JPH078163B2 - Shift structure of work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a traveling transmission that is operated by an actuator so as to be in the operation position of a shift operation lever, and detects the engaged state of a traveling clutch. A clutch sensor and a second clutch sensor for detecting the disengaged state of the traveling clutch are provided, and when the second clutch sensor detects the disengaged state of the traveling clutch, the traveling transmission is set to a predetermined value regardless of the operation position of the shift operation lever. A shift mechanism for a work vehicle provided with a control device for switching to a low speed position of the first clutch sensor and for locating the shift operation lever at an operation position based on detection of a clutch engagement operation of the first clutch sensor,
If the first clutch sensor detects that the traveling clutch is in the on state, the traveling transmission that has been in a predetermined low speed state is returned to the operation position of the shift operation lever. Compared to the case where the traveling clutch is in the engaged position when the operating position of the shift operation lever is set, the traveling aircraft that was in place gradually shifts up to the operating position of the shift operation lever to increase the traveling speed. The present invention relates to a speed change structure for a work vehicle that allows a gentle start without a sudden start.

[Conventional technology]

Detecting whether the traveling clutch is in the engaged state or the disengaged state is performed by, for example, a first limit switch or the like,
It is a second clutch sensor.

[Problems to be Solved by the Invention]

Therefore, there is no problem when these two clutch sensors are operating normally. However, if the first clutch sensor fails, for example, the running clutch is not engaged even if it is switched from the disengaged state to the engaged state. There is no signal, so
If the traveling speed change state does not increase from the predetermined low speed state or if the second clutch sensor fails, a normal signal from the second clutch sensor will not be output even if the traveling clutch changes from the on state to the off state. Therefore, since the traveling transmission does not shift to the predetermined deceleration position and is maintained at the operation position indicated by the shift operation lever, it will start at a high speed when the traveling clutch is in the on state, and the driver will have a great start. There is a problem that it will give a shock.

An object of the present invention is to provide a device which can prevent deterioration of driving operation due to a failure in advance by reasonably judging signals from the first and second clutch sensors.

[Means for Solving the Problems]

The characteristic configuration according to the present invention is that when both clutch sensors do not detect the on / off state of the traveling clutch for a predetermined time or more, or when both clutch sensors simultaneously detect the on / off state of the traveling clutch, the clutch sensors are in an abnormal state. It has a display means for displaying, and its operation and effect are as follows.

[Work]

That is, since the half-clutch state cannot be continued for a long time as the transmission state of the traveling clutch, either one of the clutch sensors must detect the ON / OFF state of the clutch. Therefore, when the first clutch sensor does not emit the signal indicating the traveling clutch on state or the second clutch sensor indicates the traveling clutch disengaged state, it indicates a half-clutch state. Since it cannot last for a long time, if the state continues for a predetermined time, it is determined as a failure. Further, when the first clutch sensor simultaneously outputs a signal indicating the engaged state of the traveling clutch and the second clutch sensor simultaneously indicates a signal indicative of the disengaged state of the traveling clutch, it is impossible because of the mechanism of the traveling clutch. , Judge as a failure.

In the case of such two states, it can be judged that at least one of the clutch sensors is out of order, and the driver is notified by the display means.

〔The invention's effect〕

Therefore, when the display means is operated, it is found that one of the clutch sensors is out of order, and when the traveling clutch is once disengaged, the shift operation lever is forcibly operated to a predetermined low speed operation position when starting. It is possible to take measures to avoid sudden start.

〔Example〕

As shown in FIG. 4, an engine (4) is provided at the front of a traveling vehicle body (3) equipped with front and rear wheels (1) and (2), and a belt type continuously variable transmission as the engine and the traveling transmission. A transmission case (6) that is transmission-coupled via a device (5), a control section (7) provided in the middle of the machine body, and a lift link mechanism driven by a lift cylinder (32) behind the control section (7). A riding type rice transplanter as an example of a paddy field working machine is configured by including a seedling planting device (9) that is vertically movable via (8). Reference numeral (34) in FIG. 4 is a cylinder for rolling the seedling planting device (9) with respect to the elevating link mechanism (8).

As shown in FIG. 1, the belt type continuously variable transmission (5) uses split pulleys (5a) and (5b) as input pulleys on the transmission case (6) side. )
By moving one (5a) with respect to the other (5b) in the perspective direction by the electric actuator (11), the wrapping angle of the belt can be changed to continuously change the speed. A main clutch (12) is provided for the output shaft of the engine (4), and the main clutch (12) is turned on and off by a foot pedal (13).
Further, as shown in FIG. 3, a main speed change lever (14) is provided at the foot of the operation portion (7), and the first forward speed used during planting traveling and the second forward speed used during road traveling. ,as well as,
It is possible to switch to three reverse speeds. Therefore, the number of stages of the continuously variable transmission (5) is superimposed at each shift position. The main control lever (14) has an upper control panel provided with a planting lever (25) for forcibly raising and lowering the seedling planting device (9), the plowing depth setting device (16), and the like.

Further, below the seedling planting device (9), there is provided a grounding sensor (15) which moves up and down due to fluctuations in grounding pressure.
The display panel of the operation section (7) is provided with an encoder-type plowing depth setting device (16). In order to maintain the set value of this plowing depth setting device (16), the detection result of the ground sensor (15) is displayed. Based on this, a raising / lowering control device for raising and lowering the seedling planting device (9) to maintain a constant planting depth is provided.

For the main clutch pedal (13), a limit switch type first clutch sensor (S ₁ ) for detecting the clutch engaged state and a limit switch type second clutch sensor (S ₂ ) for detecting the clutch disengaged state. And the second clutch sensor (S ₂ ) detects the disengaged state of the clutch, the travel shift position is set to a minimum deceleration position regardless of the shift operation position of the shift operation lever (17). Forcibly switches to the low speed position (LOW).

Another operation mechanism will be described. A shift operation lever (17) for setting the shift position of the belt type continuously variable transmission (5) is provided, and a potentiometer for detecting the shift operation amount is provided. Therefore, the actuator (11) is operated by the control signal from the control device (27) in response to the signal from the potentiometer, and the belt type continuously variable transmission (5) is shifted to a predetermined shift position. Further, a rotation detector (18) for detecting the rotation speed of the engine (4) is provided, and signals from the potentiometers of the rotation detector (18) and the shift operation lever (17) are sent to the control device. (27) and enter the actuator (1
1) Adopts a configuration to control the etc.

Based on the configuration described above, a mode in which the vehicle speed is controlled by the traveling load will be described based on the flowchart of FIG. When the engine is started, the control is not started unless the shift gear shift operation lever (17) for the continuously variable transmission is once set to the lowest speed position (LOW). Therefore, first, it is confirmed whether the operation lever (17) for the continuously variable transmission is once operated to the lowest speed position (LOW). Then, once it is operated, the ON / OFF state of the main clutch (12) is checked, and further, the position of the planting lever (25) is the "planting position" or the "raising position" of the seedling planting position. Check whether it is "neutral position" or "down position".
Then, of the three conditions of the position of the continuously variable transmission operation lever (17), the main clutch (12), and the planting lever (25), the continuously variable transmission operation lever (17) is at the lowest speed position (LOW )
When not operated, or when the main clutch (12) is disengaged, or when the planting lever (25) is in the "up position", "neutral position", or "down position" of the seedling planting device. Sets the shift target value (OBP BUP) in the software for the continuously variable transmission (5) to the lowest speed position (LOW), and the current operating position (PRERO) of the continuously variable transmission (5) is the lowest speed. If it is not in the position (LOW), it is switched to the lowest speed position (LOW) by the actuator (11).

In other words, in other words, when the engine (4) is started, the main clutch (12) is in the engaged state, and the operation lever (17) for the continuously variable transmission is not yet operated to the lowest speed position (OBP), it is the lowest. The rice transplanter will start once if the speed is maintained.
Then, when the driver notices it and once switches the operation lever (17) for the continuously variable transmission to the lowest speed position (LOW) and further to the desired shift position, the main routine control such as speed control is started. However, even if the operation lever (17) for the continuously variable transmission is once moved to the lowest speed position (LOW), if the main clutch (12) is in the disengaged or half-clutch state, it is determined that the seedling is being replenished and the lowest speed is obtained. Keep it in the position (LOW),
If the planting lever (25) is raised, it is judged that it is turning at the edge of the ridge, and it is turned slowly at the lowest speed position (LOW). In any of these cases, it is set independently of the shift instruction device (OBP) as the operation position of the continuously variable transmission operation lever (17).

Here, the position of the planting lever (25) is to be determined only when the main speed change lever (14) is set in the gear shift range corresponding to the planting position, that is, when planting work is performed.

When the operation lever (17) for the continuously variable transmission is once operated to the lowest speed position (LOW) and the main clutch (12) is in the engaged state, although not shown in the flow chart, the starting form is as described above. A method of rapidly shifting the continuously variable transmission (5) to the shift instruction position (OBP) of the operation lever (17) or gently shifting to the shift instruction position (OBP) or a predetermined deceleration value is adopted. When the main shift lever (14) is operated to the planting position, the planting work is in progress,
Looking at the position of the planting lever (25), when the planting lever (25) is in the "up position", it is determined that the vehicle is turning on the ridge, and the continuously variable transmission (5) is moved to the lowest speed position ( LOW), rotate slowly, and when the planting lever (25) is in the “planting position”, perform the planting work rapidly to the shift instruction position (OBP) of the continuously variable transmission operation lever (17). A method of shifting or gradually shifting to the shift instruction position (OBP) or a predetermined deceleration value is adopted. Further, when the planting lever (25) is in the "neutral position" and the "down position", it is assumed that seedlings are being supplied, and the continuously variable transmission (5) is set to the lowest speed position (LOW).
To

As described above, depending on the gear position of the main gear shift lever (14), it is determined whether the planting operation is being performed or the vehicle is traveling on the road, and the process proceeds to the next vehicle speed control (step I).

Next, vehicle speed control will be described in which the actuator (11) is controlled to automatically shift gears regardless of the shift instruction position (OBP) of the continuously variable transmission operation lever (17) depending on the engine load. The vehicle speed control mode and the artificial vehicle speed control mode in which the vehicle speed is set based on the operation of the operation lever (17) for the continuously variable transmission are determined by whether the accelerator lever (24) is in the full accelerator position. , The vehicle speed control mode is set at the full accelerator position. In this embodiment, the vehicle speed control is performed with the full accelerator position as the reference position, but the reference position may be other than the full accelerator position.

First, a control reference is set before performing control. If a potentiometer is provided as a sensor for detecting the accelerator position and the accelerator lever (24) is operated to the full accelerator position, first, the no-load engine speed corresponding to the full accelerator position is set as the reference engine speed. This is actually 38
It is set to 00 rpm. Then, as the engine speed as a reference for changing the shift position of the belt type continuously variable transmission (5) according to the running load, the reference engine speed (3800
1st predetermined number of revolutions (eg 3400r)
pm) and a second predetermined rotation speed lower than the first predetermined rotation speed (for example, 3000 rpm). In the flow chart, the first predetermined speed is HIGHLIMIT and the second predetermined speed is LOWLIMIT.
Is abbreviated.

In vehicle speed control, the engine speed detector (1
The actual engine speed is detected by the output from 8),
This actual engine speed (ER) is the second predetermined speed (LO
If it is less than WLIMIT), the running load is larger than the engine output, so the belt continuously variable transmission (5) is switched to the low speed side, and the actual engine speed (ER) is the second predetermined speed ( LOW LIMIT) or above, the first predetermined speed (HI
GHLIMIT) or less, the running load is balanced with the engine output, so that the belt continuously variable transmission (5) is maintained at the current gear position and the actual engine speed (ER) is equal to the first predetermined speed ( If the number of revolutions exceeds (HIGH LIMIT), the running load is smaller than the engine output, so the belt continuously variable transmission (5) is switched to the high speed side (step II).

As described above, the vehicle speed can be controlled according to the running load. However, except at the full accelerator position, the speed change lever (17)
The artificial vehicle speed control mode is performed in which the actuator (11) is operated so as to be in the operation position.

In such control, when the first and second clutch sensors (S ₁ ) and (S ₂ ) do not sense the on / off state of the running clutch for a predetermined time or more, or both clutch sensors (S ₁ ) and (S ₂ ). ₂ ) simultaneously detects the on / off state of the running clutch (12), if at least one of the first and second clutch sensors (S ₁ ) and (S ₂ ) outputs a signal indicating a failure, As shown in step I, the mode of shifting from the lowest speed state (LOW) to the operation position of the shift operation lever (17) cannot be adopted at the time of starting, so an alarm device or the like is operated as the display means (20). There is.

In addition, when there is such a failure of the clutch sensors (S ₁ ) and (S ₂ ), the safety is prioritized and the shift position of the belt type continuously variable transmission (5) is set to the lowest speed position (LOW). Measures to switch to and to stop the engine (4) are adopted.

The following failure detection method may be adopted by utilizing the countermeasure for failure display for such a sensor. That is, in order to detect a failure of the lift cylinder (32), the rolling cylinder (34), the actuator (11) for the belt type continuously variable transmission (5), and the feedback position sensor provided for them. First, when a constant operation signal is given to each of the cylinders (32) and (34) and the actuator (11) and the value of each feedback position sensor does not change, the lifting cylinder (32) and the rolling cylinder (34 ) And their feedback position sensors have a failure, the display means (20)
And the operations of the cylinders (32) and (34) are stopped to stop the lifting / rolling control related thereto. When the actuator (11) and the position sensor for feedback to the actuator (11) have a failure, the failure is similarly displayed and the traveling speed change operation is stopped.

[Other Embodiments] The first and second clutch sensors may be non-contact type sensors such as optical sensors.

The actuator (11) may be a hydraulic type and is not limited to an electric type.

As the traveling transmission, the main transmission in the mission (6) and the belt continuously variable transmission (5) are used, but either one may be used. A gear type transmission may be used instead of the belt continuously variable transmission (5).

The traveling clutch may be provided separately from the main clutch (12).

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show a shift structure embodiment of a work vehicle according to the present invention. Fig. 1 is a control configuration diagram, Fig. 2 is a control flow diagram, Fig. 3 is a plan view of a control unit, and Fig. 4 is a riding type rice transplanter. FIG. (5) …… Running transmission, (12) …… Running clutch,
(17) …… Shift operation lever, (20) …… Display means,
(S ₁ ), (S ₂ ) ... Clutch sensor.

Claims (1)

[Claims] 1. A travel transmission (5), which is operated to change gears by an actuator (11) so as to be in an operation position of a shift operation lever (17), and which detects an engaged state of a travel clutch (12). Second clutch sensor (S ₂ ) for detecting the disengaged state of the clutch sensor (S ₁ ) and the traveling clutch (12)
When the second clutch sensor (S ₂ ) detects the disengaged state of the traveling clutch (12), the traveling transmission (5) is operated at a predetermined low speed regardless of the operating position of the shift operating lever (17). A shift structure of a work vehicle provided with a control device (27) which is switched to a position and is positioned at an operation position of the shift operation lever (17) based on detection of a clutch engagement operation of the first clutch sensor (S ₁ ). Te, both clutches sensor (S _1), if (S ₂₎ does not sense the on-off state of a predetermined time or more running clutch (12) or both clutches sensor (S _1), (S ₂₎ simultaneously running clutch (12 ), The clutch sensor (S ₁ ),
Display means (20) for displaying that (S ₂ ) is in an abnormal state
Gear shifting structure for work vehicles.