JP2002031228A - Load control device for working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an engine from stalling caused by a working load and to improve working efficiency by reducing futile change commands in a working vehicle load control device outputting a change command of downshift a position of a transmission when a working load exceeds a designated value. SOLUTION: When an automatic speed reduction is requested from working load increase, a change command to shift a main transmission position one step down to a speed reduction side. A limit of the change command to the speed reduction side to restrain change commands exceeding m times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device for a work vehicle for agricultural work such as a tractor or a combine, or for construction or transportation. The present invention relates to a work vehicle load control device provided with control means for instructing a position change to a deceleration side.

[0002]

2. Description of the Related Art Conventionally, a work load is detected from a change in an engine speed or the like, and when the work load exceeds a predetermined value, a command to change a shift position of a transmission to a deceleration side is output to prevent engine stall. There is known a work vehicle provided with a load control device. For example, when the work load exceeds a predetermined value, the gear combination of the transmission is shifted down by one stage to a side having a higher reduction ratio, and the traveling output rotation is reduced to avoid engine stall. At this time, if the work load has not yet decreased, the change command is repeated to decelerate the transmission one step at a time. When the work load decreases and the engine returns to the original rotation speed, a speed increase command is output to the transmission to shift up the gear combination of the transmission.

[0003]

However, the state in which the transmission is decelerated by a large number of gears due to the work load is when the vehicle speed is not suitable at all, or when the load is released slowly in an unpredictable work state, or In such a case, an abnormality may occur in the system.

[0004] The engine of this type of working vehicle is formed so that the maximum torque point is set in a medium speed rotation range so that the engine can exhibit the stickiness at low speed running. Therefore, in the middle speed region, the engine rotation is reduced by the load but the engine stalls rarely. On the other hand, when the torque falls below a certain low torque point, the engine stalls easily.

[0005] Further, since each operation such as the forward / backward switching operation of the vehicle body, the clutch connection operation, the lifting / lowering operation of the working machine, and the operation of entering the PTO has a load fluctuation, a change command is always output.

Therefore, in a load control device for a work vehicle that outputs a command to change the shift position of the transmission to a deceleration side when the work load exceeds a predetermined value, engine load stall is prevented and useless change is prevented. The technical problem to be solved arises in order to improve the working efficiency by eliminating the output of the command, and an object of the present invention is to solve this problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and includes a means for detecting a work load, a transmission device when the work load exceeds a predetermined value. In a load control device for a work vehicle provided with a control means 50 for changing the shift position 48 to the deceleration side, a limit is provided for a position for changing the shift position to the deceleration side, and a change command exceeding this limit is checked. A work vehicle load control device configured as described above, and a work vehicle load control device configured to activate the notification means 82 when a work load exceeding the above limit is detected, and a means for detecting the work load The engine speed sensor 20 is provided as a control unit. When the engine speed continuously drops below the first limit value for a predetermined time, the change command is output. The load control device of the work vehicle, which is configured to output the change command immediately when the vehicle has fallen to the second lower limit value, the vehicle body forward / reverse switching operation detecting means 35, and the clutch engagement operation detecting means 75 , Work implement elevating / lowering operation detecting means 23 and PTO entering operation detecting means 7
And a load control device for a work vehicle configured to check or delay the change command when any of the detection means detects the change command.

[0008]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a tractor 10 as an example of a work vehicle, and the tractor 10 includes a pair of left and right front wheels 1.
1 and 11, and rear wheels 12 and 12. An engine 13 is mounted at the front of the vehicle body, and a transmission case 14 is provided from the center to the rear of the vehicle body. Are linked. A driver's seat 17 is provided above the transmission case 14, and the driver's seat 1 is provided.
7 is provided with a steering handle 18 in front of the front wheel 1
Steer 1,11.

The rotational power of the engine 13 is reduced by a transmission provided in a transmission case 14 and transmitted to the rear wheel 12 or the front and rear wheels 11 and 12.
The work machine 16 is transmitted to the PTO shaft 19 and is driven. The engine 13 is provided with an engine speed sensor 20 as means for detecting a work load. A lift cylinder 21 is provided at an upper portion of the transmission case 14. When the lift arm 22 is rotated by the expansion and contraction of the lift cylinder 21, the link mechanism 15 moves up and down, and the work machine 16 moves up and down. The rotation angle of the lift arm 22 is detected by the lift arm angle sensor 23, and the controller 50 calculates the height of the work implement 16 based on the detected value. Also, working machine 1
6, a rear cover 25 is rotatably attached to the rear end of the main cover 24.
The controller 50 calculates the plowing depth of the work implement 16 based on the detected value.

In the vicinity of the driver's seat 17, a position lever 30 for changing the height of the work machine 16, a tillage setting dial 31 for setting the tillage depth of the work machine 16, and a load control switch 3
2, a shift lever 33 and the like are provided. Shift lever 3
3, a neutral return type switch button 29 is provided.
By operating the switch button 29, the gear combination of the first and second main transmissions, which will be described later, is shifted one step at a time to the high speed side or the low speed side. A handle post 34 is provided in front of the driver's seat 17. The handle post 34 includes the steering handle 18, a forward / reverse switching lever 35 for selecting forward / backward movement of the vehicle body, and a working machine moved from a working position to a non-working position. Work machine elevating lever 36 that continuously raises or lowers continuously from the non-working position to the working position.
Is attached. The rotation operation of the steering handle 18 is transmitted to a steering device 37, and the front wheels 1 are controlled according to the steering amount.
1 turns. The steering amount of the front wheels 11 is detected by a steering angle sensor 38. Reference numeral 39 denotes a vehicle speed sensor for detecting the running speed of the vehicle body, and reference numeral 40 denotes a clutch pedal.

FIG. 2 is a diagram of a power transmission system, FIG. 3 is a hydraulic circuit diagram, and FIG. 4 is a block diagram of a load control system. The rotational power of the engine 13 is intermittently operated by a main clutch 45 in a clutch housing, and is sequentially turned into a first main transmission 46, a forward / reverse switching device 47 in the transmission case 14,
The transmission is transmitted to the second main transmission 48 and the auxiliary transmission 49.

The first main transmission 46 is provided with the transmission lever 3.
By operating the switch button 29 provided on the control unit 3, a signal is output from the controller 50, which is a control means, to the Hi-Lo clutch valve 51, and the Hi-Lo clutch 52 is switched to "high speed" or "low speed" to perform a gear shift operation. Is done.
The forward / reverse switching device 47 is provided with the forward / reverse switching lever 35.
As a result, a signal is output from the controller 50 to the forward / reverse clutch valve 53, and the forward / backward clutch 54 is switched to any one of "forward", "neutral", and "reverse" to perform a gear shift operation.

On the other hand, the second main transmission 48 is a synchromesh gear type transmission composed of four gear sets. The main transmission "3- A signal is output to the "4th speed" valve 55 or the main shift "1-2 speed" valve 56, and any one of "1st speed" to "4th speed" is caused by expansion and contraction of the shifting hydraulic cylinder 57 or 58 which is a shifting actuator. Is shifted. The auxiliary transmission 49 is a sliding mesh gear type transmission that is switched via a link mechanism by manual operation of the transmission lever 33, and has three shift positions of "low speed", "medium speed", and "high speed". ing.

Therefore, the first main transmission 46 and the second main transmission 48 cooperate with each other to form an eight-step main transmission pattern, and to set the sub transmission 49 in each of the "low speed" to "high speed" shift positions. ,
By operating each of the switch buttons 29, an eight-speed shift can be performed, and a total of 24 shift positions can be obtained from a combination of these.

The rotational power shifted by the auxiliary transmission 49 is reduced by a reduction gear 61 of a rear axle through a rear differential device 60, and the rear wheels 12 are driven. The rotational power shifted by the sub-transmission 49 is also transmitted to the four-wheel drive switching clutch 62, and is switched to "constant speed" or "increased speed" by the four-wheel drive clutch 62. The speed is reduced by the reduction gear 64 of the front axle via 63 and the front wheels 11 are driven. Further, the rotational power of the engine 13 is branched to a PTO system before the main clutch 45, disconnected and connected by a PTO clutch 65, sequentially passed through a PTO reversing device 66 and a PTO transmission 67, and protruded from the rear of the vehicle body. The power is transmitted to the PTO shaft 19.

Here, reference numeral 70 denotes a lift cylinder switching valve for controlling the lift cylinder 21; 71, a four-wheel switching valve for controlling the four-wheel switching clutch 62; 72, a brake cylinder for independently braking the left and right rear wheels; 73 is a brake valve for controlling the brake cylinder 72;
Reference numeral 4 denotes a PTO clutch valve that controls the PTO clutch 65. 75 is a clutch pedal sensor for detecting a depression operation of the clutch pedal 40, and 76 is a PT
PTO for detecting ON / OFF operation of O clutch valve 74
Reference numeral 77 denotes a clutch sensor of the first main transmission 46.
The i-Lo position sensor 78 corresponds to “3” of the second main transmission 48.
−4 speed ”position sensor, 79 is the“ 1st speed ”of the second main transmission 48.
These are the "-2nd speed" position sensors, and the position sensors 77 to 79 detect the shift positions of the main shift pattern obtained by linking the first main transmission 46 and the second main transmission 48. Reference numeral 80 denotes a front wheel rotation sensor that detects the rotation speed of the front wheel 11, 81 denotes a rear wheel rotation sensor that detects the rotation speed of the rear wheel 12, and 82 denotes a buzzer or lamp (or may be a monitor display) that is a means for informing the operator. is there.

Next, a control procedure of the load control device of the present invention will be described with reference to FIG. First, various sensors and switches are read (step 101). If the load control switch 32 is "ON", the load control is executed (step 102). If there is a manual shift operation (step 10).
3), the shift position stored in the storage shift position S _M at this time (step 104). When the work load becomes large and an automatic deceleration request is issued (step 105), the number of decelerations up to that time is m times (for example, 2 times / min) within a specified time.
A less (step 106), and, when the current shift position S _N is the storage shift position one stage from S _M lower speed position or the storage shift position S _M higher than the speed change position at that time (step 107), a change command is output in step 108 and thereafter. However, when the number of times of deceleration exceeds m, the buzzer 82 as the notification means is operated to check the change command.

[0018] In Thus, the current engine speed R _N is about to and less than 75% of the range of more than 65% of the rated rotational speed R _R 1
If 0 seconds has elapsed (step 108), a change command is output so that the main shift position is shifted down one step to the deceleration side (step 110). However, the work load is further increased, the current engine speed R _N is 65% of rated speed R _R
If it becomes less than 3 seconds, when the state continues for about 3 seconds, a change command is outputted so that the main shift position is shifted down one step to the deceleration side (steps 109 → 110). After that, the number of decelerations is counted (step 111). If the workload is still large, the change command is output again up to m times.

[0019] Here, the 65% to 75% of the at rated speed R _R in step 108, a rotation speed of slightly above the maximum torque generation point of the engine. When the state of the rotation region continues for about 10 seconds, as described above, 1
A change command is output to shift down by one step. Also,
Less than 65% of the rated rotation speed R _{R in} step 109
This is the number of revolutions at a position slightly below the maximum torque point of the engine. 1 when the state below this rotation area continues for about 3 seconds
A change command is output to shift down by one step. The “10 seconds” and “3 seconds” may be changed according to the characteristics of the engine.

As described above, the number of times the shift position is changed to the deceleration side when the work load is large, that is, the number of shift-down steps is limited to about two steps, and the change command exceeding this limit is suppressed, whereby the vehicle speed is reduced. Does not fit at all,
It is possible to prevent useless deceleration when the load is slowly released in an unpredictable work state. Further, a plurality of conditions for outputting the change command, the engine rotational speed R _N is in the range of 75% or less 65% of the rated rotational speed R _R is a first limit value, there is no relatively stalling of risk , the engine speed R _N watching about 10 seconds to output a change command for downshift if not return to the original state. In contrast, when the engine speed R _N is less than 65% of the rated rotational speed R _R is a second threshold lower than the first limit value, since the risk of stalling is very high immediately ( After about 3 seconds, a downshift change command is output. In this way, it is possible to reliably prevent the engine from stalling due to the work load while avoiding extra change commands as much as possible.

On the other hand, as shown in FIG. 6, when the operation of the forward / reverse switching lever 35 is detected by a switch as forward / reverse switching operation detecting means and a detection signal is input to the controller 50 (step 203), the clutch is operated. When the clutch pedal sensor 75 as a clutch connection operation detecting means detects the depression operation of the pedal 40 and a detection signal is input to the controller 50 (step 204), the work implement 1
When the lift arm 6 is moved up and down and detected by the lift arm angle sensor 23 as the work implement elevating operation detecting means and the detection signal is input to the controller 50 (step 205), the PTO clutch 65 engaging operation is detected by the PTO engaging operation detecting means. Is detected by the PTO clutch sensor 76 and the detection signal is input to the controller 50 (step 206),
Set the downshift permission timer for each (step 20
7).

In this case, even if there is an automatic deceleration request due to a large work load (step 208), a wait is given until the countdown of the downshift permission timer is completed (step 209). Then, a change command to shift down the main shift position by one stage to the deceleration side is output (step 210). This is because the operation such as the forward / backward switching operation of the vehicle body, the clutch connection operation, or the lifting / lowering operation of the working machine or the operation of entering the PTO certainly has a load change, and in that case, the change command is suppressed, or
A slight delay time is provided to monitor a change in load fluctuation, and a useless change command is eliminated to improve the operational feeling of the operator.

As shown in FIG. 7, when there is an automatic deceleration request due to a large work load (step 303), a change command to shift down the main shift position by one step to the deceleration side is output to increase or decrease the number of times of increase or decrease. The counting is performed (step 304 → 305).
When the load is reduced and an automatic speed increase request is issued (step 306), the number of times of increase / decrease is n times (for example, 5 times / min).
If it is below (step 307), the buzzer 82, which is a notification means, is activated (step 308) so that the operator can recognize the speed increasing operation (step 308), and a change command for shifting the main shift position to the speed increasing side by one step is issued. Output and count the number of increase / decrease (step 309 → 305).

If the number of times of acceleration / deceleration exceeds n times within a specified time when an automatic speed increase request is issued, the vehicle speed is not at all adapted to the load, so that there is no useless increase in speed. In order to avoid the speed change, if there is no manual shift operation, no command to change the speed increase is output (steps 306 → 310). This speed increase prohibition is released when the intentional manual operation of the operator is matched (step 310), and the number of increase / decrease is initialized (step 311). When the switch button 29 of the shift lever 33 is operated by an operator's manual operation, the buzzer 82 is operated to confirm the operation. The sound can be distinguished by different operation intervals, timbres, and the like.

As shown in FIG. 8, the load control switch 32 is a rotary type switch. When the load control switch 32 is set to the "lift control mode", the work machine is operated when the work load is large. Is increased to reduce the load. On the other hand, when the shift down mode is set, as described above, the control is executed to reduce the load by decelerating the transmission when the work load is large. On the other hand, when set to “auto mode”, the detection value of the front wheel rotation sensor 80 and the rear wheel rotation sensor 81
The slip ratio of the rear wheels is calculated from the detected values of the above. When the slip ratio is large, the lift control mode is executed, and when the slip ratio is small, the shift down mode is executed to reduce the load. I do. Further, when performing a loader operation, the loader mode is set. In the loader work,
In order to mount the loader on the front part of the vehicle body, the vertical movement of the lift arm 22 at the rear part of the vehicle body stops. Therefore, when the workload is large, only automatic deceleration is performed. As described above, by selectively executing the execution mode of the load control, the control procedure can be simplified and the control accuracy can be improved.

In this embodiment, the first and second main transmissions in which the gears are combined are restrained by the number of change steps. However, the shift position of a continuously variable transmission such as an HST is restrained. It can also be configured to do so. Thus, the present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0027]

According to the present invention, as described in detail in the above embodiment, the invention according to claim 1 is applicable to a case where a command to change the shift position of the transmission to a deceleration side when the work load exceeds a predetermined value. In addition, the limit of the position where the change command is issued is provided, and the change command exceeding this limit is checked, so that unnecessary deceleration in a case where the vehicle speed is not suitable at all is eliminated, which can contribute to improvement of workability.

According to the second aspect of the present invention, when the work load exceeding the above limit is detected, the notifying means is operated, so that in addition to the effect of the first aspect, the work load exceeding the limit is shifted to the deceleration side. It is possible to make the operator surely recognize that the change command has been suppressed.

According to a third aspect of the present invention, a work load is detected based on a change in engine speed, and when the engine speed drops below a first limit value and when the engine speed drops below a second limit value, By providing a difference in the timing at which the change command is output, in addition to the effects of the invention described in claim 1 or 2, the engine can stall due to the work load while avoiding an extra change command according to the characteristics of the engine as much as possible. Can be prevented.

According to a fourth aspect of the present invention, a change command is restrained or delayed for an operation in which a load change is surely made, such as a forward / reverse switching operation of a vehicle body or an operation of connecting a clutch. In addition to the effects of the described invention, useless change commands are eliminated, and the operability of the operator can be improved.

[Brief description of the drawings]

 The figure shows an embodiment of the present invention.

FIG. 1 is a side view of a tractor.

FIG. 2 is a diagram of a power transmission system.

FIG. 3 is a hydraulic circuit diagram.

FIG. 4 is a block diagram of a load control system.

FIG. 5 is a flowchart showing a control procedure of the load control device.

FIG. 6 is a flowchart showing a control procedure of the load control device.

FIG. 7 is a flowchart showing a control procedure of the load control device.

FIG. 8 is a front view of a load control switch.

[Explanation of symbols]

 Reference Signs List 10 Tractor 20 Engine speed sensor 23 Lift arm angle sensor 35 Forward / reverse switching lever 46 First main transmission device 48 Second main transmission device 41 First main transmission device 50 Controller 75 Clutch pedal sensor 76 PTO clutch sensor 82 Buzzer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F16H 59:74 F16H 59:74 (72) Inventor Yutaka Kashino 1-Yachikura, Tobe-cho, Iyo-gun, Ehime Prefecture Iseki Agricultural Machinery Engineering Department Co., Ltd. (72) Inventor Shiro Ito, Yachikura, Tobe-cho, Iyo-gun, Ehime Prefecture Iseki Agricultural Machinery Co., Ltd. Terms (Reference) 3D037 CA06 CB26 CB36 FA23 FA24 FA28 FB01 3J552 MA04 MA13 MA24 MA26 NA02 NA05 NA06 NA07 PA22 QC04 RA06 RB18 RC19 SB10 SB20 TB12 VA41W VA64W VA74Z VA76W VB01Z VB02Z VC01W VC10W VD14Z VD17Z

Claims (4)

[Claims] 1. A work vehicle comprising: a means for detecting a work load; and a control means for instructing a shift position of a transmission to change to a deceleration side when the work load exceeds a predetermined value. A load control device for a work vehicle, wherein a limit is provided at a position where a change command is issued to the deceleration side, and a change command exceeding this limit is checked. 2. The work vehicle load control device according to claim 1, wherein the notifying means is operated when a work load exceeding the limit is detected. 3. An engine speed sensor 20 is provided as a means for detecting the work load, and outputs the change command when the engine speed continuously drops below a first limit value for a predetermined time. The load control device for a work vehicle according to claim 1 or 2, wherein the change command is output immediately when the rotation falls to a second limit value lower than the first limit value. 4. A means for detecting the operation of switching the forward / backward movement of a vehicle body.
And a clutch connection operation detecting means 75, a lifting / lowering operation detecting means 23 of the work implement, and a PTO engagement operation detecting means 76, and when any of the detecting means detects, the change command is checked or 4. The load control device for a work vehicle according to claim 1, wherein the load control device is configured to delay the load.