JPS6233635Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transmission device for a tractor.

In tractors, the driving system transmission and
It had a PTO transmission, and the driving transmission consisted of a main transmission, a sub-transmission, and a creep transmission, and each transmission was provided with a separate operating lever.

Furthermore, various operating levers such as a hydraulic system are provided, and the various operating levers are lined up in a narrow area on the tractor, resulting in a decrease in operability.

Therefore, for example, there was a system in which multiple operating levers could be operated with one operation.
It is disclosed in Publication No. 4030. In this conventional device, a cam plate is provided with a plurality of cam grooves, an operating member is engaged with each of the cam grooves, and the plurality of operating members are operated by rotating the cam plate.

However, in this conventional device, the plurality of operating portions operated by changing the cam grooves are operated independently and are not operated at the same time. That is, when one operating section was operated, the other operating sections were not operated.

When multiple operating parts are operated simultaneously in relation to each other, if the inflection point positions of the cam grooves are correctly matched, multiple operating parts will start moving at the same time, making it extremely difficult to rotate the cam plate. become.

Therefore, an object of the present invention is to provide a transmission for a tractor that can be operated simultaneously with a light force by operating one operating lever, in a transmission having a plurality of transmission parts that are operated simultaneously. Therefore, the feature is that the shifting operation of the transmission gear trains provided in each of the plurality of transmission parts is performed in conjunction with each other by the shift means provided in each transmission part. In the device, a cam plate is rotatably supported on the vehicle body side of the tractor, and a plurality of cam grooves having radial irregularities are provided along the circumferential direction on the end face of the cam plate, and each cam groove corresponds to one another. The positions of the inflection points are shifted from each other in the circumferential direction, and on the other hand, an operating arm that is interlocked and connected to each of the shift means is swingably supported on the tractor body side, and the swinging end of the operating arm is The cam groove is slidably fitted into the cam groove.

Therefore, the feature is that a predetermined gear train is selected by selectively switching a plurality of shift means, and a cam groove having radial irregularities is formed along the circumferential direction on the end surface of a rotatable cam plate. There are multiple
A plurality of operation arms pivotally mounted to follow the rotation of the cam plate are slidably fitted into each cam groove, and the shift means are respectively interlocked with the arms. .

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 and 2 are comparative examples of the present invention. In the figures, numeral 1 is a transmission case of a tractor, which constitutes the vehicle body of the tractor.
A power transmission mechanism (not shown) is provided within the transmission case 1, and a traveling system transmission is provided to this mechanism. This driving system transmission includes a main transmission that converts the power from the engine to, for example, 4-speed and reverse gear, a sub-transmission that further converts the power after the main gear shift to 2-speed, and a 2-speed gear that switches to ultra-low speed. It consists of a creep transmission. Each speed change is performed by appropriately selecting a gear train. This selection is made by selectively switching a shift means such as a shifter or a shift fork, and a predetermined gear train is constructed. The shift means is operated by means of a lever, a link mechanism, or the like.

2 is its operating means, which consists of a cam mechanism;
This allows the auxiliary transmission and creep transmission to be operated at the same time.

The operating means 2 has a mounting plate 4 fixed to the side surface of the mission case 1 with bolts 3, and a main shaft 5 projecting outward is rotatably supported on the mounting plate 4. A rotation operating lever 6 is fixed to the outer end of the main shaft 5. A flange 7 is fixed to the main shaft 5, and a cam plate 8 is attached to the flange 7 with bolts 9. Cam grooves 10 and 11 are provided at two locations on the end surface of the cam plate 8, and the cam grooves 10 and 11 have irregularities in the radial direction and are provided over a predetermined length in the circumferential direction.

One cam groove 10 is for sub-shift operation, and is formed in an arc concentric with the main shaft 5 from point a to point b in the figure, and is oriented toward the center from point b to point c, and is oriented toward the center from point b to point c. The section leading to point d is formed into an arc concentric with the main axis 5. The other cam groove 11 is for creep speed change operation, and is oriented radially outward from point a' to point b', oriented toward the center from point b' to point c', and oriented radially outward from point a' to point b', and oriented toward the center from point b' to point c'. The area from point ' to point d' is formed into a mountain shape with the same height so as to point in the radial direction.

The central angles between a-b and a'-b' are the same, and similarly between b-c and b'-c', and between c-d and c'-
The central angles between d′ are formed to be equal.

12 is an arm for sub-shift operation;
2 is rotatably attached to the mounting plate 4 via a support shaft 13. The support shaft 13 and the arm 12 are fixed to rotate together. A cam floor 14 or a pin is provided at the tip of the arm 12, and the cam floor 14 fits into the cam groove 10. A connecting arm 15 is fixed to the other end of the support shaft 13,
An auxiliary transmission operation link 16 is rotatably connected to the connecting arm 15, and the link 16 is operatively connected to a protrusion 17 of a shift means of the auxiliary transmission.

Reference numeral 18 designates an arm for operating a creep speed change. This arm 18 is also rotatably supported on the mounting plate 4 via a support shaft 19, and a cam floor 20 provided at the tip of the arm 18 is inserted into a cam groove 11 for creep speed change. They are mated. A connecting arm 21 is also provided at the end of this support shaft 19.
is fixed to the arm 21, and a creep shift operation link 22 is connected to the arm 21, and the link 22 is operatively connected to a protrusion 23 of a shift means of the creep transmission.

The positional relationship between the sub-shift operating arm 12 and the creep shift operating arm 18 is as shown in FIG.
At a predetermined position on the cam plate 8, the cam floors 14 and 20 are located at points a and a', respectively.

Positioning and fixing means 2 are provided on the outer periphery of the cam plate 8.
4 are provided. The means 24 consists of engagement recesses 26 formed in the arcuate outer peripheral surface 25 of the cam plate 8 at predetermined intervals, and a ratchet portion 27 that removably engages with the recesses 26. The predetermined interval is equal to the central angle between a-b, b-c, and c-d. The ratchet portion 27 includes a ratchet arm 28 rotatably supported on the mounting plate 4, a ratchet pin 29 protruding from the tip of the arm 8, and a ratchet arm 28 for pressing the pin 29 against the arc portion 25 of the cam plate 8. It consists of a spring 30 that urges the.

A cover 31 is made of synthetic resin and integrally formed in a bowl shape, and is fitted onto the outer peripheral portion of the mounting plate 4 to cover the cam plate 8. A seal hole 32 for penetrating the main shaft 5 is provided in the center of the cover 31, and the inner circumferential surface of the seal hole 32 is tapered in cross section so as to slide against the main shaft 5 and exert a sealing action.

According to the comparative example of the present invention, by rotating the rotary operating lever 6 in the X direction shown in the figure, the cam floor 14 of the sub-shift operating arm 12 fitted in the point a of one of the cam grooves 10 is Moving to point b, the cam floor 20 of the creep shift operating arm 18, which is fitted to point a' of the other cam groove 11, moves to point b'. Since the distance between a and b of the cam groove 10 is a circular arc, the sub-shift operation arm 12 maintains a constant position without swinging due to the rotation of the cam plate 8, but the creep shift operation arm 18 does not move in the cam groove. 11 in the Z direction shown in the figure, and the creep transmission shift means is operated via the link mechanism 22 to perform a speed change operation.

By further rotating the cam plate 8, the sub-shift operation arm 12 swings in the Y direction shown in the figure between the cam grooves 10b and 10c, and the connecting arm 15 and the link 1
6, the creep shift operation arm 18 swings in the Z direction along the cam grooves 11b'-c' and returns to its original position.
The same applies to the swinging of the arms 12 and 18 between the cam grooves 10c and 10d and between the cam grooves c' and d'.

Therefore, by rotating one operating lever 6, the sub-shift and the creep shifting are operated simultaneously, which improves operability and reduces the number of operating levers 6.

In addition, since the cam grooves 10 and 11 are provided on a single cam plate 8, the structure is simple, and since the cam floors 14 and 20 are forced to move by the cam grooves 10 and 11, there is no need for a return mechanism. , tracking performance is improved.

However, in the comparative example, since the inflection points a, b, c, d, a', b', c', and d' of each cam groove correspond correctly to each other, a large operating force is required and smooth operation is not possible. It was difficult to operate.

Therefore, in the present invention, as shown in FIG. 3, inflection points a', b', c', The position of d' is shifted, and the position where point b' is delayed relative to point b is the position where point c' is earlier than point c.
It is formed offset to point c″.

By making the inflection points of both cam grooves 10 and 11 different at each shift position in this way, the shifter means operated thereby do not switch at the same time, and one of them switches slightly later or earlier. Therefore, operating force is reduced and operability is improved.

Note that the present invention is not limited to the above embodiments.

In this invention, the operating arms that fit into multiple cam grooves provided on the cam plate can be operated simultaneously by rotating the cam plate, so there is only one operating lever for multiple operating arms, resulting in improved operability. In addition, since the operating arm is fitted into the cam groove, followability is good, and since the operating arm is pivotably supported, the structure can be simplified. Since the amount of rocking can be increased and transmitted to the shifter means, the displacement of the cam groove can be reduced. In addition, in this invention, the positions of the inflection points of the plurality of cam grooves are shifted in the circumferential direction, so the operating force is reduced and smooth operation is possible, which has great practical effects. be.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, FIG. 1 is a partially sectional side view of a comparative example, FIG. 2 is a sectional view taken along the line of FIG. 1, and FIG. 3 is a side view of the embodiment. 8...Cam plate, 10, 11...Cam groove, 12,
18...Operation arm.

Claims (1)

[Scope of Claim for Utility Model Registration] In a tractor transmission device in which switching operations of transmission gear trains respectively provided in a plurality of transmission parts are operated in relation to each other by shift means provided in each transmission part. , a cam plate is rotatably supported on the vehicle body side of the tractor, a plurality of cam grooves having radial irregularities are provided along the circumferential direction on the end face of the cam plate, and each cam groove has a corresponding inflection. The positions of the points are shifted from each other in the circumferential direction, and on the other hand, an operating arm that is interlocked and connected to each of the shift means is swingably supported on the tractor body side, and a swinging end of the operating arm is connected to the cam. A tractor transmission characterized by being slidably fitted in a groove.