KR830002551Y1 - A work vehicle with a bypass passage for flowing hydraulic fluid directly into the transmissive case - Google Patents

Abstract

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Description

A work vehicle with a bypass passage for flowing hydraulic fluid directly into the transmissive case

1 is a schematic plan view of a tractor.

2 is a hydraulic circuit diagram of an important part.

3 is an enlarged cross-sectional view of an important part.

4 and 5 are enlarged cross-sectional views of important parts respectively showing different embodiments.

The present invention relates to a work vehicle provided with an oil cooling passage for reducing hydraulic oil in a hydraulic driven transmission case to a transmission case via a cooler. Considering the flow of hydraulic oil returned to the transmission case via the cooler from the hydraulically driven missile case described above in this type of work vehicle, especially in a cold or cold climate, the hydraulic oil has a high resistance due to low temperature. The resistance is also large, and as a result, the internal pressure of the hydraulic drive missile case is increased so much that oil leaks.

In this case, when the hydraulic fluid is low, it is conceivable to increase the size of the cooler with a large diameter of the oil cooling passage pipe as a means of suppressing an abnormal increase in the internal pressure of the hydraulic drive-missing case. There is a drawback that the equipment cost and operation maintenance costs are high.

In view of the above situation, the present invention uses an oil cooling passage pipe of small diameter, which is advantageous in minimizing the economical aspect of the piping equipment and the piping structure, but it ensures that the internal pressure of the hydraulic drive type case rises abnormally when the hydraulic oil is low. The purpose is to make it possible to prevent this. In order to achieve the above object, the working vehicle of the present invention is a working vehicle having an oil cooling path for reducing the hydraulic oil in the hydraulic drive mission case to the transmission case via a cooler. The hydraulic oil is provided with a bypass passage provided with a relief valve that flows the hydraulic oil to the transmission case without passing through the cooler when the pressure in the hydraulic drive mission case exceeds the set value. The bypass provided with the relief valve is installed on the partition wall of both cushion cases, and the bypass described above is formed from the flow path formed in the drain cock of both cushion cases and the pipe communicating with it. Relief valve is built into the drain cock on the hydraulically driven chuck case. Car will work, characterized in that kigo.

This makes it possible to use an oil-cooled passage of small diameter, which is advantageous in terms of the economical aspect of the piping system and the miniaturization of the piping structure. Even in this case, the hydraulic oil in the hydraulic drive mission case can be evacuated directly to the transmission mission case by a bypass passage provided with a relief valve installed between the hydraulic drive and the transmission case. The internal pressure of the case does not rise abnormally, and troubles such as oil leakage due to such abnormal increase in internal pressure can be reliably avoided.

In addition, since a small diameter of oil cooling passage pipe can be used, especially when working in a cold area, it can show the advantage that it can advantageously operate in warm air by suppressing the inflow of hydraulic oil from the electric cooler. Reached. The above-mentioned bypass passage is formed from the flow path formed by the drain cock of both of the mis- sion cases and the pipe communicating with it, and the relief valve is incorporated in the drain cock on the hydraulically driven mis- sion case side. Bypass relief relief valves required for achieving the effect can be inexpensively constructed using the drain cock, which is an essential component.

Other objects and advantages of the present invention will become apparent from the following description. When the present invention is described as an embodiment according to the accompanying drawings, FIG. 1 shows a tractor, which includes a driving unit 3 made of an engine 1, a radiator 2, and the like, to the front and rear wheels 4, 5; On the intake side of the radiator 2 which delivered the hydraulic drive transmission case 8 of the hydraulic continuously variable transmission 7 across the transmission transmission case 6 which has the transmission mechanism and the transmission mechanism of the work system. An oil cooling passage 10 for arranging the coolant 9 for operating oil cooling at the lower end and for reducing the hydraulic oil in the hydraulic driving missile case 8 that has been transferred to the trans mission case 6 via the cooler 9 is provided. The hydraulic oil supply pipe 10A and the cooling hydraulic oil return pipe 10B which are formed are provided.

The above-mentioned hydraulic continuously variable transmission 7 is driven by the engine 1, and the hydraulic pump 7A of the variable displacement type which can change the flow rate according to the change of the inclination angle, and the hydraulic pump 7A Constant capacity hydraulic motor 7B for changing gas forward and reverse speed steplessly according to the flow rate change, constant capacity type hydraulic pump 7C, filter for maintaining the flow rate in these flow paths 7D), check valve 7E, 7E, relief valve 7F, and the like.

And as shown in FIG. 3, the front and rear direction of the body over the partition wall 11 (11 ') between the hydraulic drive missile case 8 and the transmissive case 6 of the hydraulic continuously variable transmission 7 as shown in FIG. In addition to forming a bypass passage 12 penetrating the air passage, the bypass passage 12 is configured to transfer hydraulic fluid through the cooler 9 without passing through the cooler 9 when the pressure in the hydraulic actuating stroke case 8 becomes higher than the set value. The relief valve 13 which flows to the case 6 is provided.

The relief valve 13 described above communicates with the valve chamber 13B in communication with the bypass passage 12, which is connected to the valve body 13A screwed to the partition wall 11 ′ on the side of the transmission mission case 6. A screw member which is formed and provided with a ball 13C for closing the bypass passage 12 in the valve chamber 13B, and screwed into the opening of the ball 13C and the valve chamber 13B. Between 13D, the spring 13E which moves the above-mentioned ball 13C in the blocking direction, and applies an elastic pressure is retrofitted.

4 and 5 show modifications of the above-described embodiment, respectively, and in FIG. 4, the bypass line 12 is screwed into the lower walls of both of the miscellaneous cases 8 and 6, respectively. It forms from the flow paths 16 and 17 formed in the drain cock 14 and 15, and the pipe 18 which connects and communicates with it, and reliefs to the drain cock 14 of the hydraulic-driven transmission case 8 side. The valve 13 is incorporated.

In addition, the relief valve 13 has a screw member 13G in which a flow passage 13F fixed by screwing in the drain cock 14 is provided, and a ball capable of closing the flow passage 13F of the screw member 13G ( 13) and spring 13E for applying the elastic force in the closing direction to the ball 13C.

In FIG. 5, the rotational movement of the transmission shaft 9 through the partition wall 11 of the hydraulic drive missile case 8 and the partition wall 11 'of the transmission case 6 is freely rotated. Of the bearings 20 and 21 to be supported, the pressing members 22 of the bearings 20 on the hydraulic drive-missing case 8 side are provided between the two partition walls 11 and 11 '. The bypass passage 12 penetrates through 22 and the partition wall 11 of the hydraulically driven transmission case 8, and the relief valve 13 is incorporated in the press member 22 described above.

The relief valve 13 is provided with a ball 13C for closing the bypass 12 in the valve chamber 13B formed on the pressing member 22, and the ball 13C and the valve chamber. Between the screw member 13D screwed into the opening of 13B and the ball 13C is moved in the closing direction, the spring 13E which applies an elastic pressure is retrofitted.

Claims (1)

In a work vehicle provided with an oil cooling passage 10 for reducing the hydraulic oil in the hydraulic drive mission case 8 to the transmission case 6 via the cooler 9, the hydraulic drive mission case 8 described above is provided. Bypass valve (12) with relief valve (13) installed so that hydraulic oil flows to the trans-mission case without passing through the cooler when the pressure in the hydraulically-driven transmission case becomes higher than the setting between the and the transmission-mushion case (6). The work vehicle is installed with a bypass passage for flowing the hydraulic fluid directly to the trans-mission case.