JP2009103309A - Vehicular forward-backward travel clutch control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forward-backward travel clutch control device capable of always stably performing starting operation superior in a feeling by pedal operation, without receiving influence of a dimensional difference in a part and a difference in an operation method. <P>SOLUTION: This forward-backward travel clutch control device is constituted so that feed oil pressure of a forward travel clutch or a backward travel clutch 35a and 35b can be controlled based on an operation angle detecting result of a clutch pedal O. Oil is fed under predetermined constant pressure so as to quickly move a clutch piston R up to a meeting position of a clutch plate S of the forward travel clutch or the backward travel clutch 35a and 35b in the initial stage of return operation of the clutch pedal O from a state of cutting off both the forward travel clutch and the backward travel clutch 35a and 35b by stepping the clutch pedal O. When this oil feeding pressure reaches preset pressure or more, oil feeding under the constant pressure is stopped, and is linked so as to be switched to oil feeding under pressure changed in response to an operation angle of the clutch pedal O. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a forward / reverse clutch control device for a vehicle that controls the connection pressure of a forward and backward hydraulic clutch connected in series with a travel transmission unit according to the operation position of a clutch pedal.

As shown in Patent Document 1, a forward / reverse clutch control device configured to receive a clutch pedal operation signal and control transmission power between a forward clutch and a reverse clutch connected in series with a travel transmission unit is known. Yes.
This forward / reverse clutch control device adjusts the drive hydraulic pressure of the hydraulic clutch in accordance with the operation position of the clutch pedal, so that the operator can adjust the transmission power of the hydraulic clutch through the depression operation of the clutch pedal, and the clutch When the clutch is engaged, the set amount of oil is supplied in response to the clutch connection operation during pedal operation or reverse lever operation, and the clutch piston is driven to approach the clutch plate quickly near the meet point. If the clutch can be operated with good feeling, it will be stubborn.
Japanese Patent No. 3421406

  However, the structure of the hydraulic clutch has variations in the meet points due to dimensional differences between individual parts, and the clutch pedal is not evenly depressed. The oil supply of this set oil amount ends before the oil reaches, and the oil supply at the pressure corresponding to the operation position of the clutch pedal is started. On the other hand, if the set oil amount is excessive, a high pressure is applied at the time of connection. As a result, the clutch is shockedly connected, and the connection feeling is impaired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a forward / reverse clutch control device that can stably perform a start operation with good feeling by a pedal operation without being affected by a dimensional difference of parts or a difference in operation method. .

According to a first aspect of the present invention, there is provided an operation angle detection means for the clutch pedal, and a hydraulic pressure feed to the forward clutch or the reverse clutch can be controlled based on a detection result by the operation angle detection means. When the forward clutch and the reverse clutch are both disconnected from the state where both the forward clutch and the reverse clutch are disconnected, the forward clutch or the reverse clutch is connected while the clutch pedal is being operated to return to the initial stage of the clutch pedal return operation. Feeds the clutch piston to a cylinder for operating the clutch at a predetermined constant pressure so as to quickly move the clutch piston to a position where the clutch plate of the forward clutch or the reverse clutch meets, and during the oil supply at this constant pressure, When the pressure in the cylinder for use reaches the set pressure or higher, supply the oil at the above constant pressure. Sealed in, and characterized in that a reverse clutch control device before the vehicle, characterized in that tandem to switch to the oil feed at a pressure that is changed according to the operation angle of the clutch pedal.
With the above configuration, from the initial operation of the clutch pedal connection until the clutch plate meets, oil is supplied to the cylinder for clutch operation at a predetermined constant pressure, and the clutch piston operates quickly, and during oil supply at this constant pressure, When the pressure in the cylinder for operating the clutch reaches a set pressure or higher, the oil supply at the constant pressure is stopped and the oil is supplied at a pressure that is changed according to the operation angle of the clutch pedal.

According to a second aspect of the present invention, in the configuration of the first aspect, the vehicle is configured to feed oil to a cylinder for operating the forward clutch or the reverse clutch via an electromagnetic proportional pressure reducing valve. A clutch control device is provided.
In addition to the operation of the first aspect of the present invention, oil is fed to the operating cylinder of the forward clutch or the reverse clutch via the electromagnetic proportional control valve in accordance with the operation angle of the clutch pedal.

According to a third aspect of the present invention, in the configuration of the second aspect, the plurality of pressure lines are set according to the operation angle of the clutch pedal in accordance with the shift speed of the stepped transmission connected in series with the forward / reverse clutch. It is characterized by having set it as the vehicle forward / reverse control apparatus characterized by selecting so that can be selected alternatively.
By operating the clutch pedal, oil is fed to the forward clutch or the reverse clutch through a pressure line corresponding to the shift speed of the stepped transmission connected in series with the forward / reverse clutch.

The forward / reverse clutch control device has the following effects.
According to the first aspect of the present invention, even if there is a variation in the meet point of the forward clutch or the reverse clutch or the operation of the clutch pedal is not uniform, the clutch pedal is operated according to the operation position of the clutch pedal before reaching the clutch meet point. Since there is less problem that oil feeding with pressure is started or excessive pressure is generated when the clutch is connected and the clutch is shockedly connected, stable start with good feeling becomes possible.

  According to the invention of claim 2, since the oil is fed to the operating cylinder of the forward clutch or the reverse clutch via the electromagnetic proportional control valve, the clutch connection pressure can be controlled easily and reliably.

  According to the invention of claim 3, since the oil is fed to the forward clutch or the reverse clutch through the pressure line corresponding to the shift speed of the stepped transmission by the operation of the clutch pedal, the start with a good feeling according to the traveling vehicle speed is achieved. It becomes possible.

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
FIG. 1 is a side view of an agricultural tractor showing an example of a work vehicle equipped with a tractor travel control device according to the present invention.
The agricultural tractor 1 has an engine C mounted on the front part of the airframe having a front wheel A and a rear wheel B. The rotational power of the engine C is transmitted to the speed change transmission device 2 and is appropriately decelerated by the speed change transmission device 2. The power is transmitted to the front wheel A and the rear wheel B, and is also output to the rear working machine F via the rear PTO shaft E. The work machine F is supported by left and right lifting arms 54a tilted by the work machine lifting cylinder 54 so as to be lifted and lowered, and a rolling adjustment cylinder 53 is interposed so that the left and right heights of the work machine F can be adjusted. .

  For operation by the operator, a monitor J for displaying a driving state is arranged on the front side of the steering handle H, and a forward / reverse switching lever K for switching the traveling direction and an engine rotational speed setting are set on the lower side of the steering handle H. An accelerator lever L is arranged, an accelerator pedal M, a brake pedal N, and a clutch pedal O are arranged in the lower part, a cockpit P is provided at the upper part of the transmission case 2a of the transmission 2 and a shift lever Q is provided beside it. It is arrange | positioned and it is comprised by the control apparatus (travel control part) 51 so that automatic transmission is possible.

  As shown in FIG. 2, the transmission transmission apparatus 2 is provided with an input shaft 11 a that receives power from the engine C at the front stage, and a forward clutch and a reverse clutch are provided at the rear stage of the input shaft 11 a. The forward / reverse switching portion is constituted by the two-stage clutch 11 and the counter shaft 11b, and the traveling transmission shaft 12 receiving the power is configured in parallel and close. There is provided a main transmission portion by two two-stage clutches 13a and 13b for shifting the rotational power of the traveling transmission shaft 12 to the fourth speed, and a high / low switching portion by the two-stage clutch 14 for shifting the transmission power to the high and low two-speed. This is output to the drive pinion shaft 15d via the auxiliary transmission unit (traveling transmission unit) 15 using a shift gear mechanism for speed band selection (for example, “high speed”, “medium speed”, “low speed”). Driving power is transmitted from the drive pinion shaft 15d to the left and right rear wheels B via the rear wheel differential portion 16.

  Further, the driving power is branched from the drive pinion shaft 15d to the front wheel transmission shaft 17, and is connected to the front wheel differential portion 19 via the front wheel speed increasing portion by the two-stage clutch 18 for speed increasing transmission control, and travels to the left and right front wheels A. Transmit power.

  The work machine system power is received from the input shaft 11a via the PTO clutch 24 to the transmission ratio switching unit 25 of the PTO transmission shaft 21 and is transmitted from the forward / reverse switching unit 26 to the PTO shaft E at the subsequent stage.

  As shown in the hydraulic circuit diagrams of FIG. 3 and FIG. 4, the hydraulic control of each device is performed by driving the power steering unit 42 by the first system hydraulic pump 41a and by the second system hydraulic pump 41b. In addition to hydraulically driving the parts 13a and 13b, the two-stage clutch 11 of the forward / reverse switching unit, and the height switching unit 14, the left and right brakes 43, the differential lock unit 44, the front wheel speed increasing unit 18, the PTO clutch 24 and other devices are hydraulically driven. .

  The power steering unit 42 steers the front wheel A according to the operation of the handle H. The main transmission units 13a and 13b and the elevation switching unit 14 are controlled to switch to a shift position determined in accordance with the operation of the accelerator pedal M and the like via the electromagnetic switching valves 13v, 13w, 14v and 14w controlled by the control device 51. Is done. The two-stage clutch 11 of the forward / reverse switching unit is controlled by the electromagnetic switching valve 31 for forward / reverse switching controlled by the control device 51 corresponding to the operation of the forward / reverse switching lever K, and is controlled by a proportional pressure control valve (hydraulic control). Means) 32 and hydraulic pressure sensors 33a and 33b are provided, and the hydraulic pressure is controlled by the control device 51 as described later.

(Forward / reverse selector)
The forward / reverse switching unit will be described in detail. As shown in the longitudinal sectional view of the main part in FIG. 5, two output gears 34a and 34b for each traveling direction are pivotally supported on the input shaft 11a. The two-stage clutch 11 integrally forms two hydraulic clutch mechanisms 35a and 35b for each traveling direction for transmission control with respect to the two output gears 34a and 34b for each traveling direction of the input shaft 11a. Each clutch mechanism includes a clutch piston R that receives drive hydraulic pressure, a cylinder U that is formed between the clutch piston R and the clutch case T, and an axial movement of the clutch piston R by oil feeding into the cylinder U. The clutch plate S is press-contacted.

  In the hydraulic pressure supply system, three guide oil passages are formed in the shaft support portion 11c that supports the input shaft 11a, and hydraulic oils according to the traveling direction are provided via the oil passages 36a, 36b, and 36c of the input shaft 11a communicating with these. And the lubricating oil of both clutches is supplied to both hydraulic clutch mechanisms 35a and 35b. When the hydraulic clutch mechanisms 35a and 35b receive hydraulic fluid, the clutch plates S and S are pressed through the clutch pistons R and R to move to a meet position where the clutch plates S and S come into contact with each other (initial drive). Then, the clutch plates S and S are brought into pressure contact (pressure contact drive) until the drive oil pressure is further reached at that position, whereby power is transmitted within the range of the frictional force.

  As for the control system of the two-stage clutch 11 of the forward / reverse switching unit, as shown in FIG. 6 which is a control configuration diagram including the main speed change, the clutch pedal sensor 62, the forward / reverse switching lever K, The main shift position sensor 13s, the sub shift position sensor 15s for detecting the switching position of the sub shift portion by the shift gear mechanism 15, the pressure generated in the cylinder U of the forward hydraulic clutch mechanism (forward clutch) 35a and the reverse hydraulic clutch Clutch pressure sensors 33a and 33b for detecting the pressure generated in the cylinder U of the mechanism (reverse clutch) 35b are connected to input a signal, and on the output side, a solenoid 31s for operating the forward / reverse switching valve 31; A solenoid 32 s for operating a pressure control valve (electromagnetic proportional pressure reducing valve) 32 for controlling the pressure of hydraulic oil fed to the cylinders U, U, and a main shift switching valve Solenoid 13v to switching operation to the speed-second speed, hydraulically controlled by connecting the solenoid 13w or the like for switching operation of the main speed change switching valve to the third speed-fourth speed.

  The clutch pedal sensor 62 is an analog amount detection sensor such as a potentiometer that detects an operation angle in an operation stroke of the clutch pedal O. The forward / reverse switching lever K is used to select the forward / backward direction. The main shift position sensor 13s detects the main shift position switched by the control device. The sub shift position sensor 15s detects the switching position where the shift operation is performed. The forward and backward clutch pressure sensors 33a and 33b detect the pressures generated in the cylinders U and U of the forward hydraulic clutch mechanism (forward clutch) 35a and the reverse hydraulic clutch mechanism (reverse clutch) 35b, respectively. The forward / reverse switching valve 31 selectively switches the oil feeding direction to the cylinders U and U of the forward hydraulic clutch mechanism (forward clutch) 35a and the reverse hydraulic clutch mechanism (reverse clutch) 35b. The pressure control valve 32 controls the drive hydraulic pressure of the clutch piston.

The specific control processing is shown in the flowchart of FIG. 7 after the operation stroke by stepping on the clutch pedal O is divided into two regions, the shallow side is set as the “on” region and the deep side is set as the “off” region. As described above, when the clutch pedal O is operated in the direction to return (release) from the “disengaged” region, the initial drive timer setting process (S2) is performed if applicable by the determination process (S1) of “off” → “on”. Until the clutch pressure becomes equal to or higher than the specified value by the initial drive timer 0 determination process (S3), the clutch pressure is controlled by the proportional pressure control valve 32 at the initial drive current value (S4, S5a). Thus, initial driving, that is, hydraulic driving up to the meet position is performed. The initial drive timer setting process may be a flag setting process.
When the initial drive timer becomes zero or when the clutch engagement pressure detected by the clutch pressure sensor 33a or 33b exceeds a specified value, the initial drive timer reset “0” process and the clutch pressure set by the clutch pedal set value are set. By the control process (S5b), pressure driving, that is, hydraulic driving up to the pedal operation corresponding pressure is performed.

  As shown in the operation diagram of FIG. 8A, the clutch operation by the above control process is a range deeper than a position d1 where a predetermined amount is returned from the maximum depression position d0 of the depression stroke range of the clutch pedal O. Is set as the “off” area, and the shallow area as the “on” area. In the “disengaged” region, the two-stage clutch 11 including the forward clutch and the reverse clutch is held in the disengaged state. When the clutch pedal O is returned to enter the “ON” region beyond the boundary position d1 as shown in the current-flow characteristic diagram of FIG. By using the driving current, the movement of the clutch piston R is speeded up. After the timing when the clutch plate S meets, the proportional pressure control valve 32 is pressure-driven by a pressure corresponding to the return position of the clutch pedal O.

  In this manner, oil feeding at a predetermined pressure is performed from the detection of the connection operation of the clutch pedal O until the clutch plate meets, and thereafter, hydraulic control is performed according to the operation position of the clutch pedal O. Even if there is a difference in the dimensions of the hydraulic clutch parts or pedal operation, the clutch plate S of the hydraulic clutch is driven to the meet position when the clutch pedal O is connected by the operator. The trouble that the pressure becomes equivalent or the set amount is too large and an excessive pressure is generated at the time of connection is avoided, so a smooth start with a stable and good clutch alignment is always possible without connection shock by simple operation. It becomes possible.

  In addition, the initial drive current in the above configuration is a current that can secure the maximum flow rate, so that the performance during operation can be stabilized even if there is a difference in the characteristics of individual valves, and the range in which the maximum flow rate can be obtained. By making the current as low as possible, when the clutch plate S meets and starts to apply feedback, the response when reducing the current can be improved, so the pressure (drive torque) when engaging the clutch can be reduced. It can be kept low.

  Further, the specified value of the determination process (S4) for stopping the initial drive in the control process is a specified time excluding the surge immediately after the start of driving due to the drive current up to the clutch plate meet as shown in the flowchart of FIG. With the detected pressure p1 (S2a, S2b) after elapse of 10 (for example, 10 to 20 msec) as a reference, a slightly higher pressure p1 + α (for example, +0.2 when the reference pressure is 0.5) is set as a specified value. Therefore, the point where the pressure generated during the movement of the clutch piston R is exceeded is the start of the meet of the clutch plate S. By shifting from here to the control current of the pressure contact drive, the variation in the clutch configuration and flow rate can be reduced. Stable control in consideration is possible.

  In addition, since the kinematic viscosity characteristics of oil change depending on the oil temperature, the pressure during movement of the clutch piston R changes (higher pressure as the temperature becomes lower), and this pressure increases from the valve to the cylinder U when the clutch piston R moves. The differential pressure when the oil passes through the oil passage is detected by the clutch pressure sensors 33a and 33b. In order to prevent this from being erroneously detected, the data for each oil temperature is grasped in advance and the detected pressure is changed based on this data, thereby avoiding erroneous detection of pressure while the clutch piston is moving and avoiding the situation where the clutch is not connected. can do.

  Further, since the speed reduction ratio to the rear wheel B varies depending on the position of the auxiliary transmission unit (traveling transmission unit) 15, and even if the same pressure is applied to the clutch plate S, the acceleration applied to the vehicle is different. Applies a modulated pressure by a pressure line corresponding to the selected sub-shift position, that is, according to the selection of “high speed”, “medium speed”, and “low speed” of the third speed, As the pedal O is returned, the pressure is gradually increased. The pressure control equivalent current immediately after the initial drive current is a different drive current depending on the shift position of the sub-transmission unit 15, that is, the pressure is changed to be higher as the shift position becomes higher. Thus, by changing the pressure according to the shift position, the clutch pedal can be easily adjusted without depending on the auxiliary shift position. In addition, by setting the control pressure according to the shift position to move approximately in parallel, the half-clutch state can be achieved with a long pedal stroke at any sub-shift position, and the half-clutch operation can be performed. It becomes easy.

  Further, when the release region of the pedal stroke is reached by the return operation of the clutch pedal O, the sub-shift position determination (S11) and the time lapse determination processing (S12) are performed as shown in the flowchart of FIG. When the speed change is “high speed”, the clutch pressure control process (S13a) is performed for a predetermined time until the maximum pressure is reached. When the sub speed change is “low speed”, the clutch pressure is controlled sharply until the maximum pressure is reached.

  In this way, the clutch transmission torque change after the clutch pedal O is released does not become large, and the clutch is started in the high-speed range at the cultivated land in the field where μ with the road surface is high. In this case, since a large load fluctuation on the engine can be suppressed, the stalling situation can be avoided.

(At high speed)
Next, control processing during high-speed traveling will be described.
When the vehicle speed of the tractor is detected and the switching operation of the forward / reverse switching lever K is performed at a vehicle speed above a certain level, the clutch is turned off, the main gear shift is automatically decelerated to a safe gear, and the clutch is The control process of “ON” is configured. At this time, the main clutch (forward / reverse or high / low switching) is boosted. In this case, the clutch may be reengaged, and the speed may be automatically increased to the first gear and restored to the original, and an automatic shift mode for forward / reverse switching operation at high speed may be set.

  There is a control example in which when the switching operation of the forward / reverse switching lever is performed at high speed (for example, the speed is 11 km / h or more), a warning buzzer sounds and the clutch is automatically “disengaged” to enter a safety state. However, since such work causes a danger due to a forced stoppage, the above-described control processing configuration can cause a danger due to the stoppage of the travel even if the tractor switches the forward / reverse lever K when the tractor is traveling at a high speed. Can be avoided.

(Relief valve)
Next, reverse control will be described. As shown in the longitudinal cross-sectional view of FIG. 11, in the configuration in which the operation pressure of the clutch pedal O is disposed as reverse control on / off, the pedal operation pressure valve is configured as a relief valve 71 in which the set pressure is variable by mechanical operation. To do. With the above-described configuration, the simple on / off valve cannot perform the pressure operation following the movement of the clutch pedal, but such a drawback can be solved.

(control panel)
Next, the operation panel will be described.
In the vicinity of the driver's seat, as shown in the automation function set panel in FIG. 12 and its control configuration diagram, and in each setting example in FIG. 13, switches 81a and 81b for instructing the work state are provided, and various automatic control mechanisms are provided separately. An operation unit 81c for turning on / off is provided, and the automatic control function is configured so that a plurality of patterns can be turned on / off in response to a switch operation for instructing a work state. With such a configuration, the operation has been conventionally facilitated as a configuration in which fully automatic items are collectively set, but it is possible to select and set an automation function for each work.
For example, by performing a setting operation with the switch group shown in the operation unit 81c for each work designated in advance such as “plowing”, “pickling”, “work 1”, and “work 2” in FIG. It will be able to handle the work of. When “Tillage” is selected, the reverse working machine is automatically lifted up (backup), the working machine is raised during turning (auto lift), the brake is braked inside (auto brake), and the lifting / lowering control sensitivity is adjusted (3P auto). Sensitivity “Sensitive”) is obtained, and when “Work 1” and “Work 2” are selected, items arbitrarily set by the operator can be set and stored. With regard to “running” as well, each item can be turned on and off, or sensitivity settings can be set and stored.

  Moreover, the automation panel operation part which can be set for every instruction | indication of a work instruction | indication switch is comprised with the monitor which can distinguish a push type setting operation part and a setting state. With this configuration, the set state can be easily understood (FIGS. 14A, 14B, and 14C).

  Further, by providing a blank portion in the setting position portion label of the work state instruction switch so that a user-friendly name can be written, it is easy to rework so that the operation can be easily understood at the user level.

In addition, the work state instruction switch is configured to include at least one “travel” mode suitable for road travel and to select a plurality of modes suitable for work.
While driving on the road, the front wheel drive is usually driven by 2WD or auto 4WD that automatically switches between two-wheel drive and four-wheel drive according to the difference between the front and rear vehicle speeds, and other controls are cut off. . In addition, during work, there are a plurality of work patterns such as tillage work and plowing work, and the automated function used may differ depending on the work. In the present plan, it is possible to easily set the work cut-off state while traveling on the road in the setting mode, and it becomes possible to set the mode suitable for the work to be performed when it becomes work, and it is easy to use.

  Further, as shown in the example of the work instruction switch in FIG. 14A, the mode switch 81a for setting the road traveling is configured by an independent push switch, and a plurality of setting of the work mode can be selected by the other push switch 81b. Thus, a monitor 81d using an LED or the like that can determine the setting state is provided. The switch may be a two-switch (with neutral) rebound seesaw switch or a toggle switch. With this configuration, traveling and setting work can be quickly performed and easily understood.

  Further, as shown in the example of the work instruction switch in FIG. 14B, the work state instruction switch 82 can be configured at low cost by being configured with one push type switch and a monitor 82d that can determine the set state. Furthermore, as shown in the example of the work instruction switch in FIG. 14C, the setting can be easily understood by configuring the rotary VR 83 or the switch.

  The sub-shift lever is configured so that a shift position suitable for road travel and a shift position suitable for work can be selected, and the case where the sub-shift lever is shifted to a position suitable for road travel is shown in the flowchart of FIG. In addition, the setting operation is simplified by forcibly switching the setting of the work instruction switch to the traveling mode (S22).

  When the work instruction switch is switched from another mode to the travel mode, at least the automation functions (front wheel acceleration, autobrake, autolift, backup, accelerator automatic shift, etc.) that are convenient in the field are "On" the previous time. However, once it is set to “OFF”, that is, from “ON” to “ON”, it is possible to eliminate the danger by configuring it to be “OFF” until the next setting.

  As for the main shift work, when the sub-shift is set to a shift position suitable for the work, the main shift position that has been working for the longest time is memorized and the main shift is performed the next time the sub-shift is operated. In this shift to the memory position, the longest working position of the sub-shift position and the main shift position is stored for each indicated position of the work instruction switch (S21), and when the work instruction switch is switched, If the previous sub-shift position matches the current set sub-shift position, the main shift is changed to the stored main shift position (S23).

  For example, when the vehicle speed range at the main shift is about 1.5 to 5 km / h in the sub-shift “medium speed”, the normal tillage is different from 1 to 2 k, and the scraping is different from 2 to 4 k. In the case of a memory shift based only on the sub-shift range, the main shift position becomes the previous shift state when the operation is changed. For example, it is necessary to change with two main shift buttons provided on the sub-shift lever. However, in this proposal, simply by operating the work instruction switch, the shift position including the other automatic work settings and the shift position matching the user are reproduced, so that the operation is simplified.

  Automatic change of the main shift (memory position reproduction) by operating the work instruction switch is possible only when the vehicle is stopped, so it is unclear whether there is a willingness to shift when the button is operated while driving. It gives a feeling but can eliminate this.

It is a side view showing an example of a work vehicle. It is a transmission system expansion | deployment figure of a transmission transmission part. It is a hydraulic circuit diagram (1) of hydraulic control. It is a hydraulic circuit diagram (2) of hydraulic control. It is a principal part longitudinal cross-sectional view of the 2 step | paragraph clutch of a forward / reverse switching part. It is a control system block diagram of the two-stage clutch of the forward / reverse switching unit. It is a flowchart of a forward / reverse switching control process. It is an operation diagram (a) of a clutch and a current-flow rate characteristic diagram (b) of a control valve. It is a flowchart of a stop process of initial drive. It is a flowchart of the return operation process of a clutch pedal. It is a longitudinal cross-sectional view of a relief valve. It is an automation function set panel and its control block diagram. It is a switch layout diagram of the operation panel. It is a work instruction switch example (ac). It is a flowchart in the control structure of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Agricultural tractor 2 Shift transmission 11 Two-stage clutch (forward / reverse switching part)
15 Shift gear mechanism (sub-transmission part)
15s Sub-shift position sensor 31 Forward / reverse switching valve 32 Proportional pressure control valve (hydraulic control means)
33a, 33b Clutch pressure sensors 35a, 35b Hydraulic clutch mechanism (hydraulic clutch)
51 Control device (travel controller)
62 Clutch pedal sensor (operation angle detection means)
A Front wheel B Rear wheel d1 Boundary position K Forward / reverse switching lever O Clutch pedal R Clutch piston S Clutch plate

Claims (3)

An operation angle detection means (62) for the clutch pedal (O) is provided, and the hydraulic pressure supplied to the forward clutch or the reverse clutch (35a, 35b) can be controlled based on the detection result by the operation angle detection means (62). Configure
From the state where the clutch pedal (O) is depressed to disconnect both the forward clutch and the reverse clutch (35a, 35b), the forward clutch or the reverse clutch (35a, 35b) is operated while returning the clutch pedal (O). In configuring to connect,
At the initial stage of the return operation of the clutch pedal (O), the clutch piston (R) is quickly moved to a position where the clutch plate (S) of the forward clutch or the reverse clutch (35a, 35b) meets. To feed oil to the cylinder (U) for clutch operation.
During oil feeding at this constant pressure, when the pressure in the clutch operating cylinder (U) reaches a set pressure or higher, the oil feeding at the constant pressure is stopped and the clutch pedal (O) operating angle is A forward / reverse clutch control device for a vehicle, wherein the forward / reverse clutch control device is connected so as to switch to oil feeding at a pressure that is changed according to the pressure.   2. The front and rear of a vehicle according to claim 1, wherein oil is fed to a cylinder (U) for operating the forward clutch or the reverse clutch (35a, 35b) via an electromagnetic proportional pressure reducing valve (32). Advance clutch controller.   A plurality of pressure lines set in accordance with the operation angle of the clutch pedal (O) are alternatively selected according to the speed of the stepped transmission (15) connected in series to the forward / reverse clutch (35a, 35b). The vehicle forward / reverse control device according to claim 2, wherein the vehicle forward / reverse control device is selected.

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