JP4034890B2 - Agricultural tractor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an agricultural tractor that transmits output from an engine to an axle transmission system via a wet multi-plate main clutch, and prevents the accompanying torque generated when the main clutch is disconnected from being transmitted to the axle system. Regarding technology.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a technique for an agricultural tractor configured to transmit an output from an engine to an axle transmission system via a wet multi-plate main clutch is known. This transmission uses a wet multi-plate friction clutch that operates in oil as the main clutch, efficiently dissipating heat generated from the clutch through the hydraulic oil, reducing wear on the clutch part, It is supposed to extend the life of the clutch. As for the basic structure of the wet multi-plate clutch, for example, a technique such as Patent No. 1080623 is known. Regarding cooling of the main clutch, a technique such as Patent No. 1825166 is known.
[0003]
In addition, since the wet multi-plate clutch operates in oil, some accompanying torque is generated on the driven side when the clutch is disconnected due to the viscosity of the hydraulic oil. In order to prevent the inconvenience of the accompanying torque being transmitted to the axle, a technique is known in which a brake is provided in the driven axle transmission system. For example, there is a technique such as Patent No. 1116538 related to a technique for preventing the rotation.
[0004]
[Problems to be solved by the invention]
However, the above-mentioned technology has a configuration in which a new brake is provided in the axle transmission system in order to prevent transmission of the follower torque to the axle, which increases the number of parts and man-hours, which is disadvantageous in terms of cost. .
[0005]
[Means for Solving the Problems]
The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
The forward-side reverser hydraulic clutch and the reverse-side reverser hydraulic clutch for transmitting the output from the engine to the axle transmission system via the wet multi-plate main clutch and converting the axle rotation forward / reversely, the axle transmission in agricultural tractor configuration provided in the system, arranged to start safety switch in the vicinity of the clutch pedal to operate the disengagement of the main clutch, the start safety switch is depressing the clutch pedal, and the main clutch disconnection The starter safety switch is electrically connected to a key switch for rotating the flywheel of the engine and a starter motor circuit, and switches the pressure oil to the reverser hydraulic clutch. A switching valve comprising an electromagnetic valve is provided in the pressure oil supply circuit of the control valve, and the switching safety valve and the start safety switch are provided. Is electrically connected to the control device, and when the main clutch is disengaged, the reverser hydraulic clutch located on the axle side of the main clutch is disengaged when the main clutch is disengaged. Since it is a multi-plate clutch, it prevents transmission of follow-up torque generated by the viscosity of hydraulic oil to the axle .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the invention will be described. FIG. 1 is a side view showing an overall configuration of an agricultural tractor according to an embodiment of the present invention, FIG. 2 is a side view showing positions of a clutch pedal and a start safety switch, and FIG. 3 is a configuration of a main clutch and a transmission. FIG. 4 is a skeleton diagram showing the power transmission configuration of the tractor, and FIG. 5 is a hydraulic circuit diagram of the tractor.
[0007]
First, the overall configuration of an agricultural tractor according to an embodiment of the present invention will be described with reference to FIG. That is, this tractor has a bonnet 6 disposed in the front part of a main body that suspends the front wheel 1 and the rear wheel 2 forward and backward, and an engine 5 is disposed inside the bonnet 6. A steering handle 10 is provided behind the bonnet 6, and a reverser lever 82 for switching between forward and backward movement is disposed in the vicinity of the steering handle. A seat 11 is disposed behind the steering handle 10. A main transmission lever 77 projects from the side of the seat. The steering handle 10 and the seat 11 are covered with a cabin 12.
[0008]
A clutch housing 8 is disposed behind the engine 5, and a transmission case 9 is connected to the rear of the clutch housing 8 to transmit power from the engine 5 to the rear wheel 2 for driving. However, depending on the operation, a four-wheel drive that transmits the driving force to the front wheels 1 at the same time can also be used.
[0009]
Further, the driving force of the engine 5 is transmitted to the PTO shaft 15 protruding from the rear end of the transmission case 9 to drive the PTO shaft 15 and drive the working machine connected to the rear end of the machine body.
[0010]
Then, at the foot of the operator who operates the tractor, a clutch pedal 16 as a clutch operating means for connecting / disconnecting the clutch is supported so as to be tiltable as shown in FIG. 2, and when the operator steps on the clutch pedal 16, In conjunction with this, the main clutch 21 housed in the clutch housing 8 is disconnected. However, a clutch lever may be used instead of the clutch pedal 16.
[0011]
A start safety switch 17 is disposed in the vicinity of the clutch pedal 16. The start safety switch 17 is provided to prevent a sudden start of the vehicle when the engine 5 is started, and is configured to be turned on when the clutch pedal 16 is depressed. It is electrically connected to the starter motor that rotates. Accordingly, the start safety switch 17 is not turned on unless the clutch pedal 16 is fully depressed. Therefore, even if the operator rotates the key switch to the start side, power is not supplied to the starter motor, and the engine 5 does not start. It has become.
[0012]
Next, configurations of the clutch housing 8 and the transmission case 9 will be described with reference to FIGS. That is, the clutch housing 8 is fixed to the rear of the engine 5, and the transmission case 9 is attached to the rear surface of the clutch housing 8. The mission case 9 has a structure (9a, 9b) that is divided into two parts in the front and the rear, and a center plate 13 is sandwiched therebetween. A rear axle case is fixed on the left and right sides of the rear part of the transmission housing 9b in the rear half.
[0013]
Next, the configuration of the rear axle transmission system will be described.
That is, a wet multi-plate main clutch 21 linked to the clutch pedal 16 is disposed in the clutch housing 8, and the rotation of the crankshaft of the engine 5 is input to the driving shaft 22 of the main clutch 21. A driven side shaft 23 of the main clutch 21 extends rearward of the machine body, and a main transmission fourth speed gear 34 loosely fitted to the traveling clutch shaft 24 meshes with a gear 23a formed at the rear end thereof. The main transmission fourth speed gear 34 meshes with a transmission gear 44 fixed to the main shaft 25. Three transmission gears 41, 42, and 43 are further fixed or formed on the main shaft 25, and loosely fitted to the traveling clutch shaft 24 via the three transmission gears 41, 42, and 43, respectively. Power is transmitted to the main transmission first speed gear 31, main transmission second speed gear 32, and main transmission third speed gear 33. Accordingly, when the driven shaft 23 of the main clutch 21 rotates, the main transmission first speed gear 31, the main transmission second speed gear 32, the main transmission third speed gear 33, and the main transmission fourth speed gear 34 rotate at different rotational speeds. It becomes. Then, the hydraulic control valve interlocked with the main transmission lever 77 selects one of the four hydraulic clutches 51, 52, 53, and 54 so as to be in “contact”, thereby enabling four-stage shifting. The rotation of the main shaft 25 is transmitted to the traveling clutch shaft 24 through the speed change.
[0014]
The travel clutch shaft 24 extends rearward through the center plate 13. The forward rotation side gear 26 and the reverse rotation side gear 27 are loosely fitted on the same axis on the extended portion. Then, by operating the hydraulic control valve linked to the reverser lever 82, either the forward-side reverser hydraulic clutch 56 or the reverse-side reverser hydraulic clutch 57 is selected and connected, and the travel clutch shaft 24 rotates. It is transmitted to either the forward rotation side gear 26 or the reverse rotation side gear 27. However, when the reverser lever 82 is in the neutral position, the rotation is not transmitted to both the gears 26 and 27.
[0015]
The forward rotation side gear 26 is connected to the auxiliary transmission shaft 35 so as not to be relatively rotatable, and simultaneously meshes with a transmission gear 37 fixed to the creep transmission shaft 36 to transmit the rotation to both shafts 35 and 36. The reverse gear 27 is meshed with a gear 39 formed at one end of the forward / reverse shaft 38, and a gear 40 formed at the other end of the forward / reverse shaft is fixed to the creep transmission shaft 36. It meshes with the transmission gear 37. Accordingly, the rotation of the reverse rotation side gear 27 rotates the creep transmission shaft 36 in the reverse rotation direction via the forward / reverse rotation shaft 38. Further, the auxiliary transmission shaft 35 connected to the transmission gear 37 of the creep transmission shaft 36 is rotated in the reverse direction via the forward rotation gear 26.
[0016]
A sub-transmission second shaft 45 is disposed on the same shaft center at the rear portion of the sub-transmission shaft 35 so as to be free to rotate. A creep transmission gear 46 is loosely fitted to the sub-transmission second shaft 45. The creep transmission gear 46 meshes with a gear 47 formed on the creep transmission shaft 36. An input clutch slider 91 is spline-fitted to the auxiliary transmission second shaft 45 so as to be slidable in the axial direction, and is linked to a creep transmission lever (not shown). Accordingly, the input clutch slider 91 is engaged with either the sub transmission shaft 35 or the creep transmission gear 46 by the operation of the creep transmission lever, and the rotation thereof can be transmitted to the sub transmission second shaft 45. That is, depending on the selection based on the sliding of the input clutch slider 91, either the rotation of the auxiliary transmission shaft 35 or the rotation of the auxiliary transmission shaft 35 through the creep transmission by the creep transmission shaft 36 is applied to the auxiliary transmission second shaft 45. Entered.
[0017]
The output shaft 48 is supported in parallel with the auxiliary transmission second shaft 45, and two transmission gears 49 and 50 are fixed to the output shaft 48. The transmission gears 49 and 50 mesh with two transmission gears 59 and 60 that are loosely fitted to the auxiliary transmission second shaft 45. An output clutch slider 92 is spline-fitted to the auxiliary transmission second shaft 45 so as to be slidable in the axial direction. The output clutch slider 92 is linked to an unillustrated auxiliary transmission lever. Therefore, the output clutch slider 92 is slid by the operation of the auxiliary transmission lever and meshes with one of the two transmission gears 59 and 60, and the rotation of the auxiliary transmission second shaft 45 is rotated by the two transmission gears 59 and 60. 60 can be transmitted. Accordingly, the rotation of the sub-transmission second shaft 45 is output through a two-stage shift and is input to the output shaft 48 by selection based on the sliding of the output clutch slider 92.
[0018]
A rear wheel differential portion 66b is disposed in the transmission housing rear portion 9b, and the rotation of the output shaft 48 is input to the rear wheel differential portion 66b via a bevel gear 20 formed at the rear end thereof. The rear wheel 2 is driven via a transmission gear or the like.
[0019]
Next, the PTO transmission system will be described. That is, a PTO clutch shaft 29 is disposed in the transmission housing front portion 9a in parallel with the main shaft 25, and four PTO transmission gears, that is, a PTO first gear 61, a PTO second gear 62, A PTO third gear 63 and a PTO fourth gear 64 are loosely fitted. The PTO transmission gears 61, 62, 63, and 64 are meshed with the four transmission gears 41, 42, 43, and 44 fixed or formed on the main shaft 25, and the PTO transmission gears are rotated by the rotation of the main shaft 25. 61, 62, 63 and 64 are rotated at different rotational speeds. Further, a PTO reverse rotation gear 65 is loosely fitted on the PTO clutch shaft 29, and the PTO reverse rotation gear 65 meshes with the aforementioned main transmission first speed gear 31 loosely fitted on the traveling clutch shaft 24. That is, the main transmission first speed gear 31 also serves as an idle gear of the PTO reverse rotation imparting mechanism.
[0020]
Further, two PTO clutch sliders 93 and 94 are spline-fitted to the PTO clutch shaft so as to be slidable in the axial direction. The PTO clutch sliders 93 and 94 are linked to a PTO shift lever (not shown). Therefore, the rotation of the main shaft is transmitted to the PTO shaft after four stages of speed change by selection based on the sliding of both the PTO clutch sliders 93 and 94. Further, the rotation of the main shaft 25 is forward / reversely converted and transmitted to the PTO clutch shaft 29 via the main transmission first speed gear 31 and the PTO reverse gear 65. That is, the forward fourth speed and the first reverse speed are changed between the two shafts 25 and 29. The PTO clutch shaft 29 is connected to the PTO shaft 15 so as not to be relatively rotatable. The PTO shaft 15 extends rearward and drives the work machine 100 connected to the rear end of the tractor.
[0021]
Next, the front axle transmission system will be described. That is, a pipe-like front wheel input shaft 55 is fitted on the PTO shaft 15 so as to be free to rotate, and the front wheel clutch shaft 30 is pivotally supported in parallel with the front wheel input shaft 55. An input gear 67 is fixed to the front wheel input shaft 55, and the input gear 67 meshes with one of the two transmission gears fixed to the output shaft 48. Two transmission gears 18 and 19 are further fixed to the front wheel input shaft 55. The transmission gears are two gears loosely fitted to the front wheel clutch shaft 30, that is, a four-wheel drive side gear 68 and a front wheel double speed side. The gears 69 mesh with each other.
[0022]
Then, by operating the hydraulic control valve interlocked with the 4WD / front wheel double speed changeover switch (not shown), one of the two hydraulic clutches 78 and 79 is selected and connected, and the rotation of the front wheel input shaft 55 is substantially doubled. It is transmitted to the front wheel clutch shaft 30 at an increased speed or substantially constant speed. The rotation of the front wheel clutch shaft 30 is input to the front wheel side differential portion 66a via the front wheel transmission shaft 14 connected to the front end, a universal joint, etc., and drives the front wheel 1 via the axle, transmission gear, etc. in the front axle case. .
[0023]
The configuration of the hydraulic circuit provided in the tractor having the above configuration will be described with reference to FIG. That is, the hydraulic oil in the oil tank (mission case) 71 is branched in two directions through the suction strainer 73, and one of them is pumped to the power steering unit 74 by the traveling system hydraulic pump 72. This power steering unit 74 is provided to reduce the torque required to operate the steering handle 10, and is a double acting connected to the front wheel steering device by a switching valve 75 linked to the steering handle 10. The cylinder 76 is driven to give a steering angle to the front wheels 1.
[0024]
The hydraulic oil that has passed through the power steering unit 74 is branched into three, one of which operates one of the four hydraulic clutches 51, 52, 53, and 54 by a main transmission control valve 80 that is linked to the main transmission lever 77. The main shift is performed. The other is through a proportional pressure reducing valve 81, and a reverser control valve 83 interlocked with the reverser lever 82 operates either one of the two reverser hydraulic clutches 56 and 57 to switch forward or reverse of the tractor. . The proportional pressure reducing valve 81 is a switching valve made up of an electromagnetic valve. The rest passes through the electromagnetic control valve 95 and operates one of the two hydraulic clutches 78 and 79 to switch between front wheel acceleration or four-wheel drive. At the time of front wheel acceleration, the turning devices are further operated by operating the brake devices 84 and 85 provided on the left and right sides of the rear wheel so that the turning radius is small.
[0025]
Next, the hydraulic circuit of the work machine control system will be described. The hydraulic fluid branched from the oil tank 71 via the suction strainer 73 is pressure-fed by the work machine hydraulic pump 86 to the work machine control unit 88 via the external hydraulic pressure take-out part 87. Then, the work implement lifting / lowering cylinder 89 and the work implement horizontal control cylinder 90 are actuated as appropriate, and the work implement connected to the rear end of the tractor is lifted and leveled.
[0026]
Next, control of the proportional pressure reducing valve 81 for supplying pressure to the above-described reverser hydraulic clutches 56 and 57 will be described with reference to FIGS. FIG. 6 is a block diagram of the control device for the proportional pressure reducing valve. FIG. 7 is a diagram showing a control flow of the control device. That is, the proportional pressure reducing valve 81 shown in FIGS. 5 and 6 is of the solenoid electromagnetic switching type, and is electrically connected to the control device 96, and the pressure is controlled by the duty ratio of the signal sent from the control device 96. Be controlled. Reference numeral 97 denotes a battery for supplying power to the control device 96. Then, ON or OFF information of the start safety switch 17 is input to the control device 96, and the control device 96 controls the proportional pressure reducing valve 81 as follows based on the information.
[0027]
That is, as shown in FIG. 7, when the start safety switch is OFF, the control device 96 determines that the clutch pedal 16 is not depressed, that is, the main clutch 21 is in the connected state, and the proportional pressure reducing valve A signal is sent to keep 81 at sufficient pressure. Accordingly, when a sufficient pressure is supplied to the reverser control valve 83 and the reverser lever 82 linked to the reverser control valve 83 is in the forward or reverse position, the two reverser hydraulic clutches 56 and 57 are correspondingly provided. One is connected.
[0028]
On the other hand, when the start safety switch 17 is ON, the control device 96 determines that the clutch pedal 16 is depressed, that is, the main clutch 21 is disconnected, and sends a signal for switching the proportional pressure reducing valve 81. Then, drain the pump port of the reverser control valve 83 to make the pressure zero. Accordingly, no pressure is supplied to the reverser control valve 83 regardless of whether the reverser lever 82 is in the forward, reverse, or neutral position, so that neither of the two reverser hydraulic clutches 56 and 57 is operated, and the travel clutch The connection between the shaft 24 and the auxiliary transmission shaft 35 is broken. That is, by disconnecting the reverser hydraulic clutches 56 and 57 located on the axle side of the main clutch 21, transmission of the accompanying torque generated in the main clutch 21 when the clutch pedal 16 is depressed is prevented.
[0029]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
The forward-side reverser hydraulic clutch and the reverse-side reverser hydraulic clutch for transmitting the output from the engine to the axle transmission system via the wet multi-plate main clutch and converting the axle rotation forward / reversely, the axle transmission In the agricultural tractor having a configuration provided in the system, a start safety switch is disposed in the vicinity of the clutch pedal for operating the connection and disconnection of the main clutch, and the start safety switch depresses the clutch pedal and disconnects the main clutch The starter safety switch is electrically connected to a key switch that rotates the flywheel of the engine and a starter motor circuit, and a reverser control for switching pressure oil to the hydraulic clutch for the reverser. A switching valve comprising an electromagnetic valve is provided in the pressure oil supply circuit of the valve, and the switching safety valve and the start safety switch are provided. Is electrically connected to the control device, and when the main clutch is disengaged, the reverser hydraulic clutch located on the axle side of the main clutch is disengaged when the main clutch is disengaged. Because it is a multi-plate clutch, it prevents transmission of the follow-up torque generated by the viscosity of the hydraulic oil to the axle. Therefore, when the main clutch is disengaged, the switching valve is switched so that no pressure oil is fed. The hydraulic clutch is disengaged, and the accompanying torque generated when the main clutch is disconnected can be prevented from being transmitted to the axle without adding an accompanying anti-rotation brake or the like.
Therefore, it is not necessary to provide a special brake or the like in the axle transmission system, and the configuration is simple, the number of parts can be reduced, and the cost can be reduced.
[0030]
In addition, since the detection means for detecting the connection / disconnection of the main clutch is a start safety switch, the existing start safety switch can be used also as a detection means for disconnecting the main clutch, and it is not necessary to provide a detection means specially. Furthermore, it becomes a simple structure and can contribute to the number of parts reduction and cost reduction.
[Brief description of the drawings]
FIG. 1 is a side view showing an overall configuration of an agricultural tractor according to an embodiment of the present invention.
FIG. 2 is a side view showing positions of a clutch pedal and a start safety switch.
FIG. 3 is a side cross-sectional development view showing a configuration of a main clutch and a transmission.
FIG. 4 is a skeleton diagram showing a power transmission configuration of the tractor.
FIG. 5 is a hydraulic circuit diagram of the tractor.
FIG. 6 is a configuration diagram of a control device for a proportional pressure reducing valve.
FIG. 7 is a diagram showing a control flow of the control device.
[Explanation of symbols]
5 Engine 16 Clutch pedal 17 Start safety switch 21 Main clutch 56 Reverser hydraulic clutch (forward)
57 Hydraulic clutch for reverser (reverse side)
81 Proportional pressure reducing valve 96 Controller

Claims (1)

The forward-side reverser hydraulic clutch and the reverse-side reverser hydraulic clutch for transmitting the output from the engine to the axle transmission system via the wet multi-plate main clutch and for forward / reverse conversion of the axle rotation, the axle transmission In the agricultural tractor having the configuration provided in the system, when a start safety switch is disposed in the vicinity of the clutch pedal for operating the connection and disconnection of the main clutch, and the start safety switch depresses the clutch pedal and disconnects the main clutch The starter safety switch is electrically connected to a key switch that rotates the flywheel of the engine and a starter motor circuit, and a reverser control that switches and controls the pressure oil to the hydraulic clutch for the reverser. A switching valve comprising an electromagnetic valve is provided in the pressure oil supply circuit of the valve, and the switching safety valve and the start safety switch are provided. Is electrically connected to the control device, and when the main clutch is disengaged, the reverser hydraulic clutch located on the axle side of the main clutch is disengaged when the main clutch is disengaged. An agricultural tractor characterized in that since it is a multi-plate clutch, transmission of follow-up torque generated by the viscosity of hydraulic oil to the axle is prevented .

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