JP2007333174A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle equipped with a control device capable of stopping the vehicle without damaging a clutch disk, when detecting abnormal decline of an oil pressure in an oil pressure circuit without stopping an engine. <P>SOLUTION: When a pressure of a hydraulic oil supplied to each operation cylinder 85, 87, 88, 91, 92, 95 of a forward/backward movement clutch D, a clutch E for switching a main transmission and a clutch F for switching a Hi-Lo transmission, which is detected respectively by each pressure sensor 112a-117, is lowered to the first set value P1 or lower as long as a prescribed time T1 or longer, it is determined that an abnormal state is generated, and traveling is stopped by stopping supply of the hydraulic oil to each operation cylinder 85, 87, 88, 91, 92, 95 of each clutch D, E and/or F. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a work vehicle, and more particularly, to a work vehicle provided with a safety device when an abnormality occurs in a hydraulic clutch of a traveling transmission system.

In a transmission for a work vehicle such as a tractor, the amount of current supplied to a solenoid valve for operating a hydraulic clutch provided in a hydraulic circuit is changed to change the hydraulic pressure supplied to the hydraulic clutch, thereby turning the clutch on and off.
However, if the hydraulic clutch does not operate normally due to an abnormality such as an oil passage in the hydraulic circuit being clogged, the transmission control of the transmission may not be possible. As a countermeasure for this, the following patent is equipped with a control mechanism that issues a warning when the hydraulic pressure in the hydraulic circuit is reduced, and simultaneously increases the amount of current applied to the solenoid valve to decelerate the vehicle and then stops the engine There are inventions described in the literature.
JP 2004-293750 A

In the invention described in Patent Document 1, when it is detected that the hydraulic pressure in the hydraulic circuit has decreased, the vehicle is decelerated, and then the engine is stopped, thereby achieving vehicle travel safety.
However, the invention described in Patent Document 1 is configured to stop the vehicle after decelerating, and since there is heating due to excessive sliding of the disk of the hydraulic clutch between the start of deceleration of the vehicle and the stop of the vehicle, the clutch disk Is easily damaged.

  An object of the present invention is to provide a work vehicle including a control device that can stop a vehicle without damaging a clutch disk when it detects that the hydraulic pressure of the hydraulic circuit has dropped abnormally without stopping the engine. It is.

The above-mentioned problem of the present invention is solved by the following means.
According to the first aspect of the present invention, a friction transmission type forward / reverse clutch (D), a main shift switching clutch (E), and a Hi-Lo shift switching clutch (F) are provided in the driving power transmission system, and each clutch ( D), (E) and (F) pressure detecting means (116, 117; 112a, 112a, 112a, 112a) for detecting the pressure of the hydraulic oil supplied to the cylinders (85, 87, 88, 91, 92 and 95) 112b; 113a, 113b; 110, 111), and the pressure of the hydraulic oil detected by each of the pressure detecting means (116, 117; 112a, 112b; 113a, 113b; 110, 111) during traveling is set. When it falls below the first set value (P1) over a predetermined time (T1), it is determined as an abnormal state, and each clutch (D), (E) determined as the abnormal state is determined. A working vehicle provided with a control device (100) for stopping the traveling refused the supply of hydraulic fluid to the actuating cylinder (85,87,88,91,92 and 95) Beauty / or (F).

  According to a second aspect of the present invention, display means is provided in the control section, and the control device (100) includes the forward / reverse clutch (D), the main shift switching clutch (E), and the Hi-Lo shift switching clutch during traveling. The pressure of the hydraulic oil supplied to each operating cylinder (85, 87, 88, 91, 92 and 95) in (F) is within the pressure range equal to or higher than the first set pressure (P1). 2. When it is detected that the pressure has dropped below a second set pressure (P2) higher than P1), an abnormal state is displayed on the display unit, but control is performed so as not to stop traveling. The work vehicle described.

  According to the first aspect of the present invention, the vehicle can be stopped when it is detected that the hydraulic pressure in the hydraulic circuit has dropped abnormally without stopping the engine, so that the disk of the hydraulic clutch is not damaged.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the detected pressure of any one of the clutch cylinders (85, 87, 88, 91, 92, and 95) is judged pressure (P1). When a pressure equal to or lower than the higher pressure (P2) is generated and higher than the pressure (P1) is generated, only abnormality display is performed, and traveling control is continued, so that traveling can be continued with little clutch damage. Since the occurrence of an abnormality can be confirmed on the display or the like, it can be repaired at an early stage and repair before the worst situation such as clutch replacement becomes possible.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a side view of the tractor of this embodiment.
The tractor vehicle body T having a riding mode of riding four-wheel drive travels while steering the front wheels 61 with the steering handle 73. A work implement such as a rotary tillage device 84 can be mounted on the rear portion of the vehicle body T so as to be able to move up and down. The vehicle body T has an engine 62 mounted on the front end thereof via an engine bracket that is supported on the front axle housing, and a clutch housing, a transmission case 65, and the like are integrally connected to the rear side of the engine 62. A rear axle housing 75 is provided at the rearmost portion of 65, and rear wheels 63 are mounted on both left and right sides.

  FIG. 2 shows a power transmission system diagram of the tractor of this embodiment. In this embodiment, the left and right sides are referred to as left and right, respectively, and the front and rear are referred to as front and rear, respectively, in the forward direction of the tractor.

  The engine 62 has a projecting engine shaft 1 on the rear side, and the engine shaft 1 is connected to the input shaft 2 of the clutch housing portion. The output shaft 3 and the PTO shaft 14 at the rear end are interlocked via a transmission mechanism in the mission case 65, and the front wheel output shaft 5 provided at the lower portion of the mission case 65 is interlocked. The output shaft 3 is supported along the front-rear direction at a substantially central portion of the rear portion in the transmission case 65, has a drive pinion gear 53 at the rear end, meshes with the diff ring gear 46 of the rear differential 45, and extends along the rear axle housing. The rear differential shaft 10 mounted on the shaft and the rear wheel shaft 11 are interlocked via a planetary reduction mechanism. The front wheel output shaft 5 is connected to the input shaft 26 of the front differential 47 provided at the center of the front axle housing from the lower portion of the transmission case 65 through the lower portion of the engine 62, and is mounted along the front axle housing. The front differential shaft 12 and the planetary reduction mechanism are connected to the front wheel shaft 13. Note that gear drive shafts 15 and 17 for taking out power from the input shaft 2 to the hydraulic pump 80 (FIG. 3) are arranged in parallel with the input shaft 2.

  The transmission of this embodiment is provided with a PTO clutch pack 66 on a PTO countershaft 9 having a PTO shift counter gear 44 that is linked to an input gear 31 from an input shaft 2 driven by the engine shaft 1. The input shaft 2 is provided with forward / reverse switching gears 42, 42 for forward / reverse switching in the idle state, and the reverse movement switching gear 42 on one reverse side has a back counter shaft 8 arranged in parallel with the input shaft 2. A back counter gear 43 provided on the main transmission shaft 19 is meshed, and the other forward-side forward / reverse switching gear 42 is provided with an input gear 48 fixed on the main transmission shaft 19 and an effective free rotation on the main transmission shaft 19. Four main transmission gears 33 having different diameters are provided. These four main transmission gears 33 are configured as a four-speed transmission, and are switched and shifted by the clutch pack 76. The transmission including the four main transmission gears 33 is referred to as a main transmission A.

  On the main transmission shaft 19, of the four main transmission gears 33 of the main transmission A, the main transmission gear 33 (for first speed) having the smallest effective diameter and the main transmission gear having the third smallest effective diameter are provided. The clutch pack 76 is fixed between the main transmission gear 33 (for the third speed) and the main transmission gear 33 (for the second speed) having the second smallest effective diameter and the main transmission gear 33 (for the fourth speed) having the largest effective diameter. The clutch pack 76 is fixedly provided. Each of the two clutch packs 76 is provided with a friction clutch that connects each main transmission gear 33 so as to rotate integrally with the main transmission shaft 19.

  The sub-transmission shaft 20 provided coaxially with the main transmission shaft 19 is provided with two high and low-speed switching gears 34 having different effective diameters that are switched and shifted by the clutch pack 76. Furthermore, it can decelerate and can switch to high speed and low speed. The gear configuration that can be switched between high speed and low speed is referred to as a high / low transmission B.

  Further, an output shaft 3 having three auxiliary transmission gears 35 having different effective diameters is arranged coaxially with the auxiliary transmission shaft 20. The output shaft 3 is configured to be shifted in three stages by the auxiliary transmission gear 35. The configuration of the gear 35 capable of three-speed shifting is referred to as an auxiliary transmission device C.

  Further, the input gear 48 that can mesh with the forward gear of the forward / reverse switching gear 42 meshes with the back counter gear 43 on the back counter shaft 8 together with the reverse gear of the forward / backward switching gear 42. The forward-side gear 42 and the reverse-side gear 42 of the forward / reverse switching gears 42 are alternatively integrated with the input shaft 2 by switching between the two forward / reverse switching clutch packs 60 composed of independent front and rear friction clutches. In this configuration, the vehicle can be switched between forward travel and reverse travel. A structure including a gear 42 and a clutch pack 60 including a hydraulic cylinder 85 (FIG. 3), which will be described later, is referred to as a forward / reverse clutch D, and includes gears 33, including hydraulic cylinders 87, 88, 91, 92 (see FIG. 3). 39 and the clutch pack 76 are referred to as a main shift switching clutch E, and the configuration including the gears 34 and 40 including the hydraulic cylinder 95 and the clutch pack 76 are referred to as a Hi-Lo shift switching clutch F. .

As shown in FIG. 3, pressure sensors 110 and 111 for detecting the pressure of the hydraulic oil supplied to the forward / reverse clutch cylinder 85 are provided, respectively, and the pressure of the hydraulic oil supplied to the main transmission switching clutch cylinders 87, 88, 91 and 92 is provided. 113a and 113b, and pressure sensors 116 and 117 for detecting the pressure of the hydraulic oil supplied to the Hi-Lo shift switching clutch cylinder 95 are provided.
Further, a forward / reverse switching lever 115 for manually switching the forward / backward clutch D is provided at the post portion of the steering handle.

  A creep counter shaft 21 having a creep counter gear 49 that meshes with the auxiliary transmission gear 35 is provided in a parallel position with the output shaft 3. A travel counter shaft 6 having a main transmission counter gear 39 and a high / low speed switching gear 40 meshing with the main transmission gear 33 and the high / low speed switching gear 34 is disposed in parallel with the main transmission shaft 19 and the auxiliary transmission shaft 20. Rotation transmitted from the main transmission shaft 19 is changed by the main transmission gear 33, and the rotation is switched between the high and low speeds provided on the auxiliary transmission shaft 20 via the main transmission counter gear 39 and the high and low speed switching gear 40 in sequence. It is transmitted to the gear 34. The power transmitted to the high / low speed switching gear 34 is transmitted to the output shaft 3 through the clutch pack 76 and through the transmission mechanism by the auxiliary transmission gear 35 provided on the auxiliary transmission shaft 20.

  In the traveling power transmission system of the present embodiment, the auxiliary transmission countershaft 27 of the auxiliary transmission counter gear 38 that meshes with the auxiliary transmission gear 35 is rotatably supported, and the front wheels have the front wheel interlocking gear 51 that is interlocked with the output shaft 3. An interlocking shaft 28 is provided, and a PTO reduction shaft 23 having a PTO reduction gear 50 is provided on the front extension shaft core of the front wheel interlocking shaft 28. Further, a PTO interlocking shaft 4 is provided at a position parallel to the front wheel interlocking shaft 28, and the PTO forward / reverse switching gear 37 for switching the PTO interlocking shaft 4 between forward rotation and reverse rotation at the front end on the same axis as the PTO interlocking shaft 4 The switching shaft 22 and the PTO transmission shaft 18 of the PTO transmission gear 32 are arranged.

  A PTO reverse rotation counter shaft 24 having a PTO reverse rotation counter gear 52 that meshes with the PTO normal / reverse switching gear 37 is provided on the side of the PTO forward / reverse switching shaft 22, and the input shaft is inserted by the insertion of the PTO clutch pack 66. Power is transmitted from 2 to the PTO forward / reverse switching shaft 22 via the PTO transmission gear 32, the PTO transmission counter gear 44, the PTO forward / reverse switching gear 37, and the like. The forward / reverse switching gear 37 uses a clutch ring having the same form as the PTO transmission gear 32. A reverse rotation counter shaft 24 having a PTO reverse rotation counter gear 52 is provided on the side of the PTO normal / reverse switching shaft 22, and the PTO reverse rotation counter gear 52 receives the interlocking from the PTO reduction gear 50 and performs PTO forward / reverse switching. The gear 37 can be reversely rotated. A deceleration shaft 23 is disposed behind the PTO counter shaft 9.

  Further, the front wheel output shaft 5 arranged at the lower stage in the transmission case 65 is mounted on the bottom of the rear portion of the transmission case 65, and the input shaft 26 of the front differential 47 through the front wheel interlocking shaft 25, the coupling and the like. Connect to A front wheel drive shaft 7 is disposed on the side of the front wheel output shaft 5. A front wheel gear 55 is provided at the rear end of the front wheel drive shaft 7. Further, the first front wheel interlocking gear 51 on the front wheel interlocking shaft 28 meshes with the front wheel take-out gear 36 at the rear end portion of the output shaft 3 and is transmitted to the front wheel interlocking shaft 28 via the first front wheel interlocking gear 51. The driving force of the output shaft 3 is transmitted to the second front wheel interlocking gear 54 that rotates integrally with the front wheel interlocking shaft 28, and is transmitted from the front wheel interlocking gear 54 to the front wheel driving shaft 7.

  A front wheel drive clutch pack 67 is provided on the front wheel drive shaft 7, and geared from the front end of the drive shaft 7 to the front wheel output shaft 5. Further, two front wheel drive switching gears 41 having different effective diameters are arranged on the left and right sides of the front wheel drive clutch pack 67, and the two front wheel drive switching gears 41 are provided with two effective wheel diameters provided on the counter shaft 59. The front wheel drive shaft 7 can be driven at either one of the two reduction ratios by meshing with the drive counter gear 56 and selectively connecting the front wheel drive clutch pack 67.

  When the front wheel drive clutch pack 67 is shifted to the neutral position, the front wheel 61 is not driven, and a rear wheel drive two-wheel drive mode is adopted. When the front wheel drive clutch pack 67 is switched to the low speed position by hydraulic operation, the front wheel 61 is moved to the rear. A four-wheel drive configuration in which the wheel 63 is driven at a constant speed of about one time with respect to the wheel 63 is used, and when the front wheel drive clutch pack 67 is switched by hydraulic operation to shift to a high speed position, the front wheel 61 is moved to the rear wheel 63 by about 2 It is possible to travel by adopting a four-wheel drive mode in which the driving speed is doubled.

  With the meshing transmission having the above-described configuration, the rotational power of the engine 62 is transmitted through the forward / reverse clutch D that constitutes the main clutch, to the main transmission A that has four speeds, and to the high speed that has two speeds. The low transmission B and the sub-transmission C comprising three speeds are shifted to any one of a total of 24 speeds, and the rotational power obtained is driven through the rear differential 45 to drive the rear wheels 63. The rotational power changed by the auxiliary transmission C is also transmitted to a front wheel drive clutch (two-wheel drive / four-wheel drive switching clutch) pack 67, and the clutch pack 67 makes the front wheel 61 "constant speed" or "acceleration". After switching, the front wheel 61 is driven through the front differential 47.

  Further, the PTO transmission gear 32, the traveling main transmission gear 33, the high / low speed switching gear 34, the auxiliary transmission gear 35, and the like are arranged along the axis of the output shaft 3 having the drive pinion gear 53. The transmission of the traveling system is interlocked with the drive pinion gear 53 via the main transmission gear 33, the high / low speed switching gear 34, the multiple transmission gear 35, etc. arranged on the axis of the output shaft 3 from the input shaft 2. Further, the PTO shift is linked via a PTO transmission gear 32 provided at the front end portion on the axis of the output shaft 3.

Next, FIG. 3 shows a hydraulic circuit diagram of the tractor of this embodiment.
In the hydraulic circuit diagram of FIG. 3, the left and right brake cylinders 83 that brake the left and right rear wheels 63 independently, the four-wheel drive clutch cylinder 99 that switches the power transmitted to the front wheels 61 to “constant speed” or “acceleration”, steering A power steering device 103, a PTO clutch cylinder 104, PTO clutch pressure control valves 105, 106, and the like that are operated by rotating the handle 73 are provided. In addition, the circuit 101 of the dashed-dotted line portion is a main hydraulic circuit (working machine lifting / lowering, horizontal working machine extraction, external hydraulic pressure taking out, etc.) and has little relation to sub-circuits (running / brake / diff lock / PTO side circuit). Is omitted.

  The hydraulic oil discharged from the hydraulic pump 80 is hydraulically actuated by a hydraulic clutch cylinder 87 that operates the fourth speed gear 2 and the second speed gear 33 of the main transmission A via the clutch pack 76 via the pressure reducing valve 81a. A hydraulic clutch cylinder 91 and a hydraulic clutch that are supplied to a shift control valve 89 for switching the 4-2 speed for switching the clutch cylinder 88 and further operate the first speed gear 3 and the third speed gear 33 of the main transmission A, respectively. This is supplied to a shift control valve 93 for switching the first to third speeds for switching the cylinder 92.

The hydraulic fluid that passes through the pressure reducing valve 81 a is supplied to the switching valve 86 that switches between the forward clutch and the reverse clutch D of the forward / reverse clutch cylinder 85 via the on / off control valve 129 of the forward / reverse clutch cylinder 85. It can be detected by the forward clutch pressure sensor 110 and the reverse clutch pressure sensor 111 which hydraulic fluid is supplied to the forward clutch D of the forward / reverse clutch cylinder 85.
Similarly, the hydraulic oil supplied to the hydraulic clutch cylinders described above and below can be detected by a pressure sensor provided in an oil passage on the inlet side to each hydraulic clutch cylinder.

  The hydraulic oil discharged from the hydraulic pump 80 is branched and supplied to the left and right brake cylinders 83 via the pressure reducing valve 81b and the brake valve 82a. The brake valve 82a is a switching control valve that selects the rear wheel 63, and the brake valve 82a is integrated with a pressure control valve 82b that adjusts the braking force.

  Further, the hydraulic oil passing through the pressure reducing valve 81b is transmitted to the clutch pack 76 at one of the two gears 40 of “high speed” and “low speed”. Is supplied to the control valves 96a and 96b for switching the high / low hydraulic clutch cylinder 95 to be operated.

Further, the hydraulic oil passing through the pressure reducing valve 81 b is branched into the front-wheel differential lock cylinder 98 a for the front differential 47 and the rear-difference lock cylinder 98 b for the rear differential 45 through the differential lock control valve 97.
Further, hydraulic oil 99 for switching the gear 41 of the front wheel drive clutch pack 67 is supplied with hydraulic oil via the pressure reducing valve 81b via the switching control valve 94.

Similarly, the hydraulic fluid passing through the pressure reducing valve 81b is supplied to the PTO clutch cylinder 104 via the PTO valves 105 and 106, and adjusts the pressure of the PTO clutch.
Also, the hydraulic pressure from the hydraulic pump 80 shown in FIG. 3 is configured to supply hydraulic oil to the orbit roll 107 that is operated by operating the power steering handle 73.

FIG. 4 shows a control block diagram for explaining the control device 100 and its input / output device of the constant mesh transmission shown in FIG. 2 of the present embodiment, and FIG. 5 shows a schematic control flowchart of the control device 100.
In the speed change mechanism that shifts the power from the engine 62 from the forward / reverse clutch D via the main transmission A, the Hi-Lo transmission B, and the auxiliary transmission C, the hydraulic clutch cylinders 85 and 87 of the devices A to D are used. , 88, 91, 92, and 95 are provided with sensors 110, 111, 112a, 112b, 113a, 113b, 116, and 117, respectively, and hydraulic clutch cylinders 87 and 88 of the main transmission A during a shift output. , 91, 92 is configured to forcibly stop traveling when the pressure drops to a specified time (T1; for example, 1 second) or more and a specified pressure (P1; for example, 3 kgf / cm ² ) or less.

This is because, when the main transmission clutch cylinders 87, 88, 91, and 92 are in a pressure drop due to an abnormal state, the tractor suddenly travels when the abnormal state is released when the tractor is stopped. May start. Therefore, if the main transmission clutch cylinders 87, 88, 91, 92 are in a travel stop state due to a pressure drop, the tractor is forcibly stopped and the tractor starts to travel suddenly even if the abnormal state is released. Driving safety can be improved in such a way that there is no such thing.
If the operation for forcibly stopping the traveling is performed by performing the same output as when the forward / reverse switching lever 115 is operated neutral (N), the control algorithm can be easily incorporated.

  Further, in conjunction with the occurrence of an abnormal state of the main transmission clutch cylinders 87, 88, 91, 92, an abnormality display of the main transmission A is performed on a display unit of a meter unit (not shown), and a forced stop operation is simultaneously performed. Thereafter, a display for prompting the neutral (N) operation of the traveling shift corresponding to the neutral (N) operation of the forward / reverse switching lever 115 or the like is performed on the display unit of the meter unit.

Furthermore, the abnormal display continues the displayable state even if the abnormal state is released or the output state is such that the abnormal state cannot be detected, and is redisplayed every specified time even if it is a normal display by display switching etc. It is desirable to have a configuration.
This notifies the operator of the contents of the occurrence of the abnormality, and by telling the method for canceling the forced stop state, enables an easy-to-understand operation in the stop state after the occurrence of the abnormality.

  If an abnormality occurs in the main transmission clutch cylinders 87, 88, 91, 92, the shift operation of the main transmission A is accepted and allowed to run when the tractor is stopped, but the shift operation is not accepted during running. Can be configured. This is because not only the hydraulic sensors of the main transmission clutch cylinders 87, 88, 91, 92 are abnormal, but also other hydraulic control valves may be abnormal and other hydraulic clutch cylinders may be abnormal at the same time. It is. For example, when the main transmission A is shifted from the first speed position to the second speed position, the gears at the first speed position and the second speed position may mesh simultaneously due to an abnormality in the hydraulic control valve. In this case, since the vehicle stops suddenly, in order to avoid such a problem, the shift operation is not accepted during traveling as described above.

  In conjunction with the occurrence of an abnormality in the main transmission clutch cylinders 87, 88, 91, 92, the speed change operation of the main transmission A is prohibited, and after the travel stop operation is performed, the speed change position of the main transmission A is changed during the travel stop. It is possible to change to the target shift position, and when the vehicle starts running again, it is prohibited to change to a new shift position, and this state is continued until the engine 62 stops. You can also.

  In this control, when an abnormality has occurred in the main transmission clutch cylinders 87, 88, 91, and 92, a so-called “jumping step” occurs in which, when the transmission operation of the main transmission A is performed, the adjacent shift positions are skipped. Therefore, taking into consideration the possibility of simultaneous abnormalities at multiple shift positions, the control algorithm becomes complicated, so that it is only possible to change to the target shift position to ensure safety. It is.

  Further, even if the gear is shifted to the target shift position during traveling, the feeling is in a poor state. Therefore, the shift operation can be performed only when the vehicle is stopped by the above control, and the main transmission clutch cylinders 87, 88, 91, 92 are provided. In this way, only the speed change position closest to the target vehicle speed can be selected at a position where the vehicle can travel even when an abnormality occurs, and the tractor can be moved to a safe place or a repairable place after stopping.

When the pressure of the main transmission clutch cylinders 87, 88, 91, 92 drops to a specified time (T1; for example, 1 second) or more and a specified pressure (P2; for example, 14 kgf / cm ² ) or less, the main transmission clutch cylinder 87, Even when the abnormality occurs in 88, 91, 92, even if the output timing of the clutch cylinder on the entry side until the pressure of the clutch cylinder on the side from which the hydraulic oil in the clutch cylinder 87, 88, 91, 92 is released falls, If the release side clutch cylinder pressure does not release after the specified time (T2; for example, 5 seconds) has elapsed, check that the hydraulic oil does not enter the entry side clutch cylinder. It can also be configured to stop and return the output of the pull-out side clutch cylinder to continue running.

  At this time, a message indicating an abnormal display is displayed on the display screen of the meter unit, and shifting is prohibited during traveling, and shifting is enabled as long as traveling is stopped after stopping traveling. The state in which the abnormality display is possible is continued until the engine 62 is stopped, and the display is re-displayed when a specified time (T3; for example, 0.5 seconds) elapses.

  Prohibiting shifting until the tractor stops traveling is to prevent double-engagement of gears at different speed stages. Since it is not possible to run and there is a possibility that the abnormality can be canceled, a gear change while running is allowed is allowed.

Further, when an abnormality occurs in the main transmission clutch cylinders 87, 88, 91, and 92, the shift gear cylinder 87 at the target shift position of the main transmission A is being output during the output of the shift clutch cylinder 87 or the like that is not the target. When the pressure of the clutch cylinder 92 or the like is a specified pressure (P3; for example, 2 kgf / cm ² ) or more and continues for a specified time (T3; for example, 0.5 seconds), the traveling is forcibly stopped. This is to avoid double meshing of gears at different shift positions.

  At this time, the operation for forcibly stopping the traveling is the same algorithm operation as the other forcible stop operations (for example, the operation for turning off the output of the forward / reverse clutch D and the turning off of the output of the Hi-Lo shift switching clutch F). The behavior is the same). Moreover, the operation algorithm is the same as that when the forward / reverse switching lever 115 is operated to the neutral (N) position, and further, an abnormal display operation and a display for prompting the neutral (N) operation of the forward / reverse switching lever 115 are performed. . In addition, if the shift operation permission during the stop and the shift prohibition operation during the travel are made the same after the travel stop, the operation for canceling (resetting) the output of the forced travel stop is easy to understand.

  In the pressure sensors 112a to 113b of the main transmission clutch cylinders 87, 88, 91, and 92 of this embodiment, the voltage in the detection output range is set to the microcomputer A / D converter input voltage range 0 so that the disconnection of the wiring can be determined. When a sensor that outputs 0.5 to 4.5 V at normal time is used for -5 V, and an input outside the range is input to the microcomputer due to disconnection of the wiring, etc., an error is displayed and the gear shift during traveling Is prohibited, and shifting while parked is permitted.

  This is because when the pressure of the clutch cylinders 87, 88, 91, 92 cannot be detected, and there is an abnormality in the hydraulic control valves 89, 93 of the cylinders 87, 88, 91, 92, etc. This is because it becomes impossible to prevent meshing, so that the regulation condition is tightened so that the operation is not continued in such a state.

Further, when an abnormality occurs in which the clutch cylinder 95 of the Hi-Lo transmission B cannot be operated, both the clutch cylinders 87, 88, 91, 92 of the main transmission A and the clutch cylinder 95 of the Hi-Lo transmission B are abnormal. An output to return to the previous original shift position may be performed to continue traveling.
This is because if only the clutch cylinder 95 of the Hi-Lo transmission B is returned to the original shift position before the occurrence of the abnormality, there is a problem that the vehicle speed is greatly changed, so the clutch cylinder of the Hi-Lo transmission B 95 is because the clutch cylinders 87, 88, 91, 92 of the main transmission A need to be restored at the same time.

  Further, when an abnormality occurs only in the clutch cylinder 95 of the Hi-Lo transmission B, the cylinder 95 does not operate, but a shift of only the clutch cylinders 87, 88, 91, 92 of the main transmission A may be permitted. . This is because the main transmission A is made operable because the four shift positions of the clutch cylinders 87, 88, 91, 92 of the main transmission A are operating normally.

  Further, the abnormality display is continued in the displayable state until the engine 62 is stopped as in the other cases, the abnormality display is performed every specified time, and this is continued until the engine 62 is stopped. Further, while the abnormality display message is displayed, it is simultaneously displayed that the main transmission A is operable.

  In this embodiment, a plurality of sensors (not shown) capable of detecting the shift position of the sub-shift lever are provided in the operation portion of the sub-shift lever (not shown), and two or more positions of the sub-shift lever position sensor are provided. The sensor detects the sub-shift lever at the same time, that is, the sub-shift lever is not operating normally, or the sub-shift lever is operating normally. If a short-circuited state occurs during the tractor's travel, the two or more sensors simultaneously maintain the travel state immediately before the state in which the sub-shift lever is detected, and the travel state display is displayed on the meter section. Will continue to be displayed on the display.

In addition, when a state occurs in which the two or more sensors simultaneously detect the sub-shift lever while the tractor is stopped, the display on the high speed side among the three sub-shift positions of high speed, medium speed, and low speed is displayed. And the subsequent control operation is also performed at the high speed position of the auxiliary transmission.
The reason for performing the control described above is that when two or more sensors are simultaneously detecting the sub-shift lever while the tractor is traveling, the vehicle is traveling at a different shift position from the traveling state immediately before the occurrence of the state. Depending on the control algorithm, there is a possibility that the vehicle speed may be changed. Therefore, only abnormality determination is performed, and the shift position control operation for changing the running state is not performed. In addition, when two or more sensors detect the sub-shift lever at the same time while the tractor is stopped, there may be a short circuit in the sensor operation wiring. While driving in this state, the display on the high speed side is displayed on the display unit of the meter unit so as not to hinder the driving.

  The detection pressure of any one of the clutch cylinders 85, 87, 88, 91, 92, and 95 has a determination reference of a pressure (P2) higher than the determination pressure (P1), and the pressure equal to or higher than the determination reference pressure P2 and the pressure P1 or higher. If this occurs, only abnormality display is performed, and traveling control is continued.

The determination reference duration (T2) may be longer than the duration (T1) (T2> T1), and the determination pressure may be different depending on the oil temperature of the clutch cylinder.
The pressure (P1) is a pressure for determining an abnormality with a lower pressure that can be determined to be completely abnormal, and the pressure (P2) is a pressure for determining an abnormality with a higher pressure that is not normal. At this time, the duration (T2) is made longer in order not to determine that the pressure (P2) or less is abnormal due to an instantaneous pressure drop (several hundred msec) due to another clutch operation.
In this way, erroneous detection due to operation of other clutch cylinders or erroneous detection due to oil temperature can be prevented.

  In the tractor of this embodiment, the forward / reverse clutch D is also used as a main clutch, and a sensor 120 (FIG. 4) for detecting the clutch pedal operation position is provided in the operating portion of the clutch pedal (not shown). Then, for adjustment of the clutch pedal sensor 120, adjustment data that becomes a reference in a prescribed setting operation of the sensor 120 is written in the memory of the control device 100, and is stored and used.

Therefore, when the tractor is used, if the stored value of the control device 100 is an initial value (no storage operation is performed), the operation is linked with the operation of entering the main key of the tractor (the configuration may be linked with the travel start operation). Added a message to prompt adjustment operation.
This is a function that should be originally performed when the depression position and the separation position of the clutch pedal sensor 120 are adjusted for each machine at the tractor manufacturing factory before shipment of the tractor.
However, when trouble or the like occurs and the control device 100 is replaced, the reference position of the clutch pedal is lost, and an unexpected problem may occur when the operation is started. When adjusting the release position, it is possible to prompt the user to make a new setting while displaying it on the display unit.

  In this embodiment, the clutch pedal sensor 120 of the forward / reverse clutch D that sends a signal to the control device 100 in conjunction with the clutch pedal operation, and the forward / reverse clutch cylinder without passing through the control device 100 when the clutch pedal is turned off. Two clutch pedal control systems including a clutch pedal switch 121 that can operate the 85 on / off control valve 129 to the clutch disengagement side are provided.

At this time, if the control device 100 determines that the clutch pedal switch 121 that operates the forward / reverse clutch D is abnormal, the supply of hydraulic oil to the forward / reverse clutch D is blocked when the clutch pedal is depressed (neutral). The solenoid of the on / off control valve 129 of the forward / reverse clutch cylinder 85 is actuated so as to temporarily stop the vehicle.
Further, the forced stop is released again by the neutral (N) operation of the forward / reverse clutch D, but when it is determined again that the clutch pedal switch 121 is abnormal, the driving is forcibly stopped again (neutralized). Is continued while the engine 62 is running.

The clutch pedal switch 121 is actuated to start both the engine 62 start check circuit (a circuit that prevents the engine 62 from starting) and the clutch pressure supply cutoff circuit.
A contact 124 ′ of the relay Rst 124 interlocked with the clutch pedal switch 121 of FIG. 4 and a contact 125 ′ of the relay Rs 125 interlocked with the PTO on / off switch 123 are connected in series in front of the relay Rst 124. When the clutch pedal switch 121 is activated, the relay Rst 124 is activated, the circuit of the starter motor 126 is connected, and the engine 62 can be started.
Further, since the clutch pedal solenoid 128 is simultaneously activated when the PTO on / off switch 123 is “on”, the solenoid valve 129 (FIG. 3) is activated and the oil supply to the clutch cylinder 85 is shut off.

  In conjunction with the PTO on / off switch 123, when the PTO on / off switch 123 is "on", the relay Rs125 is activated to shut off the circuit of the starter motor 126, so that the main key switch 130 is set to the "start" position. Even if it is rotated, the starter motor 126 cannot be rotated, and the engine 62 is not started, so that the engine cannot be started.

  In addition to “turning off” the clutch pedal switch 121, the starting check of the engine 62 is turned off when the auxiliary transmission switch (not shown) that is turned off when the auxiliary transmission C is in the neutral position and the PTO working machine are not connected. The PTO switch 123 may be configured to be executed for the first time when either or both of them are “OFF”.

  Thus, when there is an abnormality in the clutch pedal switch 121 and the engine 62 cannot be started and when the abnormality of the clutch pedal switch 121 is not known (the clutch pedal switch 121 is in spite of the abnormality in the clutch pedal switch 121) Even when the switch is in the “ON” state, safety can be improved by preventing the engine 62 from being started by detecting “OFF” of another check switch.

As shown in FIG. 4, the clutch pedal switch 121 is normally used to turn on / off the solenoid of the on / off control valve 129 of the forward / reverse clutch cylinder 85 without going through the control device 100 when the clutch pedal is turned on / off. However, the solenoid of the control valve 129 is configured to be able to transmit a signal to the control device 100, and when it is determined that the clutch pedal switch 121 is abnormal, the solenoid of the on / off control valve 129 is input from the control device 100. -It is set as the structure which can perform the output control of this solenoid so that a cut signal may be transmitted.
Thus, even when the clutch pedal switch 121 is abnormal, the hydraulic oil is supplied to the forward / reverse clutch cylinder 85, so that the occurrence of the abnormality can be detected early.

The clutch pedal sensor 120 is arranged so that the output voltage range (0.5 to 4.5V) is regulated within the movable range, and when the sensor value is out of the range (less than 0.5V, exceeding 4.5V) In the case), the operation of the forward / reverse clutch D is switched so as to be interlocked with the clutch pedal switch 121 so that the forward / reverse clutch D is boosted in a prescribed boosting pattern.
This makes it possible to determine when the clutch pedal sensor 120 is faulty (particularly when it is faulty due to poor wiring), and can assist the operability of the forward / reverse clutch D to some extent at the time of the fault.

  In the tractor of the present embodiment, the rotation of the front wheel rotation sensor 131 that detects the rotation of the gear (shaft or the like) that synchronizes with the rotation of the front wheel 61 and the rotation of the gear (such as the shaft) that synchronizes with the rotation of the rear wheel 63 are detected. A rear wheel rotation sensor 132 sensor is provided, the vehicle speed is displayed based on the rotation of the rear wheel, and the vehicle speed is adjusted between the rear wheel 63 and the front wheel 61 when the control operation is controlled (for example, front wheel drive control is prohibited when traveling on the road). It is based on at least one of the rotations.

  This is not particularly dangerous even if there is no vehicle speed display when a sensor abnormality occurs, but the control operation can be suppressed even if there is an abnormality in either the front wheel rotation sensor 13 side or the rear wheel rotation sensor 132. This is to keep it.

  The tractor of the present invention can also be applied to vehicles for various works other than farm work.

It is a left view of the tractor of the Example of this invention. It is a power transmission diagram in the transmission of the tractor of FIG. FIG. 3 is a hydraulic circuit diagram of the power transmission diagram of FIG. 2. It is a control block diagram of the power transmission system of the tractor of FIG. FIG. 2 is a control flow diagram when an abnormality occurs in the forward / reverse clutch cylinder of the tractor in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine shaft 2 Input shaft 3 Output shaft 4 PTO interlocking shaft 5 Front wheel output shaft 6 Travel counter shaft 7 Front wheel drive shaft 8 Back counter shaft 9 PTO counter shaft 10 Rear differential shaft 11 Rear wheel shaft 12 Front differential shaft 13 Front wheel shaft 14 PTO shaft 15 , 17 Gear drive shaft 18 PTO transmission shaft 19 Main transmission shaft 20 Sub transmission shaft 21 Creep counter shaft 22 PTO forward / reverse switching shaft 23 PTO deceleration shaft 24 PTO reverse rotation shaft 25 Front wheel interlocking shaft 26 Input shaft 27 Sub transmission counter shaft 28 Front wheel Interlocking shaft 31 Input gear 32 PTO transmission gear 33 Main transmission gear 34 High / low speed switching gear 35 Sub transmission gear 36 Front wheel take-out gear 37 PTO forward / reverse switching gear 38 Sub transmission counter gear 39 Main transmission counter gear 40 High / low speed switching gear 41 Front wheel drive Switching gear 42 Forward / reverse switching gear 43 Back counter gear 44 PTO speed change Unter gear 45 Rear differential 46 Differential ring gear 47 Front differential 48 Input gear 49 Creep counter gear 50 PTO reduction gear 51 Front wheel interlocking gear 52 PTO reverse rotation gear 53 Drive pinion gear 54 Front wheel interlocking gear 55 Front wheel gear 56 Switching drive counter gear 59 Counter shaft 60 Forward / reverse travel Switching clutch pack 61 Front wheel 62 Engine 63 Rear wheel 65 Transmission case 66 PTO clutch pack 67 Front wheel drive clutch pack 73 Steering handle 75 Rear axle housing 76 Clutch pack 80 Hydraulic pump 81a, 81b Pressure reducing valve 82a Brake valve 82b Pressure control valve 83 Brake cylinder 84 Working machine 85 Forward / reverse clutch cylinder 86 Switching valve 89 Shift control valves 87, 88, 91, 92 Hydraulic clutch cylinder 93 Shift control Control valve 94 Switching control valve 95 High / low hydraulic clutch cylinders 96a, 96b Control valve 97 Differential lock control valve 98a Front wheel differential lock cylinder 98b Rear wheel differential lock cylinder 99 Four-wheel drive clutch cylinder 100 Controller 103 Power steering device 104 PTO clutch cylinder 105, 106 PTO clutch pressure control valve 107 Orbit roll 110 Forward clutch pressure sensor 111 Reverse clutch pressure sensor 115 Forward / reverse switching lever 112a, 112b, 113a, 113b, 116, 117 Clutch pressure sensor 120 Clutch pedal sensor 121 Clutch pedal switch 123 PTO ON / OFF switch 124 Relay Rst
125 relay Rs 126 starter motor 128 clutch pedal solenoid 129 forward / reverse clutch on / off control valve 130 main key switch 131 front wheel rotation sensor 132 rear wheel rotation sensor A main transmission B high / low transmission C subtransmission D forward / reverse clutch E Main transmission switching clutch F Hi-Lo transmission switching clutch T Tractor body

Claims (2)

A friction transmission type forward / reverse clutch (D), a main shift switching clutch (E), and a Hi-Lo shift switching clutch (F) are provided in the driving power transmission system,
Pressure detecting means (116, 116) for detecting the pressure of hydraulic oil supplied to the operating cylinders (85, 87, 88, 91, 92 and 95) of the clutches (D), (E) and (F), respectively. 117; 112a, 112b; 113a, 113b; 110, 111)
The first set value over a predetermined time (T1) in which the hydraulic oil pressure detected by each of the pressure detection means (116, 117; 112a, 112b; 113a, 113b; 110, 111) during traveling is set for a predetermined time (T1) or more. (P1) When it falls below, it determines with an abnormal state, and the cylinder (85, 87, 88, 91) for each clutch (D), (E) and / or (F) determined as the abnormal state. , 92 and 95) provided with a control device (100) for stopping the traveling by cutting off the supply of hydraulic oil to the working vehicle. Display means is provided in the control section,
The control device (100) operates the cylinders (85, 87, 88, 91) of the forward / reverse clutch (D), the main shift switching clutch (E), and the Hi-Lo shift switching clutch (F) during traveling. , 92 and 95), the pressure of the hydraulic oil supplied to the first set pressure (P1) or higher falls within the second set pressure (P2), which is higher than the first set pressure (P1). 2. The work vehicle according to claim 1, wherein when it is detected, an abnormal state is displayed on the display unit, but control is performed so as not to stop traveling.

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