JPH0612319Y2 - Hydraulic traveling equipment for construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic traveling device for a construction machine used as, for example, a hydraulic excavator, a hydraulic crane, or the like.

[Conventional technology]

Generally, a traveling hydraulic motor is required to run at high speed when the load is small or when traveling on level ground, but there is a demand for running at high speed. Correspond. On the other hand, when climbing up a slope or when loading cargo, the traveling speed may be slow, but there is a demand for a large torque. In this case, the hydraulic motor may be switched to a large capacity.

In this case, of the motor drive pressures supplied to the left and right traveling hydraulic motors, the high-pressure side motor pressure (hereinafter referred to as motor self pressure) is used as the pilot pressure and supplied to the hydraulic pilot type displacement control valve for variable displacement. However, there is known a self-pressure control system in which a servo actuator is driven via the displacement control valve. However, this self-pressure control system can automatically switch the displacement according to the motor self-pressure, so It can be said that this is a practical hydraulic traveling device, as compared with a device in which the capacity is manually switched according to the above.

However, when controlling the capacity of the hydraulic motor according to the motor self-pressure, like when one track is riding on a rock,
When the loads on the left and right hydraulic motors are different, the left and right motor self pressures are changed, and as a result, the tilt amounts of the left and right hydraulic motors are different. Therefore, even if the discharge flow rate from the hydraulic pump is the same, there is a drawback that the vehicle body meanders or skews due to different motor capacities (pushing-off volumes) of the left and right hydraulic motors.

In order to solve this drawback, a hydraulic traveling device having a tilt tuning mechanism for tuning the tilt amounts (motor capacities) of the left and right hydraulic motors as shown in FIG. 3 has been conventionally known. There is.

In FIG. 3, "A" is attached to the left traveling device element and "B" is attached to the right traveling device element. In FIG. 3, 1A and 1B are left portions provided on the lower traveling body. , A hydraulic motor for traveling on the right, and for the hydraulic motors 1A and 1B, for example, a swash plate type or a swash shaft type variable displacement hydraulic motor is applied.
The motor displacement can be made variable by tilting the variable displacement units 2A and 2B such as the valve plate. Servo actuators 3A and 3B are attached to the hydraulic motors 1A and 1B. Servo cylinder mechanisms, for example, are used as the servo actuators 3A and 3B, and the hydraulic actuators 1A and 1B are displaced by moving them in the X direction. Low torque as capacity,
By rotating at high speed and displacing in the Y direction shown by the arrow, the hydraulic motors 1A and 1B have large capacity and rotate at high torque and low speed. 4A and 4B are parking brakes which are negative brakes attached to the hydraulic motors 1A and 1B.

5A and 5B are hydraulic pumps provided on the upper revolving structure side and driven by an engine (not shown), 6 is a tank, and the left hydraulic motor 1A is a hydraulic pump 5A and a tank 6 via hydraulic pipes 7A and 8A. The right hydraulic motor 1B is connected to the hydraulic pump 5 via the hydraulic pipes 7B and 8B.
B, connected to the tank 6 and each of the hydraulic pipes 7A, 7B, 8
A and 8B are center joints 9 provided in the turning device.
It is divided into an upper revolving structure side and a lower traveling structure side by. Then, between the hydraulic pipes 7A and 8A, 7B and 8B, the vehicle is positioned on the upper revolving structure side (driver's cab) to move forward and backward,
Switching valves 10A and 10B for traveling for stopping are provided,
High pressure selection valves 11A and 11B and brake valves 12A and 12B are provided on the lower traveling body side, respectively. Here, each of the high pressure selection valves 11A and 11B is a hydraulic pipe 7
Of the motor drive pressures flowing between A and 8A and between 7B and 8B, the high pressure side pressure is derived as the motor self pressure, and as will be described later, the brake release pressure, the drive pressure of the actuators 3A and 3B, and the capacity control valve 17A described later. , 17B pilot pressure.

Reference numeral 13 is a communication pipe that communicates between the high pressure selection valves 11A and 11B, and the high pressure selection valves 11A and 1B are provided in the middle of the communication pipe 13.
There is provided another high pressure selection valve 14 for selecting the high pressure side of the motor self pressure derived from 1B. And
The high pressure side motor self pressure selected by the high pressure selection valve 14 is supplied to the displacement control valves 17A and 17B through the high pressure side self pressure pipes 15A and 15B. 16A, 1
Reference numeral 6B is a brake pipe for supplying the motor self pressures respectively derived by the high pressure selection valves 11A and 11B to the parking brakes 4A and 4B.

Further, 17A and 17B are displacement control valves respectively attached to the hydraulic motors 1A and 1B in order to supply a driving pressure to the actuators 3A and 3B.
Is a 4-port 2-position spool switching valve of spring offset / hydraulic pilot type, in which a spring and a hydraulic pilot section are opposed to each other, and a small capacity position with a small capacity (a) and a large capacity position with a large capacity (ro ), And has a transitional intermediate position (C). Then, the capacity control valve 17
A port on one side of A, 17B is connected to the other high pressure selection valve 14 via the above-mentioned high pressure side self pressure piping 15A, 15B, and is connected from the center joint 9 to the tank 6 via drain piping 18A, 18B. The ports on the other side are selectively connected to the chambers of the servo actuators 3A and 3B, and the hydraulic pilot section is connected to the pilot pipe 1
High pressure side self pressure piping 15A, 15B via 9A, 19B
Connected with. Here, the capacity control valves 17A, 1
7B is normally urged to a small capacity position (a) by a spring to move the servo actuators 3A and 3B to the arrow X position.
Direction, and when the pilot pressure becomes equal to or higher than a predetermined pressure, it is switched to the large capacity position (b) and the servo actuators 3A and 3B are displaced in the Y direction shown by the arrow.

Further, 20A and 20B are motor assemblies showing the whole assembly of the traveling motor.
0A and 20B are configured with a range surrounded by the drawing.

In the hydraulic traveling system configured as described above, it is assumed that the traveling switching valves 10A and 10B are switched to desired switching positions in order to drive the construction machine. Now, regarding the traveling circuit on the left side, when the traveling switching valve 10A is set to the switching position on the left side, the pressure oil from the hydraulic pump 5A is transferred to the hydraulic pipe 7.
A, switching valve 10A, center joint 9, brake valve 1
2A is supplied to the hydraulic motor 1A, and the return oil is returned to the tank 6 via the hydraulic pipe 8A, the brake valve 12A, the center joint 9, and the switching valve 10A.
To rotate. On the other hand, the same applies to the traveling circuit on the right side if the traveling switching valve 10B is set to the switching position on the right side.

At this time, the pressure oil flowing in the high-pressure side hydraulic pipes 7A, 7B is derived as the motor self-pressure by the high-pressure selection valves 11A, 11B. This motor self pressure is applied to the brake piping 16A, 1
6B is supplied to the parking brakes 4A and 4B to release the brakes. Further, each motor self-pressure is introduced from the communication pipe 13 to another high-pressure selection valve 14, and the high-pressure motor self-pressure derived by the high-pressure selection valve 14 is high-pressure self-pressure pipe 15.
It is supplied from A and 15B to the servo actuators 3A and 3B via the capacity control valves 17A and 17B, and is also supplied from the pilot pipes 19A and 19B to the hydraulic pilot section.

Here, regarding the capacity control valves 17A and 17B, when the pilot pressure is low, the capacity control valves 17A and 17B are switched to the small capacity position (a) side by the spring, and the servo actuator 3
A and 3B are displaced in the X direction shown by the arrow so that the variable capacity parts 2A and 2B
B is tilted to the small capacity side, the hydraulic motors 1A and 1B are made to have a constant small capacity, and low torque and high speed rotation are performed. On the other hand, when the pilot pressure becomes high, the displacement control valves 17A and 17B are switched to the large displacement position (B), and the hydraulic motors 1A and 1B are kept at a large displacement to rotate at high torque and low speed.

However, the left and right high-pressure selection valves 11A and 11B are communicated with each other through the communication pipe 13, and the high-pressure selection valve 1 is connected to the communication pipe 13 with the other high-pressure selection valves 1A and 11B.
4 is provided to derive the high pressure side motor self pressure, and the high pressure side motor self pressure is used as the pilot pressure to control the displacement control valve 17
It is possible to control the switching of A and 17B and use the driving pressure of the servo actuators 3A and 3B.
As a result, the operation of the capacity control valves 17A and 17B, the servo actuators 3A and 3B, and the capacity variable units 2A and 2B is left,
It can be synchronized on the right, and can prevent meandering.

[Problems to be solved by the invention]

However, the above-mentioned prior art not only requires the communication pipe 13 for communicating the left and right high-pressure selection valves 11A and 11B, but also requires the high-pressure side self pressure derived from the other high-pressure selection valve 14. Left and right capacity control valves 17A, 17
In order to supply to B, the left and right high pressure side self pressure piping 15A,
15B is required.

However, since the traveling hydraulic motors 1A and 1B are arranged near the drive wheels in order to drive the left and right crawler belts, at least two motor motors 20A and 20B are required to connect the left and right motor assemblies. Hydraulic piping is required. Further, when the servo actuators 3A and 3B are driven by the external hydraulic pressure source, three hydraulic pipes are required. As described above, the large number of hydraulic pipes connecting the motor assemblies 20A and 20B complicates the hydraulic system, which is not preferable in terms of space and price.

The present invention has been made in view of the above problems of the prior art, and in realizing the tilt tuning mechanism of the traveling hydraulic motor, the number of hydraulic pipes between the left and right motor assemblies can be increased by one. It is an object of the present invention to provide a hydraulic traveling device for such a construction machine.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a variable displacement traveling hydraulic motor having a variable displacement portion, a servo actuator for tilt-driving the variable displacement portion of the hydraulic motor,
A left and right traveling motor assembly including a hydraulic pilot type displacement control valve for controlling the displacement of the hydraulic motor by switching the pressure oil to the servo actuator is provided. A right traveling hydraulic motor is connected to a hydraulic pump and a tank via left and right hydraulic pipes, respectively, and a left and right traveling switching valve is provided in the middle of the left and right hydraulic pipes. In the hydraulic traveling device, left and right hydraulic pipes are provided with left and right high pressure selection valves for deriving, as motor self pressure, the high pressure side pressure of the motor drive pressure supplied to the hydraulic motor. Between the throttles and the hydraulic pilot portions of the left and right displacement control valves, respectively, through pilot pipes. Characterized in that the connection was.

[Action]

With this configuration, the pressure between the pair of throttles provided in the communication pipe becomes equal, so that the pressure between the throttles is directly adjusted through the left and right pilot pipes. Can be introduced into the hydraulic pilot section of No. 1, and not only a tilt tuning mechanism between hydraulic motors can be realized, but also one hydraulic pipe can be connected between the left and right motor assemblies.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.
The details will be described.

The same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted. However, in the following embodiments, the other high-pressure selection valve 14 and the high-pressure side self-pressure pipes 15A and 15B according to the prior art are not provided.

First, FIG. 1 shows a first embodiment of the present invention.

Reference numeral 21 is one communication pipe that communicates between the left and right high-pressure selection valves 11A and 11B. The communication pipe 21 is located in the motor assembly 20A, 20B in the middle of the communication pipe 21 and has a throttle 22A, 2B.
2B is provided, and the inside of the communication pipe 21 is held at a uniform pressure between the throttles 22A and 22B. The diaphragm 22
A and 22B may be fixed diaphragms or variable diaphragms. Two
3A and 23B are pilot pipes, and the pilot pipes 2
One end of 3A, 23B is located between the throttles 22A, 22B and is connected to the communication pipe 21, and the other end thereof is the capacity control valve 17
The hydraulic pilots A and 17B are respectively connected.

Reference numerals 24A and 24B are drive pressure pipes for supplying the motor self pressure derived by the high pressure selection valves 11A and 11B as drive pressures for the servo actuators 3A and 3B.
One end sides of A and 24B are connected to the high pressure selection valves 11A and 11B (in FIG. 1, the high pressure selection valves 11A and 11B and the throttle 22).
It is connected to the communication pipe 21 between A and 22B, but it is equivalent), and the other end side is connected to a port on one side surface of the capacity control valves 17A and 17B. 25A and 25B are pressure reducing valves provided in the middle of the driving pressure pipes 24A and 24B,
The pressure reducing valves 24A and 24B are for reducing the motor self pressure so as to supply equal drive pressure to the left and right servo actuators 3A and 3B. 26A and 26B control the outflow side pressure of the pressure reducing valves 25A and 25B to the parking brakes 4A and 4B.
Brake piping for supplying to B.

Although the present embodiment is configured in this way, the basic operation of the hydraulic traveling device is not different from that of the prior art. However, in this embodiment, the high pressure selection valve 11
A and 11B are communicated with each other by a communication pipe 21, a pair of throttles 22A and 22B are provided in the middle, and the pressures of the throttles 22A and 22B are used as pilot pressures to make pilot pipes 23A and 23B.
It is supplied to the capacity control valves 17A and 17B via B.
As a result, even if the left and right motor self pressures derived by the high pressure selection valves 11A and 11B respectively fluctuate, the throttle 22
Since the pressure between A and 22B is equalized by the throttles 22A and 22B, the pilot pressures supplied to the capacity control valves 17A and 17B become the same pressure, and the capacity control valve 17
The switching operation of A and 17B can be synchronized, and a tilt tuning mechanism can be configured.

On the other hand, even if the switching operations of the capacity control valves 17A and 17B are synchronized, the driving pressures of the servo actuators 3A and 3B are not sufficient unless they are equal on the left side and the right side. However, the pressure reducing valves 25A and 25B are provided in the driving pressure pipes 24A and 24B,
Since the motor self pressure is supplied to the servo actuators 3A and 3B as a reduced pressure, the capacity variable units 2A and 2B
The tilt amount of B can also be synchronized.

Thus, the throttles 22A and 22B and the pilot pipe 23
A, 23B, drive pressure pipes 24A, 24B, and pressure reducing valves 25A, 25B are connected to the left and right motor assemblies 20.
By assembling each of the motor assemblies 20A and 20B in the A and 20B, one communication pipe 21 can be added, and the tilt tuning mechanism can be simplified.

Further, in the present embodiment, the communication pipe 21 and the high pressure selection valve 11
Left and right hydraulic piping 7A and 8A, 7B via A, 11B
And 8B are substantially in communication with each other, the straightness of the vehicle body can be improved even when the displacement volumes of the left and right hydraulic motors 1A and 1B differ at the manufacturing stage.

That is, the hydraulic motors 1A, 1A, 1
B has a constant small capacity, but it is assumed that the displacement volume is different in this state. Now, the displacement volume of the left hydraulic motor 1A is q ₁ , the motor drive pressure is P ₁ , the displacement volume of the right hydraulic motor 1B is q ₂ , the motor drive pressure is P _2, and the flow rates from the hydraulic pumps 5A, 5B are If both are constant at Q ₀ , the rotation speed of the hydraulic motor 1A is N ₁ = Q ₀ / q ₁ ,
The rotation speed of the hydraulic motor 1B is N ₂ = Q ₀ / q ₂ . Then, assuming that q ₁ > q ₂ , N ₁ <N ₂ . Further, if the load torque at this time is the same, P ₁ q ₁ = P ₂ q ₂ , and P ₁ <P ₂ . Therefore, the pressure oil from the high-pressure selection valve 11B flows to the high-pressure selection valve 11A side through the communication pipe 21, the throttles 22B, 22A, and the left-side hydraulic motor 1 having a low rotation speed.
The rotation speed N _{1 of A} is increased and the rotation speed N ₂ of the right hydraulic motor 1B, which is high rotation speed, is decreased. As a result, the left and right hydraulic motors 1A and 1B act to keep the rotation speed constant,
Improves the straightness of the vehicle body.

Next, FIG. 2 shows a second embodiment of the present invention, which is characterized in that the servo piston is driven by an external hydraulic source.

In FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals, 31 in the figure is a single external hydraulic source provided on the upper swing body side, and 32 is the external hydraulic source 31. Drive pressure pipes 33A and 33B for guiding the drive pressure to the lower traveling body side through the center joint 9 are branch drive pressure pipes branched from the drive pressure pipe 32 and connected to the capacity control valves 17A and 17B. In the figure, 34A and 34B are brake pipes.

Although this embodiment is configured in this way, there is no difference from the first embodiment except that the pressure for driving the servo actuators 3A and 3B is guided from the external hydraulic power source 31.

Although the switching valves 10A and 10B for traveling are illustrated as manual switching valves in the embodiment, they may be pilot type traveling switching valves controlled by a pressure reducing valve type pilot valve. Also,
Although the separate hydraulic pressure sources for traveling are used as the hydraulic pumps 5A and 5B, a single hydraulic pressure source for traveling may be used and the pressure oil may be branched and supplied to the left and right hydraulic circuits. Further, it is needless to say that the construction machine can be applied to a hydraulic bulldozer or the like, and in this case, the center joint 9 may be unnecessary.

[Effect of device]

The hydraulic traveling device for a construction machine according to the present invention is as described above in detail, and uses one communicating pipe and a pair of throttles to equalize the motor self-pressure between the left and right high-pressure selection valves. This pressure is used as a pilot pressure to switch and control the displacement control valve, so that the tilt amounts of the left and right hydraulic motors are synchronized to prevent meandering and skewing of the vehicle body, as well as the left and right motors. The number of hydraulic pipes between the assemblies can be minimized to save space and cost, and the straightness of the vehicle body can be improved even when the displacement volumes of the left and right hydraulic motors are different. it can.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention, and FIG.
Similarly, FIG. 3 is a hydraulic circuit diagram showing the second embodiment, and FIG. 3 is a hydraulic circuit diagram showing the prior art. 1A, 1B ... Running hydraulic motors, 2A, 2B ... Capacity changing parts, 3A, 3B ... Servo actuators, 5A, 5B ...
Hydraulic pump, 6 ... Tank, 7A, 7B, 8A, 8B ... Hydraulic piping, 10A, 10B ... Travel switching valve, 11A, 11
B ... High pressure selection valve, 17A, 17B ... Capacity control valve, 20
A, 20B ... Motor assembly, 21 ... Communication piping, 2
2A, 22B ... throttle, 23A, 23B ... pilot piping, 24A, 24B, 32 ... driving pressure piping, 25A, 25
B ... Pressure reducing valve, 31 ... External hydraulic power source, 33A, 33B ... Branch drive pressure piping.

Front page continued (72) Genroku Sugiyama Genroku, Tsuchiura-shi, Ibaraki Prefecture 650 Tsuchiura factory Hitachi Construction Machinery Co., Ltd. Tsuchiura factory Tsuchiura Factory (56) References JP-A-48-40125 (JP, A)

Claims (3)

[Scope of utility model registration request] 1. A variable displacement traveling hydraulic motor having a variable displacement portion, a servo actuator for tilt-driving the variable displacement portion of the hydraulic motor, and pressure oil for the servo actuator, thereby switching the hydraulic pressure. A left and right traveling motor assembly composed of a hydraulic pilot type displacement control valve for controlling the displacement of the motor is provided, and the left and right traveling hydraulic motors of the respective traveling motor assemblies are connected through left and right hydraulic pipes. In the hydraulic traveling device of the construction machine, which is connected to a hydraulic pump and a tank, respectively, and is provided with left and right traveling switching valves in the middle of the left and right hydraulic pipes.
The right hydraulic pipe is provided with left and right high-pressure selection valves for deriving the high-pressure side pressure of the motor drive pressure supplied to the hydraulic motor as the motor self-pressure, and the high-pressure selection valves are connected through a communication pipe. However, a pair of throttles is provided in the middle of the communication pipe, and between the throttles and the hydraulic pilot portions of the left and right displacement control valves are connected via pilot pipes, respectively. Hydraulic traveling device. 2. The left and right high pressure selection valves are supplied with the motor self pressures as drive pressures for servo actuators through the respective displacement control valves, and the left and right high pressure selection valves and the displacement control are performed. The hydraulic traveling device for a construction machine according to claim (1), wherein a pressure reducing valve is provided between the valve and the utility model. 3. The construction machine according to claim 1, wherein pressure oil from an external hydraulic source is supplied as driving pressure for the servo actuator through the left and right displacement control valves. Hydraulic traveling device.