving frame 8 which is revolvably provided on the lower traveling structure 1 through a revolving device 7. A driver's cab 9 provided on the front side of the revolving frame 8, a machine room 10 provided on the revolving frame 8 on the rear side of the operator's cab 9, and a machine room 10 on the rear side of the machine room 10. The counter weight 11 and the counterweight 11 are provided.

Reference numeral 12 denotes a working device located laterally of the operator's cab 9 and provided on the front side of the revolving frame 8 so as to be able to move up and down.
The hydraulic cylinders 12A are provided with pressure oil from the hydraulic pumps 14 and 15 to be described later to perform the elevation motion.

Reference numeral 13 denotes a hydraulic oil tank provided in the machine chamber 10 and provided on the revolving frame 8. The hydraulic oil tank 13 stores hydraulic oil.

Reference numerals 14 and 15 denote variable displacement hydraulic pumps, and the hydraulic pumps 14 and 15 are used for the machine room 10.
It is coaxially connected to the output shaft of the engine 16 provided therein. The hydraulic pumps 14 and 15 are connected to the engine 1
6 is driven to discharge the hydraulic oil in the hydraulic oil tank 13.

Reference numeral 17 denotes a hydraulic oil tank 13 and each hydraulic pump 1.
The suction pipe provided between the suction pipe 1 and the suction pipe 1
7, one end side of which extends into the hydraulic oil tank 13 and the other end side of which is the suction ports 14A, 15 of the hydraulic pumps 14, 15.
A is connected. Reference numeral 18 denotes a hydraulic oil filter provided on one end side of the suction pipe 17, and the hydraulic oil filter 18 is
This is for removing abrasion powder and the like mixed in the hydraulic oil sucked into each hydraulic pump 14, 15.

Reference numerals 19 and 20 denote discharge pipes provided between the hydraulic pumps 14 and 15 and a multiple valve 21 described later,
One end side of the discharge pipe 19 is the discharge port 1 of the hydraulic pump 14.
4B, one end side of the discharge pipe 20 is the hydraulic pump 1
5 discharge port 15B. The other ends of the discharge pipes 19 and 20 are connected to the pressure oil introduction ports 21A and 21B of the multiple valve 21.

Reference numeral 21 denotes a multiple valve connected to the hydraulic pumps 14 and 15 via the discharge pipes 19 and 20, and the multiple valve 21 supplies pressure oil to various hydraulic actuators mounted on the hydraulic excavator. Each of the hydraulic cylinders 12A, 1A of the working device 12 is composed of a plurality of switching valves for controlling supply and discharge.
2A, ... Are connected via pressure oil supply / discharge pipes 22 and 22, and in the same manner, a turning device 7, a traveling motor (not shown), etc. are connected via pressure oil supply / discharge pipes. And the multiple valve 2
Each switching valve (not shown) that constitutes No. 1 is opened / closed in response to a signal from the outside, and the pressure from each hydraulic pump 14, 15 supplied to the multiple valve 21 via each discharge pipe 19, 20. The oil is selectively supplied to or discharged from a predetermined hydraulic actuator via a pressure oil supply / discharge pipe connected to each switching valve.

Reference numeral 23 is a return pipe provided between the multiple valve 21 and the hydraulic oil tank 13.
Has one end connected to the pressure oil discharge port 21C of the multiple valve 21 and the other end extending into the hydraulic oil tank 13. The return pipe 23 is connected to each hydraulic pump 1
Excess oil of the hydraulic oil discharged from Nos. 4 and 15 or return oil from various hydraulic cylinders 12A, etc.
It is supposed to be returned to the side. Reference numeral 24 denotes a full-flow filter located in the hydraulic oil tank 13 and provided in the middle of the return pipe 23. The full-flow filter 24 is mixed in the return oil returned to the hydraulic oil tank 13 side through the return pipe 23. Abrasion powder and the like are removed.

Reference numeral 25 denotes a drain hose, one end of which is connected to the drain port 14C of the hydraulic pump 14 through a branch pipe and the other end of which is connected to the return pipe 23 at the mounting position 26. Drain oil leaking from the rotor of the hydraulic pump 14 into the casing (neither is shown) at the time of operating the pump 14 is led to the return pipe 23 and discharged to the hydraulic oil tank 13 side together with the return oil flowing in the return pipe 23. It is supposed to do.

27 is another drain hose whose one end is connected to the drain port 15C of the hydraulic pump 15 and the other end is connected to the drain hose 25 at the mounting position 28. The drain hose 27 operates the hydraulic pump 15. Sometimes from the rotor of the hydraulic pump 15 to the casing (neither is shown)
The drain oil leaking inside is led out to the drain hose 25.

The other drain hose 27 is formed shorter than the drain hose 25, and the mounting position 28 corresponds to the position of the drain port 14C of the hydraulic pump 14.

Therefore, the drain oil from the hydraulic pump 15 merges with the drain oil from the hydraulic pump 14 in the drain hose 25 and further merges with the return oil from the multiple valve 21 in the return pipe 23, and then operates. It is discharged to the oil tank 13 side.

The hydraulic system according to the prior art has the above-mentioned structure. When the engine 16 is operated and the hydraulic pumps 14 and 15 are driven, the hydraulic oil in the hydraulic oil tank 13 is passed through the suction pipe 17. After being sucked into the hydraulic pumps 14 and 15, they are discharged from the hydraulic pumps 14 and 15 to the multiple valve 21 through the discharge pipes 19 and 20, respectively. And
The pressure oil discharged to the multiple valve 21 is supplied to the hydraulic actuator corresponding to the opened switching valve of the switching valves forming the multiple valve 21 to operate the hydraulic actuator. Further, excess oil in the pressure oil discharged to the multiple valve 21 or return oil from the hydraulic actuator is used as the multiple valve 21.
From the pressure oil discharge port 21C to the return pipe 23, and is returned to the hydraulic oil tank 13 side as return oil through the return pipe 23.

On the other hand, the drain oil leaked into the casing during the operation of the hydraulic pumps 14 and 15 is drained by the drain hose 2.
The hydraulic oil tank 1 is introduced to the return pipe 23 through 5, 27 and merges with the return oil flowing through the return pipe 23.
It is discharged to the 3 side.

[0019]

By the way, the drain oil discharged to the drain hoses 25 and 27 when the hydraulic pumps 14 and 15 are operated causes pulsation due to the operation of the hydraulic pumps 14 and 15, and the drain oil is discharged. Pulsation of each hydraulic pump 14,
It is increased / decreased according to the change in the rotational speed of 15 and the change in discharge pressure. The pulsation of the drain oil is the drain hoses 25, 27.
To the drain hose 2 because it propagates to and vibrates them.
There is a problem that the hydraulic pumps 14 and 15 connected to the valves 5 and 27 and various pipes are damaged, and the noise caused by the vibration deteriorates the working environment.

In particular, when the drain hose 25 connected to the drain port 14C of the hydraulic pump 14 and the drain hose 27 connected to the drain port 15C of the hydraulic pump 15 are connected at the mounting position 28 as described above, The pulsation of drain oil from the pump 14 and the pulsation of drain oil from the hydraulic pump 15 are amplified by propagating in the drain hose 27 and interfering with each other, and the hydraulic pumps 14 and 15 and various pipes are amplified. There is a problem that it is damaged by the pulsation or promotes noise due to vibration.

The present invention has been made in view of the above-mentioned problems of the prior art, and is a construction in which the pulsation of drain oil discharged from a hydraulic pump can be reduced, and the vibration and noise of hydraulic piping due to the pulsation of drain oil can be reduced. It is intended to provide a hydraulic system for a machine.

[0022]

In order to solve the above-mentioned problems, the invention of claim 1 provides a tank for storing hydraulic oil,
At least two hydraulic pumps that discharge the hydraulic oil in the tank, a discharge pipe that guides the hydraulic oil discharged from each of the hydraulic pumps to an actuator, and the actuator that is provided between the discharge pipe and the actuator A switching valve for switching pressure oil to be supplied to and discharged from the hydraulic pump, and a return pipe provided between the switching valve and the tank for returning the hydraulic oil discharged from each hydraulic pump or the return oil from the actuator to the tank. And at least two drain pipes for returning drain oil discharged from each of the hydraulic pumps to the tank side, each drain pipe having one end connected to the drain port of each hydraulic pump and the other end connected to the drain port. In a state where it is located upstream of the tank and individually connected to each of the return pipes, and the other end of each drain pipe intersects with the return pipe. Attach made as a constituent.

According to the above construction, when each hydraulic pump discharges the hydraulic oil toward the actuator, the drain oil discharged from each hydraulic pump is guided to the return pipe through each drain pipe, and returns through the return pipe. It joins the oil and is returned to the tank side. At this time, the drain oil flowing through each drain pipe causes hydraulic pulsation associated with the operation of each hydraulic pump, but since the return pipe and the other end side of each drain pipe are installed in a state where they intersect with each other, The pulsating wave traveling in the oil is reflected at the position where it is attached to the return pipe, and travels again in the oil of each drain pipe toward each hydraulic pump. At this time, the pulsating wave from each hydraulic pump of each drain pipe to the return pipe and the reflected wave from the return pipe to each hydraulic pump interfere with each other to cancel each other.
The hydraulic pulsation generated in each drain pipe can be reduced.

According to the second aspect of the present invention, each of the drain pipes has a length which is a natural number multiple of the basic length, when the basic length is approximately ¼ wavelength of the hydraulic pressure pulsation generated by the operation of the hydraulic pumps. It has been set to.

According to the above construction, when the pulsating wave traveling in the oil in each drain pipe is reflected at the connection position with the return pipe, the pulsating wave traveling from each hydraulic pump of each drain pipe to the return pipe and the return The reflected waves traveling from the pipes to the respective hydraulic pumps interfere with each other in phases that are substantially opposite to each other, whereby the hydraulic pulsation generated in the respective drain pipes can be reduced.

[0026]

FIG. 1 is a block diagram showing an embodiment of the present invention.
A description will be given based on FIG. In the embodiment, the same components as those of the conventional technique shown in FIGS. 4 to 7 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 31 indicates a hydraulic system according to the present embodiment, and the hydraulic system 31 is the same as in the prior art described above, that is, the hydraulic oil tank 13, the hydraulic pumps 14 and 15, the suction pipe 17, the discharge pipe 19 respectively. , 20, a multiple valve 21, a return pipe 23, etc., but a drain hose 3 described later.
2, 34 is different from the prior art in the configuration.

Reference numeral 32 denotes a drain hose which is a drain pipe according to the present embodiment. One end of the drain hose 32 is connected to the drain port 14C of the hydraulic pump 14, and the other end is located upstream of the hydraulic oil tank 13. It is connected to the return pipe 23 at a mounting position 33. The other end of the drain hose 32 is attached to the return pipe 23 at the attachment position 33 at a substantially right angle so as to intersect the return pipe 23.

Reference numeral 34 denotes another drain hose which is a drain pipe according to this embodiment. One end of the drain hose 34 is connected to the drain port 15C of the hydraulic pump 15, and the other end thereof is upstream of the above-mentioned mounting position 33. The return pipe 23 is connected to the return pipe 23 at a mounting position 35 spaced apart from each other. The other end of the drain hose 34 is attached at a substantially right angle so as to intersect the return pipe 23 at the attachment position 35.

Here, in a construction machine such as a hydraulic excavator, the length of the drain hose 32 (the length from the connection position with the drain port 14C of the hydraulic pump 14 to the attachment position 33 with the return pipe 23) L Is set to be a natural number multiple of the basic length as shown in the following Expression 1, when the basic length is approximately ¼ of the wavelength (λ) of hydraulic pulsation generated by the operation of the hydraulic pump 14, I learned that the hydraulic pulsation of drain oil can be reduced.

[0031]

(Equation 1) However, n is a natural number

Here, the speed of sound in the drain oil is V (m /
If s), then λ = V / f, and therefore the above equation 1 can be expressed as follows.

[0033]

(Equation 2)

Here, the frequency f of the hydraulic pulsation generated by the operation of the hydraulic pump mounted on the construction machine such as the hydraulic excavator is usually in the range of 200 to 300 Hz, and the sound velocity V in the drain oil is 1300 (m). / S), therefore, if the frequency f of the hydraulic pressure pulsation is 200 (Hz), then L = 1.625 × n (m) from the above mathematical expression 2.

As described above, in the present embodiment, for example, the length L of the drain hose 32 is set to be a natural number times the basic length of 1.625 (m).

On the other hand, the length of the drain hose 34 (the length from the connection position with the drain port 15C of the hydraulic pump 15 to the mounting position 35 with the return pipe 23) is the same as that of the drain hose 32 described above. When the basic length is approximately 1/4 wavelength of the hydraulic pulsation generated by the operation of 15,
By setting it to be a natural multiple of the basic length,
I learned that the hydraulic pulsation of drain oil can be reduced.

The hydraulic device 31 according to the present embodiment has the above-described structure, and the pressure oil discharged from the hydraulic pumps 14 and 15 to the multiple valve 21 through the discharge pipes 19 and 20 is the multiple valve 21. Is supplied to the hydraulic actuators corresponding to the opened switching valves of the respective switching valves that make up the above-mentioned switching valve to operate the hydraulic actuators. Further, surplus oil of the pressure oil discharged to the multiple valve 21 or return oil from the hydraulic actuator is led from the pressure oil discharge port 21C of the multiple valve 21 to the return pipe 23, and the return oil is returned through the return pipe 23. Is returned to the hydraulic oil tank 13 side.

On the other hand, the drain oil leaked into the casing during the operation of the hydraulic pumps 14 and 15 is the drain hose 3
2, 34, and is returned to the return pipe 23 and merges with the return oil flowing through the return pipe 23 to join the hydraulic oil tank 1
It is discharged to the 3 side.

At this time, the other end of the drain hose 32, one end of which is connected to the drain port 14C of the one hydraulic pump 14, is attached at the attachment position 33 so as to intersect the return pipe 23. Drain hose 32
The pulsating wave traveling in the drain oil inside the return pipe 23
By being reflected at the attachment position 33 of and, it becomes a reflected wave and travels in the drain oil toward the hydraulic pump 14.
Therefore, the pulsating wave that travels from the hydraulic pump 14 toward the return pipe 23 and the reflected wave that travels from the return pipe 23 toward the hydraulic pump 14 interfere with each other and cancel each other out. It can be reduced.

The other end of the drain hose 34, one end of which is connected to the drain port 15C of the other hydraulic pump 15, intersects the return pipe 23 at a mounting position 35 separated from the above mounting position 33. Since the pulsating wave traveling in the drain oil in the drain hose 34 is reflected at the attachment position 35 with the return pipe 23, it becomes a reflected wave to move the drain oil into the hydraulic pump 15 side. Proceed towards. Therefore, the hydraulic pump 15
From the return pipe 23 to the return pipe 23 and the reflected wave traveling from the return pipe 23 to the hydraulic pump 15 interfere with each other to cancel each other, and the drain hose 34
It is possible to reduce the hydraulic pulsation that occurs in the.

Moreover, since the mounting position 33 of the drain hose 32 to the return pipe 23 and the mounting position 35 of the drain hose 34 to the return pipe 23 are provided as individual positions, the hydraulic pulsation of the drain oil from the hydraulic pump 14 is provided. It is possible to prevent the oil pressure pulsation of the drain oil from the hydraulic pump 15 from being interfered with and amplified.

As a result, the vibration of the drain hoses 32 and 34 is significantly reduced, and the hydraulic motors 14 and 15 connected to the drain hoses 32 and 34 and various pipes are prevented from being damaged, and noise caused by the vibration is prevented. You can

The length of the drain hoses 32 and 34 is
When the basic length is approximately ¼ wavelength of the hydraulic pulsation generated by the operation of the hydraulic pumps 14 and 15, each hydraulic pump 1 is set to be a natural number multiple of the basic length.
The pulsating waves traveling from 4, 15 to the return pipe 23 and the reflected waves traveling from the return pipe 23 to each of the hydraulic pumps 14 and 15 are almost opposite in phase with each other due to the relationship of crest and belly and belly and crest. Can be interfered with.

As a result, the pulsating wave traveling from each hydraulic pump 14 and 15 toward the return pipe 23 and the reflected wave traveling from the return pipe 23 toward each hydraulic pump 14 and 15 are effectively canceled out, Drain hose 32,3
The hydraulic pulsation of the drain oil flowing through 4 can be remarkably reduced, and the vibrations of the drain hoses 32 and 33 that cause damage to the hydraulic pumps 14 and 15 and various pipes can be further reduced.

In the above embodiment, the hydraulic system provided with the two hydraulic pumps 14 and 15 is taken as an example, but the present invention is not limited to this, and the hydraulic system provided with three or more hydraulic pumps. It can also be applied to a device.

The drain hoses 32 and 33 which are the drain pipes described in the above embodiment are not limited to flexible pipes such as rubber hoses, and fixed pipes such as metal pipes may be used.

Further, in the above-mentioned embodiment, the case where the hydraulic excavator is installed in the machine room is taken as an example, but the present invention is not limited to this, and may be applied to other construction machines such as hydraulic cranes and wheel loaders. Can be applied.

[0048]

As described above in detail, according to the invention of claim 1, the other end of each drain pipe whose one end side is connected to the drain port of each hydraulic pump is located on the upstream side of the tank to be the return pipe. Since they are individually connected, the hydraulic pulsation of drain oil discharged from one hydraulic pump and the hydraulic pulsation of drain oil discharged from the other hydraulic pump can be prevented from interfering with each other and being amplified.

Further, by mounting the other end side of each drain pipe so as to intersect with the return pipe, the pulsating wave propagating in the oil in each drain pipe is reflected at the mounting position with the return pipe and is reflected. Since waves are made to travel toward each hydraulic pump side, the pulsating wave traveling from each hydraulic pump toward the return pipe interferes with the reflected wave traveling from the return pipe toward each hydraulic pump. By canceling each other out, the pulsation generated in each drain pipe can be reduced. As a result, the vibration of each drain pipe can be reduced, and the hydraulic pump and various pipes connected to each drain pipe can be prevented from being damaged and the noise caused by the vibration can be prevented.

According to the second aspect of the present invention, when the length of each drain pipe is a basic length of about 1/4 wavelength of hydraulic pulsation generated by the operation of each hydraulic pump, a natural number of the basic length. By doubling the setting, the pulsating wave traveling from each hydraulic pump to the return pipe and the reflected wave traveling from the return pipe to each hydraulic pump are made to interfere with each other in almost opposite phases. Could be offset. As a result, the hydraulic pulsation of the drain oil flowing through each drain pipe can be significantly reduced, and the vibration of each drain pipe that causes damage to each hydraulic pump and various pipes can be further reduced.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram when a hydraulic system according to an embodiment of the present invention is used in a hydraulic excavator.

FIG. 2 is a partially cutaway plan view showing a hydraulic apparatus according to an embodiment of the present invention mounted in a machine chamber of a hydraulic excavator.

3 is a cross-sectional view as seen from the direction of arrows III-III in FIG.

FIG. 4 is an external view showing a hydraulic excavator to which a hydraulic device according to the related art is applied.

FIG. 5 is a hydraulic circuit diagram when the hydraulic device according to the prior art is used in the hydraulic excavator shown in FIG.

FIG. 6 is a plan view showing a state in which a hydraulic device according to a conventional technique is installed in a machine room of a hydraulic excavator.

FIG. 7 is a cross-sectional view seen from the arrow VII-VII direction in FIG.

[Explanation of symbols]

 13 Hydraulic oil tank 14, 15 Hydraulic pump 14C, 15C Drain port 19, 20 Discharge pipe 21 Multiple valve (switching valve) 23 Return pipe 32, 34 Drain hose (Drain pipe) 33, 35 Mounting position

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Uchike 650 Kazutachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Engineering Co., Ltd. Engineering Co., Ltd.

Claims (2)

[Claims] 1. A tank for storing hydraulic oil, at least two hydraulic pumps for discharging hydraulic oil in the tank, a discharge pipe for guiding the hydraulic oil discharged from each hydraulic pump to an actuator, and the discharge pipe. And a switching valve provided between the actuator and the actuator for switching the pressure oil supplied to and discharged from the actuator, and the switching valve for returning the hydraulic oil discharged from each hydraulic pump or the return oil from the actuator to the tank. It comprises a return pipe provided between the tank and at least two drain pipes for returning drain oil discharged from the respective hydraulic pumps to the tank side. Connected to the drain port of the pump, the other end of which is located upstream of the tank and individually connected to each of the return pipes, and the other end of each drain pipe And a hydraulic pipe for a construction machine configured to be installed in a state where the return pipe and the return pipe are crossed with each other. 2. Each of the drain pipes is set to a length that is a natural number multiple of the basic length when the basic length is approximately ¼ wavelength of hydraulic pulsation generated by the operation of each hydraulic pump. Item 1. A hydraulic system for a construction machine according to Item 1.