JPH02481Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a gear pump device for a rice transplanter that has one rotary directional control valve built into the main body to control discharged oil.

Conventionally, the directional switching valve built into this type of gear pump usually has a three-position directional switching function, and its circuit configuration is shown in FIG. 1 is a gear pump, and 2 is a manual directional control valve built into the main body of the gear pump 1. 3 is a tank,
4 is a hydraulic cylinder as an actuator, and 5 is a pressure regulating valve. The directional control valve 2 has three operating positions A, B, and C, where A is a discharge oil feeding position;
B is the neutral position, and C is the oil drain position. In such a device, for example, if the hydraulic cylinder 4 is required to have the ability to maintain its position in an intermediate state, it is generally done to increase the amount of wrap of the passage in the neutral position as a means to increase the ability. However, such a means is extremely inconvenient if the directional control valve is used as is for automatic operation, since the amount of lapping will impair control accuracy.

An example of a gear pump that requires a built-in directional switching valve to be used for both manual operation and automatic operation is an agricultural implement such as the present device. Figure 2 shows an automatic rice transplanter that uses hydraulic operation, but when the automatic rice transplanter is traveling on the road to transport it to a destination, manual operation is required to keep the running wheels 6 at a position below the float 7. By operating the directional switching valve 2 and activating the hydraulic cylinder 4, the float 7 can be brought into a high state. However, during rice planting work, it is necessary to keep the seedling planting depth constant regardless of the unevenness of the seedling planting surface. Therefore, the movement of the tip of the float 7 is transmitted to the directional switching valve 2 via the link mechanism of the feedback lever 8 and the switching valve operating lever 9, thereby automatically switching the hydraulic circuit of the directional switching valve 2. By activating the hydraulic cylinder 4 and converting it into a relative vertical movement of the running wheels 6 via the wheel operating link 10,
The posture of the machine body is controlled, and the planting depth when planting the seedlings 13 on the seedling platform 12 is adjusted to a constant level using the planting claws 11. Note that 14 is an engine.

In this way, when a single directional switching valve is used for both manual and automatic purposes, the lap provided for maintaining the neutral state is particularly suitable for automatic rice transplanters that require high precision in switching. In such cases, it becomes a fatal flaw.

This invention was made in view of the drawbacks of the above-mentioned conventional gear pump devices of this type.

In other words, the purpose of this invention is to provide a single directional switching valve that has both manual and automatic operation functions in a compact manner, while also being able to perform reliable and stable switching operations for manual operation. Another object of the present invention is to provide a gear pump device for use in a rice transplanter, which is equipped with a directional switching valve that can perform sensitive switching operations for automatic operation.

As a means to achieve the above object, this invention has a rotary directional switching valve built into the main body, and uses manual operation of this switching valve and automatic operation linked to the movement of the float to raise and lower the traveling wheels. In a gear pump device for a rice transplanter, the directional control valve has at least five switching positions, and the positions are arranged on both sides of one discharge oil supply position. A neutral position for manual operation and a drain position connecting the cylinder port to the tank port are sequentially formed on either the front or rear, and a neutral position for automatic operation and a drain position connecting the cylinder port to the tank port are formed on the other side. The oil position is formed sequentially, the amount of wrap at the neutral position for automatic operation is set smaller than the amount of wrap at the neutral position for manual operation, and the oil drain passage is further provided with a restriction.

Next, the structure of the gear pump device according to this invention will be specifically explained using drawings showing embodiments. In FIGS. 3 to 8, 21 is the upper body of the gear pump, and 22 is the lower part. The main body, 23 is the drive shaft, 24 is the follow shaft,
Drive shaft 23 and follow shaft 2
4 are integrally formed with a gear that functions as a pump. Reference numeral 25 denotes a directional switching valve, and its switching passages include passages a, b, c and throttle passages d and e along a common cross section, as shown in FIG. A passage 31 communicating with is bored. Next, the operation of switching the pressure oil by the directional switching valve 25 configured as described above will be explained.

() During discharge oil supply The oil supplied through the suction port 27 is sent to the discharge port 28 via the gear pump 1 consisting of the drive shaft 23 and the follower shaft 24, and then passes through the passage 29 and the passage 30 to the directional control valve. 25 and is fed through a passage 31 to a cylinder port 32 to a hydraulic cylinder.

() At neutral time Oil entered from the suction port 27 is sent to the discharge port 28 via the gear pump 1, and is then passed through the passage 29 and the passage 3.
0, enters the directional control valve 25, passes through the passage 31, passage 33, passage 34, and passes through the passage 35 bored in the center of the follower shaft 24, and then enters the tank port 3.
6 and is refluxed to the tank. Note that in the neutral circuit configuration, the gear pump 1 is operated in an unloaded state.

() When oil is drained, the oil returned from the hydraulic cylinder 4 enters the directional control valve 25 through the cylinder port 32, is throttled by the throttle passage d or e bored in the valve, and then flows through the passages 33, 34, and 35. It is returned to the tank 3 via the tank port 36. Therefore, the hydraulic cylinder 4
falls slowly. In addition, even in the circuit configuration during oil draining, the gear pump 1 is operated in an unloaded state as in the neutral state.

() At the time of overload When the load on the hydraulic cylinder 4 becomes overloaded, the oil sent to the discharge port 28 via the gear pump 1 passes through the passage 29, the relief valve 26, and then flows into the passages 37, 34. , 35 to tank port 3
6 and then refluxed to tank 3.

The above-mentioned functions are commonly explained for both automatic and manual operation of the directional control valve 25. The directional control valve 25 shown in this embodiment is operated as shown in FIG. , the discharge oil supply position A
Two operating positions are arranged at the front and rear of the . That is, a neutral position B and an oil drain position C for manual operation are arranged on one side, and a neutral position D and an oil drain position E for automatic operation are arranged on the other side.
Moreover, both of the oil drain positions C and E have a restriction in the oil drain passage. FIG. 7 shows an example of a directional control valve that realizes such a passage arrangement in an easy-to-understand manner. According to the figure, the discharge oil feeding position A straddles both the manual and automatic ranges, and therefore, the position A is a position that is commonly used regardless of the manual/automatic classification. Next, when comparing adjacent neutral positions B and D, it can be seen that the amount of lap in automatic neutral position D is set to be significantly smaller than that in manual neutral position B, although they are also neutral positions. By appropriately arranging the passages a, b, and c and the throttle passages d and e for the directional control valve 25, it is possible to achieve a manual neutral position with a relatively large amount of wrap using one directional control valve. ,
It becomes possible to continuously realize the automatic neutral position with a relatively small amount of wrap.

In the embodiment used in the above explanation, an example is shown in which two manual operation positions and two automatic operation positions are provided before and after one discharge oil supply position. It is clear that by further increasing the number of operating positions, even more fine-grained switching operations can be realized.

The gear pump according to this invention has a neutral position for manual operation and an oil drain position sequentially formed on either the front or rear side of the discharge oil supply position, and a neutral position and oil drain position for automatic operation on the other side. Equipped with a rotary directional valve with sequential oil drain positions,
By simply changing the switching direction of the directional switching valve, it is possible to select between manual and automatic operation of the hydraulic cylinder. In addition, in the above-mentioned directional control valve, the amount of wrap at the neutral position for automatic operation is set smaller than the amount of wrap at the neutral position for manual operation, so the hydraulic cylinder is reliably held in the neutral position for manual operation. At the same time, during automatic operation, the vertical movement switching operation can be performed sensitively. Furthermore, since a restriction is provided in the oil drain passage, the hydraulic cylinder can be lowered gently, making it easy to adjust the position of the cylinder, and ensuring that the wheel position of the rice transplanter is kept below the float when traveling on the road. During rice transplantation, it exhibits unique effects such as being able to easily maintain the planting depth of seedlings at a constant level regardless of the unevenness of the planting surface.

[Brief explanation of the drawing]

Figure 1 is a hydraulic circuit diagram of a conventional gear pump, Figure 2 is a partially cutaway side view of an automatic rice transplanter equipped with a gear pump, and Figure 3 is a cross-section of the gear pump according to this invention. Figure 4 is a sectional view taken along the - line in Figure 3, and Figure 5 is a sectional view taken along the - line in Figure 3.
6 is an enlarged view of the part in FIG. 5, FIG. 7 is an explanatory diagram for explaining the action of the gear pump according to this invention, and FIG. 8 is an illustration according to this invention. FIG. 2 is a hydraulic circuit diagram regarding a gear pump. 1... Gear pump, 2, 25... Directional switching valve,
3... Tank, 4... Hydraulic cylinder, 5... Pressure regulating valve, 21... Upper body, 22... Lower body,
23...Drive shaft, 24...Follow shaft, 26...Relief valve, 27...Suction port, 28...Discharge port, 29, 30, 3
1, 33, 34, 35, 37, a, b, c... passage, 32... cylinder port, 36... tank port, d, e... throttle passage, A... discharge oil feeding position, B, D: Neutral position, C, E: Oil drain position.

Claims (1)

[Scope of utility model registration request] One rotary directional valve is built into the main body,
In a gear pump device for a rice transplanter, which controls oil discharged to a hydraulic cylinder for lifting and lowering traveling wheels through manual operation of the switching valve and automatic operation linked to the movement of the float, at least five directional switching valves are provided. This position has a neutral position for manual operation and an oil drain position that connects the cylinder port to the tank port, which are sequentially formed either before or after one discharge oil supply position. On the other hand, a neutral position for automatic operation and an oil drain position connecting the cylinder port to the tank port are sequentially formed, and the amount of lap at the neutral position for automatic operation is greater than the amount of lap at the neutral position for manual operation. A gear pump device for a rice transplanter, which is small in size and further includes a restriction in the oil drainage passage.