JP5814808B2 - Work vehicle - Google Patents

Description

The present invention relates to a work vehicle equipped with a relief valve. More specifically, a valve body and a valve seat that are provided with a first oil passage on the high pressure side and a second oil passage on the unload side in the casing, and that can open and close the first oil passage and the second oil passage. and, said valve body elastically energizable spring to the valve seat and, on the work vehicle provided with a relief valve that is configured by providing in the casing.

Conventionally, as this type of relief valve, there has been one configured so that the relief pressure of the valve body can be changed (for example, see Patent Document 1).
The change of the relief pressure of the valve body in the relief valve is realized by a mechanism that makes it possible to change the urging force of the spring.
Specifically, one end of the spring is brought into contact with the valve body, and the other end is received by a screw member provided so as to be capable of screwing along the biasing direction of the spring, and the screw member is screwed. Thus, the urging force of the spring against the valve body can be changed.

As described above, the relief pressure can be changed by changing the urging force of the spring. Therefore, instead of moving the spring receiving portion (screw member) back and forth, the valve seat is moved relative to the valve body. A modification in which the springs are moved closer to and away from each other along the biasing direction can also be considered.
As described above, the position of the valve seat can be changed along the biasing direction of the spring, so that the relief pressure of the valve body can be changed by the biasing force of the spring, and the first oil is moved by the movement of the valve seat. The throttling action of the road can also be expected, and the relief pressure can be controlled to a higher degree.

As a possible modification, as shown in FIG. 4, a valve seat 72 is provided in the casing 8 so as to be movable along the urging direction of the spring 73, and the valve seat 72 is opposite to the valve body 71. A lateral hole 80 perpendicular to the moving direction of the valve seat 72 is formed in the casing portion corresponding to the base end side of the valve seat (hereinafter referred to as the base end side of the valve seat), and the base end of the valve seat 72 can be brought into contact with the lateral hole 80 It is conceivable to provide a horizontal screw member 81 having a tapered surface 81a so that it can be screwed.
In the case of the relief valve of this example, the horizontal screw member 81 applies a pressing force along the screwing direction to the valve seat 72 by screwing the horizontal screw member 81. At this time, a part of the screwing force acts as a component force for moving the valve seat 72 to the valve body side by the tapered surface 81a of the lateral screw member 81, and the valve seat 72 can be brought close to the valve body side.

JP-A-10-181628 (FIG. 10)

Of the conventional relief valves described above, according to the example described in Patent Document 1, the adjustment of the relief pressure is limited only to the adjustment of the urging force of the spring, and tends to be a simple control.
In addition, according to the above-mentioned “possible modification”, the relief pressure can be controlled to a higher degree, so that the function can be improved, but a lateral hole for accommodating the lateral screw member is formed in the casing. In addition, there is a concern about wear due to sliding contact between the valve seat and the tapered surface of the lateral screw member, and therefore, it is necessary to use an expensive material that is difficult to wear.
That is, there are problems in that it takes time to form and cost for the member.

Accordingly, an object of the present invention is to provide a work vehicle equipped with a relief valve that solves the above-described problems, enables high-level control of the relief pressure, and is highly economical.

A first characteristic configuration of the present invention is a hydraulic side clutch device for turning that individually switches driving of the left and right traveling devices based on the operation of the steering operation tool, and the above-described operation based on the operation of the traveling operation tool. A hydraulic circuit for supplying and discharging hydraulic oil to and from the side clutch device, a relief oil path connected to the oil chamber of the side clutch in the hydraulic circuit, and a variable relief valve provided in the relief oil path When provided with, in the casing of the relief valve, the a first oil passage on the high-pressure side communicating with said oil chamber, a second oil passage unload side, by closely spaced from the previous SL first oil passage first and second oil passage and can open and close the valve body and valve seat, the front Kibentai elastic energizable spring, a provided in the valve seat, the relief valve, and the said valve body and the valve seat, Abutting by the biasing force of the spring When the first oil passage and the second oil passage are in a closed state, and the pressure of the first oil passage exceeds the urging force of the spring, the valve body and the valve seat are separated from each other, and the first oil passage and the second oil passage are separated from each other. wherein the oil passage and the second oil passage is configured to be opened, the valve seat is provided a compressible seat adjustment mechanism the spring by moving said spring side of the front Stories valve seat An operation portion exposed outside the casing is provided at an end opposite to the valve body, and the valve seat adjustment mechanism is linked to the steering operation tool and is used for the operation of the steering operation tool. Based on the above, provided a pressing portion capable of pressing the operation portion on the spring side,
The pressing portion, the traveling operation tool rotation operation amount becomes larger, the in time and the amount of pressing the operation portion is configured to be larger.

According to the first characteristic configuration of the present invention, by adopting a structure for changing the relief pressure by moving the valve seat to the valve body side, in addition to the change of the relief pressure by the urging force of the spring, for example, The throttling action of the first oil passage can be expected, and the relief pressure can be controlled to a higher degree.
In addition, since the operation portion exposed outside the casing is provided at the end of the valve seat opposite to the valve body, the valve body and the valve seat are accommodated in a series of holes in the casing, The structure can be simplified, and there is no need to bother to form a lateral hole for housing the lateral screw member in the casing as in the above-mentioned “possible modification”.

Further, the valve seat adjustment mechanism is formed so as to change the relief pressure of the valve body by pressing the operating portion toward the valve body so that the valve seat is moved closer to and away from the valve body. The direction of the force and the direction of the operating force coincide with each other, and there is no need to change the acting direction of the force on the tapered surface as in the above-mentioned “conceivable modification”, and the operating force can be applied to the valve seat without waste. . Accordingly, wear between the valve seat operating portion and the valve seat adjusting mechanism can be reduced, so that the present invention is not limited to expensive materials that are difficult to wear, and costs can be reduced.
In addition, since the contact portion between the operation portion and the valve seat adjustment mechanism is located outside the casing, maintenance is not required and maintenance costs can be reduced.

  As a result of the above, it is difficult to form, and it is possible to reduce the member cost and the maintenance cost, and it is possible to provide a relief valve with high functionality and economy.

  According to a second characteristic configuration of the present invention, there is provided a valve body adjustment mechanism for moving a spring receiving portion that receives the side of the spring opposite to the valve body along a biasing direction of the spring.

According to the second characteristic configuration of the present invention, it is possible to combine the adjustment of the relief pressure by the valve seat adjustment mechanism and the adjustment of the relief pressure by the valve body adjustment mechanism, and more complicated control is possible. Can be a functional relief valve.
As an example, the valve seat adjustment mechanism adopts a configuration in which the relief pressure is changed according to the steering angle in conjunction with an operating lever such as a power steering, while the valve body adjustment mechanism uses the spring. By finely adjusting the urging force, it is possible to realize complicated relief pressure control such as fine adjustment of the overall relief pressure.

  According to a third characteristic configuration of the present invention, an adjustment amount of the relief pressure of the valve body by the valve seat adjustment mechanism is set larger than an adjustment amount of the relief pressure of the valve body by the valve body adjustment mechanism. It is in.

  According to the third characteristic configuration of the present invention, the relief pressure itself can be finely adjusted by the valve body adjusting mechanism while being finely adjusted by the valve seat adjusting mechanism, and fine relief pressure control can be performed. Can be implemented.

Combine left side view Diagram showing hydraulic circuit structure Sectional view showing variable relief valve Sectional drawing which shows the modification of the conventional variable relief valve

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the parts indicated by the same reference numerals as those in the conventional example indicate the same or corresponding parts.

As shown in FIG. 1, a cutting part 2 is provided on the left side of the front part of the aircraft supported by the right and left crawler travel devices 1, a driving unit 3 is provided on the right side of the front part of the aircraft, and a rear left side of the aircraft. A threshing device 4 and a grain tank 5 are provided on the right side of the rear part of the machine body to constitute a combine.
A feeder 6 is supported so as to be swingable up and down around a horizontal axis (not shown) of the machine body, and a cutting portion 2 is supported by the feeder 6. An elevating mechanism 7 composed of a single-acting hydraulic cylinder or the like is connected between the machine body and the feeder 6. When the elevating mechanism 7 is extended, the cutting unit 2 is driven up, and the elevating mechanism 7 is contracted. Then, the cutting unit 2 is driven downward.

In addition, a control tower 50 is provided at the front of the operation unit 3, and an operation lever 51 is provided in the control tower 50. The operation lever 51 is configured to be freely operable in the front-rear direction and the left-right direction.
By operating the operation lever 51 forward (or rearward), the elevating mechanism 7 can be expanded and contracted, and by operating the operation lever 51 right (or left), the aircraft can be turned clockwise. Turn (or turn left).

A mission case (corresponding to a casing) 8 is arranged between the front parts of the right and left crawler traveling devices 1, and the power of the engine (not shown) is transmitted to the input shaft 17 of the mission case 8, It is transmitted to the crawler traveling device 1 via the output shaft 18 provided in the mission case 8.
As shown in FIG. 2, the mission case 8 is provided with a hydrostatic continuously variable transmission 11 and a side clutch device S that can individually drive and switch the left and right crawler travel devices 1 (see FIG. 1). .

The hydrostatic continuously variable transmission 11 and the side clutch device S are connected by an oil passage, and can be linked and driven by the flow of hydraulic oil accompanying the operation of the operation lever 51 (see FIG. 1). Yes.
A hydraulic circuit communicating with the mission case 8 will be described.
As shown in FIG. 2, a trochoid charge pump 37 and a hydraulic pump 38 that are driven by the rotation of the input shaft 17 are attached to the mission case 8.
In addition, a filter 39 (a fine mesh paper filter) is attached to the mission case 8, and the lubricating oil in the mission case 8 is charged via the internal oil passage 40, the filter 39 and the internal oil passage 41 as hydraulic oil. A pump 37 and a hydraulic pump 38 are supplied.

The hydrostatic continuously variable transmission 11 is configured by connecting a variable displacement hydraulic pump 14 and a hydraulic motor 15 by a pair of oil passages 16 and has a neutral stop position.
Engine power is transmitted to the input shaft 17 of the hydrostatic continuously variable transmission 11 (hydraulic pump 14), and is transmitted from the output shaft 18 of the hydrostatic continuously variable transmission 11 (hydraulic motor 15) to the traveling system. Is done.
In the hydraulic circuit for the hydrostatic continuously variable transmission 11, an internal oil passage 52 from the charge pump 37 is connected to the oil passage 16 via a pair of check valves 53 and a throttle 54. A relief valve 56 is provided in the branched internal oil passage 55, and the internal oil passage 55 is connected to the lowermost case in the hydrostatic continuously variable transmission 11.

  An internal oil passage 58 is formed at the lowermost portion of the hydrostatic continuously variable transmission 11 of the transmission case 8 so that the excess hydraulic oil of the hydrostatic continuously variable transmission 11 is provided in the internal oil passage 58. To the working pump 60 for driving the lifting mechanism 7. The remaining hydraulic oil supplied to the work pump 60 is returned to the lowermost part of the transmission case 8 via the return oil passage 59.

  The side clutch device S includes left and right oil chambers corresponding to the left and right crawler travel devices 1, and is driven from the input shaft 17 as the hydraulic pressure increases as hydraulic oil is supplied to each oil chamber. A clutch mechanism (not shown) for switching so that the force is not transmitted to the axle 27 of the crawler traveling device 1, and a transmission shaft (not shown) interposed between the input shaft 17 and the axle 27 of the crawler traveling device 1. ) And a brake mechanism (not shown) that applies a braking force to the left side (or right direction) of the operation lever 51 in proportion to the operation width. The action state of the device S is changed.

As shown in FIG. 2, the hydraulic circuit for the side clutch device S includes a power steering switching valve 44 connected to an internal oil passage 42 from the hydraulic pump 38, and the side clutch device through the internal oil passage 43 from the switching valve 44. The hydraulic oil is configured to be supplied to the right and left oil chambers of S, and the variable relief valve passes through the internal oil passage (corresponding to the first oil passage) 46 from the right and left oil chambers of the side clutch device S. (An example of the relief valve of the invention) 45 and a relief valve 49 are connected. The hydraulic oil from the variable relief valve 45 is returned to the lowermost part of the transmission case 8 through an internal oil passage (corresponding to a second oil passage) 47.
The operation lever 51 and the switching valve 44 are mechanically linked so that the switching valve 44 is operated by operating the operation lever 51 in the left-right direction. The operation lever 51 and the variable relief valve 45 are also mechanically linked.

  The variable relief valve 45 is configured such that the relief pressure changes and the operating state of the side clutch device S changes according to the operation width of the operation lever 51 in the left direction (or right direction).

Next, the variable relief valve 45 will be described in detail.
As shown in FIG. 3, the variable relief valve 45 is connected to the internal oil passage 46 in the vertical through hole 70 extending between the high pressure side internal oil passage 46 and the unload side internal oil passage 47 in the transmission case 8. A valve body 71 and a valve seat 72 capable of opening and closing the internal oil passage 47 are accommodated. The valve seat 72 is disposed above the valve body 71.

  In addition to the valve body 71 and the valve seat 72, the through hole 70 has a spring 73 capable of elastically urging the valve body 71 to the valve seat 72, and a spring 74 capable of elastically urging the valve seat 72 to a cam body 77 described later. Are provided below the valve body 71 and the valve seat 72. The spring 73 has a smaller diameter than the spring 74 and is disposed in the inner space of the spring 74.

The through hole 70 is formed with a female screw portion 70a at the lower end portion, and a male screw member 75 with an O-ring 75a is screwed into the female screw portion 70a so that the lower end portion of the through hole 70 can be sealed. It is configured. The distal end portion of the male screw member 75 is configured as a spring receiving portion 75 b that supports the lower end portions of the springs 73 and 74.
The spring receiving portion 75b is formed with a protrusion 75c fitted into the spring 73 at a circular central portion to prevent lateral displacement of the spring 73 in the through hole 70.

The male screw member 75 moves upward (or downward) in the through hole 70 by being screwed.
That is, as the male screw member 75 is screwed, the spring receiving portion 75 b at the upper end of the male screw member 75 moves along the biasing direction of the spring 73. Therefore, in a state where the vertical position of the valve seat 72 is restricted, the distance between the spring receiving portion 75b and the valve body 71 is changed by screwing the male screw member 75, and the elastic restoring force of the spring 73 is also changed. As a result, the contact force of the valve body 71 with respect to the valve seat 72 can be adjusted, and the relief pressure can be finely adjusted. In the embodiment, the male screw member 75 functions as a valve body adjustment mechanism T.
The male screw member 75 is screwed with a nut 75d for preventing loosening so that the adjusted position can be locked.

As shown in FIG. 3, the valve body 71 is composed of a round bar that is long in the vertical direction, and a valve part 71a formed in a truncated cone shape having a larger diameter than the general part is provided in the upper and lower middle portions. is there. The upper end portion is provided with a guide portion 71b which is formed in a cylindrical shape having a larger diameter than the general portion and is slidably fitted into the general portion 72b of the valve seat 72.
In a state where the valve body 71 is fitted in the valve seat 72, the outer peripheral space between the valve portion 71 a and the guide portion 71 b becomes the pressure chamber 76 communicating with the internal flow path 46.
A lower end side portion from the valve portion 71a is fitted into the upper end portion of the spring 73 to prevent a relative displacement between the spring 73 and the valve body 71 in the lateral direction.
The urging force of the spring 73 acts on the lower surface portion of the valve portion 71a.

As shown in FIG. 3, the valve seat 72 is a cylindrical body whose upper end is closed, and a main body 72 b is formed. It is constructed integrally.
The large diameter portion 72a and the vicinity thereof are exposed to the outside of the mission case 8.
A cam body 77, which will be described later, is disposed on the upper surface side of the large diameter portion 72a so as to come into contact therewith. Along with the rotation of the cam body 77, a pressing force downward (from the valve body 71 side) acts on the large diameter portion 72a, and the valve seat 72 is lowered. Since the upward elastic biasing force from the spring 74 acts on the lower end surface of the valve seat 72, the valve seat 72 returns to the upper end position when the cam body 77 is released.

The main body 72b of the valve seat 72 is fitted in the through hole 70 so as to be slidable up and down.
In addition, a through hole 72c for communicating the pressure chamber 76 with the internal flow path 46 is formed in the upper and lower intermediate part of the main body 72b.
The lower end edge part in the inner peripheral part of the main body part 72b becomes a seat part 72d, and the valve part 71a of the valve body 71 is brought into contact, whereby the communication state between the internal flow path 46 and the internal flow path 47 can be blocked. Further, when the hydraulic pressure exceeding the contact force between the seat portion 72d and the valve portion 71a acts on the internal flow path 46, the valve body 71 is pushed down, and the hydraulic oil flows into the internal flow path 47 from the through hole 70. Since the internal flow path 46 and the internal flow path 47 are communicated, the hydraulic pressure of the internal flow path 46 is reduced.
The oil pressure at the boundary where the working oil flows from the internal flow path 46 to the internal flow path 47 becomes the relief pressure of the variable relief valve 45.

The relief pressure changes depending on the position adjustment by screwing of the male screw member 75 (valve element adjustment mechanism T) and the position change of the valve seat 72 by the pressing force of the cam body 77, in short, the valve element 71 by the spring 73. It changes according to the magnitude of the biasing force.
In the present embodiment, the valve seat adjustment mechanism Z that changes the relief pressure of the valve body 71 by causing the valve seat 72 to approach the valve body 71 by pressing the large diameter portion 72a toward the valve body 71 side, A cam body 77 is used.
The adjustment amount of the relief pressure of the valve body 71 by the valve seat adjustment mechanism Z is set larger than the adjustment amount of the relief pressure of the valve body 71 by the valve body adjustment mechanism T.

The cam body 77 is configured to swing in the left-right direction in conjunction with the left-right operation of the operation lever 51. Therefore, when the operation lever 51 is in a neutral state, the cam body 77 also maintains the horizontal posture, and the valve seat 72 is positioned at the upper limit (see FIG. 3A).
When the operation lever 51 is swung to the right end (or left end), the cam body 77 is swung to the end position by right rotation (or left rotation), and presses the valve seat 72 to lower it to the lower limit (see FIG. 3 (B)). In this state, the relief pressure of the valve body 71 reaches the upper limit value. Accordingly, the side clutch device S is turned off so that the driving force from the input shaft 17 is not transmitted to the right axle 27 (or the left axle 27) of the crawler traveling device 1, and the brake mechanism also acts. The aircraft turns around. When the swinging operation of the operation lever 51 is small, in addition to the brake mechanism not acting, the relief pressure of the valve body 71 decreases from the upper limit value, so the clutch mechanism of the side clutch device S also acts in the disengaged state. The turning radius is increased.

According to the variable relief valve 45 of the present embodiment, by forming one straight through hole 70 in the mission case 8, the relief valve can be configured by charging the valve body 71 and the valve seat 72 therein. Thus, the variable relief valve 45 can have a very simple structure. Therefore, it is possible to reduce production labor, material costs, and maintenance management costs such as maintenance.
Further, complicated relief pressure adjustment combining the valve body adjustment mechanism T and the valve seat adjustment mechanism Z can be realized.
That is, both high functionality and low cost can be realized.

[Another embodiment]
Other embodiments will be described below.

<1> The relief valve 45 is not limited to the variable relief valve described in the previous embodiment. For example, the relief valve 45 is replaced with a valve body that includes both the valve body adjustment mechanism T and the valve seat adjustment mechanism Z. A configuration in which the adjustment mechanism T is omitted may be used.
<2> The valve seat adjustment mechanism Z is not limited to the one configured by the cam body 77 described in the previous embodiment. For example, the valve seat adjustment mechanism Z includes a hydraulic cylinder or other known pressing mechanism. There may be.

  In addition, as mentioned above, although the code | symbol was written in order to make contrast with drawing convenient, this invention is not limited to the structure of an accompanying drawing by this entry. In addition, it goes without saying that the present invention can be carried out in various modes without departing from the gist of the present invention.

  The relief valve of the present invention can be applied not only to a combine but also to a construction vehicle such as an agricultural tractor, a riding rice transplanter, or a wheel loader.

8 Mission case (equivalent to casing)
46 Internal oil passage (equivalent to the first oil passage)
47 Internal oil passage (equivalent to second oil passage)
71 Valve body 72 Valve seat 72a Large diameter part (an example of an operation part)
73 Spring 75b Spring receiving part T Valve body adjustment mechanism Z Valve seat adjustment mechanism

Claims (3)

Based on the operation of the steering operation tool, a hydraulic side clutch device for turning that individually switches the drive of the left and right traveling devices;
A hydraulic circuit for supplying and discharging hydraulic oil to and from the side clutch device based on an operation of the travel operation tool,
The hydraulic circuit includes a relief oil passage connected to the oil chamber of the side clutch, and a variable relief valve provided in the relief oil passage,
In the casing of the relief valve, a first oil passage on the high-pressure side communicating with said oil chamber, a second oil passage for unloading side, and the second oil passage and the pre-Symbol first oil passage by closely spaced and open valve body and valve seat, front elastic energizable spring to the valve seat to Kibentai, the provided,
In the relief valve, the valve body and the valve seat come into contact with each other by the biasing force of the spring, so that the first oil passage and the second oil passage are closed, and the pressure of the first oil passage is reduced. The valve body and the valve seat are separated as the urging force of the spring is exceeded, and the first oil passage and the second oil passage are opened,
Providing a valve seat adjustment mechanism capable of compressing the spring by moving the valve seat toward the spring;
The said valve body of said valve seat at the opposite end, provided with an operation portion which is exposed to the outside of the casing,
The valve seat adjustment mechanism is provided with a pressing portion that is linked to the steering operation tool and that is capable of pressing the operation portion toward the spring based on the operation of the steering operation tool.
The work vehicle in which the pressing portion is configured such that as the turning operation amount of the travel operation tool increases, the amount of pressing the operation portion increases. 2. The work vehicle according to claim 1, further comprising: a valve body adjustment mechanism that moves a spring receiving portion that receives a side of the spring opposite to the valve body along a biasing direction of the spring. The work vehicle according to claim 2, wherein an adjustment amount of the relief pressure of the valve body by the valve seat adjustment mechanism is set larger than an adjustment amount of the relief pressure of the valve body by the valve body adjustment mechanism.

Images