JP4081209B2 - Slow descent device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a slow descent device that lowers the speed in the vicinity of a grounding portion and prevents shocking grounding when the working machine of a tractor that is lifted and lowered by a hydraulic lift device is lowered.
[0002]
[Prior art]
Conventionally, a slow descent device composed of a stop valve, slow return valve, and check valve has been installed in the lifting hydraulic circuit so that the work machine will descend suddenly and the work machine will not be damaged by impacting grounding. The technology provided is known. This is a technique disclosed in Japanese Utility Model Publication No. 1-22682 and Japanese Patent Laid-Open No. 7-250507. These slow descent devices have a structure in which the slow return valve and the check valve are integrated, or a structure in which the stop valve and the slow return valve are integrated, thereby reducing the size and cost of the apparatus.
[0003]
[Problems to be solved by the invention]
However, in the above-described prior art, in the configuration in which the slow return valve and the check valve are integrated, the stop valve is configured separately, and in the configuration in which the stop valve and the slow return valve are integrated, a check is performed. The valve was constructed separately. For this reason, the oil path becomes longer and there is a limit to downsizing the slow descent device. To further reduce the size and cost, reduce the number of parts and use common parts. In order to satisfy these requirements, it is desirable that the three valves be integrated.
[0004]
[Means for Solving the Problems]
The above is the problem to be solved by the present invention. Next, means for solving the problem will be described.
[0005]
In the elevating valve (60) connected to the hydraulic pump (P) and the slow descent device (20) disposed between the elevating cylinder (12), the slow descent device (20) is screwed to the adjustment handle (21). A tool (22) is fixed, and the screw tool (22) is extended into a cylinder (27) which is a valve housing hole formed in the valve case (20a) of the slow descent device (20). The screw (24) attached to the end of the cylinder (27) is screwed, the poppet (28) is slidably disposed in the cylinder (27), and the rear end of the cylinder (27) The spring receiver (30) is disposed on the end of the cylinder (27). The spring receiver (30) is interposed between the spring receiver (30) and the poppet (28). A recessed portion formed at the end of the poppet (28) with the end of the screw tool (22) fixed. (28a) is extended to the inside, and a pin (26) is fixed at the end, the pin (26) is at the tip of the screw tool (22), and the pin (26) is a recess of the poppet (28). (28a) is engaged with a hook hole (28h), and a slit (28b) is formed on the outer periphery of the recess (28a) to form a passage for hydraulic oil, and the adjustment handle (21) is operated. When the screw tool (22) is rotated, the screw tool (22) moves in the front-rear direction, and the position of the pin (26) provided at the rear end of the screw tool (22) is moved and adjusted. The poppet (28) sliding in the cylinder (27) is restricted by the urging force and hydraulic pressure of the spring (29), and the seat surface (81) formed on the outer periphery of the rear end of the screw tool (22). ) And the abutment of the recess (28a) of the poppet (28) Between the seat surface (80) formed on the rear outer periphery of the poppet (28) and the valve seat (82) formed on the cylinder (27) of the valve case (20a), A slow return throttle (92) that is a clearance space is configured, and the adjustment handle (21) is used to adjust the front / rear position of the screw tool (22), thereby closing both the check valve space (91) and the slow return throttle (92). By doing so, a stop valve is configured .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is an overall side view showing a tractor having a slow descent device according to the present invention, FIG. 2 is a hydraulic circuit diagram including the slow descent device according to the present invention, and FIG. 3 is a diagram of the slow descent device according to the present invention. It is sectional drawing and shows the state in which a stop valve is fully open. FIG. 4 is also a cross-sectional view of the slow descent device, showing a state in which the stop valve is closed in the forward direction. FIG. 5 is also a cross-sectional view of the slow descent device, showing a state where the stop valve is opened by about 2 mm. FIG. 6 is a cross-sectional view showing a state where the slow descent device acts as a slow return valve.
[0007]
First, the overall configuration of the tractor of the present invention will be described with reference to FIG. A bonnet 3 is disposed at the front of the machine that suspends the front wheel 1 and the rear wheel 2 in the front and rear, and the engine 4 is built in the bonnet 3. A steering handle 5 is provided behind the bonnet 3, and a seat 6 is provided behind the steering handle 5. A clutch housing 7 is connected to the rear of the engine 4, and a transmission case 8 is connected to the rear of the clutch housing 7, and the power from the engine 4 is transmitted to the rear wheel 2 for driving. From the rear end of the machine, a work machine mounting device 9 constituted by a three-point link protrudes and can be moved up and down by a lift arm 11 of a hydraulic lift device 10 to be described later. A work machine such as a rotary can be attached to the rear end of the work machine mounting device 9.
[0008]
Next, a hydraulic circuit for raising and lowering the work implement mounting apparatus 9 will be described with reference to FIG. Between the hydraulic pump P and the hydraulic lift device 10, an external hydraulic control valve 40 for taking out hydraulic pressure to the outside is interposed so that a work machine such as a front loader or a mower can be moved up and down and driven. Yes. On the downstream side of the external hydraulic control valve 40, a lift valve unit 60 that controls the lift operation of the hydraulic lift device 10 is disposed via a horizontal control hydraulic circuit 50. Then, the switching valve 41 of the external hydraulic control valve 40 is used to switch between guiding the hydraulic oil pumped from the hydraulic pump P to the hydraulic pressure extraction port 42 or to the lifting valve unit 60 side. I have to.
[0009]
The hydraulic pump P pumps up hydraulic oil stored in an oil tank (mission case) T through a filter 71, and the pumped hydraulic oil passes through a relief valve 72 on the way by the hydraulic pump P to control external hydraulic pressure. Pumped to the valve 40. When the lift arm 11 is moved up and down, the switching valve 41 of the external hydraulic control valve 40 is not switched, and the neutral position is not guided to the hydraulic pressure take-out port 42 but is pumped to the lifting valve 60 side. It is configured as follows. The flow of the hydraulic oil pressure-fed to the lift valve 60 is controlled by opening / closing operations of the lift electromagnetic valve 61 and the lift electromagnetic valve 62 of the lift valve 60, thereby controlling the lift operation of the hydraulic lift device 10. .
[0010]
Further, when hydraulic fluid is supplied to other hydraulic actuators without controlling the hydraulic lift device 10, it is guided to the external hydraulic control valve 40 by the switching operation of the switching valve 41 of the external hydraulic control valve 40. The hydraulic fluid is guided to the hydraulic pressure take-out port 42. The hydraulic oil is pressure-fed to an external cylinder (not shown) that is an external actuator connected to the hydraulic pressure take-out port 42 to expand and contract the external cylinder. In this embodiment, the external hydraulic control valve 40 including the switching valve 41 and the hydraulic pressure take-out port 42 has a two-unit configuration, and can control two external actuators.
[0011]
The hydraulic lift device 10 is interposed between the elevating valve 60 and the elevating cylinder 12 and supplies hydraulic oil to the elevating cylinder 12, and includes a check valve 13, a slow return valve 14, a stop valve 15, and the like. The slow descent device 20 is provided. Then, as described above, when the work implement is lifted and lowered, the hydraulic oil flows into and out of the lift cylinder 12 from the lift valve 60 side via the hydraulic lift device 10, and the lift arm 11 is lifted and lowered.
[0012]
When the work implement is raised, hydraulic oil is pumped into the hydraulic lift device 10 from the lift valve 60 side. Since the check valve 13 is pushed open by the pressure-fed hydraulic oil, the hydraulic oil that has passed through the check valve 13 and the slow return valve 14 is pressure-fed to the elevating cylinder 12 via the open stop valve 15. This raises the work implement.
[0013]
On the other hand, when lowering the work implement, the hydraulic oil in the elevating cylinder 12 returns to the elevating valve 60 side via the hydraulic lift device 10, but at this time, the check valve 13 is closed, so that the return from the elevating cylinder 12 is performed. The oil flows out while being throttled by the return valve 14. As a result, the hydraulic oil in the elevating cylinder 12 is prevented from rapidly decreasing, and the lift arm 11 is gradually lowered.
[0014]
Next, the configuration of the above-described slow descent device 20 according to the present invention will be described with reference to FIGS. In the following description, the left side of the drawing is the front of the slow descent device 20. The slow descent device 20 is disposed below the seat 6, and a front adjustment handle 21 protrudes from the lower portion of the seat 6 into the control section. A screw tool 22 is fixed to the adjustment handle 21, and the screw tool 22 extends into a cylinder 27 that is a valve housing hole formed in the valve case 20 a of the slow descent device 20. A screw body 24 is attached to the front end portion of the cylinder 27, and the screw body 22 is screwed onto the screw body 24. Further, when the stop bolt 23 is screwed, the screw body 22 is loosened. Is preventing.
[0015]
A poppet 28 is disposed in the cylinder 27 so as to be slidable back and forth in the cylinder 27, and a spring receiver 30 is disposed at the rear end of the cylinder 27. A spring 29 is interposed therebetween. The spring receiver 30 is fixed to the rear end portion of the cylinder 27, and the cylinder 27 communicates with an oil path 32 reaching the elevating cylinder 12 through an oil path 30 r provided in the spring receiver 30.
[0016]
On the other hand, the screw tool 22 screwed on the screw body 24 projects into the cylinder 27, and its end extends into the recess 28a formed at the front end of the poppet 28. 26 is fixed. The pin 26 protrudes up and down at the tip of the screw tool 22, and the protrusion is engaged with a hooking hole 28 h provided in the recess 28 a of the poppet 28. In addition, a slit 28b is formed in the outer peripheral portion of the concave portion 28a, and serves as a passage for hydraulic oil.
[0017]
In the above configuration, when the screw handle 22 is rotated by operating the adjustment handle 21, the screw tool 22 is operated in the front-rear direction, and the position of the pin 26 provided at the rear end of the screw tool 22 is determined. Moved and adjusted. In other words, the poppet 28 sliding on the cylinder 27 by the biasing force and hydraulic pressure of the spring 29 is regulated by the pin 26, but the sliding range of the poppet 28 is controlled by the operation of the adjustment handle 21. Is adjusted.
[0018]
Here, FIG. 3 shows a state in which the screw 22 (pin 26) is moved in the forward direction by operating the adjustment handle 21, and the function of the stop valve 15 is fully opened. That is, as the pin 26 is moved forward, the poppet 28 moves forward, and a space 90 is formed between the seat surface 80 formed on the rear outer periphery of the poppet 28 and the valve seat 82 of the valve case 20a. Then, the oil passages 31 and 32 communicate with each other through the space 90, and the hydraulic oil flows in and out.
[0019]
FIG. 4 shows a state where the screw 22 is moved backward by operating the adjustment handle 21 and the stop valve 15 is fully closed. That is, when the poppet 28 moves rearward, the seat surface 80 comes into contact with the valve seat 82 of the valve case 20a, and the hydraulic oil passage is closed. Further, the seat surface 81 formed on the outer periphery of the rear end of the screw tool 22 also comes into contact with the inner peripheral surface of the recess 28a of the poppet 28, and the hydraulic oil passage is closed. For this reason, hydraulic oil does not flow in and out between the oil passages 31 and 32.
[0020]
Next, FIG. 5 shows a case where the stop valve 15 is opened to a certain setting by operating the adjustment handle 21. That is, the seat surface 80 is in contact with the valve case 28 a and is closed, but a space 91 is formed between the seat surface 81 and the poppet 28. When the working machine is raised, the hydraulic oil from the oil passage 31 passes through the slit 28b of the poppet 28, one flows from the hook hole 28h to the oil passage 32 side through the space 91, and the other passes through the slit 28b. It flows through the front side of the poppet 28, flows into the recess 28 a from the front portion of the poppet 28, and flows to the oil passage 32 side through the space 91. Then, hydraulic oil is pumped from the oil passage 32 to the lift cylinder 12 and the lift arm 11 is raised.
[0021]
Conversely, when the lift arm 11 is lowered, the hydraulic oil in the elevating cylinder 12 flows out and flows into the cylinder 27 side through the oil passage 32. At this time, as shown in FIG. 6, the poppet 28 is pushed down toward the screw tool 22 against the urging force of the spring 29 by the pressure of the hydraulic oil. Then, the recess 28a of the poppet 28 comes into contact with the sheet surface 81, thereby blocking the passage of the hydraulic oil passing through the slit 28s. That is, it performs the role of the check valve 14 described above.
[0022]
As the poppet 28 moves forward, the seat surface 80 is slightly separated from the valve seat 82, and a slow return throttle 92, which is a gap space, is formed between the seat 80 and the valve seat 82. Then, the hydraulic oil flowing out from the elevating cylinder 12 through the slow return throttle 92 flows out to the oil passage 31 side. As a result, when the lift arm 11 is lowered, the hydraulic oil in the elevating cylinder 12 flows out only from the slow return throttle 92, so that sudden outflow can be prevented and the lift arm 11 can be gradually lowered.
[0023]
As described above, in the slow descent device 20 according to the present invention, the structure that realizes the functions of the check valve 13, the slow return valve 14, and the stop valve 15 described using the hydraulic circuit is provided in the poppet 28. The seat surface 80 and the seat surface 81 provided on the screw tool 22 are configured so as to be integrally formed in the valve case 20a. As a result, the number of parts can be reduced and the cost can be reduced by using shared parts, and the slow descent device 20 can be downsized. Further, since the screw tool 22, the poppet 28 and the like are all arranged on the same axis in the cylinder 27, the structure is simple and compact.
[0024]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
In the elevating valve (60) connected to the hydraulic pump (P) and the slow descent device (20) disposed between the elevating cylinder (12), the slow descent device (20) is screwed to the adjustment handle (21). A tool (22) is fixed, and the screw tool (22) is extended into a cylinder (27) which is a valve housing hole formed in the valve case (20a) of the slow descent device (20). The screw (24) attached to the end of the cylinder (27) is screwed, the poppet (28) is slidably disposed in the cylinder (27), and the rear end of the cylinder (27) The spring receiver (30) is disposed on the end of the cylinder (27). The spring receiver (30) is interposed between the spring receiver (30) and the poppet (28). A recessed portion formed at the end of the poppet (28) with the end of the screw tool (22) fixed. (28a) is extended to the inside, and a pin (26) is fixed at the end, the pin (26) is at the tip of the screw tool (22), and the pin (26) is a recess of the poppet (28). (28a) is engaged with a hook hole (28h), and a slit (28b) is formed on the outer periphery of the recess (28a) to form a passage for hydraulic oil, and the adjustment handle (21) is operated. When the screw tool (22) is rotated, the screw tool (22) moves in the front-rear direction, and the position of the pin (26) provided at the rear end of the screw tool (22) is moved and adjusted. The poppet (28) sliding in the cylinder (27) is restricted by the urging force and hydraulic pressure of the spring (29), and the seat surface (81) formed on the outer periphery of the rear end of the screw tool (22). ) And the abutment of the recess (28a) of the poppet (28) Between the seat surface (80) formed on the rear outer periphery of the poppet (28) and the valve seat (82) formed on the cylinder (27) of the valve case (20a), A slow return throttle (92) that is a clearance space is configured, and the adjustment handle (21) is used to adjust the front / rear position of the screw tool (22), thereby closing both the check valve space (91) and the slow return throttle (92). As a result, the stop valve is configured, so that the number of parts can be reduced, the cost can be reduced by using common parts, and the slow descent device can be downsized.
[0025]
In addition, the stop valve, slow return valve and check valve can be arranged on the same axis , and are housed in the valve housing hole drilled in the valve case, so the structure is simple and compact. It was.
[Brief description of the drawings]
FIG. 1 is an overall side view showing a tractor having a slow descent device according to the present invention.
FIG. 2 is a hydraulic circuit diagram of the slow descent device according to the present invention.
FIG. 3 is a sectional view showing a state where the stop valve of the slow descent device according to the present invention is fully opened.
FIG. 4 is a cross-sectional view showing a state in which a stop valve of the slow descent device is also closed in the same manner.
FIG. 5 is a cross-sectional view showing a state where the stop valve of the slow descent device is also opened by about 2 mm.
FIG. 6 is a cross-sectional view showing a state where the slow descent device acts as a slow return valve.
[Explanation of symbols]
13 Check valve 14 Slow return valve 15 Stop valve 20 Slow descent device 20a Valve case 22 Screw tool 26 Pin 27 Cylinder 28 Poppet 29 Spring 30 Spring receiver

Claims (1)

In the elevating valve (60) connected to the hydraulic pump (P) and the slow descent device (20) disposed between the elevating cylinder (12), the slow descent device (20) is screwed to the adjustment handle (21). A tool (22) is fixed, and the screw tool (22) is extended into a cylinder (27) which is a valve housing hole formed in the valve case (20a) of the slow descent device (20). The screw (24) attached to the end of the cylinder (27) is screwed, the poppet (28) is slidably disposed in the cylinder (27), and the rear end of the cylinder (27) The spring receiver (30) is disposed on the end of the cylinder (27). The spring receiver (30) is interposed between the spring receiver (30) and the poppet (28). A recessed portion formed at the end of the poppet (28) with the end of the screw tool (22) fixed. (28a) is extended to the inside, the pin (26) is fixed at the end, the pin (26) is at the tip of the screw tool (22), and the pin (26) is the recess of the poppet (28) ( 28a) is engaged with a hook hole (28h), and a slit (28b) is formed in the outer peripheral portion of the recess (28a) to form a passage for hydraulic oil, and the adjustment handle (21) is operated to turn the screw When the tool (22) is rotated, the screw tool (22) moves in the front-rear direction, and the position of the pin (26) provided at the rear end of the screw tool (22) is moved and adjusted, and the spring ( 29) The poppet (28) sliding in the cylinder (27) is regulated by the urging force and hydraulic pressure of 29), and the seat surface (81) formed on the outer periphery of the rear end of the screw tool (22) Due to the abutment of the recess (28a) of the poppet (28), the check valve A gap is formed between the seat surface (80) formed on the rear outer periphery of the poppet (28) and the valve seat (82) formed on the cylinder (27) of the valve case (20a). A slow return throttle (92), which is a space, is formed, and the position of the screw tool (22) is adjusted by the adjustment handle (21) to close both the check valve space (91) and the slow return throttle (92). A slow descent device comprising a stop valve .

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