JPH0591952U - Front wheel speed increasing 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 itself, 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 device for a mobile agricultural machine, which can be safely released to obtain a safe and reliable steering operation of a tractor. [Structure] A rotation shaft 26a of a rotary valve 26 is pivotally supported by a pinion 31, and a rack shaft 8 meshing with the pinion 31 is integrally formed with a stepped portion 32a, and the presence or absence of the stepped portion 32a is detected. The switch 34 is provided near the rack shaft 8.

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 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. In addition, there is a safety drawback that the front wheel speed increasing device that ensures accuracy and reliability cannot be driven or released.

[0004]

[Problems to be solved by the present invention]

 The present invention has been made in view of the above circumstances 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 to change the tilting movement of the shift lever itself. The front wheel speed increase in a mobile agricultural machine can be performed reliably without using the vehicle, and the unnecessary front wheel speed increase drive when switching to the high speed side can be accurately released to obtain a highly safe steering operation of the tractor. It is intended to provide a device.

[0005]

[Means for Solving the Problems]

 In order to solve the problem, the first technical means adopted by the present invention is that a pinion is rotatably supported on a rotary shaft of a rotary valve that forms a clutchless speed change mechanism, and a rack shaft that meshes with the pinion is stepped. The front wheel is detected by the presence / absence of the stepped portion during the forward / backward movement of the rack shaft linked to the gear shift lever switching operation. It is characterized in that it is configured to switch between driving and stopping of the speed increasing device, and as a second technical means, a pinion is pivotally supported on the rotary shaft of the rotary valve forming the clutchless speed change mechanism, and The rack shaft that meshes with the pinion is linked to the gear shift lever, and a detection switch is provided so as to face the protruding / retracted area of the rack shaft end face. During the reciprocating operation, the drive of the front wheel acceleration apparatus according to the presence or absence detection of the rack shaft end face and is characterized by being configured to Ru switching stop.

[0006]

[Action]

 Therefore, according to the present invention, when the steering angle of the front wheels becomes equal to or larger than a predetermined value when the gearshift lever is switched to the low speed side, the front wheels are accelerated by driving the front wheel speed increasing device and the rack is accompanied by the high speed side switching. It is possible to reliably detect the retracting operation of the shaft with the detection switch, and it is possible to accurately release the front wheel speed-up drive, and to prevent the vehicle from tipping over or slipping due to steep turning.

[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 the rotary valve 26 is pivotally supported at a substantially central portion of the accommodating portion 30, and a pinion 31 having meshing teeth 31a, 31a ... Is rotated. The rack teeth 8a, 8a formed on one side in the longitudinal direction of the rack shaft 8 are supported by the tip of the shaft 26a and are meshed with each other. On the other side in the longitudinal direction of the rack shaft 8, a long groove 32 having a stepped portion 32a is engraved, and a stopper bolt 33a for restricting the retracting stroke of the rack shaft 8 by facing the inside of the long groove 32, 33b penetrates the upper part of peripheral wall 30a, and is attached.

A detection switch 34 is projectingly provided between the stopper bolts 33a and 33b so that the detector 34a faces the long groove 32. The detection switch 34 is slid by the stepped portion 32a. It is configured to switch to a closed (conducting) state and to be in an open (broken) state between the long grooves 32 reaching the stepped portion 32a.

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 each of the neutral and F1 to F8 (low speed side shift and high speed side shift) switching positions in response to a shift switching operation of the shift lever 1. By operating the first hydraulic actuator 24, the second hydraulic actuator 25, and the third hydraulic actuator 27 according to each switching position, a low speed switching from the neutral state to the fourth speed and from the fifth speed to the eighth speed are performed. The speed change operation for high speed switching is performed.

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 transmission 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 detection 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 tilted by one step in the direction of arrow C from the neutral position to the low speed side, 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, which mesh with the rack teeth 8a of the rack shaft 8. 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 shifted to the first speed on the low speed side. Since the detector 34a of the detection switch 34 is on the stepped portion 32a of the long groove 32, the detection switch 34 is closed.

In the above low-speed traveling state, when the steering is operated to turn the aircraft 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 detects the angle. Through the switch 31 and the speed-up changeover switch 52, the solenoid 53 is projected and the shift rail 43 of the center differential device 18 is moved together with the sleeve 42 to the leftmost position in the arrow C direction. The engagement between the differential shaft 38 and the differential case 40 by the differential lock ball 41 is released. 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 in, the rotary valve 26 is switched to the position of F5 in association with the rotation of the rotation shaft 26a, the second hydraulic actuator 24 is contracted, and the second transmission unit 9 is driven at high speed. When the gear shift operation is performed to the fifth speed on the side, the detector 34a slides and is disengaged from the stepped portion 32a, and the detection switch 34 that has been in the closed state is switched to the open state. In this state, the steering is operated to turn the aircraft, the angle switch 49 is closed, and even if the speed increasing switch 52 remains switched to the closed state, the changeover switch 54 and the detection switch 34 are closed. Since the solenoid is open, the solenoid 53 is not energized and does not operate, 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 detection switch 34 is closed or opened, the front wheels can be accelerated in the entire shift change range (F1 to F8) by the shift 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 running at low speed, the front wheel speed-up drive can be reliably performed, and the unnecessary front wheel speed-up drive can be accurately released when running at high speed, thus providing a highly safe tractor steering operation. You can

Next, FIG. 8 shows an embodiment in which the detection switch is configured to detect the presence or absence of the end surface of the rack shaft 8. Here, the rack shaft protruding outward from the case 7a is shown. 8 has a protrusion 58 embedded in the end face 8b thereof, and the end face 8b is covered with a bellows-like protective body 59, and the detection switch 34 provided at one end of the protective body 59 is provided with the protrusion 58. It is configured to detect the presence or absence of the end face 8b by performing a pressing operation. As shown in FIG. 9, the detection switch 34 connects between the contacts 61a and 61b via a conduction plate 60, presses the conduction plate 60 toward the contact side by an urging ammunition 62, and functions as a normally-closed switch. When the protrusion 58 presses the conduction plate 60 in cooperation with the high speed side switching operation of the speed change lever 1, the detection switch 34 is opened and the front wheel speed increasing drive is released. With the above configuration, the front wheel acceleration can be driven and released only by adding the detection switch 34, the protective body 59, etc. without changing each mechanism member that constitutes the existing no-clutch transmission mechanism 7. .. Further, as shown in FIG. 10, a notched inclined surface 63 is formed on the end surface 8b of the rack shaft 8 and the detection switch 34 is opened by pressing the detector 34a along the inclined surface 63. Even if it is, the same effect can be obtained.

In this embodiment, the detector 34a of the detection switch 34 provided between the stopper bolts 33a and 33b is mounted on the stepped portion 32a formed in the long groove 32 of the rack shaft 8 to move the detection switch 34. Although the configuration is shown to be closed, the configuration is not limited to this, and as shown in FIG. 11, the detection switch 34 is configured by a proximity switch, and the detection switch 34 is provided inside the stopper bolt 33. The detection switch 34 may be opened and closed depending on the distance between the stepped portion 32a facing the detector 34a, and, as shown in FIGS. 12 and 13, on one side of the rack shaft 8, A groove 32b for guiding the detector 34a of the detection switch 34 is formed separately from the long groove 32, and the detector 34a rides up from the groove 32b when the rack shaft is retracted and retracted. The detection switch 34 may be configured to be closed when the child 34a is pressed by the side surface of the rack shaft 8.

[0024]

[Effect of the device]

 In short, according to the present invention, the pinion is pivotally supported on the rotary shaft of the rotary valve that forms the clutchless speed change mechanism, and the stepped portion is integrally formed on the rack shaft that meshes with the pinion, and the stepped portion is detected. A detection switch is installed in the vicinity of the rack shaft, and is configured to switch between driving and stopping the front wheel speed increasing device by detecting the presence or absence of the stepped portion when the rack shaft linked to the gear shift lever switching operation is moved forward or backward. In addition, a pinion is rotatably 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 is linked to a speed change lever, and the rack shaft end surface is exposed to the protruding / retracted area. The front wheel speed-increasing device is driven by detecting the presence or absence of the end surface of the rack shaft when the rack shaft moves forward and backward. Since it is configured to switch the stop, it has a simple structure to detect the protruding / retracted state of the rack shaft, but without considering the groove width of the guide groove and rattling of the gear shift lever The speed device can be easily driven and released to facilitate the simplification of the structure.At the same time, the unnecessary drive speed increase of the front wheels at the time of switching to the high speed side can be properly released, which is safe and highly reliable. This is a very useful and practical effect that the front wheel speed-up drive can be switched.

[0025]

[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 action explanatory view showing an operation relation of a pinion gear and a detection switch.

FIG. 8 is a partially cross-sectional enlarged side view showing another example of the clutchless transmission mechanism.

FIG. 9 is a sectional view of a main part of the same.

FIG. 10 is a partially sectional enlarged side view showing another example of the clutchless speed change mechanism.

FIG. 11 is a partially sectional enlarged side view showing another example of the clutchless speed change mechanism.

FIG. 12 is a partially sectional enlarged side view showing another example of the clutchless speed change mechanism.

FIG. 13 is a sectional view of the main part of the same.

[0026]

[Explanation of symbols]

 1 Gearshift lever 7 No-clutch gearshift mechanism 8 Rack shaft 8b End face 26 Rotary valve 26a Rotating shaft 31a Interlocking tooth 31 Pinion 32a Stepped portion 34 Detection switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masato Namikawa, 667, Ijiya-cho, Higashi-Izumo-cho, Yatsuka-gun, Shimane Prefecture 1 Mitsubishi Agricultural Machinery Co., Ltd. Address 1 Inside Mitsubishi Agricultural Machinery Co., Ltd. (72) Inventor Kazuo Matsumoto Address: 667 Izuyacho, Higashi Izumo-cho, Yatsuka-gun, Shimane Prefecture 1 Inside Mitsubishi Agricultural Machinery Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A detection for supporting a pinion on a rotary shaft of a rotary valve forming a clutchless speed change mechanism, integrally forming a stepped portion on a rack shaft meshing with the pinion, and detecting the stepped portion. A switch is provided in the vicinity of the rack shaft, and is configured to switch between driving and stopping the front wheel speed increasing device by detecting the presence or absence of the stepped portion when the rack shaft advancing and retracting linked to the switching operation of the shift lever is operated. Front wheel speed-increasing device for mobile agricultural machinery. 2. A pinion is rotatably supported by a rotary shaft of a rotary valve forming a clutchless speed change mechanism, and a rack shaft meshing with the pinion is interlocked with a speed change lever. A front wheel speed increasing device for a mobile agricultural machine, characterized in that a front wheel speed increasing device is configured to switch between driving and stopping of the front wheel speed increasing device by detecting the presence or absence of the rack shaft end face when a rack shaft detection switch is provided.