JP3356879B2 - Work vehicle load detection structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detecting structure for detecting a load applied to an engine in a work vehicle such as an agricultural tractor or a combine.

[0002]

2. Description of the Related Art In an agricultural tractor, which is an example of a work vehicle, a load applied to an engine is detected, and various controls are performed based on the detected load. In this case, a rotation speed sensor for detecting the rotation speed of the engine is provided, and the rotation speed of the engine when there is no load applied to the engine and there is no load corresponding to each accelerator opening of the engine is obtained and stored in advance. . Then, by calculating the difference between the engine speed corresponding to the current accelerator opening and the engine speed at no load corresponding to the accelerator opening, the current load applied to the engine is detected. There are things that make up.

[0003]

Since the rotation speed sensor as described above electrically detects the rotation speed of the engine, the attitude of the rotation speed sensor may change due to vibrations of the body or the like, or the rotation speed sensor may be used for a long period of time. If the rotation speed sensor changes over time, the detection value of the rotation speed sensor may change as a whole. Also, the detection value of the rotation speed sensor may change as a whole due to seasonal changes in temperature. Therefore, it is necessary to appropriately correct the detection value of the rotation speed sensor under no load, which is a reference when detecting the load of the engine.

In this case, a manual correction switch for correcting the detection value of the rotation speed sensor when there is no load is provided, and the operator operates the correction switch when there is no load such as at the start of a day's work. It can be considered that the detection value of the rotation speed sensor at the time of no load is corrected. However, it is a cumbersome operation for the operator to frequently operate the dedicated correction switch to correct the detection value of the rotation speed sensor when there is no load. Further, if the operator operates the correction switch by mistake, the detection value of the rotation speed sensor under no load may be corrected to a wrong value, and there is room for improvement. According to the present invention, in a load detection structure of a work vehicle configured to detect a load applied to an engine based on a rotation speed of the engine, the detection value of the rotation speed sensor at the time of no load can be definitely corrected with good operability. It is intended to be.

[0005]

The feature of the present invention resides in the following configuration in the above-described work vehicle load detection structure. That is, the main clutch is disposed between the engine controlled by the governor and the lower transmission.
A speed sensor for detecting a rotational speed of the engine, provided with a accelerator opening sensor for detecting an accelerator opening of the engine, the control of the governor, no
Engine speed at load is constant according to accelerator opening
The stable rotation speed that converges to a stable value and the stable rotation speed
The map data corresponding to the issued accelerator opening
A storage storing means, every time the main clutch is transmission interrupted operation, if the transmission interruption state is in is in no-load state is maintained, the detection value of the rotational speed sensor yield a constant value
The main clutch is engaged during the bundle operation and the
When the load state is released, no load before release
Based on the change in the detection value of the rotation speed sensor in the state.
A convergence value at which the change in the detected value settles to a constant value.
Calculation means for setting the estimated value to the stable rotation speed, and each time the calculation means determines the stable rotation speed,
The determined stable rotation speed is stored in the map data in the storage means.
The map data at the stable rotation speed
Correction means for updating the data, the detected value of the rotation speed sensor when the engine is not loaded and stored as the corrected map data in the storage means, and the current detection value of the rotation speed sensor. And a load detecting means for obtaining a load applied to the engine based on the difference.

[0006]

When a load is applied to the engine as in normal running, when the operator operates the main clutch to cut off the transmission, the engine is disconnected from the lower-side transmission so that no load is applied to the engine. It becomes the state of the load. In this state, the detection value of the rotation speed sensor (the rotation speed of the engine) gradually increases, for example, as shown by the solid line in FIG.
At this time, an attempt is made to reach the detection value R2 of the engine speed sensor when no load is applied to the engine corresponding to the accelerator opening. Then, when the operator operates the main clutch again to the transmission side, the detection value of the rotation speed sensor returns to the original detection value when the load is applied.

In this case, according to the present invention, when the main clutch is operated to the power transmission cutoff side, based on the change in the detection value of the rotational speed sensor, the engine idle state corresponding to the accelerator opening at this time is determined. Detection value R of rotation speed sensor under load
2 is estimated. As described above, when the detection value of the engine speed sensor at the time of no load corresponding to a certain accelerator opening is estimated, the engine speed at the time of no load corresponding to each accelerator opening stored in the storage means is stored. The detection value of the number sensor is corrected by the detection value of the engine speed sensor at the time of no load corresponding to the aforementioned accelerator opening.

As described above, according to the present invention, every time the transmission of the main clutch is interrupted, the detected value of the engine speed sensor at the time of no load, which corresponds to each accelerator opening, is stored in the storage means. It is automatically corrected. in this case,
Since the operation of the main clutch to the power transmission cutoff side is one of the operations frequently performed by the operator, the attitude of the rotation speed sensor changes due to the vibration of the aircraft, etc. However, the detected value of the rotation speed sensor at the time of no load, which is a reference when detecting the load of the engine, is always maintained at a corrected and correct value. Also, since the operation of the main clutch to the power transmission cutoff side is one of the operations performed by the worker in a normal state, it is said that a dedicated correction switch is operated to correct the detection value of the rotation speed sensor at no load. There is no need for troublesome operations.

[0009]

As described above, in the load detecting structure for a work vehicle configured to detect the load applied to the engine based on the number of revolutions of the engine, the rotation at no load serving as a reference when the load of the engine is detected. Correction of the detection value of the number sensor is automatically performed by operating the main clutch to the power transmission cutoff side, which is one of the normal operations, so that the rotational speed at no load is definitely better. The detection value of the sensor can be corrected, and the functionality of the load detection structure of the work vehicle can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (1) FIG. 1 shows the inside of a transmission case 8 of a four-wheel drive type agricultural tractor, which is an example of a work vehicle, and an engine 1
Is transmitted via the transmission shaft 2 and the clutch mechanism 3 to P
It is transmitted to the TO shaft 4. Power from the engine 1 is forward clutch 5 (corresponding to the main clutch) or reverse clutch 6 (corresponding to the main clutch), cylindrical shaft 11, main transmission A (corresponding to the lower-side transmission), transmission clutch 19, first clutch The power is transmitted to the rear wheels 7 via the auxiliary transmission B, the second auxiliary transmission C, and the rear wheel differential 7a. The power branched immediately before the rear wheel differential device 7a is transmitted to the front wheels 10 via the transmission shaft 9, the hydraulic clutch type front wheel transmission D, the front wheel transmission shaft 12, and the front wheel differential device 10a.

The forward clutch 5 and the reverse clutch 6 are of a multi-plate friction type hydraulically operated type in which a friction plate (not shown) and a piston (not shown) are combined. Operated. When the forward clutch 5 is operated to the transmission side, the power of the engine 1 flows directly from the forward clutch 5 to the cylindrical shaft 11, and the body advances. Reverse clutch 6
Is operated to the transmission side, the power of the engine 1 is transmitted to the cylindrical shaft 11 in the reverse rotation state via the reverse clutch 6 and the transmission shaft 31, and the body moves backward.

The main transmission A is of a synchromesh type in which two sets of shift gears S1 are slid and can be shifted in four stages. Power from the cylindrical shaft 11 on the engine 1 side is transmitted to the transmission shaft 35. The transmission is transmitted from the transmission shaft 35 to the cylindrical transmission shaft 40, and the transmission is shifted to four speeds and transmitted to the transmission clutch 19. The first auxiliary transmission B is also of a synchromesh type that slides the shift gear S2. Hydraulic cylinders T1 and T2 for sliding operation of both shift gears S1 of main transmission A and hydraulic cylinder T3 for sliding operation of shift gear S2 of first auxiliary transmission B are provided. The second auxiliary transmission C is a manually operated type in which a shift gear is directly slid by a shift lever (not shown).

(2) As shown in FIG. 1, the hydraulic cylinder T
1 and T2, when the transmission clutch 19 is operated to the transmission cutoff side as described later, the transmission shaft 34 of the first auxiliary transmission B on the lower side of the transmission clutch 19, as described later, A transmission clutch E is provided which can connect the transmission shaft 35 on the side of the forward and reverse clutches 5 and 6 in the main transmission A. The transmission clutch E is configured as a multi-plate friction type biased to a transmission blocking side by a spring (not shown), and operates the transmission clutch E to the transmission side by supplying hydraulic oil.

Thus, when the transmission oil E is removed and the transmission clutch E is operated to be in the transmission cutoff state, the transmission shaft 35 on the main transmission A and the transmission shaft 34 on the first auxiliary transmission B shown in FIG. The transmission cutoff state is a normal running state of the aircraft. Conversely, when the transmission clutch E is operated in the transmission state by supplying the hydraulic oil, the transmission shaft 35 on the main transmission A side and the transmission shaft 34 on the first auxiliary transmission B side are connected, and the engine 1 Power is transmitted to the front wheel 10 and the rear wheel 7 via the transmission shafts 35 and 34. This transmission state is controlled by the main transmission A by the hydraulic cylinders T1, T2, and T3.
And a state in which the first auxiliary transmission B is being shifted.

(3) Next, the hydraulic cylinders T1, T2, T
3. The hydraulic control system of the transmission clutch 19 and the transmission clutch E will be described. As shown in FIG.
Is supplied to the three sets of hydraulic cylinders T1, T2, T3 via the rotary valve 15 and the hydraulic cylinder T
A pilot oil passage 16 is provided for supplying and discharging pilot hydraulic oil during the operations of T1, T2, and T3. Hydraulic oil from the hydraulic pump 13 is supplied to the rotary valve 15 via the oil passage 17, and hydraulic oil is supplied to the forward and reverse clutches 5, 6 via the oil passage 18 and the forward / reverse switching valve 27. .

Hydraulic oil is supplied from an oil passage 20 branched from the oil passage 18 to a transmission clutch 19 via a pilot-operated switching valve 26, and the pilot oil passage 16 is connected to the switching valve 26. Control valves 21 and 22 are provided for controlling the supply and discharge of the pilot hydraulic oil from the pilot oil passage 16, and the pilot oil passages 23 and 24 from the hydraulic cylinders T 1 and T 2 for the main transmission A and the first auxiliary transmission The pilot oil passage 25 from the hydraulic cylinder T3 for the device B is connected to the control valves 21 and 22, respectively, as shown in FIG.
The hydraulic oil in an oil passage 38 branched from the oil passage 18 is supplied to a transmission clutch E via a pressure control valve 39 of an electromagnetic proportional type.

As shown in FIG. 2, the shift lever 14 capable of mechanically operating the rotary valve 15 between the neutral position and the first to eighth speed positions, a position sensor 29 for detecting the operated position of the shift lever 14, and forward / reverse switching Move the valve 27 to the forward position F, the neutral position N
Forward and backward lever 33 operable at three positions of reverse position R
It has. Hydraulic pump 13 rather than forward / reverse switching valve 27
The hydraulic oil is supplied to the forward / reverse switching valve 27 side to supply the hydraulic fluid to the forward / reverse switching valve 27 side, and the oil is discharged from the forward / reverse switching valve 27 side to the transmission position. A switching valve 41 urged toward the supply position is provided with an oil discharge position for operating the forward and reverse clutches 5 and 6 to the transmission blocking side, and a clutch pedal 42 mechanically linked to the switching valve 41. And a clutch sensor 43 for detecting the operating position of the clutch pedal 42.

As shown in FIG. 1, between the engine 1 and the forward and reverse clutches 5, 6, a rotation speed sensor 30 for detecting the rotation speed of the engine 1 by a ring gear 28 for starting the engine 1 is provided. An accelerator pedal 32 for the engine 1 is provided, and an accelerator opening sensor 36 for detecting the accelerator opening of the engine 1 based on the operation position of the accelerator pedal 32 is provided.

(4) Next, the operation of each part during the gear shifting operation will be described. FIG. 2 shows a state in which the forward / reverse lever 33 is operated to the forward position F and the speed change lever 14 is operated to the first speed position, and the hydraulic cylinder T1 of the main transmission A is moved to the first speed position to operate the hydraulic cylinder T2. Is located in the neutral position,
The hydraulic cylinder T3 of the first auxiliary transmission B is located on the low speed side. As a result, the control valve 21 is switched by the pilot hydraulic oil from the hydraulic cylinder T1, and the pilot hydraulic oil from the hydraulic cylinder T3 is transmitted to the pilot oil passage 16 via the pilot oil passage 25 and the control valves 22 and 21. Then, the switching valve 26 is switched to the communication position shown in FIG.

Accordingly, the operating oil from the oil passage 18 is supplied to the forward clutch 5 via the forward / reverse switching valve 27 and is operated on the transmission side (the reverse clutch 6 is disconnected for transmission by the forward / reverse switching valve 27). Operation to the side). Then, the hydraulic oil from the oil passage 20 is supplied to the transmission clutch 19 via the switching valve 26, the transmission clutch 19 is operated to the transmission side, and the transmission clutch E is operated to the transmission cutoff side by the pressure control valve 39. The aircraft is traveling in the first forward speed state.

(5) It is assumed that the shift lever 14 has been operated from the first speed position to the second speed position in the first forward speed state as shown in FIG. By this operation, the pressure control valve 39 is operated by the control device 37 based on the detection of the position sensor 29, hydraulic fluid is supplied from the oil passage 38 to the transmission clutch E, and the piston (not shown) of the transmission clutch E Lightly pressed against a plate (not shown) (time point A1 in FIG. 3).

Next, as shown in FIG. 2, the hydraulic cylinder T1 starts to move from the first speed position to the second speed position with the hydraulic oil from the rotary valve 15 (time point A2 in FIG. 3). The pilot pressure is reduced, the control valve 21 is switched, and the pilot oil passage 16 is in a drained state. As a result, the switching valve 26 is switched to release the operating oil from the transmission clutch 19, and the transmission clutch 19 is operated to the transmission cutoff side (time point A3 in FIG. 3), and at the same time, the oil passage 38 and the pressure control are performed. Hydraulic oil is supplied to the transmission clutch E from the valve 39, and the transmission clutch E is operated to the transmission side.

As described above, the operation of the pressure control valve 39 to the transmission side of the transmission clutch E based on the detection of the position sensor 29 is not delayed (time point A1 in FIG. 3). On the other hand, the start of the operation of the hydraulic cylinder T1 tends to be slightly delayed due to the flow path resistance of each part (point A in FIG. 3).
2), the operation of the transmission clutch 19 to the power transmission cutoff side is further delayed (time point A3 in FIG. 3). In this case, as described above, the operation of the transmission clutch 19 to the power transmission cutoff side is more
Since the transmission clutch E is operated to the transmission side a little earlier, when the transmission clutch 19 is operated to the transmission interruption side,
The transmission clutch E allows the front wheels 10 to be driven without interruption.
And transmitted to the rear wheel 7. As a result, when the operation of the transmission clutch 19 is switched to the transmission interrupting side and the operation of the transmission clutch E is switched to the transmission side, the transmission of power is interrupted for a moment, and the traveling speed of the aircraft is changed by the traveling load or the traction load. Does not drop instantaneously.

As described above, the transmission clutch 19 shown in FIG.
When the transmission is operated to the transmission interruption side, the first sub-transmission B and the second sub-transmission C on the downstream side from the transmission clutch 19 become:
The power of the engine 1 stops flowing. However, since the transmission clutch E is operated to the transmission side a little before this, the power of the engine 1 is transmitted to the forward clutch 5 (or the reverse clutch 6), the cylindrical shaft 11, the transmission shaft 35 of the main transmission A, the transmission clutch The transmission is transmitted from the first auxiliary transmission B and the second auxiliary transmission C to the front wheels 10 and the rear wheels 7 via the transmission shaft E and the transmission shaft 34, so that the aircraft advances even when there is a running load or a traction load.

(6) During the gear shifting operation as described above,
The operating pressure of the transmission clutch E is controlled to be high or low, and the control of the operating pressure will be described next. As shown in FIG.
The rotational speed of the engine 1 is detected by a rotational speed sensor 30 between the main transmission A and the forward and reverse clutches 5 and 6. As will be described later, the detection value of the rotation speed sensor 30 when no load is applied to the engine 1 is obtained in advance in accordance with each accelerator opening, and the rotation speed sensor when the engine 1 is not loaded. As shown in FIG. 4, the detected values of 30 are stored in the control device 37 as map data corresponding to each accelerator opening.

As shown in FIG. 3, when the shift lever 14 starts to be operated from the first speed position to the second speed position in the first forward speed state, at the time A1 when hydraulic oil starts to be supplied to the transmission clutch E. The detected value R1 of the no-load speed sensor 30 corresponding to the accelerator opening at this time (the detected value of the accelerator opening sensor 36) (determined from FIG. 4).
Then, the difference F from the current detection value of the rotation speed sensor 30 is obtained, and the current load applied to the engine 1 is estimated (corresponding to load detection means). In this case, it can be determined that the larger the difference F is, the larger the load applied to the engine 1 is.
The operating pressure P of the transmission clutch E corresponding to the determined load
1 is set to increase in proportion to the load. Accordingly, as shown in FIG. 3, when the transmission clutch 19 is operated to the transmission interruption side and the transmission clutch E is operated to the transmission side (time point A3 in FIG. 3), the transmission clutch E is controlled by the control device 37 and the pressure control valve 39. The above-described operating pressure P1 is maintained (see time point A3 to time point A6 in FIG. 3).

As described above, while the transmission clutch E is operated to the transmission side to transmit the power of the engine 1 to the front wheels 10 and the rear wheels 7 and advance the body, the time A shown in FIG.
The shift operation to the second speed position by the hydraulic cylinder T1 is performed between the time point A4 and the time point A4. When the shift operation is completed, the pilot hydraulic oil is again supplied from the hydraulic cylinder T1 to the pilot oil passage 23 as shown in FIG. 2, and the control valve 21 is switched to the position shown in FIG. Is supplied again to the pilot valve and the switching valve 2
6 is switched to the communication position shown in FIG. As a result, as shown from time A4 to time A5 in FIG. 3, the operating oil is supplied to the transmission clutch 19, and the transmission clutch 19 is operated to the transmission side, so that the transmission clutch 19 is operated to the transmission side. After a short delay, the transmission clutch E is operated to the transmission cutoff side by the pressure control valve 39 (point A in FIG. 3).
6).

In this case, as described above, the transmission clutch 19
The transmission clutch E is operated to the transmission cut-off side slightly later than the operation to the transmission side, so that when the transmission clutch E is operated to the transmission cut-off side, the power is not interrupted by the transmission clutch 19 and the front wheels 10 are not interrupted. And transmitted to the rear wheel 7. Accordingly, when the operation of the transmission clutch 19 is switched to the transmission side and the operation of the transmission clutch E is switched to the transmission interruption side,
The transmission of power is not interrupted for a moment, and the traveling speed of the aircraft does not instantaneously decrease due to the traveling load or the towing load.

The above state is a state between the first forward speed state and the second forward speed state, and a state between the fifth forward speed state and the sixth forward speed state, and between the third forward speed state and the fourth forward speed state. 2 between the seventh forward speed state and the eighth forward speed state.
Is operated, the control valve 22 is switched, and the above-described automatic operation is performed. Between the fourth forward speed state and the fifth forward speed state, the hydraulic cylinders T1, T2, and T3 operate. The automatic operation as described above is performed. Then, even when the forward / reverse lever 33 is operated to the reverse position R and the hydraulic oil is supplied to the reverse clutch 6, the automatic operation as described above is performed between the first reverse speed state and the eighth reverse speed state. Done.

(7) In the control of the operating pressure of the transmission clutch E described above, the detection of the rotational speed sensor 30 at the time of the no-load of the engine 1 based on the current accelerator opening of the engine 1 (the value detected by the accelerator opening sensor 36). The setting of the value will be described. The detection value of the rotation speed sensor 30 when no load is applied to the engine 1 is obtained in advance in accordance with each accelerator opening, and the detection value of the rotation speed sensor 30 when the engine 1 is not loaded is calculated. As shown in FIG. 4, it is stored in the control device 37 as map data corresponding to each accelerator opening (corresponding to storage means).

When the load is applied to the engine 1 as in normal running, the operator depresses the clutch pedal 42 shown in FIG. 1, the engine 1 and the main transmission A are cut off as shown in FIG. 1, and the engine 1 is in a no-load state where no load is applied. In such a state, the action of the all-speed governor (not shown) (which automatically adjusts the fuel injection amount so that the rotation speed of the engine 1 becomes the rotation speed corresponding to the accelerator opening) is performed. As shown by the solid line in FIG. 5, the detection value of the rotation speed sensor 30 (the rotation speed of the engine 1) gradually increases, and the rotation speed sensor 30 at the time of no load of the engine 1 corresponding to the accelerator opening at this time. Attempts to reach the detection value R2. Then, when the operator returns the clutch pedal 42 to operate the forward or reverse clutches 5 and 6 again to the transmission side, the detection value of the rotation speed sensor 30 (the rotation speed of the engine 1) becomes smaller than the original load. Return to the detection value in the hung state.

In this case, when the forward or reverse clutches 5 and 6 are operated to the transmission interrupting side and are again operated to the transmission side, the detection of the clutch sensor 43 causes the control device 37 to move forward or backward as shown by the solid line in FIG. Based on the change in the detection value of the rotation speed sensor 30 (the rotation speed of the engine 1) between the time when the reverse clutches 5 and 6 are operated to the transmission cutoff side and the time when the reverse clutches are again operated to the transmission side, the accelerator opening at this time is determined. The corresponding detection value R2 of the engine speed sensor 30 when the engine 1 is not loaded is estimated. When the detection value of the rotation speed sensor 30 (the rotation speed of the engine 1) reaches the detection value R2 and stabilizes before the forward or reverse clutches 5 and 6 are operated to the transmission side,
This is defined as a detection value R2 of the engine speed sensor 30 when the engine 1 is not loaded, which corresponds to the accelerator opening at this time (corresponding to a calculating means).

As described above, the forward or reverse clutch 5,
6 is operated to the transmission cutoff side, when the detection value R2 of the engine speed sensor 30 at no load of the engine 1 corresponding to the accelerator opening at this time is estimated, the engine corresponding to this accelerator opening is estimated. The no-load detection value R2 of the rotation speed sensor 30 is taken into the map data of FIG. 4, and the map data (the portion corresponding to the accelerator opening described above) is obtained.
Is corrected (corresponding to correction means). Such correction of the map data is performed every time the forward or reverse clutches 5, 6 are operated to the transmission interruption side.

[Another Embodiment] When the load applied to the engine 1 is detected according to the present invention, the detected load is used not only for the traveling speed change of the working vehicle as described above, but also for the plow on the agricultural tractor. The present invention can also be applied to draft control for automatically raising and lowering the plow according to the load on the engine 1 when the vehicle is towed. Further, in a backhoe as an example of a construction machine, the present invention can be applied to load control in which a discharge amount of a hydraulic pump for a backhoe device is automatically changed according to a load applied to an engine.

Incidentally, reference numerals are written in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a transmission system in a transmission case.

FIG. 2 is a hydraulic circuit diagram of a hydraulic cylinder, a transmission clutch, a transmission clutch, a forward / reverse clutch, etc. for a shift operation.

FIG. 3 is a diagram showing states of a hydraulic cylinder, a speed change clutch, a transmission clutch, and a rotation speed sensor during a shift operation from a first speed position to a second speed position.

FIG. 4 is a diagram showing a relationship between an accelerator opening and a value detected by a rotation speed sensor (engine rotation speed) when the engine is not loaded;

FIG. 5 is a diagram illustrating a state of a change in a detection value of a rotation speed sensor (engine rotation speed) when the engine is not loaded when a forward or reverse clutch transmission is cut off;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 5, 6 Main clutch 30 Speed sensor 36 Accelerator opening sensor A Transmission

Continuation of the front page (56) References JP-A-5-131867 (JP, A) JP-A-3-164541 (JP, A) JP-A-5-332678 (JP, A) JP-A-60-211336 (JP) , A) Hikaru 2-149849 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 27/00-27/04 F02D 41/00-45/00 F16H 61/04 F16H 59:24 F16H 59:42

Claims (1)

(57) [Claims] A speed sensor (30) for arranging a main clutch between an engine (1) controlled by a governor and a lower transmission (A) and detecting a speed of the engine (1). And an accelerator opening sensor (36) for detecting the accelerator opening of the engine (1). The governor controls the engine speed at no load.
Is stable and converges to a constant value corresponding to the accelerator opening.
Accelerator opening that shows constant speed and its stable speed
Storage means for storing map data that associates the door, each of said main clutch is transmission interrupted operation, when in the maintained its transmission cutoff state no load condition, the rotary
While the detection value of the number sensor (30) converges to a constant value
The main clutch is engaged and operated to release the no-load condition
In the case of the
Based on a change in the detection value of the rotation speed sensor (30)
To estimate a convergence value at which the change in the detected value settles to a constant value.
And calculating means for setting the estimated value to the stable rotation speed, and each time the stable rotation speed is obtained by the calculation means ,
The obtained stable rotation speed is stored in the map data of the storage means.
The map data at the stable rotation speed
Correction means for updating the data, and the rotation speed sensor (3
A load detection structure for a work vehicle, comprising: load detection means for calculating a load applied to the engine (1) based on a difference between the detection value of (0) and the current detection value of the rotation speed sensor (30).