JP5181979B2 - Gearbox for work vehicle - Google Patents

Description

  The present invention relates to a work vehicle to which working machines for agriculture, construction, transportation, etc. are connected, and more particularly to a transmission such as a tractor.

  2. Description of the Related Art Conventionally, a transmission for a work vehicle such as a tractor has a configuration in which the hydraulic clutch is turned on and off by operating a hydraulic cylinder and operating a control valve for the hydraulic clutch. The operation of the control valve for the hydraulic clutch is controlled so that it is normally performed automatically without any manual operation. In order to make the sliding operation of the shift gear by the hydraulic cylinder smooth, it is necessary to completely disengage the hydraulic clutch. Therefore, when the shift operation by the hydraulic cylinder is started, the control valve is operated to the oil drain side to start from the hydraulic clutch. Oil for hydraulic clutch engagement operation is drained.

  Then, hydraulic oil is supplied to the hydraulic clutch after the shifting operation by the hydraulic cylinder is completed, but it takes a certain amount of time to supply the hydraulic oil necessary for the hydraulic clutch to be engaged and operated from a state where the hydraulic pressure is not present. Further, in order to shorten the supply time, there has been a problem that, when hydraulic fluid is rapidly supplied to the hydraulic clutch after completion of the shifting operation by the hydraulic cylinder, a shock connected to the hydraulic clutch is increased.

Japanese Patent Application Laid-Open Publication No. 2004-228688 discloses a traveling speed change structure for a work vehicle that includes an actuator that slides a shift gear for shifting in a driving gear transmission based on an operation command. The first clutch and a second clutch capable of rapid clutch engagement are provided in series with the travel transmission system, and (b) the second clutch is rapidly disengaged in conjunction with the start of a shift operation by the actuator; and First control means for operating the first clutch to reduce the operating pressure of the first clutch to a predetermined low pressure (P2) and disengaging the first clutch is provided. (C) The second clutch is rapidly entered in conjunction with the end of the shifting operation by the actuator. And second control means for gradually increasing the operating pressure of the first clutch to engage the clutch, and (d) detecting the clutch pedal and the depression position of the clutch pedal. Comprising a that sensor, the range of (e) a clutch pedal position (G2) is operated narrowing seen Stepping in the range up to a predetermined low pressure from the pressure (P1) of the computer enters the operating pressure of the first clutch (P2) an inner, a third control means for depressurizing the pressure corresponding to the depression position, (f) by operating narrowing seen further stepping from the clutch pedal position (G2) fourth control means for operating off a second clutch A traveling speed change structure for a work vehicle including

With the above configuration, when the shift operation by the actuator is started, the second clutch is rapidly disengaged, and the operating pressure for entering operation in the first clutch is released to a predetermined low pressure. At this time, the first clutch is not completely disengaged, but the second clutch is completely disengaged and the entire traveling system is disengaged, and the gear shifting operation is performed by the actuator. When the speed change operation is completed, the second clutch is rapidly entered and operated. However, since the first clutch is not completely disengaged, no power is transmitted, and then the first clutch is completely engaged. However, in this case, since a certain amount of operating pressure remains, the time required to fully engage the first clutch is shortened. Further, even when the operating pressure of the first clutch is increased, since the pressure is gradually increased, the shock when the first clutch is engaged does not increase.
JP-A-4-231220

In the invention described in Patent Document 1, by providing a first clutch that is turned on and off at a predetermined low pressure and a second clutch that is turned on and off rapidly, the time required for the entire speed change operation can be shortened while holding down a shock. The shift performance is improved.
As described above, in the invention described in Patent Document 1, control is performed so that the shock does not increase in a short time until the operating pressure corresponding to the clutch pedal position detected by the sensor by operating the clutch pedal. When the clutch pedal is operated rapidly, the operating pressure indicated by the clutch pedal depression position increases and the operation pressure for the engagement operation in the clutch also rises. Thus, depending on the depression position of the clutch pedal, Even when the operating pressure is high, the operating pressure rises to the instructed operating pressure (indicated pressure).

  When the shift control is performed only with the command pressure determined according to the position of the clutch pedal, the volume of the hydraulic clutch in the clutch is filled with the hydraulic oil until the torque is actually transmitted to the drive shaft or the like. Due to time and response delay (time lag) of the hydraulic valve itself, there is a difference (time difference) between the actual operating pressure and the operation of the operator.

  According to the time chart of the first clutch operating pressure, the second clutch on / off state, the clutch pedal position, etc. shown in FIG. 3 of the invention described in Patent Document 1, the clutch pedal is changed from the disengaged state position G3 to the engaged state position G1. It is moving. At that time, the clutch pedal is in the fully engaged state between the predetermined position G2 and the engaged state position G1, and the first clutch is in the half-clutch state to prevent a shock. When the clutch pedal reaches the engaged state position G1 (which is a complete connection position), the first clutch is completely engaged.

However, when the clutch pedal is moved from the predetermined position G2 and the engaged state position G1 to the engaged state position G1, it is moved suddenly, although not as much as when it is suddenly moved from the cut state position G3 to the engaged state position G1. And suddenly start. Further, when the clutch pedal comes to the engaged state position G1, the operator thinks that the clutch is completely connected at this timing, but there is a case where it is suddenly accelerated later due to a delay in the rise of hydraulic pressure.
That is, the operator recognizes that in the on-state position G1, the operator does not accelerate any more because he / she removes his / her foot from the clutch pedal. However, in such a case, if the vehicle accelerates suddenly due to a delay in the rise of hydraulic pressure, the operator's feeling is inconsistent and the operability is poor.

In this way, when the work vehicle starts to move, the operating pressure instructed by the sudden operation of the clutch pedal becomes too high and the vehicle starts suddenly, which is inconsistent with the operator's feeling and the feeling during operation is not suitable. Problems arise. In addition, sudden start is not preferable from the viewpoint of safety.
Therefore, when the shift control is performed only with the command pressure determined according to the position of the clutch pedal, it cannot be said that the operability and the safety are still excellent.

  An object of the present invention is to provide a transmission device for a work vehicle such as a tractor that is excellent in operability and safety and capable of optimal shift control.

The problems of the present invention are solved by the following means.
According to the first aspect of the present invention, there is provided a drive source (62), a traveling device (61, 63) operated by the power of the drive source (62), and a power of the drive source (62) connected from a disconnected state to a connected state. The connection state is continuously changed according to the hydraulic pressure of the internal hydraulic oil supplied or discharged until the rotational power of the drive source (62) is transmitted to the traveling device (61, 63) or is not transmitted. and the reverse hydraulic clutch before serving as a replacement for a main clutch (D), a clutch pedal (119) for adjusting the hydraulic pressure operation of the forward-reverse hydraulic clutch (D) inside the hydraulic oil, the clutch pedal (119 ) and clutch operation amount sensor for detecting an operation amount of (119a), forward and backward in accordance with the detection value detected from the clutch operation amount detecting sensor (119a) by the operation of the clutch pedal (119) Indicated pressure processing function unit that performs processing for the hydraulic pressure of the working oil pressure clutch (D) and (X), the hydraulic oil of the hydraulic clutch in accordance with the detected value of the clutch operation amount sensor (119a) (D) When the change speed of the hydraulic pressure is equal to or higher than a predetermined value, the hydraulic pressure change function includes an instruction pressure restriction processing function unit (Y) that performs a process of restricting the change speed of the hydraulic pressure of the hydraulic oil, and operates the clutch pedal (119). When the hydraulic oil pressure change rate corresponding to the detection value detected by the clutch operation amount detection sensor (119a) is greater than or equal to a predetermined value and the hydraulic oil pressure rises, the indicated pressure regulation A control device (100) having a selection function unit that performs a process of selecting the indicated pressure processing function unit (X) when the hydraulic pressure of the hydraulic oil decreases while the processing function unit (Y) is selected is provided , System The change in the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch (D) when the clutch pedal (119) is returned after the clutch pedal (119) is fully depressed, which is controlled by the device (100), is first controlled by the control device. The forward / reverse pressure boosting solenoid (90) for boosting the hydraulic pressure of the forward / reverse hydraulic clutch (D) from the dead zone area (F) of (100) and the forward solenoid (86F) for switching the forward side or the reverse side The forward / reverse hydraulic clutch (D) outputs a signal to the reverse solenoid (86R) for switching to increase the operating pressure, and then stabilizes the operating pressure by lowering the operating pressure over a longer time than when the signal is increased. Is in the non-connected state (Q), and further, when the clutch pedal (119) is continuously returned, the operating pressure rises in the half-clutch state region (R). When the pedal (119) is released, the response time is delayed and the operating pressure rises (J), and then the operating pressure becomes substantially constant and the forward / reverse hydraulic clutch (D) changes to the connected state in order. Only the region (R) in the half-clutch state where the traveling device (61, 63) starts to move and then accelerates is selected and operated by the control device (100) by the control device (100). This is a transmission for a work vehicle.

According to a second aspect of the present invention, there is provided a transmission for a work vehicle according to the first aspect , wherein at least two kinds of pressure change speeds in the half-clutch state region (R) are set and the pressure change speed can be changed. It is.
According to a third aspect of the present invention, in setting a plurality of pressure change speeds in the half clutch state region (R), the pressure change speed is set according to the difference in traction load. Device.

According to the first aspect of the present invention, the control device (100) has a change speed of the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch (D) according to a value detected by the clutch operation amount detection sensor (119a). When it is equal to or greater than the predetermined value, that is, when the change rate is fast, the command pressure regulation processing function unit (Y) that performs the process of regulating the change rate of the hydraulic pressure of the hydraulic oil instructed by the clutch pedal (119) is provided.
Therefore, even if a shift (time shift) occurs between the actual power transmission operation in the hydraulic clutch (rise of hydraulic pressure) and the operation of the operator, the amount of operation of the clutch pedal (119) when the work vehicle starts to move. The change speed of the operating pressure (sometimes referred to as the indicated pressure) instructed by is regulated and the indicated pressure changes at a constant change speed, so that torque is not transmitted at once and safety is improved. At the same time, the operator feels good and the operability is excellent for the operator.

Further , the control device (100) is configured to increase the hydraulic pressure of the hydraulic oil when a change speed of the hydraulic pressure of the hydraulic oil according to a detection value by the clutch operation amount detection sensor (119a) is a predetermined value or more. Selects the command pressure regulation processing function unit (Y), and has a function of performing a process of selecting the command pressure processing function unit (X) when the hydraulic pressure of the hydraulic oil drops.
Even if the change speed of the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch (D) corresponding to the detection value detected by the clutch operation amount detection sensor (119a) is equal to or higher than a predetermined value, the clutch pedal is depressed in the direction to depress the clutch. When the operation according to (119) is performed rapidly, the clutch is disengaged with the commanded pressure according to the operation of the clutch pedal (119).

Thus, when the hydraulic pressure of the hydraulic fluid descends suddenly, quickly by controlling so as to indicated pressure of the clutch pedal (119), a reverse hydraulic clutch before the clutch pedal (119) (D) Even if it is turned off, the hydraulic pressure of the hydraulic oil does not drop easily, and it is possible to prevent the distance traveled until the work vehicle stops. Since the distance traveled until the work vehicle stops is not increased in this way, there is not much gap between the operation of the clutch pedal (119) and the actual operation of the work vehicle for the operator, resulting in a sense of incongruity or poor operability. Can be prevented.
On the other hand, when the hydraulic pressure of the hydraulic oil rises, the change speed of the operating pressure instructed by the operation amount of the clutch pedal (119) is regulated, so that the sudden start of the work vehicle is prevented and the safety is further improved. Is increasing.
Then, the command pressure regulation processing function unit (Y) is selected and operated by the control device (100) only in the half-clutch state region (R region) where the work vehicle starts to move and then accelerates. Thus, it is possible to prevent the responsiveness due to the operator's operation instruction of the clutch pedal (119) from being deteriorated, so that it does not take time for the forward / reverse hydraulic clutch (D) to be connected.
According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the regulation pressure change rate is made variable so that regulation suitable for various conditions such as work contents, operator, etc. The pressure change speed can be set, and the work efficiency of various works, the operability of the work vehicle, and the running performance are improved.
According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, even when the command pressure due to the operation of the clutch pedal (119) rises at once, an appropriate regulation pressure change according to the traction load By changing to the speed, the operator can start and operate with the same feeling even if the traction load changes, so the operability and running performance of the work vehicle are improved.

  Embodiments of the present invention will be described below with reference to the drawings. In the present specification, left and right are respectively referred to as left and right in the forward direction of the work vehicle, and front and rear are referred to as front and rear, respectively. Here, the left and right traveling axles in the present specification refer to traveling axles in the left and right direction facing the traveling direction of the work vehicle. And according to embodiment of this invention, it demonstrates below by taking as an example the tractor which is an example of a working vehicle.

  FIG. 1 shows a left side view of a tractor according to an embodiment of the present invention, and FIG. 2 shows a power transmission diagram in the transmission of the tractor of FIG. 3 shows a hydraulic circuit diagram of the power transmission diagram of FIG. 2, and FIG. 4 shows a control block diagram of the tractor of FIG. FIG. 5 shows an enlarged side view around the clutch pedal.

  The tractor vehicle body T having the riding mode of riding four-wheel drive travels while steering the front wheels 61 with the steering handle 73 (FIGS. 6 and 7). A work machine such as a rotary tiller can be mounted on the rear part of the vehicle body T so as to be lifted and lowered by a three-point link mechanism. The vehicle body T has an engine 62 mounted on the front end via an engine bracket that is supported on a front axle housing (not shown), 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 (not shown) is provided at the rearmost portion of the transmission case 65, and the rear wheels 63 are mounted on the left and right sides.

FIG. 2 shows a power transmission diagram in the transmission of the tractor of FIG.
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.

  2 is provided with a PTO clutch pack 66 on a PTO countershaft 9 having a PTO shift counter gear 44 linked to an input gear 31 from an input shaft 2 driven by the engine shaft 1. Yes. The configuration of the PTO power transmission unit including the PTO clutch pack 66 and the input gear 31 is referred to as a PTO clutch E.

  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. A transmission including the four main transmission gears 33 is referred to as a main transmission hydraulic clutch A.

  Of the four main transmission gears 33 of the main transmission hydraulic clutch A, the main transmission gear 33 (for first speed) having the smallest effective diameter and the third main transmission having the smallest effective diameter are disposed on the main transmission shaft 19. A clutch pack 76 is fixed between the 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 second speed) having the largest effective diameter. The clutch pack 76 is fixedly provided between the 4th speed). 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.

  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 configuration including these gear 42, clutch pack 60 and the like including a hydraulic cylinder 85 (FIG. 3) to be described later is referred to as a forward / reverse hydraulic clutch D. The forward / backward hydraulic clutch D is continuously connected in accordance with the hydraulic pressure of the internal hydraulic oil supplied or discharged from the disconnected state to the connected state of the power of the engine 62.

Further, a forward / reverse switching lever 115 (FIG. 6) for manually switching the forward / backward hydraulic clutch D is provided at the post portion of the steering handle 73, and a clutch pedal (clutch operating means) 119 (FIGS. 5, 6, 7) is provided. ) Is provided under the foot of the handle post.
By operating the clutch pedal 119, an instruction pressure processing function unit (X) of a controller (control device) 100 described later (X) (see FIG. 2) so that the operating pressure according to the operation amount (operation position) of the clutch pedal 119 is obtained. According to 4), the hydraulic pressure of hydraulic oil supplied to or discharged from the forward / reverse hydraulic clutch D (hydraulic pressure of hydraulic oil inside the forward / backward hydraulic clutch D) can be adjusted.
As shown in FIG. 5, a return spring 120 is connected to the upper part of the clutch pedal 119, and a return gas damper 121 is connected to the lower part, and the clutch pedal 119 is attached upward by the return spring 120 and the return gas damper 121. It is energized. When the clutch pedal 119 is depressed or returned in the direction of the arrow L, the operation position (corresponding to the operation amount) of the clutch pedal 119 is detected by a clutch pedal sensor 119a (potentiometer or the like).

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 capable of switching between high speed and low speed is referred to as a high / low shift clutch 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 gear transmission mechanism C.

Further, a creep counter shaft 21 having a creep counter gear 49 that meshes with the auxiliary transmission gear 35 is provided in parallel 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.
This traveling power transmission system is provided with a forward / reverse rotation PTO which is a transmission mode for rotating the PTO interlocking shaft 4 provided with a PTO forward / reverse switching gear 37 mechanism.

  A front wheel interlocking gear 51 that has a front wheel interlocking gear 51 that rotatably supports the subtransmission countershaft 27 of the subtransmission countergear 38 that meshes with the subtransmission gear 35 and that is interlocked from the output shaft 3 via the front wheel take-out gear 36. A shaft 28 is provided, and a PTO reduction shaft 23 having a PTO reduction gear 50 is provided on the front extension axis 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 composed of a main transmission hydraulic clutch A having four speeds and a second speed through a forward / reverse hydraulic clutch D constituting the main clutch. The high and low speed transmission clutch B and the auxiliary transmission gear transmission mechanism C composed of three speeds are used to change the speed to any one of the total 24 speeds, and the resulting rotational power passes through the rear differential 45 and the rear wheels 63 Driven. Further, the rotational power changed by the auxiliary transmission gear transmission mechanism C is also transmitted to a front wheel drive clutch pack (two-wheel drive / four-wheel drive switching clutch) 67, which causes the front wheels 61 to be “constant speed” or “acceleration”. , The front wheel 61 is driven via 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 power transmission diagram of FIG.
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, a PTO clutch switching valve 105, a PTO clutch proportional pressure control valve 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 supplied to a hydraulic clutch cylinder 88 that operates the gears 33 for the fourth speed and the second speed of the main transmission hydraulic clutch A via the clutch pack 76 via the pressure reducing valve 81a. The main transmission (2-4) clutch proportional pressure control valve (2-4 speed boosting solenoid) 89 for switching the hydraulic clutch cylinder 87 is supplied to each gear for the first speed and the third speed of the main transmission hydraulic clutch A. 33 is supplied to a main transmission (1-3) clutch proportional pressure control valve (1-3 speed boosting solenoid) 93 for switching between the hydraulic clutch cylinder 91 and the hydraulic clutch cylinder 92, respectively.

  The hydraulic fluid that passes through the pressure reducing valve 81a is switched by a switching valve 86 (forward solenoid 86F, forward hydraulic clutch D) that switches between the forward and reverse hydraulic clutches D of the forward / reverse clutch cylinder 85 via the on / off control valve 129 of the forward / reverse clutch cylinder 85. The reverse solenoid 86R) is supplied. The forward clutch pressure sensor 110 (FIG. 4) and the reverse clutch pressure sensor 111 (FIG. 4) detect whether the hydraulic oil is supplied to the forward or reverse hydraulic clutch D of the forward / reverse clutch cylinder 85. it can. Further, a forward / reverse boost solenoid 90 for boosting the hydraulic pressure of the forward / reverse clutch D is provided.

  Similarly, the hydraulic oil supplied to the hydraulic clutch cylinders described above and below is a pressure sensor (for example, for the first to fourth speeds of the hydraulic clutch A) provided in the oil passage on the inlet side to each hydraulic clutch cylinder. Or the pressure sensor 146 of the PTO clutch E (FIG. 4)). In addition, as shown in FIG. 4, when the signals of the sensors and switches are input to the controller 100, the controller 100 outputs signals corresponding to the instructions of the sensors and switches to the display unit 215 of the meter panel 213. To display it.

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

  When the clutch pedal 119 is not operated (when the foot pedal 119 is not depressed), the forward / reverse switching clutch packs 60 and 60 are in a connected state (a state in which the clutch is engaged), and the engine power moves forward in the transmission. Is transmitted to the drive mechanism on the side or the drive mechanism on the reverse drive side. When the clutch pedal 119 is operated (when the foot pedal 119 is depressed), the forward or reverse clutch pack 60 is released (clutch disengaged state). Switching between the forward side and the reverse side is performed by the forward / reverse lever 115.

6 shows a top view of the vicinity of the cockpit of the tractor of FIG. 1, FIG. 7 shows a perspective view of the same, and FIG. 8A shows the switch box 180 shown in FIGS. A plan view is shown, and FIG. 8B shows a side view of FIG.
On the left side of the pilot seat 16 of the tractor, the forward / reverse switching lever 115 for switching the tractor forward and backward, the parking brake 172, and the PTO change lever 173a on the front side can be changed to 2nd speed-N (neutral) -1st speed. ), The rear PTO change lever 173b and the like are arranged. There are three types of PTO change levers 173b on the rear side depending on the model (the same figure is shown except that the functions are different).

  The Z type is a forward / reverse switching lever (forward rotation on the front side and reverse rotation on the rear side), and the WX type is an economy PTO switching lever (front side is off-rear side is on). . The GWD type is a ground PTO switching lever (the front side is turned off and the rear side is turned on). When turned on, the rotation of the PTO shaft is synchronized (synchronized) with the vehicle speed.

  On the other hand, on the right side of the pilot seat 16 of the tractor, an accelerator pedal 175 and an accelerator lever 176 (increase the engine speed when it is tilted forward, it becomes idling when it is closest to the front), and further a farm field, construction, civil engineering workshop, etc. There is an engine speed storage switch 177a for setting an engine speed at the time of work in a work area (hereinafter referred to as “farm field”) and storing it in the memory (storage unit) 100a. The engine speed storage switch 177a is a so-called seesaw switch. When the upper or lower side is pressed and the finger is released, the engine speed storage switch 177a automatically returns to the non-pressed state. In addition, the memory 100a of the controller 100 is a changeover switch because two kinds of engine speeds can be stored.

  For example, when the upper side of the engine speed storage switch 177a is pressed, the engine speed becomes the A speed, and when the lower side is pressed, the B speed becomes the B speed. When the upper side is pressed and the finger is released, the engine speed memory switch 177a returns to the position before the press, but the switch 177a is in the on state, and the engine speed is controlled and held by the controller 100 so that it becomes the A speed. Is done. Similarly, when the lower side is pressed and the finger is released, the engine speed storage switch 177a returns to the position before pressing, but the switch 177a is in the on state, and the engine speed is controlled by the controller 100 to the B speed. Retained. The engine speed is detected by the engine speed sensor 112 (FIGS. 2 and 4).

  In the case of the present embodiment, an example in which two different engine speeds can be stored is shown, but a configuration in which three or more higher engine speeds can be stored may be used. In this case, it is necessary to change the switch. For example, when the switch is configured to see up and down and to the left and right, four rotational speeds can be stored.

  The engine speed setting switch 177b behind the engine speed memory switch 177a is also a seesaw switch. When the upper side or the lower side is pressed and the finger is released, the state automatically returns to the non-pressed state. Then, after pressing the engine speed memory switch 177a (upper or lower), pressing the upper side of the engine speed setting switch 177b in the pressed state increases the engine speed, or pressing the lower side rotates the engine speed. The number goes down. The engine speed storage switch 177a does not have to be pressed. The newly set rotation speed is stored in the memory 100a.

  Further, an auxiliary transmission lever 179 (low speed, medium speed, high speed, road speed) is provided behind the accelerator lever 176. The low speed is 8 speeds, the medium speed is 8 speeds, the high speed is 8 speeds, and the road speed is 4 speeds ( A shift such as a high-speed 8-speed upper 4-speed) is possible. The auxiliary transmission lever 179 operates in the front-rear direction and the left-right direction along the lever guide 179a. When it is tilted to the front right side, it moves at a high speed 179c, when it is tilted to the front left side, it travels on the road 179b. When defeated, the speed becomes 179e. The front-rear direction position and the left-right direction position are detected by a sub-shift lever position sensor (not shown), and the sensor signal is input to the controller 100 (FIG. 4). In addition, operations of gear stages such as main shift increase / decrease switches (sensors) 192 a and 192 b described later are also input to the controller 100.

  Further, a forward / reverse lever sensor 167 (FIG. 4) for detecting the operation position of the forward / reverse switching lever 115, an accelerator position sensor 175a (FIG. 4) for detecting the depression position of the accelerator pedal 175, and a clutch for detecting the operation position of the clutch pedal 119. When a sensor signal from the pedal sensor 119a or the like is input to the controller 100, the controller 100 performs control according to each operation content.

FIG. 2 shows an enlarged view of the auxiliary transmission gear transmission mechanism C.
When the position of the auxiliary transmission lever 179 is low, the gear 137 meshes with the gear 139, and the transmission flow is the auxiliary transmission shaft 20, the auxiliary transmission gear 35, the auxiliary transmission counter gear 38, the gear 134, the gear 140, the gear 135, and the creep counter. The gear 49a, the creep counter gear 49b, the gear 136, the gear 139, the gear 137, and the output shaft 3 are provided.

When the position of the auxiliary transmission lever 179 is medium speed, the gear 131 meshes with the gear 133, and the transmission flow is the auxiliary transmission shaft 20, the auxiliary transmission gear 35, the auxiliary transmission counter gear 38, the gear 134, the gear 140, the gear 133, and the gear. 131, the output shaft 3.
When the position of the auxiliary transmission lever 179 is high, the gear 131 meshes with the gear 130, and the transmission flow is the auxiliary transmission shaft 20, the auxiliary transmission gear 35, the gear 130, the gear 131, and the output shaft 3.
At the road traveling speed, there is no change in the position of the sub-shift lever, and it is in the high-speed position, and the upper four speeds (5-speed to 8-speed) are used.

  The sub-transmission gear transmission mechanism C in the transmission has three stages, but the shift position of the sub-transmission lever 179 is four stages (low speed 179e, medium speed 179d, high speed 179c, road traveling speed 179b). Since the main transmission hydraulic clutch A has four stages and the high / low transmission clutch B has two stages, the number of shift stages corresponding to the sub-shift positions at low speed, medium speed, and high speed is eight. That is, the sub-shift is 8 steps at low speed, the sub-shift is 8 steps at medium speed, and the sub-shift is 8 steps at high speed. The road traveling speed is four stages on the upper side (high speed side) of the eight high speeds, and only the upper four stages are used by the controller 100. Therefore, even if the auxiliary transmission lever 179 is set to the road traveling speed, the transmission mechanism in the transmission does not move and remains at the high speed position.

  The first sub-control lever 178a is an external hydraulic pressure takeout lever for supplying high-pressure oil when the rotary tiller device of the tractor is removed to drive another working machine. A sub-control lever second station 178b is disposed behind the sub-control lever first station 178a, and a third station (not shown) or a fourth station (not shown) may be provided.

  The draft ratio adjustment dial 182 is a dial for adjusting the sensitivity of the draft control. The dial ratio adjustment dial 182 is set to the position side when turned to the left side, becomes the draft side when turned to the right side, and is set regardless of the load as it is set to the position side (left side). This is the control to maintain the tillage depth. Further, when the draft ratio adjustment dial 182 is turned to the right, priority is given to load. That is, when a load greater than a predetermined value acts on the work implement, control is performed so that the lifting cylinder of the work implement (not shown) of the work implement (rotary tillage device, etc.) is slightly raised in order to reduce the load below the working depth.

Therefore, the draft ratio can be adjusted according to the state of the field and the preference of the operator. Table 1 shows the relationship between the adjustment of the draft ratio and the state of the field.
(Table 1)
Draft ratio 1 5
Adjustment dial (turn counterclockwise) (turn clockwise)
Plowing depth Shallow ← → Deeper Soil Light ← → Heavy

  In other words, as the position is turned to the position side (left), the amount of change in the vertical tillage of the rotary tiller with respect to the load decreases, and the plowing depth is given priority. As the draft is turned to the right (right), the amount of change in the lift of the rotary tiller with respect to the load increases and the load is reduced.

  The raising adjustment dial 183 of the rotary tiller is for adjusting the height of the rotary tiller, and when turned to the left, the height of the rotary tiller is lowered, and when turned to the right, the height is increased. With the raising adjustment dial 183, the height of the three-point link mechanism of the rotary tiller can be adjusted. Depending on the working machine, it may hit the tractor body when it is raised to the highest level, but such a problem can be prevented by adjusting the height of the working machine by the expansion and contraction of the lift cylinder. In addition, a work machine that does not need to be raised so much can be adjusted with the raising adjustment dial 183 to perform efficient work.

The tilt adjustment dial 184 adjusts the tilt of the rotary tiller, and when it is turned to the left, it goes up to the right, and when it is turned to the right, it goes down to the right. Further, the 4WD change-over switch 185 can be switched between a traveling loader, 2WD, 4WD, full turn and 2WD turn.
The traveling loader is used during road traveling and loader work, and is usually a two-wheel drive. However, if the tractor enters a muddy area or becomes a steep slope or uneven road, it automatically becomes a four-wheel drive. Then, when the brake is applied, it automatically becomes four-wheel drive, and when it stops during driving, it becomes four-wheel drive. In other words, the four-wheel drive enables the travel brake function to be more exerted than in the case of the two-wheel drive, and the travel stop can be stably performed.

  In the case of 2WD (two-wheel drive), the rear wheels 63, 63 are driven, and in the case of 4WD (four-wheel drive), the four wheels (front wheels 61, 61, rear wheels 63, 63) are driven. Further, in the full turn, the speed of the front wheels 61 and 61 is increased when turning in 4WD, and the turn becomes quick. Further, in a hard field or the like, the 2WD turn is driven by the front wheels 61 and 61 only when turning, so that the turning can be performed quickly and smoothly.

Further, by manually operating a manual raising / lowering switch 186 of a horizontal cylinder (not shown), a horizontal cylinder of a three-point link mechanism such as a rotary tiller can be moved. And the right-and-left inclination of a rotary tiller is adjusted with the state of a farm field. The manual raising / lowering switch 186 is used for attaching / detaching a working machine such as a rotary tiller.
Further, when the PTO on / off switch 187 is pressed and turned to the right, the PTO is turned on and the rotary tiller is activated. When the PTO is turned on, the rotary tiller is stopped when the PTO is automatically turned off. Further, when the PTO manual automatic switch 188 is turned to the left, it becomes manual, and the operation of the rotary tiller is manually set and operated. In this case, the rotary tiller is always operated when the PTO shift is turned on by the PTO on / off switch 187.

Further, when the PTO manual automatic switch 188 is turned to the right, the automatic operation is performed automatically. In this case, when the rotary tiller is raised, the rotation of the rotary tiller is automatically stopped, and when the rotary tiller is lowered, the rotation of the rotary tiller is automatically resumed.
When the PTO manual automatic switch 188 is set to the manual side, when the PTO on / off switch 187 is on and a change is made (which means a state when the PTO change lever 173 is not neutral) The PTO shaft 14 rotates. When the PTO manual automatic switch 188 is set to the automatic side, the rotation is stopped by stepping on the clutch pedal 119 or raising the rotary tiller. This function is mainly used for paddy field work.

The diff lock switch 189 is a seesaw switch. When the opposite side of the cockpit 16 is pressed, the diff lock switch is set. When the diff lock switch 189 is pressed again, the diff lock is released. In addition, in order to prevent an erroneous operation due to the operator's arm being inadvertently hit, the seat 16 side cannot be pushed.
And the work implement position lever 190 for controlling the raising / lowering position of the work implement is disposed on the armrest portion 30 on the right side of the cockpit 16, and when the work implement position lever 190 is tilted to the rear side, the work implement rises, When the machine is tilted forward, the work implement descends. By detecting the operation angle of the work machine position lever 190 with a potentiometer (not shown), the work machine moves up and down according to the detected value.

  The work implement lift switch 191 is a seesaw switch. When the rear side is pushed once, the rotary tiller is raised to the maximum position, and when the front side is pushed once, the work implement lift lever 191 is lowered to the set position of the work implement position lever 190. The maximum position is a position adjusted with the raising adjustment dial 183.

  Further, the main shift increase / decrease switches 192a and 192b are switches for shifting up (shifting down) the shift stage of the main shift, and the shift stages (low speed, medium speed, high speed, road driving) operated by the sub shift lever 179. Speed) for further manual shifting. As described above, the main gear speed increase / decrease switch 192a, 192b further reduces the low speed to 8 speeds (1st to 8th speed main shift position), the medium speed to 8 speeds (1st speed to 8th speed main shift position), and the high speed to Further, it is possible to shift to 8 speeds (1st to 8th main shift position) and a road traveling speed to 4th speed (usually high speed 5th to 8th main shift position).

  The main shift speed increasing switch 192a is a switch for shifting up the shift stage (main shift position) of the main shift, and the shift stage is shifted up each time it is pressed, and the main shift deceleration switch 192b is shifted down the shift stage. This switch shifts the gear position every time it is pressed. Regardless of the engine speed, when manually operated, the speed is changed according to the operated gear.

There is a cigar lighter 194 behind these switches. A work machine ascent / descent monitor lamp 195 in the switch box 180 is lit when a work machine such as a rotary tiller is raised or lowered. The AT shift work sensitivity dial 196 acts when an AT shift work switch 200 described later is turned on.
When the AT shift work switch 200 is turned on, an automatic shift (auto drive) described later operates, but the AT shift work sensitivity dial 196 is a dial that changes the sensitivity of the automatic shift that automatically increases and decreases the vehicle speed. Turn to the right to increase sensitivity and turn to the left to decrease sensitivity. When the switch in the switch box 180 is not operated, the lid 211 is closed to prevent dust and the like from entering the switch box 180.

  The lowering speed dial 197 is a dial for adjusting the work implement lowering speed, and when turned to the right, the speed increases and the work implement descends faster. Therefore, it is suitable for a working machine having a light weight (for example, a paddy paddy machine). On the other hand, when it is turned to the left, the speed decreases and the work machine descends slowly. In this case, it is suitable for a heavy work machine (for example, a ski work machine).

  When the brake adjustment dial 198 is turned to the left, the brake is weakened, and when it is turned to the right, the brake is applied strongly. The brake adjustment dial 198 acts when an auto brake on / off switch 206 described later is turned on.

  Further, when the AT shift road switch 199 is turned on, an appropriate gear position of the upper four speeds of the eight auxiliary gear shift high speeds according to the engine speed when traveling on the road with the auxiliary gear shift lever 179 set to the road traveling speed. The automatic shift function capable of shifting automatically is turned on, and automatic shift control is performed. When the AT shift road switch 199 is turned on, even if the main shift increase / decrease switches 192a and 192b are operated, the shift is made only by depressing the accelerator pedal 175.

  Note that the main shift increase / decrease switch 192a, 192b is manually operated when the AT shift road switch 199 is turned off. When the sub-shift is on the road, the upper four speeds (5 to 8) of the sub-shift high speed are used. When the AT shift road switch 199 is off, the main shift increase / decrease switches 192a and 192b are operated. Thus, for example, when the third speed to the eighth speed are set, and then the AT shift road switch 199 is turned on, the automatic shift is performed between the third speed and the eighth speed only by operating the accelerator pedal 175.

  When the AT shift work switch 200 is turned on, the main shift position (8th speed from 1st to 8th speed) in the memory 100a has the longest usage time at each position (low speed, medium speed, high speed) of the auxiliary speed change lever 179. However, when the AT shift work switch 200 is turned on and the sub-shift lever 179 is operated to shift (low speed, medium speed, high speed), the main shift position stored in the memory 100a is reached. The gear is automatically shifted.

  When the AT shift on-road switch 199 is turned on when the sub-shift lever 179 is on the road at the road speed, the shift is automatically controlled according to the engine speed, and only the clutch 119 is operated when starting and stopping. No shifting operation is required. Even if the clutch pedal 119 is not depressed, if the forward / reverse switching lever 115 is neutral, the vehicle body T is in a stopped state. If the accelerator pedal 175 is depressed by operating the forward / reverse switching lever 115, the acceleration is accelerated. While automatic shifting. During automatic shift (automatic drive) control, the vehicle is automatically shifted so that the vehicle speed corresponds to the engine speed corresponding to the amount of depression of the accelerator pedal 175.

  That is, when the accelerator pedal 175 is depressed, the engine speed becomes high and the current main shift position (the current shift position of the eight-speed shifts of the main shift hydraulic clutch A and the high / low shift clutch B in FIG. 2). However, if it is not possible to increase the vehicle speed even after accelerating in 8), the controller 100 shifts up to the current shift position. When decelerating by stepping on the brake, the accelerator pedal 175 is not stepped on, so the gear is automatically shifted to a shift position corresponding to the vehicle speed.

  When the connection sensitivity shift switch 201 is pressed, the connection sensitivity is switched on when the connection sensitivity shift switch 201 is pressed again. When the connection sensitivity shift switch 201 is switched on and off, the connection feeling when the main shift is shifted by the main transmission hydraulic clutch A can be changed. For example, when the connection sensitivity shift switch 201 is turned on, the lamp 201a is turned on to perform a gradual shift, and when turned off, the lamp 201a is turned off to make a quick connection (fast clutch connection). When the connection sensitivity shift switch 201 is turned off in the operation of the traction system for attaching a plow or the like to the rear portion, the connection time of the main transmission hydraulic clutch A is shortened when the main transmission hydraulic clutch A performs a shift operation of the main transmission.

Further, the connection sensitivity PTO switch 202 can change the way the PTO clutch E is connected. Each time the connection sensitivity PTO switch 202 is pressed, the light is turned on in the order of rotary, pasture 1 and pasture 2. When the connection sensitivity PTO switch 202 is set to a rotary, the connection of the PTO clutch E becomes faster. Mainly used on working machines such as rotary tillers. As soon as the PTO shaft 14 begins to rotate, it rotates with a rotational force that does not lose the resistance of the soil in the field.
Further, when the connection sensitivity PTO switch 202 is set to pasture 1 or pasture 2, the connection of the PTO clutch E becomes loose. There are two types of shifts possible with pasture 1 and pasture 2. Mainly used for work machines that slowly connect the PTO clutch E, such as pasture work machines and snow blowers. The connection sensitivity PTO switch 202 is used on the PTO shaft 14 in the same manner as when the rotary is used.

  The horizontal sensitivity switch 203 is a switch for switching the operation sensitivity of the automatic horizontal control device of the work machine. When the horizontal sensitivity switch 203 is pressed, the operation sensitivity becomes dull and the movement of the automatic horizontal control becomes slow. When the horizontal sensitivity switch 203 is pressed again, the operation sensitivity is restored. When the backup on / off switch 204 is turned on, the rotary tiller automatically rises when the tractor moves backward.

  When the auto lift on / off switch 205 is turned on and the steering handle 73 is turned, the rotary tiller is automatically raised. When the auto brake on / off switch 206 is turned on and the steering handle 73 is turned, the brake is automatically applied only to the rear wheel 63 on the inside of the turn. The horizontal changeover switch 207 can perform horizontal control of a working machine such as a rotary tiller. When the horizontal selector switch 207 is pressed, the lamps are lit in the order of automatic horizontal, manual, parallel, and inclined. In the automatic level, the level is automatically maintained by a level sensor (not shown). In the case of manual operation, the tilt adjustment dial 184 is used for manual adjustment. In parallel, the rotary tiller is always kept parallel to the tractor body T. And in inclination, it controls so that a rotary tiller may have a fixed angle with respect to the ground.

  The three-point selector switch 208 selects the three-point selector switch 208 of the switch box 180 by selecting a mounting hole for a lift cylinder (not shown). Select 1 for category 1 work machines (when attaching to the front hole of the lower link), and select 2 for category 2 work machines (when attaching to the rear hole of the lower link). Then, when the auto accelerator switch 209 is turned on and the rotary tiller is raised, the engine speed is reduced to about 1700 rpm.

  Depending on the tractor, there is a case where a main clutch that is turned on and off in accordance with the operation of the clutch pedal 119 is provided on the input shaft 2 on the upstream side of the input gear 31. However, according to the present embodiment, the main clutch is not provided. Instead, the forward / reverse clutch D is controlled.

  According to this embodiment, by operating the clutch pedal 119, the operation position (corresponding to the operation amount) of the clutch pedal 119 is detected by the clutch pedal sensor 119a, and the forward / reverse hydraulic pressure is based on the detected value. The hydraulic pressure (also referred to as operating pressure) of the hydraulic oil inside the clutch D is adjusted. The controller 100 is provided with a command pressure processing function unit (X) that outputs to the forward solenoid 86F or the reverse solenoid 86R so as to obtain an operating pressure (also referred to as a clutch operation command pressure) according to the operation position of the clutch pedal 119. Therefore, the operating pressure is controlled to an instruction pressure (an operating pressure instructed by the operation of the clutch pedal 119) determined according to the operation position of the clutch pedal 119. Within the controller 100, there is a conversion table for comparing the detected value (sensor value) detected by the clutch pedal sensor 119a with the operating pressure. Using this conversion table, the detected value is changed to a pressure value and the pressure value is output as an output value. It is said.

  When the clutch pedal 119 is fully depressed (the forward / reverse switching clutch packs 60 and 60 are disconnected), the operating pressure indicated by the depression position of the clutch pedal 119 increases and the forward / reverse hydraulic clutch D However, even when the operating pressure corresponding to the depression position of the clutch pedal 119 is high as described above, the operating pressure (indicated pressure) is also increased.

  When the shift control is performed only with the command pressure determined according to the operation position of the clutch pedal 119, that is, when there is only the command pressure processing function unit (X), the volume in the forward / reverse hydraulic clutch D is the hydraulic fluid. The time until the torque is actually transmitted to the drive shaft (the shaft downstream of the forward / reverse hydraulic clutch D) or the response delay of the output itself to the forward solenoid 86F or the reverse solenoid 86R (time lag) The actual operating pressure and the operator's operation will deviate due to the above. Moreover, it is further delayed when the oil temperature (outside temperature) is low. If there is a shift (time shift) between the actual power transmission operation in the forward / reverse hydraulic clutch D (rising of hydraulic pressure) and the operator's operation, an instruction is given by rapidly returning the clutch pedal 119 when the tractor starts to move. The pressure becomes too high and the vehicle starts suddenly, which is different from the operator's feeling and causes problems such as the feeling of being out of operation. For example, a phenomenon occurs in which acceleration occurs despite the fact that the clutch pedal 119 is lifted (at this time, the operator thinks it will not accelerate any more).

  Therefore, according to the present embodiment, the controller 100 has the change speed of the operating pressure corresponding to the detected value detected by the clutch pedal sensor 119a in addition to the indicated pressure processing function unit (X) equal to or higher than a predetermined value. In other words, that is, when the clutch pedal 119 is operated faster than the preset operating speed of the clutch pedal 119, the operating pressure indicated by the depression position of the clutch pedal 119 is output to the forward solenoid 86F or the reverse solenoid 86R. An instruction pressure regulation processing function unit (Y) for performing a process for regulating the change speed is provided.

  Therefore, even if a shift (time shift) occurs between the power transmission operation (rising of the hydraulic pressure) in the actual forward / reverse hydraulic clutch D and the operation of the operator, the operation of the clutch pedal 119 is performed when the tractor starts to move. The change speed of the command pressure is regulated, and the command pressure changes slowly at a constant change speed (preset operation speed), so that torque is not transmitted at once and safety is improved. The operator feels the same and the operability is excellent for the operator.

FIG. 9 shows a control example by the controller 100 of the changing speed of the hydraulic pressure (working pressure) of the hydraulic oil in the forward / reverse hydraulic clutch D by the pedal operation of the clutch pedal 119.
The horizontal axis in FIG. 9 indicates time (t), and the vertical axis indicates the operating pressure (kgf / cm ² ). Further, FIG. 9 shows that the clutch pedal 119 is returned after the clutch pedal 119 is completely depressed (the forward / reverse switching clutch packs 60 and 60 are in a disconnected state and the time (t) = 0 at this time). The change of the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch D is shown.

  The straight line P in FIGS. 9A and 9B is a straight line indicating the change speed of the indicated pressure (indicated pressure change speed) determined according to the operation position of the clutch pedal 119, and the straight line K is the above-mentioned line K. It is the straight line which shows the change speed (regulation pressure change speed) of the control pressure which controls the command pressure change speed. 9A and 9B, the straight line indicated by the solid line is the operating pressure that is actually controlled by the controller 100. That is, as shown by the straight line K in FIG. In (b), the operating pressure is controlled like a straight line P.

For example, as shown in FIG. 9A, when the change speed (inclination of the straight line P) of the indicated pressure determined according to the operation position of the clutch pedal 119 is larger than a predetermined value (inclination of the straight line K), When the gradient of the straight line P is steeper than the gradient of the straight line K, the operating pressure is not controlled as in the straight line P (dotted line), but is controlled as in the straight line K (solid line) indicating the regulated pressure change rate. The predetermined value is a preset operation speed of the clutch pedal 119 and is, for example, about 1 to ² kgf / cm ² per 500 msec.

  On the other hand, as shown in FIG. 9B, when the change speed (inclination of the straight line P) of the command pressure determined according to the operation position of the clutch pedal 119 is smaller than a predetermined value (inclination of the straight line K), When the slope of the straight line P is gentler than the slope of the straight line K, the operating pressure is not controlled unlike the straight line K (dotted line) indicating the regulated pressure change speed, and the straight line P (solid line) indicating the command pressure change speed is not controlled. To be controlled.

  By adopting this configuration, when the change speed of the operating pressure corresponding to the detected value detected from the clutch pedal sensor 119a by the operation of the clutch pedal 119 is equal to or higher than a predetermined value, that is, the straight line P indicating the change speed of the indicated pressure. When the inclination (gradient) of the valve is steep, it is not controlled by the change speed of the command pressure according to the operation amount of the clutch pedal 119, but is regulated by preventing a sudden increase in the change speed of the operating pressure by applying a constant pawl. As a result, the safety of the tractor is improved. Further, the deviation between the power transmission operation in the forward / reverse hydraulic clutch D and the operator's operation is eliminated, the feeling at the time of the operator's operation is matched, and the operability is excellent for the operator.

  Further, as described above, the detected value is changed to the pressure value using the conversion table in the controller 100, and the pressure value is used as the output value. However, as the clutch pedal 119 is moved at a higher speed, the detected value is replaced with the pressure value. Detection is detected by the clutch pedal sensor 119a if only the change speed of the indicated pressure or the regulation pressure (gradient of the straight lines P and K) is observed. You may judge directly by the value. It does not matter if a high-speed CPU is installed.

FIG. 10 shows another example of control by the controller 100 of the changing speed of the hydraulic pressure (working pressure) of the hydraulic oil by operating the clutch pedal 119.
Further, when the change speed of the operating pressure in the hydraulic clutch D according to the detected value detected from the clutch pedal sensor 119a by the operation of the clutch pedal 119 is a predetermined value or more, the operating pressure according to the detected value is When the pressure rises (when the straight line P indicating the change speed of the command pressure has a positive slope), the command pressure regulation processing function unit (Y) is selected and the detection value detected by the clutch pedal sensor 119a is selected. When the operating pressure decreases (when the slope of the straight line P indicating the change rate of the command pressure becomes a negative gradient), the controller 100 has a function unit that performs processing for selecting the command pressure processing function unit (X). It may be provided.

  The case where the operating pressure (indicated pressure) corresponding to the detected value detected from the clutch pedal sensor 119a is increased by the operation of the clutch pedal 119 means that the slope of the straight line P becomes a positive slope, and the clutch pedal sensor The case where the operating pressure corresponding to the detection value detected by 119a decreases means that the slope of the straight line P becomes a negative slope. Therefore, in the example shown in FIG. 9, the case where the operating pressure according to the detected value detected by the clutch pedal sensor 119a increases is shown.

  In the case where the command pressure is rapidly decreased by rapidly depressing the clutch pedal 119, even if the change speed of the operating pressure in the hydraulic clutch D according to the detected value detected by the clutch pedal sensor 119a is equal to or higher than a predetermined value. That is, even when the slope of the straight line P indicating the change speed of the command pressure is steep, by controlling the clutch pedal 119 so that the command pressure of the clutch pedal 119 is quickly reached, the operating pressure can be easily reduced even when the clutch is disengaged by the clutch pedal 119. It is possible to prevent the distance traveled before the tractor stops without being lowered. In addition, since the moving distance until the tractor stops is not increased in this way, there is not much gap between the operation of the clutch pedal 119 and the actual operation of the tractor for the operator, and there is a sense of incongruity or the operability is deteriorated. Can be prevented.

  On the other hand, when the operating pressure rises, the speed of change of the command pressure by the operation of the clutch pedal 119 is restricted, thereby preventing the tractor from starting suddenly and improving safety.

FIG. 10 shows a case where the hydraulic pressure of the hydraulic oil is lowered by depressing the clutch pedal 119 after the operating pressure is controlled as shown in FIG. Also in FIG. 10, the command pressure of the clutch pedal 119 is indicated by a straight line P as in FIG. 9, but when the command pressure of the clutch pedal 119 increases for easy viewing (when the clutch pedal 119 is returned from the depressed state, When the forward / reverse switching clutch packs 60, 60 change from the non-connected state to the connected state), the straight line P1 is used. When the indicated pressure of the clutch pedal 119 decreases (when the clutch pedal 119 is depressed from the non-operating state, (When the forward switching clutch packs 60, 60 change from the connected state to the disconnected state) is represented as a straight line P2.
A straight line H in FIG. 10 indicates a case where the clutch pedal 119 is not operated, that is, a case where the forward / reverse switching clutch packs 60 and 60 are connected and the tractor is traveling.
Then, when the tractor stops, when the clutch pedal 119 is depressed from the non-operating state, the command pressure (indicated by the straight line P2) of the clutch pedal 119 decreases. When the clutch pedal 119 is depressed, even if the change speed of the operating pressure in the hydraulic clutch D is equal to or higher than a predetermined value, that is, the slope of the straight line P indicating the change speed of the indicated pressure of the clutch pedal 119 is steep ( Even when the inclination (absolute value) of the straight line P is larger than that of the straight line K), the controller 100 causes the command pressure of the clutch pedal 119 to quickly reach the indicated pressure by selecting the indicated pressure processing function unit (X). Be controlled.

  By adopting this configuration, when the operating pressure corresponding to the detected value detected by the clutch pedal sensor 119a decreases, the change speed of the operating pressure in the hydraulic clutch D corresponding to the detected value is a predetermined value or more. Even if it exists, it is quickly controlled to the command pressure of the clutch pedal 119. Therefore, when the operator depresses the clutch pedal 119 and disconnects the hydraulic clutch D, the operating pressure quickly decreases to the command pressure of the clutch pedal 119, so that the distance that the tractor moves before stopping can be prevented. . And since the movement distance until the stop of the tractor does not become longer in this way, there is not much gap between the operation of the clutch pedal 119 and the actual operation of the tractor for the operator, and there is no sense of incongruity and the operability of the tractor is improved. .

  When the clutch pedal 119 is returned after the clutch pedal 119 is completely depressed in this way, that is, when the operating pressure increases, the change speed of the operating pressure according to the detected value detected from the clutch pedal sensor 119a is When the value is equal to or greater than the predetermined value, the controller 100 selects the command pressure regulation processing function unit (Y) and regulates the change speed of the command pressure due to the operation of the clutch pedal 119. The command pressure regulation processing function unit (Y ) May operate only in the half-clutch state where the tractor begins to move and then accelerates.

FIG. 11 shows another example of control by the controller 100 of the change speed of the hydraulic pressure of the hydraulic oil by the operation of the clutch pedal 119.
FIG. 11 shows a case where the clutch pedal 119 is returned after the clutch pedal 119 is completely depressed (the forward / reverse switching clutch packs 60, 60 are in a disconnected state, and the time (t) = 0 at this time). A change in hydraulic pressure of hydraulic oil in the forward / reverse hydraulic clutch D is shown. First, a region F in the figure indicates a dead zone portion of the controller 100. The operating pressure is 0 and does not change from time (t) = 0 to t0. Then, the controller 100 outputs signals to the forward / reverse boost solenoid 90 and the forward solenoid 86F or the reverse solenoid 86R from time (t) = t0 to t1, and the operating pressure rises (curve G1), and then the operating pressure slightly increases. The operating pressure is stabilized by descending (curve G2). The time t2 ((t) = 0 to t2) of the region Q during this period is a short time of about 0.1 second to 0.3 second, and is controlled by the controller 100 as curves G1 and G2. As shown by the curve G2, the operating pressure is stabilized by repeating slight increases and decreases.

At this time ((t) = t2), the operating pressure is higher than when (t) = 0, but the forward / reverse switching clutch packs 60, 60 are not connected, and the engine power Is not yet transmitted to the drive mechanism in the transmission.
Further, when the clutch pedal 119 is continuously returned, the operating pressure increases (region R), and a half-clutch state is reached from time (t) = t2 to t3, and the clutch pedal 119 is completely reached when (t) = t3. Is released, the response time is somewhat delayed and the operating pressure rises (region J). When (t) = t4, the forward / reverse switching clutch packs 60, 60 are completely connected (straight line H), and the engine power Is transmitted.

  The operating pressure in the hydraulic clutch D follows this process by the operation of the clutch pedal 119, but the tractor is accelerated to some extent before the forward / reverse switching clutch packs 60, 60 are connected (region Q) or after starting. If the command pressure regulation processing function unit (Y) is selected in the state (J area), it may take time for the forward / reverse switching clutch packs 60, 60 to be connected, Responsiveness to the operation instruction of the clutch pedal 119 may deteriorate.

  Therefore, by adopting this configuration, the controller 100 selects and operates the command pressure restriction processing function unit (Y) only in the half-clutch state region (R region) where the tractor starts moving and then accelerates. By doing so, it is possible to prevent the responsiveness due to the operator's operation instruction of the clutch pedal 119 from being deteriorated, and to prevent the forward / reverse switching clutch packs 60, 60 from taking time. it can.

  In the half-clutch region (R region), the rate of change of the regulated pressure that regulates the rate of change of the command pressure by the operation of the clutch pedal 119 (regulated pressure change rate, corresponding to the straight line K in FIGS. 9 and 10). At least two types may be set. For example, as shown in FIG. 11, straight lines K1 and K2 having different inclinations are set in two stages according to the operation time of the clutch pedal 119, and the operating pressure is thus regulated.

  When the tractor begins to move, if the rate of change in the regulated pressure is large (the slope of the straight line K is steep), the operating pressure suddenly rises and the shock that connects the hydraulic clutch D at the time of start increases. The feeling during operation may not fit. However, if the rate of change of the regulation pressure is reduced when the tractor is started (the slope of the straight line K is made gentle), the shock at the time of start is reduced, but this time, the response due to the operation instruction of the clutch pedal 119 by the operator is poor. Thus, there is a problem that a feeling of acceleration is not felt and smooth acceleration cannot be performed.

However, by adopting this configuration, by setting two or more types of regulated pressure change speeds, the regulated pressure change speed can be changed between when the tractor starts and after that, depending on the tractor's running conditions. Shifting control is possible.
For example, when the tractor begins to move, the change speed of the regulated pressure is reduced, that is, the gradual start (slope) of the straight line K1 is moderated so that the operating pressure is regulated in such a manner that the tractor starts slowly. Can reduce the shock. On the other hand, after that, the speed of change of the regulation pressure is increased and the slope (gradient) of the straight line K2 is made steep so that the tractor is smoothly accelerated so that the response by the operation instruction of the operator's clutch pedal 119 is not deteriorated. It can be made so that it does not take time until the forward / reverse switching clutch packs 60, 60 are connected.

Then, such a regulated pressure change rate (the straight line K in FIGS. 9 and 10, the K1, K2, etc. in FIG. 11) may be arbitrarily changed and set. The regulated pressure change speed can be easily changed and set by providing an adjustment dial, a switch (not shown), and the like, and is controlled to the regulated pressure change speed set by the controller 100.
When working on traction systems such as rotary tillers, there are differences in traction load depending on the type and amount of work, the operator's sense of operation varies from individual to individual, and the same depending on the work content There are cases where it is suitable as a change in operating pressure and cases where it is not. For example, a large load is applied to ski work, but the load varies greatly depending on the hardness of the field.

Therefore, the variation in evaluation due to the difference in the above conditions can be reduced by making the regulation pressure change rate variable. Evaluation means that the operator recognizes the state of the field.
For example, when it is felt that the regulation pressure change rate is slow (the working pressure rises slowly), the slope (gradient) of the straight line K in FIGS. 9 to 11 may be made steep so as to increase the regulation pressure change rate. When it is felt that the regulation pressure change speed is high (the increase in the operating pressure is fast), the slope (gradient) of the straight line K in FIGS. 9 to 11 may be made gentle so as to slow down the regulation pressure change speed.

By adopting this configuration, it is possible to achieve a regulated pressure change speed suitable for various conditions such as work content and operator, and work efficiency of various work, tractor operability, and traveling performance are improved.
In addition, the regulation pressure changing speed is changed and set not only by the inclination of the straight line K but also by a straight line in which the operating pressure changes in a zigzag shape, a staircase shape, or the like according to the operation time of the clutch pedal 119 (horizontal axis t). Or it can be a curve.

FIG. 12 shows a control example when a plurality of the regulated pressure change speeds are set.
The regulation pressure change speed may be changed and set according to the shift position operated by the sub-shift lever 179 and the main shift increase / decrease switches 192a and 192b. As for the shift position, the position of the sub-shift lever 179 described above can be shifted in eight steps at low speed, medium speed, and high speed. Therefore, a total of 24 shift speeds are possible. As an example, FIG. 12 shows the regulated pressures of 5 speeds (5th speed), 5 speeds (5th speed), 5 speeds (5th speed), and 5 speeds (5th speed). The case where the change speed is set is shown.

The shock that is connected to the hydraulic clutch D varies depending on the shift position (shift stage) operated by the auxiliary shift lever 179 and the main shift increase / decrease switches 192a and 192b even when the same regulated pressure change speed is set.
For example, if the auxiliary transmission lever 179 is connected at a fast instruction pressure (the increase in operating pressure is fast) despite the low speed position, a shift shock occurs. Further, when the auxiliary transmission lever 179 is connected at a slow command pressure (the increase in the working pressure is slow) regardless of the high speed position, a reaction delay occurs. However, by adopting this configuration, the regulation pressure change speed is changed to an appropriate regulation pressure change speed in accordance with the shift position operated by the auxiliary transmission lever 179 and the main transmission increase / decrease switch 192a, 192b. By setting several types of change speed patterns, even when the shift position is different, it is possible to absorb a shock that the hydraulic clutch D is connected to, a difference in response of operation, and the like.

  For example, as shown in FIG. 12, when the position of the auxiliary transmission lever 179 is set so that the regulation pressure change speed (inclination of the straight line K) increases in the order of low speed, medium speed, and high speed, the shock and responsiveness at the time of starting. This will alleviate the differences and improve tractor operability and running performance. Even when the command pressure P due to the operation of the clutch pedal 119 increases at a stretch, the command pressure regulation processing function unit (Y) of the controller 100 controls the regulation pressure change speed suitable for the position of the auxiliary transmission lever 179. This improves tractor operability and safety.

FIG. 13 shows another control example when a plurality of the regulated pressure change speeds are set.
Moreover, you may enable it to change and set a regulation pressure change speed not only according to the said speed change position but according to the difference of traction loads, such as a rotary tiller. The traction load can be detected and measured by a sensor (not shown) that detects a load applied to the lower link.

When the traction load is large, it is necessary to increase the operating pressure when the tractor starts to move, or the change speed of the operating pressure for producing the same acceleration as compared with the case where the traction load is small.
Therefore, as shown in FIG. 13, when the traction load is large, the rising working pressure is increased, and when the traction load is small, the rising working pressure is lowered, and the change speed of the working pressure thereafter (the slope of the straight line K) is increased. ) Are set to be the same.

  By adopting this configuration, even when the command pressure P due to the operation of the clutch pedal 119 increases at a stretch, even if the traction load changes, the operator can change to the appropriate regulation pressure change speed according to the traction load. Since the vehicle can be started and operated with the same feeling, the operability and running performance of the tractor are improved.

FIG. 14 shows another control example when a plurality of the regulated pressure change speeds are set.
Furthermore, the regulation pressure change speed may be changed according to the engine speed as well as the shift position and the traction load.

  When the engine speed is high, the force that presses the clutch plate of the forward / reverse switching clutch pack 60 is acted on by the centrifugal force generated by the rotation of the input shaft 2 that is the clutch input shaft of the forward / reverse switching clutch pack 60. As compared with the case where the engine speed is small, the power transmission torque of the input shaft 2 is increased, leading to a shock that the hydraulic clutch D is connected. Therefore, when the engine speed is large, there arises a problem that the operator feels uncomfortable when compared with the case where the engine speed is small.

Therefore, as shown in FIG. 14, when the engine speed is small, the rising working pressure is increased, and when the engine speed is large, the rising working pressure is lowered, and the change speed of the working pressure thereafter (straight line K). Are set to be the same.
By adopting this configuration, even when the indicated pressure P by the operation of the clutch pedal 119 is increased at once, by allowing change regulation pressure change rate according to the engine speed caused by the magnitude of the engine speed The difference in feeling as described above can be absorbed, and the operability and running performance of the tractor are improved.

  INDUSTRIAL APPLICABILITY The present invention can improve the operability of a work vehicle such as a tractor, and can be used for various work vehicles such as agriculture, building, and transportation.

It is a left view of the tractor of one Embodiment 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 tractor of FIG. FIG. 2 is an enlarged side view around a clutch pedal of the tractor of FIG. 1. It is a top view of the vicinity of the cockpit of the tractor of FIG. It is a perspective view of the vicinity of the cockpit of the tractor of FIG. FIG. 8A is a plan view of the switch box of FIGS. 6 and 7, and FIG. 8B is a side view. It is the figure which showed the example of control by the controller of the change speed of the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch by the clutch pedal operation of the tractor of FIG. It is the figure which showed another example of control by the controller of the change speed of the hydraulic pressure of the hydraulic oil in the forward-reverse hydraulic clutch by the clutch pedal operation of the tractor of FIG. It is the figure which showed another example of control by the controller of the change speed of the hydraulic pressure of the hydraulic oil in the forward-reverse hydraulic clutch by the clutch pedal operation of the tractor of FIG. It is an example of control when a plurality of regulated pressure change speeds are set. It is another example of control when a plurality of regulation pressure change speeds are set. It is another example of control when a plurality of regulation pressure change speeds are set.

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 16 Pilot seat 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 30 Armrest 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 counter 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 Countershaft 60 Forward / reverse switching clutch pack 61 Front wheel 62 Engine 63 Rear wheel 65 Mission case 66 PTO clutch pack 67 Front wheel drive clutch pack 73 Steering handle 76 Clutch pack 80 Hydraulic pump 81a, 81b Pressure reducing valve 82a Brake valve 82b Pressure control valve 83 Brake cylinder 85 Forward / reverse clutch cylinder 86 Forward / reverse clutch proportional pressure control valve (switching valve)
86F, 86R Solenoid 89 Main speed change (2-4) clutch proportional pressure control valve 90 Forward / reverse pressure increase solenoid 87, 88, 91, 92 Hydraulic clutch cylinder 93 Main speed change (1-3) clutch proportional pressure 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 4WD switching clutch cylinder 100 Control processing device (controller)
100a Memory 101 Main hydraulic circuit 103 Power steering device 104 PTO clutch cylinders 105, 106 PTO clutch proportional pressure control valve (PTO valve)
107 Steering hydraulic distributor 110 Forward clutch pressure sensor 111 Reverse clutch pressure sensor 112 Engine rotation sensor 115 Forward / reverse switching lever 119 Clutch pedal 119a Clutch pedal sensor 120 Return spring 121 Return gas damper 129 On / off control valves 130, 131, 133 137, 139, 140 Gear 145, 146 Pressure sensor 167 Forward / reverse lever sensor 172 Parking brake 173 PTO change lever 175 Accelerator pedal 175a Accelerator position sensor 176 Accelerator lever 177a, 177b Engine speed memory switch 178a, 178b Sub-control lever 179 Deputy Shift lever 179a Lever guide 179b Sub shift path upper speed position 179c Sub shift high speed position 179d Sub shift middle speed position 17 e Sub-speed low speed position 180 Switch box 182 Draft ratio adjustment dial 183 Raise adjustment dial 184 Tilt adjustment dial 185 4WD changeover switch 186 Manual raise / lower switch 187 PTO on / off switch 188 PTO manual automatic switch 189 Differential lock switch 190 Work machine position lever 191 Raise / lower switch (Work machine lift switch)
192a, 192b Main shift increase / decrease switch
194 Cigarette lighter 195 Working machine ascent / descent monitor lamp 196 AT shift work sensitivity dial 197 Lowering speed dial 198 Brake adjustment dial 199 AT shift road switch 200 AT shift work switch 201 Connection sensitivity shift switch 201a Lamp 202 Connection sensitivity PTO switch 203 Horizontal sensitivity Switch 204 Backup On / Off Switch 205 Auto Lift On / Off Switch 206 Auto Brake On / Off Switch 207 Horizontal Change Switch 208 Three-point Change Switch 209 Auto Accelerator Switch 211 Lid 213 Meter Panel 215 Display A Main Shift Hydraulic Clutch B High / Low Shift Clutch C Sub-transmission gear transmission mechanism D Forward / reverse clutch E PTO clutch T Tractor vehicle body X Command pressure processing function unit Y Command pressure regulation processing function unit

Claims (3)

A drive source (62);
A traveling device (61, 63) that is operated by the power of the drive source (62);
From the non-connected state to the connected state, the driving power source (62) travels from the non-connected state to the connected state by continuously changing the connected state according to the hydraulic pressure of the internal hydraulic oil supplied or discharged. A forward / reverse hydraulic clutch (D) that functions as a substitute for the main clutch that transmits to or disengages from the devices (61, 63) ;
A clutch pedal (119) for adjusting the hydraulic pressure of the forward-reverse hydraulic clutch (D) inside the working fluid by the operation amount,
A clutch operation amount detection sensor (119a) for detecting an operation amount by the clutch pedal (119);
An instructed pressure processing function unit for performing a process of making the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch (D) according to the detection value detected from the clutch operation amount detection sensor (119a) by the operation of the clutch pedal (119). X) and the change rate of the hydraulic pressure of the hydraulic oil in the hydraulic clutch (D) corresponding to the detected value of the clutch operation amount detection sensor (119a) is equal to or higher than a predetermined value, the change rate of the hydraulic pressure of the hydraulic oil Hydraulic pressure of hydraulic oil corresponding to the detected value detected from the clutch operation amount detection sensor (119a) by the operation of the clutch pedal (119). When the pressure change speed is equal to or higher than a predetermined value and the hydraulic pressure of the hydraulic oil increases, the indicated pressure restriction processing function unit (Y) is selected while the hydraulic pressure of the hydraulic oil is selected. When descending a control device (100) is provided with a selecting function unit for performing a process for selecting the indicated pressure processing function unit (X),
The change in the hydraulic pressure of the hydraulic oil in the forward / reverse hydraulic clutch (D) when the clutch pedal (119) is fully depressed and then the clutch pedal (119) is returned is controlled by the control device (100).
First, the forward / reverse boost solenoid (90) for boosting the hydraulic pressure of the forward / reverse hydraulic clutch (D) from the dead zone region (F) of the control device (100) and the forward solenoid (86F) for switching on the forward side or A forward / reverse hydraulic clutch that increases the operating pressure by outputting a signal to a reverse solenoid (86R) for switching on the reverse side and then stabilizes the operating pressure by lowering the operating pressure over a longer time than when the signal is increased. (D) is an unconnected region (Q),
Furthermore, when the clutch pedal (119) is continuously returned, the half-clutch state region (R) in which the operating pressure increases,
When the clutch pedal (119) is completely released continuously, the response time is delayed and the operating pressure rises (J),
After that, the operating pressure becomes substantially constant, and the forward / reverse hydraulic clutch (D) is changed to the connected region in order.
The control device (100) selects and operates the command pressure restriction processing function unit (Y) only in the half-clutch state region (R) where the travel device (61, 63) starts to move and then accelerates. A transmission for a work vehicle. 2. The work vehicle transmission according to claim 1, wherein at least two types of pressure change speeds in the half-clutch state region (R) are set, and the pressure change speeds are changeable. 3. The transmission for a work vehicle according to claim 2, wherein the pressure change speed is set in accordance with a difference in traction load when setting a plurality of pressure change speeds in the half-clutch state region (R).

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