JPH0536163U - Neutral return device for hydraulic transmission for vehicle speed control - Google Patents

Abstract

(57) [Abstract] [Purpose] A neutral return device for a hydraulic transmission device using a torque spring is to reliably maintain the neutral position of the pump swash plate. [Structure] Both ends of a torque spring 9A, which extend parallel to a movable pin 8 that rotates integrally with the swash plate 4 and a stopper pin 10 that fixes the position, intersect each other on the movable pin rotation fulcrum shaft 6 and extend in parallel. , 9B, the engaging member 11 having elastic portions 11A, 11B facing between the movable pin and both ends of the spring and engaged with both ends of the spring is provided while being held by the movable pin.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a neutral return device for returning a vehicle speed control hydraulic transmission device, such as a tractor, to a neutral state and holding the neutral state.

[0002]

[Prior Art]

 For example, as disclosed in Japanese Utility Model Laid-Open No. 49-27701, a torque spring is used as a spring for returning a swash plate of a variable displacement hydraulic pump to a neutral position and holding it at the same position to bring a hydraulic transmission into a neutral state. The technique used is known. Such a torque spring urges a movable pin (for example, a pump swash plate or a pin fixed to a servo lever) provided to rotate integrally with the pump swash plate to return the swash plate to the neutral position. The movable pin is wound around the rotation fulcrum shaft of the movable pin, and both ends are crossed with each other to be parallel and extended toward the movable pin. The movable pin is clamped at both ends and engaged with the pin. It is supposed to be. In order to support one end of the both ends of the torque spring and obtain elastic deformation of the other end when the pump swash plate is rotated in the direction of moving the vehicle forward or backward from the neutral position, A position-fixed stopper pin, which is parallel to the movable pin, is sandwiched between both ends of the spring and engaged with the both ends, like the movable pin. The stopper pin may be located at a position farther or closer to the rotation fulcrum shaft than the movable pin.

[0003]

[Problems to be solved by the device]

 It is difficult to finish the torque spring with the above-mentioned shape so that both ends are precisely parallel.Therefore, a gap is formed between the both ends of the spring and the movable pin, and the pump swash plate is loose in the neutral position. There was a situation in which the swash plate position was not maintained accurately and the vehicle started in the forward or reverse direction even when the hydraulic power transmission was set to the neutral state. Therefore, an object of this invention is to reliably maintain the neutral position of the pump swash plate by a neutral return device using a torque spring that can be made compact.

[0004]

[Means for Solving the Problems]

 To this end, the present invention provides a movable pin 8 that rotates integrally with the swash plate 4 of the variable displacement hydraulic pump 2 of the hydraulic transmission 1 as shown in the accompanying drawing, and the rotation fulcrum shaft 6 of the movable pin 8 is provided. A torque spring 9 wound around is provided, and both ends 9A and 9B of the torque spring 9 are crossed with each other as seen in the axial direction of the above-described rotation fulcrum shaft 6 and movable pin 8. In parallel, the movable pin 8 is extended toward the movable pin 8, and the movable pin 8 and the stopper pin 10 which is parallel to the movable pin 8 and fixed in position are clamped by the both ends 9A and 9B of the torque spring 9 described above. , 9B, the following measures were taken in the neutral return device of the hydraulic transmission for vehicle speed control. That is, as shown in FIGS. 1 and 3 and 4, the present invention is an elastic member that engages with both ends 9A, 9B of the torque spring 9 and the both ends 9A, 9B of the torque spring 9 as described above. The engaging member 11 having the portions 11A and 11B is provided while being held by the movable pin 8. Further, according to this invention, the engaging member 11 is formed of a leaf spring having a pair of elastic legs 11A and 11B as the elastic portion, while the movable pin 8 is attached to the swash plate 4. It is also proposed to screw them together in a tightened state.

[0005]

[Action]

 The engaging member 11 is made of a leaf spring as described above, is made of an elastic wire as shown in FIG. 6, or is made of an elastic material such as rubber attached to the peripheral surface of the movable pin 8. However, in any case, since the movable pin 8 is engaged with the spring end portions 9A, 9B via the elastic portions (elastic leg portions) 11A, 11B of the engaging member 11, the spring end portions 9A , 9B are not precise in parallelism, the movable pin 8 is brought into close contact with both spring end portions 9A, 9B by both elastic portions 11A, 11B, and rattling occurs in the pump swash plate 4 in the neutral position. Such a phenomenon no longer occurs. When the swash plate 4 is rotated from the neutral position in the direction to move the vehicle forward or backward, one end of the spring both ends 9A, 9B is received and supported by the stopper pin 10 and the other end. The movable pin 8 elastically deforms the spring end portion via the elastic portion 11A or 11B on that side, but since the engaging member 11 is held by the movable pin 8, the engaging member 11 is used during the swash plate operation. The elastic portion 11A or 11B of the above is not substantially elastically deformed, and the problem that the operating force is increased by the engaging member 11 does not occur.

[0006]

[Effect of the device]

 Therefore, according to the present invention, there is provided a neutral return device for a vehicle speed control hydraulic power transmission device which surely maintains the neutral position of the swash plate 4 without increasing the rotational operation force of the pump swash plate 4. When the engaging member 11 is made of a leaf spring and the movable pin 8 is fastened together with the movable pin 8 to the pump swash plate 4 as in claim 2, the engaging member 11 can be easily formed by sheet metal working and can be easily formed by the movable pin 8. You will be able to hold.

[0007]

【Example】

 The illustrated embodiment relates to an example in which the present invention is implemented in a tractor, and in FIGS. 2 and 3, reference numeral 16 indicates a mission case of the tractor. A relatively thick plate member 17 is mounted on the front surface of the upper half of the mission case 16, and the hydraulic transmission 1 is mounted on the rear surface of the upper half of the plate member 17 and positioned in the mission case 16. It comprises the hydraulic pump 2 and the fixed volume hydraulic motor 3 fixed on the front surface of the lower half of the swash plate 5. The pump shaft 2a of the hydraulic pump 2 is projected to the front of the plate member 17 to receive input conduction from an engine (not shown). The charge pump 18 using the pump shaft 2a as a pump shaft is It is attached to the front surface of the member 17. The rear end of the motor shaft 3a of the hydraulic motor 3 is projected into the transmission case 16 and a bevel gear 19 having a small diameter is fitted therein. A transmission shaft 21 fitted with a large-diameter bevel gear 20 that meshes with the bevel gear 19 is horizontally mounted in the transmission case 16, and a small-diameter gear 22 is fixedly installed on the transmission shaft 21. This gear 22 meshes with a large-diameter input gear 24 of the differential gear 23 shown in FIG. 8, and the left and right output shafts 25 of the differential gear 23 drive left and right rear tractor wheels (not shown). ing.

As shown in FIGS. 2 and 3, the swash plate 4 of the axial plunger type hydraulic pump 2 is disposed inside the mission case 16 on the pump rear end side, and includes the rotation fulcrum shaft 6 and the support shaft 7. Thus, the mission case 16 is supported rotatably around the common axis of the shafts 6 and 7. In the illustrated example, the movable pin 8 is screwed to a rear end portion of one side surface of the swash plate 4 by a screw portion 8a formed on the movable pin 8 to integrally rotate with the swash plate 4 around the rotation fulcrum shaft 6. An opening closed by a side lid 27 is formed on one side wall of the mission case 16, the rotation fulcrum shaft 6 is supported by the mission case 16 via the side lid 27, and the side lid 27 is provided with the above-mentioned structure. The stopper pin 10 is fixedly supported. This support is performed by the eccentric shaft portion 10a integrally formed with the stopper pin 10. The outer end portion of the eccentric shaft portion 10a is screwed into the nut 12 so that the eccentric shaft portion 10a can be screwed. The position of the stopper pin 10 is slightly changed by screwing to change the engagement position with both ends 9A and 9B of the torque spring, and the neutral position of the swash plate 4 can be adjusted. An operation arm 13 is attached to the rotation fulcrum shaft 6 outside the transmission case 16, and a shock absorber 14 is attached to the operation arm 13.

In the example shown in FIGS. 1-4, the engaging member 11 is made of a leaf spring as shown in FIG. It is assumed that the engaging member 11 has a pair of flat elastic legs 11A and 11B projectingly formed above and below a flat plate portion 11a along one side surface of the swash plate 4. A hole 11c for inserting the screw portion 8a of the movable pin 8 is formed. A bent plate portion 11b is formed at the rear end of the flat plate portion 11a along the back surface of the swash plate 4. The movable pin 8 is screwed to the swash plate 4 while being prevented from rotating by the bent plate portion 11b. The engaging member 11 is held by the movable pin 8 by tightening 11a to the swash plate 4. FIG. 6 shows another example of the engaging member 11. This engaging member 11 has a pair of elastic legs (elastic parts) 11A from a coil portion having a hole 11c for inserting the movable pin 8 to the upper and lower elastic legs (elastic portions). , 11B are formed to extend. As described above, the engaging member may be made of an elastic material such as rubber attached to the peripheral surface of the movable pin 8.

As shown in FIGS. 1 and 3 and 4, the torque spring 9 is wound around the rotation fulcrum shaft 6 in the transmission case 16, and both ends 9A and 9B are crossed as described above, and then parallel to each other. It is overhanging backwards. The upper and lower elastic legs 11A and 11B of the engaging member 11 are respectively engaged with the upper and lower spring ends 9A and 9B on the upper surface side and the lower surface side of the movable pin 8, respectively. The stopper pin 10 is adapted to engage with the upper and lower spring ends 9A and 9B by two annular groove portions for preventing disengagement. Although the stopper pin 10 is arranged rearward of the movable pin 8 in the illustrated example, it may be arranged between the rotation fulcrum shaft 6 and the movable pin 8 as described above.

Although not directly related to the present invention, the structure of the other parts of the transmission shown in FIGS. 2 and 3 will be briefly described. The transmission case 16 is arranged between the rear wheels of the left and right tractors (not shown). On the other hand, a mid PTO shaft 28 for driving a work machine (not shown) such as a mid mount type mower is provided in the lower part of the case 16 from the inside of the transmission case 16 to the suction port of the charge pump 18. In order to clean the oil guided to 18a, a filter 29 mounted on the lower front surface of the transmission case 16 is provided so as to protrude forward in the forward direction. The pump shaft 2a drives the mid PTO shaft 28. It is also used in. That is, a clutch shaft 30 concentrically arranged with the pump shaft 2a is provided at a position above the latter half of the transmission case 16 and a hydraulic multi-plate PTO clutch 31 is arranged between the pump shaft 2a and the clutch shaft 30. The clutch shaft 30 is linked to the mid-PTO shaft 28 by a gear train including gears 32, 33, and 34 arranged at the rear end of the transmission case 16. In the PTO clutch 31, the support metal 35 that supports the driving-side friction element 31a is fitted to the rear end of the pump shaft 2a, and the clutch housing 36 that supports the driven-side friction element 31b is fitted to the clutch shaft 30. It is worn. The clutch housing 36 is formed with the gear 32 at the starting end of the gear train, and is additionally provided with a brake 37 for preventing inertial rotation on the driven side of the clutch 31. The brake 37 is provided with a brake shoe 37a facing the outer peripheral surface of the clutch housing 36, and when the PTO clutch 31 is in the engaged state, the brake shoe 37a is separated from the clutch housing 36 by a piston 37b which exerts a clutch acting hydraulic pressure. In the cut state of the PTO clutch 31, the spring 37c biases the brake shoe 37a via the piston 37b to frictionally engage the clutch housing 36.

Similarly, as shown in FIGS. 2 and 3, the inside of the mission case 16 accommodates a pump accommodation chamber 40 for accommodating the hydraulic pump 2, a PTO clutch 31 and gears 32, 33, 34 rows by a proper partition wall. It is partitioned into a PTO system transmission mechanism accommodating chamber 41 and a traveling system transmission mechanism accommodating chamber 42 which accommodates the traveling system transmission mechanism from the rear end of the motor shaft 3a to the differential device 23 (FIG. 8). As shown in FIG. 2, an oil passage 43 for guiding the leak oil of the hydraulic motor 3 to the pump housing chamber 40 is formed in the plate member 17 so that the pump housing chamber 40 is filled with oil. Further, as shown in FIGS. 3 and 7, an appropriate number of diagonal oil guide grooves 35a for guiding oil from inside the pump storage chamber 40 to the friction elements 31a and 31b of the PTO clutch 31 are formed in the support metal 35. After lubricating and cooling the friction elements 31a and 31b, the oil is centrifugally discharged to the outside of the clutch housing 36 to fill the PTO system transmission mechanism accommodating chamber 41 shown in FIG. By filling the storage chamber 41 with oil, the PTO system transmission member rotating at a relatively high speed rotates in the oil, and the oil and the air are simultaneously stirred to mix a large amount of air into the oil. The phenomenon is prevented. The PTO system transmission mechanism housing chamber 41 and the traveling system transmission mechanism housing chamber 42 are communicated with each other through an opening 44 provided at the lower end of the partition wall. Therefore, the charge pump 18 from the inside of the transmission case 16 hardly mixes air into the hydraulic oil supplied from the discharge port 18b of the pump 18 to the hydraulic transmission 1, and the change in the gear ratio due to the occurrence of cavitation in the hydraulic transmission 1. Also, problems such as fluctuations in the neutral area do not occur.

In the transmission mechanism / hydraulic circuit diagram of FIG. 8, reference numeral 46 indicates an engine, and the transmission mechanism is as described above. Reference numeral 47 denotes an oil passage for supplying oil to the charge pump 18 from the traveling system transmission mechanism housing chamber 42 in the mission case 16 through the filter 29. The charge pump 18 supplies hydraulic oil to the closed circuit of the hydraulic transmission 1, and also supplies hydraulic oil to the PTO clutch 31 and other hydraulic operating devices 48 such as a mower lift cylinder. It is used to supply. That is, the flow rate adjusting valve 50 is inserted and installed in the discharge circuit 49 of the charge pump 18, and the regulated flow circuit 51 is connected to the PTO clutch 31 and the brake 37 attached thereto through the electromagnetic switching valve 52, while the surplus The flow circuit 53 is connected to the closed circuit of the hydraulic transmission 1 via a pressure reducing valve 54 and a pair of check valves 55 that set the supply hydraulic pressure to the hydraulic transmission 1. A resistance valve (relatively low pressure) for maintaining the oil pressure of the discharge circuit 49 when the discharge circuit 49 is inactivated relative to another hydraulic pressure operating device 48 by a switching valve (not shown) Relief valve 56). In FIG. 8, reference numeral 57 is a relief valve for setting a working hydraulic pressure for the PTO clutch 31, and 58 is a relief valve for setting a working hydraulic pressure for another hydraulic operating device 48 that operates at a relatively high pressure. As shown in the drawing, the drain oil of the pressure reducing valve 54 is combined with the oil of the surplus flow circuit 53 through the circuit 59, and the relief oil of the relief valve 57 is provided in the PTO transmission mechanism accommodating chamber 41 and the relief valve 58. The relief oil and the return oil from the other hydraulically operated device 48 are returned to the pump accommodating chamber 40, respectively. As described above, depending on the structure in which the flow rate adjusting valve 50 is provided, the adjusting flow circuit 51 is connected to the PTO clutch 31, and the surplus flow circuit 53 is connected to the closed circuit of the hydraulic power transmission device 1, the hydraulic power transmission device 1 may be disconnected for some reason. The PTO clutch 31 is safely protected even when the oil leak in the case becomes serious. The switching valve 52 for the PTO clutch 31 is provided on the rear lid 60 of the transmission case 16 as shown in FIG. 2, and the relief valve 57 for the PTO clutch 31 is provided on the rear lid 60 as shown in FIG. , Each installed. Other valves are mainly installed in the plate member 17 shown in FIGS.

[Brief description of drawings]

FIG. 1 is a partially longitudinal side view showing an example of the present invention.

FIG. 2 is a partially developed vertical sectional side view of a mission case of a tractor equipped with the same embodiment.

FIG. 3 is a cross-sectional plan view of the mission case.

FIG. 4 is a schematic perspective view of an example.

FIG. 5 is an exploded perspective view of two members of the embodiment.

FIG. 6 is a perspective view showing another example of an engaging member.

FIG. 7 is a schematic perspective view showing one member in the transmission mechanism of the tractor.

FIG. 8 is a mechanical and circuit diagram showing a transmission mechanism and a hydraulic circuit of the tractor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic transmission device 2 Hydraulic pump 3 Hydraulic motor 4 Swash plate 6 Rotation fulcrum shaft 7 Support shaft 8 Movable pin 8a Screw part 9 Torque springs 9A, 9B End part 10 Stopper pin 11 Engaging member 11A, 11B Elastic leg part (elasticity) Part) 11c hole 16 mission case

Claims (2)

[Scope of utility model registration request] 1. A movable pin (8) which rotates integrally with a swash plate (4) of a variable displacement hydraulic pump (2) of a hydraulic transmission (1).
And a torque spring (9) wound around the rotation fulcrum shaft (6) of the movable pin (8), and the both ends (9A, 9B) of the torque spring (9) are rotated as described above. The fulcrum shaft (6) and the movable pin (8) are crossed with each other when viewed along the axial direction, and then extend parallel to each other toward the movable pin (8), and the movable pin (8) and its position A vehicle speed control hydraulic pressure in which a stopper pin (10) fixedly provided is clamped between both ends (9A, 9B) of the torque spring (9) and engaged with the both ends (9A, 9B). In the neutral return device of the power transmission device, both ends (9A, 9B) of the torque spring (9) and the both ends (9A, 9B) of the spring are faced between the movable pin (8).
A neutral return device characterized in that an engaging member (11) having elastic portions (11A, 11B) engaging with B) is provided while being held by a movable pin (8). 2. The engaging member (11) is formed of a leaf spring having a pair of elastic legs (11A, 11B) as the elastic portion, while the movable pin (8) is attached to the swash plate (4). 3. The neutral return device according to claim 1, wherein the engaging member (11) is screwed together in a closed state.