JPH0591954U - Front wheel acceleration release device for mobile agricultural machinery - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to drive and release the front wheel speed increasing device reliably without utilizing the tilt change of the speed change lever, and to accurately perform unnecessary front wheel speed increasing drive when switching to the high speed side. (EN) Provided is a front wheel speed increasing release device that can be released to obtain a highly safe steering operation of a mobile agricultural machine. A pinion 31 lacking a meshing tooth 31a in a predetermined peripheral area A is pivotally supported on a rotary shaft 26a of a rotary valve 26, and a rack shaft 8 which is movable forward and backward and meshes with the pinion 31 is interlocked with a shift lever 1. At the same time, a proximity switch 34 that faces the peripheral surface of the pinion 31 to connect and disconnect the front wheel speed increasing device is provided, and the proximity switch 34 is switched to the disconnection state in association with the high speed side switching operation of the speed change lever 1. I chose

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is a tractor equipped with a front wheel speed increasing device configured to increase the speed of the front wheels at a speed double that of the rear wheels in response to the operation of a hydraulic brake. The present invention relates to a front wheel speed increasing canceling device for a mobile agricultural machine capable of canceling the speed increasing state of the front wheels.

[0002]

[Prior Art]

 Generally, a traveling drive system of a tractor is provided with a transmission having a main transmission mechanism, an auxiliary transmission mechanism, a forward / reverse switching mechanism, and the like together with a hydraulic clutch, so that the transmission can be switched by intermittently operating the hydraulic clutch. ing. In recent years, the shift lever and the hydraulic clutch are connected via a separately provided hydraulic control device for the transmission, and the hydraulic clutch is configured to be intermittently controlled in cooperation with the switching operation of the shift lever. A tractor that employs a so-called no-clutch transmission mechanism that does not require the depression operation of the clutch pedal has been proposed. On the other hand, the traveling drive system of the tractor can be switched between two-wheel drive and four-wheel drive, and the steered angle of the front wheels is equal to or greater than a predetermined value during four-wheel drive traveling. There is known a tractor front wheel speed-increasing device which is configured to drive the front wheel at a speed double that of the rear wheel when the above condition occurs, thereby enabling swiveling of the vehicle speedily and smoothly. (Actual Kaihei No. 2-2235)

When a front wheel speed increasing device is added to the tractor equipped with the above-mentioned no-clutch mechanism, in order to prevent the vehicle body from tipping over or slipping due to a steep turning, the shift lever is switched to the high speed side. At this time, the front wheel speed-up device is used to release the front wheel speed-up drive.In the past, however, the intermittent switch was used by utilizing the movement of the shift lever itself that tilts toward the high speed side along the guide groove. Since it was designed to be turned on and off to switch between driving and releasing the front wheel speed increasing device, it is extremely difficult to adjust the operating position of the intermittent switch due to the groove width of the guide groove and rattling of the link part of the speed change lever. Therefore, there is a safety drawback that the front wheel speed increasing device cannot be driven and released reliably.

[0004]

[Problems to be solved by the present invention]

 The present invention has been made in view of the above circumstances in order to solve the drawbacks of the related art. The purpose of the present invention is to drive and release the front wheel speed increasing device and to use the tilting change of the speed change lever. The front wheel speed-increasing canceling device for mobile agricultural machinery can be performed reliably, and the unnecessary front wheel speed-increasing drive when switching to the high-speed side can be accurately canceled to obtain a highly safe steering operation of the tractor. Is intended to be provided.

[0005]

[Means for Solving the Problems]

 In order to solve the problem, a technical means adopted by the present invention is that a pinion having a missing meshing tooth in a predetermined peripheral region is pivotally supported on a rotary shaft of a rotary valve forming a clutchless transmission mechanism, and the pinion is meshed with the pinion. In addition to linking the rack shaft that can move back and forth with the gear shift lever, a proximity switch that faces the peripheral surface of the pinion and connects and disconnects the front wheel speed increasing device is provided, which is linked to the high speed side switching operation of the gear shift lever. It is characterized in that it is configured to switch the proximity switch to the off state.

[0006]

[Action]

 Therefore, according to the present invention, when the steering angle of the front wheels becomes equal to or greater than a predetermined value when the shift lever is switched to the low speed side, the front wheels are accelerated by the drive of the front wheel speed increasing device, and the pinion is switched when the high speed side is switched. The presence or absence of meshing teeth can be reliably detected by the proximity switch, the front wheel speed increasing device can be released accurately, and it is possible to prevent the aircraft from tipping over or slipping due to steep turning. it can.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings. In FIG. 1, reference numeral 1 denotes a gear shift lever provided on the side of a driver's seat (not shown) located substantially in the center of the tractor 2. The gear shift lever 1 is coaxial with a sub gear shift lever 4 on a rotary support shaft 3. A pivot arm 5 is pivotally supported, and a pivot arm 5 is attached to the pivot base end portion of the gear shift lever 1, and a rack shaft 8 of a clutchless gear shift mechanism 7 is attached via the pivot arm 5 and a link mechanism 6. Is configured to move forward and backward. Further, a switching lever 1a for switching between two-wheel drive, four-wheel drive and front-wheel speed-up drive is provided in the vicinity of the speed change lever 1, and the traveling drive type of the tractor 2 is changed according to the condition of the road surface. It is designed to be switched.

A travel drive system of a tractor equipped with the no-clutch transmission mechanism 7 will now be schematically described with reference to FIG. 2. The no-clutch transmission mechanism 7 includes a second transmission portion 9, a first transmission portion 10, The rotational driving force from the engine 17 is transmitted to the rear wheels 16 via the hydraulic clutch 11, the forward / reverse switching mechanism 12, the first subtransmission unit 13, the second subtransmission unit 14, and the rear differential device 15, and the second It is configured to transmit the rotational driving force of the engine 17 from the sub-transmission unit 14 to the front wheels (not shown) through the center differential device 18 and the front differential device (not shown). The drive system is a part-time four-wheel drive system that allows the drive to be switched as needed. Further, the second and the first transmission parts 9 and 10 are provided with first and second PTO transmission parts 19 and 20, respectively, and a third PTO transmission part 23 for driving the PTO shaft 22 via a transmission shaft 21. It is designed to supply rotational drive force to the.

The first transmission section 10 and the second transmission section 9 switch between a low speed state from neutral to fourth speed and a high speed switching from fifth speed to eighth speed by a first hydraulic actuator 24 and a second hydraulic actuator 25, respectively. Each of the actuators 24 and 25 described above corresponds to a gear shift operation, and is actuated and controlled in accordance with a rotation switching position of a rotary valve 26 described later. Reference numeral 27 is a third hydraulic actuator provided in the first subtransmission unit 13. The control operation by the third hydraulic actuator 27 causes the output rotation of the forward / reverse switching mechanism 12 to be in the high speed stage H and the low speed stage L. It is designed to be switched to two stages.

The forward / reverse switching mechanism 12 serves to transmit the output rotation of the hydraulic clutch 11 as it is or reversely and transmits it to the first sub transmission unit 13, and via a shift rail 28 interlocked with a shuttle transmission lever (not shown). It is designed to be switched. Further, the second sub-transmission unit 14 switches the output rotation of the first sub-transmission unit 13 between the high-speed stage H and the low-speed stage L, and the shift operation is performed via the shift rail 29 interlocked with the sub-transmission lever 4. It has become so.

On the other hand, as shown in FIG. 3, on one side of the case 7a in which the clutchless mechanism 7 is housed, a storage portion 30 in which the rack shaft 8 is slidably fitted is provided by the peripheral wall 30a. A rotary shaft 26a of a rotary valve 26 is pivotally supported at a substantially central portion of the accommodating portion 30, and a pinion 31 lacking the meshing teeth 31a, 31a ... The rack teeth 8a, 8a formed on one side in the longitudinal direction of the rack shaft 8 are supported by the tip end of the rotating shaft 26a and are meshed with each other. Further, a long groove 32 is formed on the other side in the longitudinal direction of the rack shaft 8 described above, and a stopper bolt 33 having a tip end facing inside the long groove 32 is attached by penetrating the upper portion of the peripheral wall 30a. There is.

A proximity switch 34 is provided on the lower portion of the peripheral wall 30a so that its detector 34a faces the peripheral surface of the pinion 31. The proximity switch 34 is opened in a predetermined peripheral area A where there are no meshing teeth 31a, 31a. The proximity switch 34 is configured to be in a closed (conductive) state in the (disconnected) state and other meshing tooth peripheral regions.

Further, in FIG. 5, the center differential device 18 constitutes a front wheel speed increasing device together with a hydraulic brake 35 for shifting, and a 4WD shaft 37 is attached to one side gear 36 a of the center differential device 18. The other side gear 36b, which is coupled to transmit the rotational driving force to the front wheel side and is coupled to the differential shaft 38, is rotatably supported by the case 39 via the shift hydraulic brake 35. Further, a diff lock ball 41 is interposed between the diff shaft 38 and the diff case 40 so that the diff lock ball 41 can be engaged and disengaged. The sleeve 42 is linked to the switching lever 1a through a shift fork 44 and a shift arm 45 mounted on the shift rail 43.

The shift rail 43 also serves as a switching valve for the oil passage 35a of the hydraulic brake 35 for shifting, and when the switching lever 1a is selected as a switching position for two-wheel drive or four-wheel drive, the shift rail 43 is not operated at the shift position. The passage 35a is shut off, and at the shift position where the switching lever 1a is selected for the front wheel speed-up drive switching position, the pressure oil supplied to the oil passage 35a moves in the direction of the arrow B together with the sleeve 42 to move the oil passage 35a. It is configured to open.

FIG. 6 is a hydraulic circuit diagram showing an oil passage to each mechanism. This hydraulic circuit includes a speed change hydraulic brake 35, a steering hydraulic pressure control device via a flow dividing valve mechanism 47 connected to an oil pump 46. The pressure oil is supplied to the rotary valve 48, the rotary valve 26, and the hydraulic clutch 11 for shifting. Here, the speed change hydraulic brake 35 is pressure-oil controlled by opening and closing the operation switching valve 50 by intermittently operating the angle switch 49 that detects the turning angle of the front wheels. It is controlled by opening and closing the valve 51. Further, the rotary valve 26 has a rotary switching system configuration that is continuously switched to the neutral and F1 to F8 (low speed side shift and high speed side shift) switching positions in response to the shift change operation of the variable speed lever 1. That is, the first hydraulic actuator 24, the second hydraulic actuator 25, and the third hydraulic actuator 27 are operated according to each switching position to switch from the neutral state to the fourth speed and the low speed to the fifth speed to the eighth speed. It is designed to perform high-speed switching gear shifting operations.

Next, the control circuit diagram shown in FIG. 4 will be described. Reference numeral 52 is a speed-up switching switch that is closed when the switching lever 1a is switched to front-wheel speed-up driving, and 53 is a solenoid linked to the shift rail 43 of the center differential device 18, and the solenoid 53 is The speed increasing / decreasing switch 52 is operated in association with the closing operation. Further, 54 is a changeover switch attached to the rotation base of the auxiliary transmission lever 4, and the changeover switch 54 is closed when the auxiliary transmission lever 4 is switched to the low speed side and is switched to the high speed side. When the auxiliary shift lever 4 is switched to the low speed side, the steering angle of the machine body becomes a predetermined value or more, the angle switch 49 is closed, and the proximity switch 34 is turned on / off to accelerate the front wheels. Is configured to be intermittent. Reference numeral 55 is a battery, 56 is a display lamp connected in parallel between the solenoid 53 and the angle switch 49, and 57 is a fuse.

In the above configuration, when the front wheel speed-up drive is switched by operating the switching lever 1a, the speed-up switch 52 is closed and the sleeve 42 of the center differential device 18 is moved to the right side in FIG. It is operated to the left by two steps in the direction of arrow C from the approached position, the differential shaft 38 and the differential case 40 are engaged via the differential lock ball 41, and the rotational driving force of the engine 17 is transmitted to the front wheels via the 4WD shaft 37. Then, the tractor 2 is switched to the four-wheel drive state. When the auxiliary transmission lever 4 is switched to the high speed side in the state of switching to the front wheel speed-up drive, the shift rail 29 is moved and the second auxiliary transmission section 14 is switched to the high speed side, and the main switching valve 51 is used. The hydraulic clutch 11 is connected at a predetermined rotation speed, and the changeover switch 54 attached to the rotation base end portion of the auxiliary transmission lever 4 is opened to switch to the open state.

In this state, when the shift lever 1 is switched and tilted by only one step from the neutral position to the low speed side in the direction of arrow D, the link mechanism 6 operates in association with the rotation of the rotation arm 5 as shown in FIG. 7) and FIG. 7 (b), the rack shaft 8 of the clutchless speed change mechanism 7 is pushed in, and the rotation shaft 26a is rotated by the rotation of the meshing teeth 31a, 31a ... Rotate. Then, the first hydraulic actuator 25 contracts in response to the switching of the rotary valve 26 to the F1 position by the rotation of the rotation shaft 26a, and the first transmission unit 10 is operated to the first speed on the low speed side. Further, at the time of shifting at the low speed side, the detector 34a of the proximity switch 34 is close to the meshing teeth 31a, 31a ... Of the pinion 31, so that the proximity switch 34 is closed.

In the above low-speed traveling state, when the steering is operated to turn the machine body and the turning angle becomes a predetermined value or more, the angle switch 49 shown in FIG. 4 is closed and the angle switch 49, the proximity switch 49 Through the switch 31 and the speed increasing switch 52, the solenoid 53 operates to project. Accordingly, the shift rail 43 of the center differential device 18 moves together with the sleeve 42 to the leftmost position in the direction of arrow C, and the engagement between the differential shaft 38 and the differential case 40 by the differential lock ball 41 is released. Be done. Then, the hydraulic oil brake 35 operates by the pressure oil in the oil passage 35a to lock the differential shaft 38, so that the side gear 36a of the center differential device 18 rotates together with the 4WD shaft 37 at the double speed during four-wheel drive, The rotational drive of the front wheels is increased, and the tractor 2 can make a speedy and smooth turn by the front wheels that rotate at a speed double that of the rear wheels 16.

Further, when the speed change lever 1 is tilted in the direction of arrow D in four steps to switch to the high speed side from the low speed traveling state, as shown in FIGS. 7C and 7D, the no-clutch speed change mechanism 7 is provided. The rack shaft 8 is further pushed, the rotary valve 26 is switched to the position F5 in association with the rotation of the rotation shaft 26a, the second hydraulic actuator 24 is contracted, and the second transmission section 9 is driven at high speed. The gear is operated to the 5th speed on the side. At this point, the meshing teeth 31a, 31a of the pinion 31 meshing with the rack shaft 8 are further rotated by the pushing operation of the rack shaft 8, and the predetermined peripheral region A 1 without meshing teeth moves to the detection position of the detector 34a. Therefore, the detection distance by the detector 34a becomes long, and the proximity switch 34 is opened. In this state, even if the angle switch 49 is closed and the speed increase switch 52 is still closed, the switch 54 and the proximity switch 34 are operated by turning the steering wheel to turn the aircraft. Since the solenoid is open, the solenoid 53 does not operate because it is in a non-energized state, and the front wheels are not accelerated.

When the auxiliary transmission lever 4 is switched to the low speed side in the traveling state of the front wheel speed-up drive, the changeover switch 54 attached to the rotation base end portion of the auxiliary transmission lever 4 is switched to the closed state. Instead, regardless of whether the proximity switch 34 is closed or opened, the front wheels can be accelerated in the entire range (F1 to F8) of speed change by the speed change lever 1. Here, the speedup control of the front wheels by the speed change lever 1 and the auxiliary speed change lever 4 can be summarized as shown in Table 1.

[Table 1] Therefore, when the aircraft is traveling at a high speed, the unnecessary front wheel speed increasing drive can be properly released, and a highly safe steering operation of the tractor can be obtained.

[0022]

[Effect of the device]

 In essence, the present invention has a pinion having a lacking meshing tooth in a predetermined peripheral region that is pivotally supported on the rotary shaft of a rotary valve that forms a clutchless speed change mechanism, and a rack shaft that meshes with the pinion and is movable back and forth. In order to switch the proximity switch to the disconnection state by providing a proximity switch for connecting and disconnecting the front wheel speed increasing device facing the peripheral surface of the pinion and linking it to the high speed side switching operation of the speed change lever. Because of the configuration, driving and releasing of the front wheel speed increasing device can be easily performed without considering the groove width of the guide groove and rattling of the link part of the speed change lever. This is an extremely useful and practical effect that the front wheel speed-increasing drive can be released accurately and a highly safe steering operation of the mobile agricultural machine can be obtained.

[0023]

[Brief description of drawings]

FIG. 1 is a schematic side view of a main part of a tractor including a front wheel speed increasing mechanism.

FIG. 2 is a system diagram of a traveling drive system of a tractor.

FIG. 3 is a partially sectional enlarged side view of a clutchless speed change mechanism.

FIG. 4 is a connection diagram of a control system.

FIG. 5 is a cross-sectional view of essential parts of a center differential device.

FIG. 6 is a connection diagram of hydraulic control.

7 (a), (b), (c) and (d) are rack shafts,
It is an operation explanatory view showing an operation relation of a pinion gear and a proximity switch.

[0024]

[Explanation of symbols]

 1 Gearshift lever 7 No-clutch gearshift mechanism 8 Rack shaft 26 Rotary valve 26a Rotating shaft 31a Interlocking tooth 31 Pinion 34 Proximity switch A Predetermined range

Claims (1)

[Scope of utility model registration request] 1. A pinion with missing meshing teeth in a predetermined peripheral region is rotatably supported by a rotary shaft of a rotary valve forming a clutchless speed change mechanism, and a rack shaft that meshes with the pinion and is movable back and forth is interlocked with a speed change lever. A proximity switch for connecting and disconnecting the front wheel speed increasing device facing the peripheral surface of the pinion is provided, and the proximity switch is configured to switch to the disconnection state in connection with the high speed side switching operation of the speed change lever. Front wheel speed-up release device for mobile agricultural machinery.