JP2000158958A - Agricultural tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the transmission of co-running torque to an axle at the cutting of a main clutch by providing a detecting means for detecting the connec tion and disconnection of the main clutch and a selector valve on a oil feeding circuit for a reverser control valve for connecting and disconnecting a reverser hydraulic clutch, and interlocking the detecting means to the selector valve. SOLUTION: When a starting safety switch 17 if OFF, a control device 96 judges that a main clutch is in the connected state without operation of a clutch pedal 16, and transmits a signal for keeping a proportional pressure reducing valve 81 at a sufficient pressure. When the starting safety switch 17 is ON, on the other hand, the control device 96 judges the disconnection of the main clutch, transmits a signal for switching the proportional pressure reducing valve 81 and drain the pump port of a reverser control valve to release the pressure. Since no hydraulic pressure is supplied to the reverser control valve, two reverser hydraulic clutches are not operated. According to this, the transmission of the co-running torque caused at the cutting of the main clutch to an axle can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural tractor for transmitting the output from an engine to an axle transmission system via a wet-type multi-plate main clutch. In this agricultural tractor, the co-rotating torque generated when the main clutch is disconnected is transmitted to the axle system. Related to technology for preventing such a situation.

[0002]

2. Description of the Related Art Conventionally, the technology of an agricultural tractor configured to transmit the output from an engine to an axle transmission system via a wet-type multi-plate type main clutch has been known. This transmission uses a wet multi-plate friction clutch that operates in oil as the main clutch, thereby efficiently dispersing the heat generated by the clutch through the hydraulic oil, reducing wear of the clutch portion, The life of the clutch will be extended. With respect to the basic structure of a wet multi-plate clutch, for example, a technique as disclosed in Japanese Patent No. 1080623 is known. As for cooling of the main clutch, a technique such as Japanese Patent No. 1825166 is known.

[0003] Further, since the wet multi-plate clutch operates in oil, a slight torque is generated on the driven side when the clutch is disconnected due to the viscosity of the operating oil. There is known a technique in which a brake is provided in a driven axle transmission system in order to prevent the inconvenience in which the co-rotating torque is transmitted to the axle. For example, it is a technique such as Patent No. 1116538 relating to a technique for preventing entrainment.

[0004]

However, the above-mentioned technique requires a new brake in the axle transmission system in order to prevent the transmission of the co-rotating torque to the axle, resulting in an increase in the number of parts and man-hours. Was disadvantageous in terms of cost.

[0005]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described. According to the first aspect of the present invention, the output from the engine is transmitted to the axle transmission system via a wet-type multi-plate type main clutch, and a hydraulic clutch for a reverser for converting rotation forward and reverse is provided in the axle transmission system. In the agricultural tractor, a detection valve for detecting connection and disconnection of the main clutch, and a switching valve in a circuit for supplying pressure oil to a reverser control valve for connecting and disconnecting a hydraulic clutch for a reverser, a switching valve is provided. It is linked.

According to a second aspect of the present invention, the detecting means for detecting the connection / disconnection of the main clutch is a starting safety switch.

Next, embodiments of the present invention will be described. FIG. 1 is a side view showing the overall configuration of an agricultural tractor according to one embodiment of the present invention, FIG. 2 is a side view showing the positions of a clutch pedal and a starting safety switch, and FIG. 3 is a configuration of a main clutch and a transmission. FIG. FIG. 4 is a skeleton diagram showing a power transmission configuration of the tractor, and FIG. 5 is a hydraulic circuit diagram of the tractor.

First, the overall configuration of an agricultural tractor according to one embodiment of the present invention will be described with reference to FIG. That is, in this tractor, a bonnet 6 is disposed at a front portion of a main body that suspends a front wheel 1 and a rear wheel 2 back and forth, and an engine 5 is disposed inside the hood 6. Bonnet 6
A steering handle 10 is provided at the rear of the vehicle, and a reverser lever 82 for switching between forward and backward movement is provided near the steering handle. The steering handle 1
The seat 11 is arranged behind the zero. A main speed change lever 77 is provided on the side of the seat. The steering handle 10 and the seat 11 are covered by a cabin 12.

A clutch housing 8 is disposed behind the engine 5, a transmission case 9 is connected behind the clutch housing 8, and power from the engine 5 is supplied to the rear wheels 2.
To be driven. However, depending on the operation, a four-wheel drive that transmits the driving force to the front wheels 1 at the same time is also possible.

The driving force of the engine 5 is transmitted to a PTO shaft 15 protruding from the rear end of the transmission case 9 and
The TO shaft 15 is driven to drive a working machine connected to the rear end of the machine.

At the foot of the operator who operates the tractor, a clutch pedal 16 serving as clutch operating means for connecting and disconnecting the clutch is supported so as to be tiltable as shown in FIG. 2, and the operator steps on the clutch pedal 16. The main clutch 21 housed in the clutch housing 8 is disengaged in conjunction therewith. However, a clutch lever may be used instead of the clutch pedal 16.

A starting safety switch 17 is provided near the clutch pedal 16. The start safety switch 17 is provided to prevent the vehicle from suddenly starting 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 a starter motor that rotates. Therefore, unless the clutch pedal 16 is fully depressed, the start safety switch 17 is turned on.
Therefore, even if the operator turns the key switch to the starting side, power is not supplied to the starter motor, and the engine 5 does not start.

Next, the configuration inside the clutch housing 8 and the transmission case 9 will be described with reference to FIGS. That is, the clutch housing 8 is fixedly provided behind the engine 5, and the transmission case 9 is attached to the rear surface of the clutch housing 8. The transmission case 9 is divided into two parts (9a and 9b), and a center plate 13 is sandwiched between the two. Rear axle cases are fixedly provided on the left and right sides of the rear portion of the transmission housing 9b.

Next, the configuration of the rear axle transmission system will be described. That is, a wet multi-plate type main clutch 21 linked to the clutch pedal 16 is disposed in the clutch housing 8, and a driving side shaft 22 of the main clutch 21 is disposed.
, The rotation of the crankshaft of the engine 5 is input. A driven side shaft 23 of the main clutch 21 extends rearward of the fuselage, and a main speed 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. The main shaft 25 has three transmission gears 41.4.
The main transmission first-speed gear 31 and the main transmission second gear 31, which are loosely fitted to the traveling clutch shaft 24 via the three transmission gears 41, 42, 43, respectively. Power is transmitted to the speed gear 32 and the main transmission third speed gear 33. Therefore, when the driven side shaft 23 of the main clutch 21 rotates, the main speed first speed gear 31, the main speed second speed gear 32, the main speed third speed gear 33, and the main speed fourth speed gear 34 rotate at different rotational speeds. Becomes Then, one of the four hydraulic clutches 51, 52, 53, and 54 is selected and brought into "contact" by a hydraulic control valve interlocked with the main shift lever 77, thereby enabling four-step shifting. The rotation of the main shaft 25 is transmitted to the traveling clutch shaft 24 via the speed change.

The traveling clutch shaft 24 is mounted on the center plate 1.
3 and extend rearward. A forward rotation side gear 26 and a reverse rotation side gear 27 are loosely fitted on the same axis on the extended portions. 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 rotation of the traveling clutch shaft 24 is controlled. The power is transmitted to either the forward rotation gear 26 or the reverse rotation gear 27. However, when the reversing lever 82 is in the neutral position, the rotation is not transmitted to both the gears 26 and 27.

The forward rotation gear 26 is non-rotatably connected to the auxiliary transmission shaft 35, and at the same time, meshes with a transmission gear 37 fixed to the creep transmission shaft 36.
・ Communicate to 36. The reverse rotation gear 27 meshes with a gear 39 formed at one end of a forward / reverse rotation shaft 38, and a gear 40 formed at the other end of the forward / reverse rotation shaft is fixed to a creep speed change shaft 36. The transmission gear 37 meshes. Accordingly, the rotation of the reverse rotation gear 27 causes the creep speed change shaft 36 to rotate in the reverse rotation direction via the forward / reverse rotation shaft 38. Further, the auxiliary transmission shaft 35 connected thereto is rotated in the reverse direction via the forward rotation gear 26 meshing with the transmission gear 37 of the creep transmission shaft 36.

A subtransmission second shaft 45 is provided at the rear of the subtransmission shaft 35.
Are arranged on the same axis so as to be freely rotatable, and a creep speed change gear 46 is loosely fitted to the auxiliary speed change second shaft 45. The creep speed change gear 46 meshes with a gear 47 formed on the creep speed change 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). Therefore, the input clutch slider 91 can be engaged with either the auxiliary transmission shaft 35 or the creep transmission gear 46 by operating the creep transmission lever, and can transmit the rotation to the auxiliary transmission second shaft 45. That is, according to the selection based on the sliding of the input clutch slider 91, the rotation of the sub-transmission shaft 35 or the creep transmission shaft 3
6 is input to the auxiliary speed change second shaft 45.

An output shaft 48 is supported in parallel with the auxiliary transmission second shaft 45. The output shaft 48 has two transmission gears 49
50 is fixed. The transmission gears 49 and 50 mesh with two transmission gears 59 and 60 loosely fitted on the auxiliary transmission second shaft 45. An output clutch slider 92 is spline-fitted to the sub-transmission second shaft 45 so as to be slidable in the axial direction. The output clutch slider 92 is linked to an unillustrated auxiliary shift lever. Therefore, the output clutch slider 92 is slid by operation of the sub-transmission lever, and meshes with either one of the two transmission gears 59 and 60 to rotate the sub-transmission second shaft 45 to the two transmission gears 59 and 60. 60 can be transmitted. Therefore, the output clutch slider 9
By the selection based on the sliding of 2, the rotation of the sub-transmission second shaft 45 is output through two-stage transmission, and is input to the output shaft 48.

A rear wheel differential portion 66b is disposed at the rear portion 9b of the transmission housing, and the rotation of the output shaft 48 is input to the rear wheel differential portion 66b via the bevel gear 20 formed at the rear end of the rear wheel differential portion 66b. The rear wheel 2 is driven via an internal axle, a transmission gear, and the like.

Next, the PTO transmission system will be described. That is, a PTO clutch shaft 29 is arranged in the transmission housing front portion 9a in parallel with the main shaft 25,
The O clutch shaft 29 has four PTO transmission gears, ie, PT
The first O gear 61, the second PTO gear 62, the third PTO gear 63, and the fourth PTO gear 64 are loosely fitted. The PTO transmission gears 61, 62, 63, and 64 are four transmission gears 41, 42, 43, 44 fixed or formed on the main shaft 25.
, And the rotation of the main shaft 25 causes the PTO transmission gears 61, 62, 63, and 64 to rotate at different rotational speeds. The PTO clutch shaft 29 has a PTO reverse gear 6
5 is loosely fitted, and the PTO reverse rotation gear 65 meshes with the above-mentioned main speed first speed gear 31 loosely fitted on the traveling clutch shaft 24. That is, the main speed first gear 31 also functions as an idle gear of the PTO reverse rotation imparting mechanism.

The PTO clutch shaft has two PTOs.
Clutch sliders 93 and 94 are spline-fitted slidably in the axial direction. Also, the PTO clutch slider 93
94 is linked to a PTO shift lever (not shown).
Therefore, by the selection based on the sliding of the two PTO clutch sliders 93 and 94, the rotation of the main shaft is transmitted to the PTO shaft after passing through the four-stage shift. Also, the main transmission first speed gear 31,
The rotation of the main shaft 25 is forward / reverse converted via the PTO reverse rotation gear 65 and transmitted to the PTO clutch shaft 29. In other words, the fourth forward speed and the first reverse speed are shifted between the two shafts 25 and 29. The PTO clutch shaft 29 is connected to the PTO shaft 15 so as not to rotate relatively. The PTO shaft 15 extends rearward and drives a work machine 100 connected to the rear end of the tractor.

Next, the front axle transmission system will be described. That is, a pipe-shaped front wheel input shaft 55 is rotatably fitted to the PTO shaft 15, and the front wheel clutch shaft 30 is 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 is connected to the output shaft 4.
8 is engaged with one of the two transmission gears 49 fixed to the transmission gear 8. The front wheel input shaft 55 further includes two transmission gears 1.
8 and 19 are fixedly mounted, and the transmission gear is a front wheel clutch shaft 30.
The two gears, ie, the four-wheel drive-side gear 68 and the front-wheel double-speed gear 69, which are loosely fitted to the gears, respectively mesh with each other.

Then, one of the two hydraulic clutches 78 and 79 is selected and connected by operating a hydraulic control valve that is interlocked with a 4WD / front wheel double speed changeover switch (not shown).
The rotation of the front wheel input shaft 55 is transmitted to the front wheel clutch shaft 30 at approximately double speed or approximately constant speed. Front wheel clutch shaft 30
Is input to the front wheel side differential portion 66a via a front wheel transmission shaft 14 connected to the front end, a universal joint and the like, and drives the front wheel 1 via an axle, a transmission gear and the like in the front axle case.

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 via a suction strainer 73, and one of the oil is pumped to a power steering unit 74 by a traveling hydraulic pump 72. The power steering unit 74 is provided to reduce the torque required to operate the steering handle 10. The power steering unit 74 is a double acting power steering unit 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.

The hydraulic oil that has passed through the power steering unit 74 is branched into three, and one of the four hydraulic clutches 51, 52, 53, and 54 is operated by a main transmission control valve 80 linked to a main transmission lever 77. Is operated to perform the main shift. The other goes through the proportional pressure reducing valve 81,
The two hydraulic clutches 56 for the reverser are operated by the reverser control valve 83 linked to the reverser lever 82.
One of the wheels 57 is operated to switch the tractor between forward and reverse. The proportional pressure reducing valve 81 is constituted by a switching valve formed of an electromagnetic valve. The rest passes through the electromagnetic control valve 95 and the two hydraulic clutches 78
One of 79 is operated to switch between front wheel acceleration or four-wheel drive. At the time of increasing the speed of the front wheels, the braking devices 84 and 85 provided on the left and right sides of the rear wheels are operated to make the turning radius smaller by operating the inner one.

Next, the hydraulic circuit of the work machine control system will be described. From the oil tank 71 to the suction strainer 7
The hydraulic oil branched through 3 is a working machine hydraulic pump 86
As a result, it is pressure-fed to the working machine control unit 88 via the external hydraulic pressure take-out part 87. And the working machine lifting cylinder 8
9 and the work machine horizontal control cylinder 90 are appropriately operated to perform elevation and level control of the work machine connected to the rear end of the tractor.

Next, the hydraulic clutch for reverser 56
Control of the proportional pressure reducing valve 81 that supplies pressure to 57 will be described with reference to FIGS. 6 and 7. FIG. 6 is a configuration diagram of a control device of 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 a 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. Controlled.
Reference numeral 97 denotes a battery that supplies power to the control device 96. Then, information on whether the start safety switch 17 is ON or OFF 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.

That is, as shown in FIG. 7, when the starting safety switch is OFF, the control device 96 controls the clutch pedal 16
Is not depressed, that is, the main clutch 21
Is determined to be in a connected state, and a signal is sent to keep the proportional pressure reducing valve 81 at a sufficient pressure. Accordingly, when a sufficient pressure is supplied to the reverser control valve 83 and the reverser lever 82 associated with the reverser control valve 83 is in the forward or reverse position, the two hydraulic clutches 56 and 57 for the reverser are correspondingly provided. One is connected.

On the other hand, when the starting 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 switches the proportional pressure reducing valve 81. A signal is sent to drain the pump port of the reverser control valve 83 to make the pressure zero. Therefore, no matter whether the reverser lever 82 is in the forward, reverse, or neutral position, no hydraulic pressure is supplied to the reverser control valve 83.
57 does not operate, and the connection between the traveling clutch shaft 24 and the auxiliary transmission shaft 35 is disconnected. That is, the main clutch 21
Hydraulic clutch 56.5 for reverser located closer to axle
By disconnecting 7, the transmission of the co-rotating torque generated in the main clutch 21 to the axle when the clutch pedal 16 is depressed is prevented.

[0029]

The present invention is configured as described above.
The following effects are obtained. That is, as set forth in claim 1, an output from the engine is transmitted to an axle transmission system via a wet-type multi-plate main clutch, and a hydraulic clutch for a reverser for performing forward / reverse conversion of rotation is provided to the axle transmission system. In the agricultural tractor having the configuration provided, a switching valve is provided in a circuit for supplying pressurized oil to a detecting means for detecting connection / disconnection of the main clutch and a reverser control valve for connecting / disconnecting the hydraulic clutch for a reverser, and the switching valve and the Since the detection means is linked, the switching valve is switched when the main clutch is disengaged, and the hydraulic oil for the reverser is disengaged by not sending the pressure oil, and the rotational torque generated when the main clutch is disengaged is transmitted to the axle. This can be prevented without adding an anti-rotation brake or the like. Therefore, it is not necessary to provide a brake or the like specially in the axle transmission system, and the configuration is simple, the number of parts can be reduced, and the cost can be reduced.

According to a second aspect of the present invention, since the detection means for detecting the connection / disconnection of the main clutch is a start safety switch, the existing start safety switch can also be used as the main clutch disconnection detection means. Need not be specially provided, and a simpler configuration can be achieved, which contributes to reduction in the number of parts and cost.

[Brief description of the drawings]

FIG. 1 is a side view showing the overall configuration of an agricultural tractor according to one 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 sectional development view showing the 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 of a proportional pressure reducing valve.

FIG. 7 is a diagram showing a control flow of the control device.

[Explanation of symbols]

 Reference Signs List 5 engine 16 clutch pedal 17 starting safety switch 21 main clutch 56 hydraulic clutch for reverser (forward side) 57 hydraulic clutch for reverser (reverse side) 81 proportional pressure reducing valve 96 control device

Claims (2)

[Claims] 1. An axle transmission system in which an output from an engine is transmitted to an axle transmission system via a wet-type multi-plate main clutch, and a hydraulic clutch for a reverser for performing forward / reverse conversion of rotation is provided in the axle transmission system. In the agricultural tractor, a switching means is provided in a circuit for supplying pressurized oil to a detecting means for detecting the connection / disconnection of the main clutch and a reverser control valve for connecting / disconnecting the hydraulic clutch for the reverser, and the switching valve and the detection means are linked. A farm tractor characterized by the following. 2. The agricultural tractor according to claim 1, wherein
An agricultural tractor, wherein the detection means for detecting the connection / disconnection of the main clutch is a starting safety switch.