JPH0627280U - Quick turn device for tractor - Google Patents

Abstract

(57) [Summary] [Purpose] While making it easy to adjust the presence or absence of front wheel acceleration,
Smooth gear shifting. [Constitution] When the main transmission lever is shifted, the rack shaft 11 slides, and the rotary valve 15 rotates via the pinion 13. A potentiometer 30 is attached to the valve 15 to detect the rotation angle of the valve 15. Set the sub gearshift lever to the high speed side and the main gearshift lever to 6 ~
When shifting to the 8th speed (the whole is neutral and the 1st to the 8th speed), the sliding amount of the rack shaft 11 increases, the rotation angle of the rotary valve 15 also increases, and the voltage generated by the potentiometer 30 exceeds a predetermined value. At this time, the front wheel acceleration is released. Since the rotation angle of the rotary valve 15 can be accurately detected by the potentiometer 30,
It is easy to adjust the switch operating position for releasing, and the resistance of the potentiometer 30 during gear shifting hardly increases.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a quick turn device that accelerates a front wheel with respect to a rear wheel when turning a headland, and more particularly to a quick turn device that includes a release mechanism that prohibits acceleration of the front wheel during high speed traveling.

[0002]

[Prior art]

 In tractors, etc., when the steering operation amount exceeds the specified value with respect to the traveling machine body, the front wheels are accelerated relative to the rear wheels in order to reduce the turning radius when turning on a headland. A device that does this (hereinafter referred to as "quick turn device") is known.

By the way, when the vehicle turns, the steering wheel is largely turned off. Therefore, if the vehicle turns at high speed, the traveling machine body may fall down. In addition, if the front wheels are further accelerated, the risk of falling is further increased.

Therefore, in order to prevent a fall, the operation of the front wheel speed increasing mechanism is prohibited at high speed. The release mechanism prohibits this operation.

The release mechanism stops the operation of the front wheel speed increasing mechanism by detecting the swing position of the main speed change lever. The main gear shift lever is swingably attached to the traveling body and moves along the guide groove of the lever guide. For example, N (neutral), 1st to 8th speed is displayed in the guide groove, and the traveling speed corresponding to the display can be obtained by shifting the main gearshift lever and setting it to the position of these displays. ing. That is, with reference to the position of N (neutral), the traveling speed becomes higher as the amount of movement of the main transmission lever increases toward the 8th speed. The release mechanism turns on the switch when the movement amount of the main transmission lever exceeds a predetermined value (for example, when the main transmission lever is set to 6th gear or higher), and thereby releases the operation of the front wheel speed increasing mechanism. I am doing it.

When the main shift lever is shifted, the rotary valve rotates by an angle corresponding to the set position to switch the oil passage of the hydraulic circuit, thereby changing the shift gear and completing the shift. Several members, such as a rod, a link, a rack shaft, and a pinion, are interposed between the rotary valve and the main speed change lever, and by operating the main speed change lever, these members are interposed. Finally, it is designed to rotate the rotary valve. Even if the main speed change lever is set to the 6th to 8th speed in combination with the auxiliary speed change lever that switches the traveling speed to the high speed side (H) and the low speed side (L), the auxiliary speed change lever is set to the low speed side (L). In this case, the operation of the front wheel speed increasing mechanism is not prohibited, but the operation is prohibited when the auxiliary speed change lever is on the high speed side (H) and the main speed change lever is in the 6th to 8th speed.

In addition to the main shift lever described above, a rack shaft is a detection target for detecting the amount of movement of the release mechanism. The rack shaft meshes with a pinion that is fixed to the rotary valve, and the rotary valve is rotated through this pinion. For example, when the amount of movement (sliding amount) of the rack shaft becomes larger than a predetermined value, the rack shaft turns on the switch to activate the release mechanism.

[0008]

[Problems to be solved by the device]

 However, according to the above-mentioned conventional technique, since several members are interposed between the main shift lever that is detected by the release mechanism and the rotary valve that shifts the shift gears, the main shift The movement of the main speed change lever may not be faithfully transmitted to the rotary valve due to the looseness of the lever attachment and the looseness of the connection between the interposed members, and the movements of the two may not correspond to each other. As a result, the position detection accuracy is poor and it is difficult to adjust the switch operating position of the release mechanism.

On the other hand, when the rack shaft is to be detected, there is a problem that the gear shifting operation cannot be smoothly performed due to the contact resistance of the switch.

Therefore, in the present invention, the rotational position detection means directly detects the rotational angle of the rotary valve, thereby improving the position detection accuracy and facilitating the adjustment of the switch, and performing the gear shift operation. It is an object of the present invention to provide a quick turn device for a tractor that is smoothly operated.

[0011]

[Means for Solving the Problems]

 The present invention has been made in view of the above circumstances, and is rotated by a quick turn device (QT) for increasing the speed of the front wheels with respect to the rear wheels and a gear shift operation means (2) during turning. In a tractor equipped with a transmission that selects a transmission gear based on the rotation angle of a rotary valve (15), a detection means (33) for detecting the steering operation amount, and an output of the detection means (33). A front wheel speed-increasing mechanism (35) that speeds up the front wheels when the torque exceeds a predetermined value, a rotational position detecting means (30) for detecting the rotational angle of the rotary valve (15), and the rotational position detecting means (30). A release mechanism (37) for releasing the operation of the front wheel speed increasing mechanism (35) when the output of 30) exceeds a predetermined set value.

[0012]

[Action]

 Based on the above configuration, the rotary valve (15) for switching the oil passage to shift the shift gear is accurately held at a position corresponding to each shift stage by, for example, a detent mechanism. Therefore, when the rotational angle of the rotary valve (15) is detected by the rotational position detecting means (30) such as a potentiometer, the detection accuracy is remarkably improved. Moreover, the extra resistance for detection hardly acts on the rotary valve (15).

[0013]

[Effect of device]

 As described above, according to the present invention, since the release mechanism (37) detects the rotation angle of the rotary valve (15) by the rotation position detection means (30), the detection accuracy is significantly improved, The switch adjustment can be facilitated, and the resistance that is excessively loaded for detection can be reduced to enable smooth gear shifting operation.

The reference numerals in the parentheses are for the purpose of comparing the drawings, and do not limit the configuration of the present invention in any way.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

First, an outline of the transmission of the tractor will be described with reference to FIG. The speed change device includes a main speed change lever 2 that shifts along a guide groove 1 a of the lever guide 1. The main shift lever 2 is formed in a bent shape, and a bracket 3 is fixed to the base end portion thereof. The bracket 3 is rotatably supported by a pin 5 on the traveling body side, and a connecting portion 3a is provided so as to project. One end of the rod 6 is connected to the connecting portion 3a, and the other end of the rod 6 is connected to one end of an L-shaped link 9 which is swingably supported by a shaft 7 on the traveling body side. The other end of the link 9 is connected to one end of a rod 10, and the other end of the rod 10 is connected to a rack shaft 11.

As shown in FIG. 2, the rack shaft 11 is supported by a holding portion 12a of a valve case 12 so as to be slidable in the longitudinal direction, and a rack 11a in the longitudinal direction is formed at an intermediate portion thereof. . The pinion 13 meshes with the rack 11a. The pinion 13 is formed in a substantially cylindrical shape, has a tooth portion 13a screwed to the rack 11a in the middle portion of the outer periphery, and radial bearings Br and Br are fitted on both sides of the tooth portion 13a. Thus, it is rotatably supported. A spline 13b is formed on the inner peripheral surface of the pinion 13, and the pinion 13 is fixed to the shaft portion 15a of the rotary valve 15 via the spline.

The rotary valve 15 has a large-diameter portion 15b, and a large number of oil passages 15c for supplying pressure oil to a hydraulic actuator (not shown) that shifts a transmission gear are formed in the large-diameter portion 15b. ing. The entire rotary valve 15 is rotatably supported by the radial bearings Br and Br via the pinion 13 described above.

At the boundary between the shaft portion 15a and the large diameter portion 15b of the rotary valve 15, a disc-shaped positioning plate 16 having a diameter larger than that of the large diameter portion b is fixed. The plate 16 has a large number of conical recesses 16a into which balls and detent balls, which will be described later, engage.

The rotary valve 15 is inserted into a cylindrical recess 17 a of the valve body 17. The valve body 17 is formed in a substantially cylindrical shape and is fastened to the valve case 12 via a bolt (not shown). The valve body 17 has a large number of oil passages oriented axially or radially. In one of the oil passages in the axial direction, for example, a traveling hydraulic clutch switching valve including a return spring 19a, a spool 19b, and a ball 19c is housed. In this valve, when the positioning plate 16 rotates together with the rotary valve 15, the ball 19c is pushed up from the recess 16a, and the spool 19c moves upward to switch the oil passage, thereby operating the hydraulic clutch. Is. A detent mechanism including a return spring 20a and a detent ball 20b is housed in the other oil passage in the axial direction of the valve body 17. This detent mechanism allows the rotary valve 15 to maintain a predetermined rotation angle accurately.

A potentiometer 30 as a rotational position detecting means is attached to the rotary valve 15. A shaft 15d is provided on the end surface of the shaft portion 15a of the rotary valve 15, and the shaft 15d penetrates through the through hole 12b of the valve case 12 in which the oil seal 22 is mounted and extends further outward. ing. On the other hand, a shaft 30a is extended also from the potentiometer 30 side, both shafts 15d and 30a are connected via a coupling ring 23, and further fixed by a screw 25. The whole potentiometer 30 is fixed to a bracket 27 fixed to the valve case 12 via bolts 26.

An auxiliary shift lever 29 is disposed behind (on the right side in FIG. 1) the main shift lever 2 that operates the rotary valve 15 described above. The sub speed change lever 29 is swingably supported by a traveling machine body (not shown), and the sub speed change switch 31 is turned on and off by a tongue piece 29a on the base end side. The auxiliary shift switch 31 is turned on when the auxiliary shift lever 29 is located on the low speed side (L), and is turned off when it is located on the high speed side (H).

Next, the quick turn device QT will be described with reference to the circuit diagram of FIG.

The power supply 39 is turned on when the quick turn switch 32 for enabling the operation of the quick turn device QT and the auxiliary shift lever 29 are shifted to the low speed side (L), and is shifted to the high speed side (H). The auxiliary shift switch 31 which is turned off when the steering wheel is turned off, the angle sensor switch 33 which is turned on when the steering operation angle with respect to the traveling machine body, that is, the steering operation amount exceeds a predetermined value, and the front wheels are accelerated when energized. The quick turn solenoid 35 is connected in series. Further, a comparator (release mechanism) 37 that compares the voltage of the potentiometer 30 based on the rotation of the rotary valve 15 with a preset predetermined voltage is arranged, and when the voltage from the potentiometer 30 exceeds the predetermined voltage. A release switch 37a (built into the comparator) that is turned off is connected in parallel with the auxiliary transmission switch 31. Further, a display lamp 36 that is turned on when the front wheels are being accelerated is connected.

Next, the operation of the quick turn device QT will be described. In the following description, it is assumed that the main gearshift lever 2 is subject to front wheel speedup when the gearshift lever is shifted to the 6th to 8th speeds.

First, the quick turn switch 32 is turned on so that the quick turn device QT can be operated. In this state, when the auxiliary shift lever 29 is set to the low speed side (L), the auxiliary shift switch 31 is turned on. At this time, if the steering operation amount exceeds a predetermined value, the angle sensor switch 33 is used. The quick turn solenoid 35 is energized to accelerate the front wheels. That is, when the auxiliary transmission lever 29 is on the low speed side (L 2), the front wheels are accelerated when the steering wheel is greatly turned, regardless of the shift position of the main transmission lever 2.

On the other hand, when the auxiliary transmission lever 29 is set to the high speed side (H), the presence or absence of front wheel speed increase is determined by the shift position of the main transmission lever 2 in addition to the steering operation amount. When the main shift lever 2 is shifted in the direction of arrow K1 and is set to, for example, the 1st to 5th speed, the rack shaft 11 slides in the direction of arrow K2 via the rod 6, the link 7, and the rod 10 of FIG. . By this sliding in the K2 direction, the rotary valve 15 rotates, and the potentiometer 30 integrated with the rotary valve 15 also rotates to generate a voltage proportional to the rotation angle, but the rotation angle is small and the generated voltage does not reach the predetermined voltage. Therefore, the release switch 37a is turned on, and when the steering operation amount is large, the front wheel acceleration is activated.

On the other hand, even when the auxiliary shift lever 29 is also set to the high speed side (H), when the main shift lever 2 is set to the 6th to 8th speed, the shift amount of the main shift lever 2 is large. The amount of slide of the rack shaft 11 and the amount of rotation of the rotary valve 15 and the potentiometer 30 increase, and the generated voltage exceeds a predetermined voltage accordingly. Then, the release switch 37a is turned off, the quick turn solenoid 35 is not energized, and as a result, the front wheel acceleration is released.

As described above, the comparator 37 as the release mechanism turns on and off the release switch 37a based on the potentiometer 30 accurately detecting the rotation angle of the rotary valve 15, so that the operation is sure. Become.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a transmission.

FIG. 2 is a sectional view showing the periphery of a rotary valve and a potentiometer.

FIG. 3 is a circuit diagram of a quick turn device.

[Explanation of symbols]

2 gear shifting operation means (main gear shifting lever) 15 rotary valve 30 rotational position detecting means (potentiometer) 33 detecting means (angle sensor switch) 35 front wheel speed increasing mechanism (quick turn solenoid) 37 releasing mechanism (comparator) QT quick turn device

Claims (1)

[Scope of utility model registration request] 1. A quick turn device for increasing the speed of a front wheel relative to a rear wheel during turning, and a transmission device for selecting a transmission gear based on a rotation angle of a rotary valve that is rotationally operated via a transmission operation means. In a tractor equipped with, a detecting means for detecting the steering operation amount, a front wheel speed increasing mechanism for speeding up the front wheels when the output of the detecting means exceeds a predetermined value, and a rotating angle of the rotary valve is detected. A quick turn in a tractor, comprising: a rotational position detecting means; and a release mechanism for releasing the operation of the front wheel speed increasing mechanism when the output of the rotational position detecting means exceeds a predetermined set value. apparatus.