JP2002005104A - Hydraulic power source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce pulsation of pressure oil even when a frequency of the pulsation of the pressure oil delivered from a hydraulic pump changes according to a change in a rotating speed of a prime mover. SOLUTION: A pipe length variable mechanism 22 composed of a cylinder 23, a piston 24 and a compression spring 26 is arranged on the tip side of a pulsation reducing hose 17, and is constituted so that the piston 24 is slidingly displaced in the cylinder 23 according to delivery pressure from the hydraulic pump. Thus, a dimension S up to the piston 24 from the opening end 19A of a connecting port 19 arranged on the tip side of the pulsation reducing hose 17 changes according to the delivery pressure from the hydraulic pump, and even when the frequency of the pulsation of the pressure oil delivered from the hydraulic pump changes according to a change in the rotating speed of the prime mover because of a change in the pipe length including the total length of the pulsation reducing hose 17 for introducing the pressure oil from the hydraulic pump, the pulsation of this pressure oil can be surely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic power source device used for, for example, a hydraulic excavator, a hydraulic crane, etc., and more particularly to a hydraulic power source device capable of reducing pulsation of a discharge pipe connected to a discharge side of a hydraulic pump. About.

[0002]

2. Description of the Related Art In general, a traveling or working hydraulic circuit or the like mounted on a construction machine such as a hydraulic excavator or a hydraulic crane includes a hydraulic pump driven by a prime mover and a hydraulic oil supplied from the hydraulic pump. It is roughly constituted by a plurality of hydraulic actuators that operate and a plurality of hydraulic pipes connecting between these hydraulic actuators and the hydraulic pump.

[0003] Since hydraulic oil discharged from a hydraulic pump generates pulsation, among the hydraulic piping connecting between the hydraulic pump and the hydraulic actuator, in particular, the discharge piping connected to the discharge port of the hydraulic pump has an internal part. Vibrates in accordance with the pulsation of the pressure oil flowing through the oil.

[0004] When the discharge pipe vibrates due to the pulsation of the pressure oil, hydraulic equipment such as a control valve to which the discharge pipe is connected is damaged, and noise is generated due to the vibration of the discharge pipe. is there.

On the other hand, by connecting a pulsation reducing hose (hereinafter referred to as a pulsation reducing hose) separate from the discharge pipe to the discharge side of the hydraulic pump, pulsation of pressure oil flowing through the discharge pipe is reduced. It is known that this can be achieved (for example, JP-A-7-180792).

Here, in the above-described pulsation reducing hose according to the prior art, the base end is connected to the discharge side of the hydraulic pump and the distal end is closed by a plug or the like, and a part of the pressure oil discharged from the hydraulic pump is introduced. Things. And
This pulsation reducing hose reflects the pressure oil introduced from the hydraulic pump at the closed end on the distal end side, returns to the base end side, and joins the pressure oil discharged into the discharge pipe, thereby forming the base of the pulsation reducing hose. The pulsation of the pressure oil returned to the end side and the pulsation of the pressure oil discharged into the discharge pipe interfere with each other to cancel each other, thereby reducing the pulsation of the pressure oil flowing through the discharge pipe.

[0007]

By the way, the frequency f of the pulsation of the pressure oil discharged from the hydraulic pump is represented by the rotational speed of the prime mover, and the reduction ratio of the power transmission device for transmitting the rotational speed from the prime mover to the hydraulic pump at a reduced speed. Is B, and C is the number of pistons of the hydraulic pump.

[0008]

(Equation 1)

The length (pipe length) L of the pulsation reducing hose required to reduce the pulsation of the pressure oil having the above-mentioned frequency f is given by It is represented as 2.

[0010]

(Equation 2)

Accordingly, from the above equation (1), the frequency f of the pulsation of the pressure oil discharged from the hydraulic pump becomes lower as the rotation speed A of the prime mover becomes lower, and from the above equation (2), the length L of the pulsation reducing hose becomes , As the frequency f of the pulsation of the pressure oil decreases,
That is, it is necessary to increase the rotation speed A of the prime mover as the rotation speed A decreases.

However, the pulsation reducing hose according to the prior art described above has a fixed pipe length, so that when the rotation speed of the prime mover changes and the frequency of pulsation of the pressure oil changes, this pulsation reduces. However, there is a problem that it is not possible to reliably reduce.

The present invention has been made in view of the above-described problems of the prior art, and ensures that even if the frequency of the pulsation of the pressure oil discharged from the hydraulic pump changes with the change in the rotation speed of the prime mover, this pulsation can be reliably achieved. It is an object of the present invention to provide a hydraulic power source device capable of reducing power consumption.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a hydraulic pump driven by a prime mover, a discharge pipe connected to a discharge side of the hydraulic pump, and discharge from the hydraulic pump. A base end side for introducing a part of the pressure oil is connected to the discharge side of the hydraulic pump or in the middle of the discharge pipe, and is applied to a hydraulic power source device including a pulsation reducing hose for reducing pulsation generated in the discharge pipe. You.

The first aspect of the present invention is characterized in that a pipe length including the entire length of the pulsation reducing hose is provided at the tip side of the pulsation reducing hose in accordance with the discharge pressure from the hydraulic pump. That is, a variable pipeline length mechanism is provided.

With this configuration, for example, when the rotation speed of the prime mover is high and the discharge pressure from the hydraulic pump is low, the pipeline length variable mechanism reduces the pipeline length including the entire length of the pulsation reducing hose, When the rotation speed of the prime mover is low and the discharge pressure from the hydraulic pump is high, the conduit length variable mechanism increases the conduit length including the entire length of the pulsation reducing hose. As described above, by changing the length of the pipeline into which a part of the pressure oil discharged from the hydraulic pump is introduced to an appropriate length in accordance with the discharge pressure from the hydraulic pump, the rotation speed of the prime mover is changed. Irrespective of this, the pulsation of the pressure oil flowing in the discharge pipe can be reduced.

According to a second aspect of the present invention, there is provided a variable line length mechanism, wherein a cylinder provided at a distal end of a pulsation reducing hose is slidably inserted into the cylinder in accordance with a discharge pressure from a hydraulic pump. The present invention is characterized in that the piston is configured to change the length of the pipeline by being displaced, and a spring that constantly biases the piston toward the open end of the pulsation reducing hose.

With this configuration, when the rotation speed of the prime mover decreases and the discharge pressure from the hydraulic pump increases, the piston slides in the cylinder against the spring due to the discharge pressure to reduce pulsation. Keep away from the open end of the hose. Thereby, the length of the pipeline into which the pressure oil from the hydraulic pump is introduced can be changed according to the discharge pressure from the hydraulic pump.

A third aspect of the present invention resides in that the cylinder has a configuration in which the base end is connected to a pulsation reducing hose and the tip end is connected to a tank via a drain pipe.

With this configuration, it is possible to suppress the occurrence of oil lock or the like in the piston in the cylinder, and the piston can smoothly move in the cylinder according to the discharge pressure from the hydraulic pump.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a hydraulic power source device according to the present invention will be described in detail with reference to FIGS.

In the figure, reference numeral 1 denotes a hydraulic excavator, which is a tracked lower traveling body 2, an upper revolving body 3 rotatably mounted on the lower traveling body 2, and an upper revolving body. Body 3
And a working device 4 provided at the front of the device so as to be able to move up and down.

The upper revolving unit 3 includes a revolving frame 6 provided on the lower traveling unit 2 via a revolving device 5, a cab 7 provided on the revolving frame 6, a building cover 8,
The building cover 8 houses a motor 9, a hydraulic power source device 11, and the like, which will be described later.

Reference numeral 9 denotes a prime mover located inside the building cover 8 and disposed on the revolving frame 6, and 10 denotes a power transmission device attached to the prime mover 9, and the power transmission device 10 includes the prime mover 9
Is reduced and transmitted to the hydraulic pump 12 described later.

Reference numeral 11 denotes a hydraulic power source device according to the present embodiment,
The hydraulic power source device 11 is housed in the building cover 8 and includes a hydraulic pump 12, a suction pipe 13, a discharge pipe 16, a pulsation reducing hose 17, and the like, which will be described later.

Reference numeral 12 denotes a hydraulic pump constituting the hydraulic power source device 11, and the input shaft of the hydraulic pump 12 is connected to the power transmission device 10 via gears or the like. The hydraulic pump 12 is driven by the prime mover 9 to
The hydraulic fluid is discharged to hydraulic actuators (not shown) such as a hydraulic motor for traveling of the lower traveling body 2, hydraulic cylinders of the working device 4, and a hydraulic motor for turning of the turning device 5.

Reference numeral 13 denotes a suction pipe connecting between a suction port of the hydraulic pump 12 and the hydraulic oil tank 14. A base end of the suction pipe 13 is connected to the hydraulic oil tank 14, and a distal end thereof is connected to the hydraulic pump 12. Connected to suction port. The suction pipe 13 guides the working oil stored in the working oil tank 14 to a suction port of the hydraulic pump 12.

Reference numeral 15 denotes a piping connection block attached to the hydraulic pump 12. Inside the piping connection block 15, an oil passage (not shown) communicating with the discharge port of the hydraulic pump 12 is provided.
Are formed. The pipe connection block 15 is configured to be connected to a discharge pipe 16, a pulsation reduction hose 17, and the like, which will be described later.

Reference numeral 16 denotes a discharge pipe connected to the discharge side of the hydraulic pump 12. The base end of the discharge pipe 16 is connected to a pipe connection block 15 and communicates with the discharge port of the hydraulic pump 12. Is connected to a control valve (not shown).

The pressure oil from the hydraulic pump 12 supplied to the control valve through the discharge pipe 16 is supplied to a hydraulic actuator (both not shown) through a hydraulic pipe connected to an output port of the control valve. It has become.

Reference numeral 17 denotes a pulsation reduction hose connected to the discharge side of the hydraulic pump 12. The pulsation reduction hose 17 is made of, for example, a high pressure rubber hose, the base end of which is connected to the pipe connection block 15, and the tip end of which is connected to the pipe. Connection block 1
5 and is fixed to the suction pipe 13 via a bracket 18.

The pulsation reducing hose 17 communicates with the discharge port of the hydraulic pump 12 through the piping connection block 15 so that a part of the pressure oil discharged from the hydraulic pump 12 is introduced.

As shown in FIG. 3, a cylindrical connection port 19 for connecting a cylinder 23 to be described later is provided at the tip end of the pulsation reduction hose 17, and an open end 19A of the connection port 19 is provided. Is an open end on the distal end side of the pulsation reducing hose 17. A large-diameter flange portion 19B is formed at an axially intermediate portion of the connection port 19, and a nut 20 is rotatably engaged with the flange portion 19B. On the outer peripheral side of the connection port 19, an entire circumferential groove 19C is formed near the opening end 19A, and an O-ring 2 is formed in the entire circumferential groove 19C.
1 is attached.

Reference numeral 22 denotes a conduit length variable mechanism provided on the distal end side of the pulsation reducing hose 17. The conduit length variable mechanism 22, as shown in FIG.
It is constituted by a compression spring 26 and the like.

Reference numeral 23 denotes a cylinder connected to the connection port 19 of the pulsation reducing hose 17. The cylinder 23 is made of, for example, a metal pipe, and a part of the pressure oil discharged from the hydraulic pump 12 together with the pulsation reducing hose 17 is introduced. This constitutes a pipeline. Here, a male screw 23A is formed on the outer periphery of the base end side of the cylinder 23, and a female screw 23B is formed on the inner periphery of the distal end side.

The cylinder 23 is fixed to the connection port 19 by screwing a nut 20 to a male screw 23A with the base end side inner circumference fitted to the outer circumference of the connection port 19. The cylinder 23 is positioned in the length direction by contacting the flange 19 </ b> B of the connection port 19, and the space between the connection port 19 and the cylinder 23 is sealed by the O-ring 21.

Reference numeral 24 denotes a piston slidably provided on the inner peripheral side of the cylinder 23. An outer peripheral groove 24A is formed on the outer peripheral side of the piston 24, and an O-ring 25 is provided in the entire peripheral groove 24A. Installed. The piston 24 covers the cylinder 23, and the space between the piston 24 and the cylinder 23 is sealed by an O-ring 25.

Reference numeral 26 denotes a compression spring located in the cylinder 23 and compressed between the piston 24 and a later-described reducer 27. The compression spring 26 directs the piston 24 toward the open end 19A of the connection port 19. It is always energized.

For example, when the prime mover 9 is stopped and pressure oil is not discharged from the hydraulic pump 12, the piston 2
As shown in FIG. 3, reference numeral 4 denotes a connection port 1 by a compression spring 26.
9 is kept in contact with the open end 19A. At this time, the length of the pipeline (the pipeline length) through which the pressure oil from the hydraulic pump 12 is introduced is the entire length of the pulsation reducing hose 17.

On the other hand, the prime mover 9 operates and the hydraulic pump 12
Pressure oil is discharged from the pulsation reduction hose 1
7, the piston 24 separates from the open end 19A of the connection port 19 against the compression spring 26, as shown in FIG. The dimension S between the opening end 19A of the connection port 19 and the piston 24 changes according to the discharge pressure from the hydraulic pump 12, and at this time, The length is the pulsation reducing hose 17
Is the length obtained by adding the above-mentioned dimension S to the total length.

Reference numeral 27 denotes a reducer provided on the distal end side of the cylinder 23. The reducer 27 has a through hole 27A penetrating in the axial direction.
3B. The reducer 27 connects between the cylinder 23 and a drain pipe 28 described later.

Reference numeral 28 denotes a drain pipe whose base end is connected to the tip end of the cylinder 23 via a reducer 27, and the tip end of the drain pipe 28 is connected to the hydraulic oil tank 14. Therefore, the front end side of the cylinder 23 passes through the through hole 27A of the reducer 27,
This allows the piston 24 to slide smoothly in the cylinder 23 without causing an oil lock or the like.

The hydraulic power source device 11 according to the present embodiment has the above-described configuration, and its operation will be described below.

First, the prime mover 9 stops and the hydraulic pump 12
When pressure oil is not being discharged from the
As shown in FIG. 3, the piston 24 of the second
As a result, the state of contact with the opening end 19A of the connection port 19 is maintained.

Next, the prime mover 9 operates and the hydraulic pump 12
Is driven, the hydraulic pump 12 sucks the hydraulic oil in the hydraulic oil tank 14 through the suction pipe 13, pressurizes this hydraulic oil, and discharges it as high-pressure hydraulic oil. Then, the pressure oil discharged from the hydraulic pump 12 is guided to a control valve through a discharge pipe 16, and is supplied to a hydraulic actuator via the control valve.

At this time, a part of the pressure oil discharged from the hydraulic pump 12 is introduced into the pulsation reduction hose 17, and the pressure oil is supplied to the piston of the conduit length variable mechanism 22 provided at the distal end of the pulsation reduction hose 17. The light is reflected by 24 and returns to the proximal end side of the pulsation reducing hose 17. Thereby, the pulsation of the pressure oil returned to the base end side of the pulsation reduction hose 17 and the pulsation of the pressure oil discharged into the discharge pipe 16 interfere with each other to cancel each other, and the pressure oil flowing through the discharge pipe 16 Pulsation can be reduced.

Here, from the above equations 1 and 2, the prime mover 9
When the load acting on the hydraulic pump 12 increases and the rotational speed decreases, the frequency of the pulsation of the pressure oil discharged from the hydraulic pump 12 decreases. Therefore, in order to reduce the pulsation, the pipeline including the entire length of the pulsation reduction hose 17 is used. It is necessary to increase the length.

On the other hand, in the present embodiment, the prime mover 9
When the rotation speed of the hydraulic pump 12 decreases and the discharge pressure from the hydraulic pump 12 increases, the piston 24 of the conduit length variable mechanism 22 is connected to the pulsation reducing hose 17 against the compression spring 26 as shown in FIG. The opening 19 is separated from the opening end 19A of the opening 19 by a dimension S.

Accordingly, the length of the conduit through which the pressure oil from the hydraulic pump 12 is introduced is increased by the dimension S between the opening end 19A of the connection port 19 and the piston 24, and the total length of the pulsation reducing hose 17 is increased. Can be changed to an appropriate length. Accordingly, the pulsation of the pressure oil reflected by the piston 24 and returned to the base end side of the pulsation reduction hose 17 and the pulsation of the pressure oil discharged into the discharge pipe 16 interfere with each other, and the pressure flowing through the discharge pipe 16 The pulsation of the oil can be reliably reduced, and damage to a control valve or the like to which the discharge pipe 16 is connected, and noise due to vibration of the discharge pipe 16 can be suppressed.

The sliding surface between the piston 24 and the cylinder 23 can be sealed by the O-ring 25 provided on the outer peripheral side of the piston 24, so that the pressure oil introduced into the cylinder 23 passes through the piston 24. And cylinder 23
Can be prevented from leaking to the front end side of the device.

Further, since the distal end side of the cylinder 23 is connected to the hydraulic oil tank 14 through the reducer 27 and the drain pipe 28, the piston 24 can be connected to the hydraulic pump 12 without causing an oil lock or the like in the cylinder 23. Can smoothly slide in the cylinder 23 according to the discharge pressure of the cylinder.

Even if, for example, a part of the pressure oil introduced into the cylinder 23 passes through the piston 24 and leaks to the tip of the cylinder 23, the leaked oil is transferred to the hydraulic oil tank 14 through the drain pipe 28 or the like. You can go back.

Thus, according to the present embodiment, the cylinder 23, the piston 24,
A pipe length variable mechanism 22 including a compression spring 26 and the like is provided, and a piston 24 is slidably displaced in a cylinder 23 in response to a discharge pressure from the hydraulic pump 12, thereby providing a connection provided on the distal end side of the pulsation reduction hose 17. Since the dimension S from the open end 19A of the port 19 to the piston 24 changes, the hydraulic pump 1
The length of the pipeline including the entire length of the pulsation reducing hose 17 can be changed in accordance with the discharge pressure from the pulsation reducing hose 17.

For this reason, even when the frequency of the pulsation of the hydraulic oil discharged from the hydraulic pump 12 changes with the change in the rotation speed of the prime mover 9, the length of the pipeline through which the hydraulic oil from the hydraulic pump 12 is introduced Can be changed to an appropriate length.
Thereby, the pulsation of the pressure oil flowing in the discharge pipe 16 can be reliably reduced by the pulsation reduction hose 17,
Damage to a control valve or the like to which the discharge pipe 16 is connected, and noise due to vibration of the discharge pipe 16 can be suppressed.

In the above-described embodiment, the case where the base end side of the pulsation reducing hose 17 is connected to the discharge port of the hydraulic pump 12 through the piping connection block 15 is described as an example. However, the present invention is not limited to this. For example, the base end side of the pulsation reducing hose 17 may be connected to the middle of the discharge pipe 16.

In the above-described embodiment, the hydraulic power source device mounted on the hydraulic excavator has been described as an example. However, the present invention is not limited to this, and may be applied to other construction machines such as a hydraulic crane and a wheel loader. The present invention can be widely applied to a hydraulic power source device mounted thereon and a hydraulic power source device mounted on various industrial machines.

[0057]

As described above in detail, according to the first aspect of the present invention, the length of the pipeline including the entire length of the pulsation reducing hose is changed at the tip side of the pulsation reducing hose in accordance with the discharge pressure from the hydraulic pump. Since the variable pipeline length mechanism is provided, for example, when the rotation speed of the prime mover is high and the discharge pressure from the hydraulic pump is low, the pipeline length including the entire length of the pulsation reducing hose is reduced by the variable pipeline length mechanism. On the other hand, when the rotation speed of the prime mover is low and the discharge pressure from the hydraulic pump is high, the pipeline length including the entire length of the pulsation reducing hose can be increased by the pipeline length variable mechanism. Therefore, even when the frequency of the pulsation of the hydraulic oil discharged from the hydraulic pump changes due to the change in the rotation speed of the prime mover, the pulsation of the discharge pipe connected to the discharge side of the hydraulic pump is reliably reduced by the pulsation reduction hose. can do.

According to the second aspect of the present invention, the variable pipe length mechanism is provided with a cylinder provided at the tip of the pulsation reducing hose, and slidably inserted into the cylinder to discharge from the hydraulic pump. The hydraulic pump is configured by a piston that changes the length of the pipeline by being displaced in accordance with the pressure and a spring that constantly urges the piston toward the open end of the pulsation reducing hose. When the discharge pressure from the hose changes, the piston moves in the cylinder in accordance with the change in the discharge pressure and moves away from the open end of the pulsation reducing hose. Thereby, the pipe length including the entire length of the pulsation reducing hose can be changed to an appropriate length in accordance with the discharge pressure from the hydraulic pump.

According to the third aspect of the invention, since the base end of the cylinder is connected to the pulsation reducing hose and the front end is connected to the tank, the piston causes an oil lock or the like in the cylinder. Without sliding, the inside of the cylinder can be smoothly slid according to the discharge pressure from the hydraulic pump.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a hydraulic power source device according to the present invention in a state mounted on a hydraulic shovel.

FIG. 2 is an enlarged sectional view of a main part of the hydraulic pump, a suction pipe, a discharge pipe, a pulsation reducing hose, and the like, which are enlarged from the direction of arrows II-II in FIG.

FIG. 3 is an enlarged cross-sectional view showing a main part of the variable conduit length mechanism in FIG. 2;

FIG. 4 is an enlarged sectional view of a main part at a position similar to FIG. 3 showing a state in which a piston has moved inside a cylinder.

[Explanation of symbols]

 Reference Signs List 9 prime mover 11 hydraulic source device 12 hydraulic pump 14 hydraulic oil tank (tank) 16 discharge pipe 17 pulsation reduction hose 19A open end 22 pipe length variable mechanism 23 cylinder 24 piston 26 compression spring (spring) 28 drain pipe

Claims (3)

[Claims] 1. A hydraulic pump driven by a prime mover, a discharge pipe connected to a discharge side of the hydraulic pump, and a base end of the hydraulic pump for introducing a part of pressure oil discharged from the hydraulic pump. A pulsation reducing hose connected to the discharge side or in the middle of the discharge pipe and reducing a pulsation generated in the discharge pipe, a discharge pressure from the hydraulic pump is provided at a tip side of the pulsation reduction hose. A hydraulic power source device characterized in that a line length variable mechanism for changing the line length including the entire length of the pulsation reducing hose according to the above is provided. 2. The variable line length mechanism includes a cylinder provided at a distal end of the pulsation reducing hose, and is slidably inserted into the cylinder to be displaced in accordance with a discharge pressure from the hydraulic pump. A piston that changes the pipe length by
2. The hydraulic power source device according to claim 1, wherein the piston is constituted by a spring which constantly biases the piston toward an open end of the pulsation reducing hose. 3. The hydraulic power source device according to claim 2, wherein the cylinder has a configuration in which a proximal end is connected to the pulsation reducing hose and a distal end is connected to a tank via a drain pipe.