JP2001316081A - Revolving hydraulic circuit for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure relaxation of shock during stopping of revolution of an upper revolving-superstructure of a construction machine and prevent the occurrence of cavitation. SOLUTION: This revolving hydraulic circuit for a construction machine, wherein an pressure oil forcedly fed by a revolving pump 2 is changed over by a revolving change valve 13 or 13A and fed to a revolving motor 4 for performing revolving operation of the upper revolving superstructure with the rotation of the revolving motor 4, comprises a communication oil passage 14 provided between both end oil passages 5, 6 for the revolving motor 4 and a fixed restriction 15 arranged across the communication oil passage 14, so that a high/low pressure generated in both end oil passages 5, 6 for the revolving motor 4 can be regulated by the fixed restriction 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swing hydraulic circuit of a construction machine, and more particularly, to a crane or the like, which alleviates a shock when the swing of an upper swing body is stopped and prevents cavitation. The present invention relates to an intended hydraulic hydraulic circuit for construction equipment.

[0002]

2. Description of the Related Art A conventional swing hydraulic circuit for a construction machine of this type will be described with reference to FIGS. In FIG. 5, reference numeral 1 denotes a swing hydraulic circuit. The swing hydraulic circuit 1 switches the pressure oil fed from a swing pump 2 by a swing switching valve 3 to perform a swing operation of an upper swing body (not shown). Rotating motor 4 for performing
It is configured to send to. The turning switching valve 3 is configured to shut off the oil passages 5 and 6 at both ends of the turning motor 4 in the neutral position. For example, when stopping the turning operation, the turning operation lever 7 is operated. When the swing switching valve 3 is returned to the neutral position, the oil passages 5 and 6 at both ends of the swing motor 4 are shut off, and the upper swing body is suddenly braked. Therefore, particularly when the swing switching valve 3 is returned to the neutral position while the upper swing body is swinging at a high speed, the upper swing body receives a large shock due to its large inertia.

In FIG. 6, reference numeral 8 denotes another swing hydraulic circuit. The swing hydraulic circuit 8 switches the pressure oil fed from the swing pump 2 by a swing switching valve 9 and turns the upper swing body (FIG. (Not shown) to the turning motor 4 for performing the turning operation. The turning switching valve 9 is configured such that the oil passages 5, 6 at both ends of the turning motor 4 communicate with the tank 10 when the turning switching valve 9 is in the neutral position. When is returned to the neutral position, the upper revolving structure is not braked,
The turning motion due to the inertial motion continues. Therefore, when stopping the upper revolving superstructure, a method is used in which the revolving operation lever 11 is reversely operated to stop the upper revolving superstructure by a brake operation by the reverse rotation of the revolving motor 4. In this case, if the reverse operation is performed suddenly, a large shock may be applied to the upper revolving structure, and furthermore, pressure oil may be lost in a part of the oil passages 5 and 6 at both ends, causing cavitation.

Conventionally, in order to avoid the above-mentioned problem, as a method of obtaining a swing switching valve having a characteristic of less shock and good workability, a valve of the swing switching valve 3 or 9 is repeatedly tested by repeating actual machine tests. A method of adjusting the opening area of a spool (not shown) has been used.

[0005]

In the conventional swing hydraulic circuit of a construction machine described above, when the swing switching valve is configured to shut off the oil passages at both ends of the swing motor at the neutral position, the swing is reduced. When the switching valve is returned to the neutral position, the oil passages at both ends of the swing motor are shut off, whereby the upper swing body is suddenly braked. Particularly, when the swing switching valve is returned to the neutral position while the upper swing body is rotating at a high speed, the upper swing body generates a large shock due to its large inertia.

In the case where the swing switching valve is configured to open the oil passages at both ends of the swing motor in the neutral position, the swing switching valve is reversely operated when the upper revolving unit is stopped, so that the reverse rotation is performed. Although the upper revolving structure was stopped by performing the brake operation according to the above, if the reverse operation was performed suddenly, a large shock to the upper revolving structure was generated, and further, the pressure oil was partially discharged in the oil passage. There was a risk of cavitation.

Furthermore, in order to avoid the above-mentioned problem, a method of adjusting the opening area of the valve spool of the swing switching valve has been used. However, the adjustment is a time-consuming operation, and the adjustment is difficult. However, it was difficult to reliably reduce the shock of the upper swing body.

Therefore, there is a technical problem to be solved in order to reliably alleviate the shock when the upper revolving structure of the construction machine stops turning and to prevent the occurrence of cavitation. The purpose is to solve the problem.

[0009]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and pressurized oil fed from a swing pump is switched by a swing switching valve and sent to a swing motor. In a swing hydraulic circuit of a construction machine that performs a swing operation of an upper swing body by rotation, a communication oil passage is provided between oil passages at both ends of the swing motor, and a hydraulic pressure adjusting unit is arranged between the communication oil passages. A swing hydraulic circuit for a construction machine configured to adjust the high / low pressure generated in the oil passages at both ends of the swing motor when the swinging of the upper swing body is stopped, and the hydraulic adjustment means includes a fixed throttle The swing hydraulic circuit of the construction machine, and the swing hydraulic circuit of the construction machine, wherein the hydraulic adjustment means is a variable throttle.
The hydraulic pressure adjusting means provides a swing hydraulic circuit of a construction machine which is a relief valve, and the hydraulic pressure adjusting means provides a swing hydraulic circuit of a construction machine which is a variable relief valve.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. For convenience of explanation, the same components as those of the conventional example will be denoted by the same reference numerals. First, the first and second aspects of the present invention will be described with reference to FIG. In FIG. 1 (A), reference numeral 12 denotes a swing hydraulic circuit. The swing hydraulic circuit 12 switches the pressure oil fed from the swing pump 2 by a swing switching valve 13 to swing an upper swing body (not shown). It is configured to send the rotation to the turning motor 4 for performing the operation. When the swing switching valve 13 is in the neutral position (b), the oil passages 5 at both ends of the swing motor 4 are provided.
6, and a communication oil passage 14 communicating between the oil passages 5, 6 is provided between the oil passages 5, 6 at both ends of the turning motor 4, and the communication oil passage 14 A fixed throttle 15 as a hydraulic pressure adjusting means is provided therebetween.

The pressure oil discharged from the swirl pump 2 is moved to the left or right position (a) or (c) of the swivel switching valve 13.
And enters the turning motor 4, the turning motor 4 rotates and turns the upper turning body. When the swing operation lever 16 is operated to switch the swing switching valve 13 to the neutral position (b) during the swing operation of the upper swing body, the oil passages 5 and 6 at both ends of the swing motor 4 are shut off, and both ends are turned off. A high pressure is generated in one of the oil paths 5 and 6, and a low pressure is generated in the other oil path. However, the one high-pressure oil passage side pressure oil is supplied to the fixed throttle 1 provided between the communication oil passages 14.
5 flows to the other low-pressure oil passage side, whereby the high-pressure oil passage side is depressurized, and the upper revolving unit slowly stops. Accordingly, the upper revolving superstructure reliably reduces the shock.

In addition, in place of the swing switching valve 13, a swing switching valve 13A shown in FIG. 1 (B) has a structure in which oil passages 5, 6 at both ends of the swing motor 4 are connected to a tank 10 at a neutral position. Can also be used. At that time,
The swing switching valve 1 for stopping the upper swing body
When the reverse operation of 3A is performed, the shock of the upper revolving structure is reliably reduced by the fixed throttle 15, and the occurrence of cavitation can be prevented.

Next, a third aspect of the present invention will be described with reference to FIG. In FIG. 2 (A), reference numeral 17 denotes a swing hydraulic circuit, and the swing hydraulic circuit 17 is a variable throttle 1 instead of the fixed throttle [15 in FIG. 1 (A)].
8 are provided.

When the swing operation lever 16 is operated to switch the swing switching valve 13 to the neutral position (b) during the swing operation of the upper swing body, the oil paths 5 and 6 at both ends of the swing motor 4 are shut off. A high pressure is generated in one of the oil passages 5 and 6, and a low pressure is generated in the other oil passage. However, the one high-pressure oil passage-side pressure oil flows through the variable throttle 18 provided between the communication oil passages 14 to the other low-pressure oil passage side. Stop slowly. Accordingly, the upper revolving superstructure reliably reduces the shock. In addition, since the variable aperture 18 is adjustable, the adjustment enables an optimal stopping operation of the upper swing body.

In addition, instead of the swing switching valve 13, a swing switching valve 13A shown in FIG. 2 (B) is constructed such that the oil paths 5, 6 at both ends of the swing motor 4 communicate with the tank 10 at a neutral position. Can also be used. At that time,
The swing switching valve 1 for stopping the upper swing body
When the reverse operation of 3A is performed, the shock of the upper swing body can be reliably reduced by the variable throttle 18, and the occurrence of cavitation can be prevented.

Next, the invention according to claim 4 will be described with reference to FIG. In FIG. 3 (A), reference numeral 19 denotes a swing hydraulic circuit. The swing hydraulic circuit 19 includes the communication oil passage [14 in FIG. 1 (A)] and the fixed throttle [FIG. 1 (A), two communication oil passages 20 and 21 are provided between both end oil passages 5 and 6 of the turning motor 4 to communicate the oil passages 5 and 6 with each other. Oilway 20
A relief valve 22 is provided between the communication oil passages 21 as a hydraulic pressure adjusting means that operates at a predetermined high pressure in the oil passage 5 to reduce the pressure in the oil passage 5.
The relief valve 23 is provided as hydraulic pressure adjusting means that operates at a predetermined high pressure to reduce the pressure in the oil passage 6.

When the swing operation lever 16 is operated to switch the swing switching valve 13 to the neutral position (b) during the swing operation of the upper swing body, the swing switching valve 13 causes the oil passages 5 at both ends of the swing motor 4 to rotate. , 6 are shut off, and a high pressure is generated in one of the oil passages 5, 6. When the pressure oil on the high pressure oil passage side exceeds a predetermined pressure, the pressure oil passes through the relief valve 22 or 23. It flows to the other low-pressure oil passage side, whereby the high-pressure oil passage side is depressurized, the upper revolving unit stops slowly, and the shock is reliably alleviated.

In addition, instead of the swing switching valve 13, the swing switching valve 13A shown in FIG. 3B is configured to connect the oil passages 5, 6 at both ends of the swing motor 4 to the tank 10 at a neutral position. Can also be used. At that time,
The swing switching valve 1 for stopping the upper swing body
When 3A is operated in reverse, the relief valve 22 or 2
3, the shock of the upper swing body can be reliably reduced, and the occurrence of cavitation can be prevented.

Next, the invention according to claim 5 will be described with reference to FIG. In FIG. 4A, reference numeral 24 denotes a swing hydraulic circuit, and the swing hydraulic circuit 24 is replaced with a variable relief valve 25, instead of the relief valve (22, 23 in FIG. 3). 26 are provided.

When the swing operation lever 16 is operated to turn the swing switching valve 13 to the neutral position (b) during the swing operation of the upper swing body, the swing switching valve 13 causes the oil passages 5 at both ends of the swing motor 4 to rotate. , 6 are shut off, and a high pressure is generated in one of the oil passages 5, 6. When the pressure oil on the high-pressure oil passage side exceeds a predetermined pressure, the pressure oil passes through the variable relief valve 25 or 26. To the other low-pressure oil passage side,
As a result, the high-pressure oil passage side is depressurized, the upper revolving unit slowly stops, and the shock is reliably alleviated. still,
The variable relief valves 25, 26 are capable of adjusting the relief pressure, which allows an optimal stopping operation of the upper revolving superstructure.

Also, instead of the swing switching valve 13, a swing switching valve 13A shown in FIG. 4 (B) is configured to connect the oil passages 5, 6 at both ends of the swing motor 4 to the tank 10 at a neutral position. Can also be used. At that time,
The swing switching valve 1 for stopping the upper swing body
When 3A is operated in reverse, the variable relief valve 25,
The shock of the upper revolving structure can be reliably reduced by 26, and the occurrence of cavitation can be prevented.

Further, although not shown, the hydraulic pressure adjusting means may be provided in the swivel switching valve 13. In this case as well, the same effects as described above can be expected. However, when the hydraulic pressure adjusting means is provided outside the swing switching valve 13, the circuit diameter of the hydraulic pressure adjusting means can be increased, and There are advantages such as easy adjustment and setting.

The present invention can be variously modified without departing from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

[0024]

According to the present invention, as described in detail in the above embodiment, the invention according to claim 1 provides a communication oil passage between oil passages at both ends of a swing motor in a swing hydraulic circuit of a construction machine. Since the oil pressure adjusting means is provided between the communication oil passages,
When the upper revolving unit stops turning, high and low pressures generated in the oil passages at both ends of the revolving motor are adjusted by the hydraulic pressure adjusting means, so that a shock when the upper revolving unit stops turning can be reduced, and cavitation and the like can be reduced. Is prevented from occurring.

According to the second aspect of the present invention, since a fixed throttle is provided as the hydraulic pressure adjusting means, as in the case of the first aspect of the present invention, when the turning of the upper turning body is stopped, the two ends of the turning motor are stopped. The high / low pressure generated in the oil passage is adjusted by the fixed throttle, so that the shock at the time of stopping the turning of the upper turning body can be reduced, and the occurrence of cavitation and the like can be prevented.

The third aspect of the present invention is the second aspect of the present invention.
Because a variable aperture is provided in place of the fixed aperture of the described invention,
In addition to the effect of the invention described in the second aspect, the adjustment of the variable aperture enables an optimal stopping operation of the upper-part turning body.

Further, in the invention according to the fourth aspect, a relief valve is provided as the hydraulic pressure adjusting means.
Similarly to the effect of the invention described above, when the upper revolving structure stops rotating, the high and low pressures generated in the oil passages at both ends of the revolving motor are adjusted by the relief valve at a predetermined pressure, and the shock when the upper revolving structure stops rotating. Can be alleviated, and the occurrence of cavitation and the like can be prevented.

The fifth aspect of the present invention is the fourth aspect of the present invention.
Since the variable relief valve is provided in place of the relief valve according to the invention described above, in addition to the effect of the invention according to the fourth aspect, the adjustment of the variable relief valve enables an optimal stopping operation of the upper-part turning body.

As described above, the present invention is an invention having a very remarkable effect, such as being able to surely alleviate a shock when the upper revolving structure of the construction machine stops turning and preventing the occurrence of cavitation.

[Brief description of the drawings]

FIG. 1 (A) shows an embodiment of the present invention, and shows a turning hydraulic circuit of a construction machine using a fixed throttle as a hydraulic pressure adjusting means. (B) A swing switching valve configured to shut off the oil passage of the swing pump at the neutral position and to communicate oil passages at both ends of the swing motor to the tank.

FIG. 2 (A) shows an embodiment of the present invention, and shows a swing hydraulic circuit of a construction machine using a variable throttle as a hydraulic pressure adjusting means. (B) A swing switching valve configured to shut off the oil passage of the swing pump at the neutral position and to communicate oil passages at both ends of the swing motor to the tank.

FIG. 3 (A) shows an embodiment of the present invention, and shows a swing hydraulic circuit of a construction machine using a relief valve as a hydraulic pressure adjusting means. (B) A swing switching valve configured to shut off the oil passage of the swing pump at the neutral position and to communicate oil passages at both ends of the swing motor to the tank.

FIG. 4 (A) shows one embodiment of the present invention, and shows a swing hydraulic circuit of a construction machine using a variable relief valve as a hydraulic pressure adjusting means. (B) A swing switching valve configured to shut off the oil passage of the swing pump at the neutral position and to communicate oil passages at both ends of the swing motor to the tank.

FIG. 5 shows a conventional example, in which a turning hydraulic circuit of a construction machine is configured to shut off oil passages at both ends of a turning motor at a neutral position of a turning switching valve.

FIG. 6 shows a conventional example, in which a turning hydraulic circuit of a construction machine is configured to open oil passages at both ends of a turning motor at a neutral position of a turning switching valve.

[Explanation of symbols]

 2 swing pump 4 swing motor 5, 6 oil passage 12, 17, 24 swing hydraulic circuit 13, 13A swing switching valve 14, 20, 21 communication oil passage 15 fixed throttle 18 variable throttle 19 swing hydraulic circuit 22, 23 relief valve 25, 26 Variable relief valve

Claims (5)

[Claims] In a swing hydraulic circuit of a construction machine, pressure oil fed from a swing pump is switched by a swing switching valve and sent to a swing motor, and the swing motor rotates to rotate the upper swing body. A communication oil passage is provided between both oil passages of the swing motor, and a hydraulic pressure adjusting means is provided between the communication oil passages. A swing hydraulic circuit for a construction machine, wherein a low pressure is adjusted by the hydraulic adjusting means. 2. The swing hydraulic circuit for a construction machine according to claim 1, wherein said hydraulic pressure adjusting means is a fixed throttle. 3. The swing hydraulic circuit for a construction machine according to claim 1, wherein said hydraulic pressure adjusting means is a variable throttle. 4. The swing hydraulic circuit for a construction machine according to claim 1, wherein said hydraulic pressure adjusting means is a relief valve. 5. The swing hydraulic circuit for a construction machine according to claim 1, wherein said hydraulic pressure adjusting means is a variable relief valve.