JPH05141516A - Pressure raising device for hydraulic clutch of working vehicle - Google Patents

Abstract

PURPOSE:To keep the meet time of a hydraulic clutch during both heavy tracking work and light tracking work constant. CONSTITUTION:During plowing work, when the draft sensor (d) of a draft controller detects high value, it judges that the working vehicle is performing heavy tracking. Then, a mucrocomputer 3 sets a pressure control valve 6 at a high hydraulic pressure raising ratio, and a hydraulic clutches 9a and 10a are meet at a high hydraulic pressure raising ratio. While the working vehicle turns during plowing or performs rotary work, the draft sensor (d) detects low value, judging that it is performing light tracking work. Then, the pressure control valve 6 is set at a low hydraulic pressure raising ratio, the hydraulic clutches meet at a low hydraulic pressure raising ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working vehicle having a speed change portion for switching power transmission paths by a plurality of hydraulic clutches, for example, a tractor having a full power shift transmission, and more specifically, to a hydraulic pressure boosting of the hydraulic clutch. The present invention relates to a hydraulic clutch boosting control device for appropriately controlling the above.

[0002]

2. Description of the Related Art Generally, the above-mentioned power shift transmission is used for shifting gears, for example, when shifting from first gear to second gear.
When it is necessary to disengage the high-speed hydraulic clutch and also to connect the second-speed hydraulic clutch, and when the auxiliary transmission is simultaneously shifted, in addition to switching between the two hydraulic clutches of the main transmission, It is necessary to shift the individual hydraulic clutches at the same time. Therefore, if the engagement timings of the two hydraulic clutches that are switched are different, a problem such as a shift shock occurs, but the meet range of the clutch greatly differs due to a change in axle load torque based on the traction resistance.

The applicant of the present invention has found that both light towing work such as rotary tillage and heavy towing work such as plow tillage have good responsiveness at the time of shifting and shocks at the time of shifting, both of which have large differences in axle load torque. In order to reduce the noise and improve the shifting feeling, as shown in Fig. 3 (a),
It proposes a means for continuously setting the boost curves of two or more different clutches in the clutch meet range with respect to the time axis.

According to this, after the initial rise of the clutch hydraulic pressure, the hydraulic control is performed with a curve having a relatively low increase rate of the clutch hydraulic pressure with respect to time for a light traction load, and after the passage of the light traction control curve region, The hydraulic pressure is controlled by a heavy traction load control curve with a relatively high clutch hydraulic pressure increase rate.

[0005]

However, in the conventional means, the heavy traction load control curve for controlling the clutch hydraulic pressure increase rate relatively high with respect to the time axis is, as described above, the clutch hydraulic pressure increase rate. Since the program control is performed after the end of the relatively low light traction control range, in FIG. 3 (a), it takes time t _L to cause the clutch meet at the low pressure value P _L , while the meet at the high pressure value P _H. It takes time t _H to start.

Accordingly, the conventional clutch control apparatus, in a case to meat at low pressure value P _L, and when to meat at a high pressure value P _H, as shown in FIG. _{3 (a), t H -t} L, i.e. , Time t _HL time difference occurs, during high pressure meet, time t
There was a problem that _HL was delayed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hydraulic clutch boosting control device for a work vehicle that can shift the clutch during heavy towing without causing a delay as compared with the clutch shift during light towing work. To do.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and includes a plurality of hydraulic clutches (9
a) and (10a), in a power shift work vehicle having a speed change portion (7) for switching and changing the power transmission path, with traction force detection means (D), (203) for detecting traction force applied from the work machine. , Traction force determination means (d), (110), (20) for determining whether the work vehicle is performing heavy traction work or light traction work based on the traction force detection means.
5) and when the traction force determination means determines that the work is a light traction work, the hydraulic pressure supplied to the hydraulic clutch is increased at a relatively low boost rate, and when it is determined that the work is a heavy traction work, it is relatively high. And a hydraulic pressure control means (3) for controlling to increase the pressure at a rate of pressure increase.

[0009]

Based on the above means, in the hydraulic clutch control system for a working vehicle of the present invention, the traction force determination means (D), (110) and (206) are based on the traction force detection means (D) and (203). ) Determines whether it is heavy towing work or light towing work. For example, the draft sensor (d), which is the traction force determination means, the switch (110) that operates in conjunction with the top link bracket (102) of the draft control mechanism, or the internal pressure sensor (205) of the drawbar cylinder (203), When it is determined that the work is heavy towing, the hydraulic control means (3) sets a hydraulic boost control curve having a relatively high hydraulic boost rate. In this state,
The work vehicle generally carries out heavy towing work such as plow work, and the axle load torque thereof is large, and therefore the meet pressure of the clutch hydraulic pressure is high (P _H ), but due to the high pressurizing rate mentioned above, the predetermined time (t _A ) The hydraulic clutch meets at.

When the work judging means judges that the work is a light towing work, the hydraulic control means (3) sets a low boost control curve. In this state, the work vehicle is in a traveling state at the end of the field during plow work or is performing light towing work such as rotary work, and its axle load torque is also small, and therefore the meet pressure of the clutch hydraulic pressure is also low ( P _L ) is
Due to the above-described low boost rate, the hydraulic clutch will meet at a predetermined time (t _A ).

[0011]

As described above, according to the hydraulic clutch control device for a working vehicle of the present invention, the traction force determination means (d), (110), (20) are based on the traction force detection means.
Since 5) determines whether heavy towing work or light towing work is being performed, it is possible to perform control during heavy towing load without causing a large "delay" with respect to clutch shift, as in light towing work.

The reference numerals in parentheses refer to the drawings, but do not limit the structure of the present invention in any way.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the hydraulic clutch boost control device for a power shift working vehicle according to the present invention will be described below with reference to the drawings. 1 to 4 are diagrams illustrating a first embodiment of the present invention in which a hydraulic pressure increase rate (with respect to time) is selected according to an output from a draft sensor. FIG. 1 is a block diagram showing a control device of this embodiment, FIG. 2 is a diagram showing a relationship between a top link thrust corresponding to a towing load and a draft sensor output, and FIG. 3 is a control of a conventional example and the present invention embodiment. It is a figure which compares and explains a characteristic. FIG. 4 is a characteristic diagram for determining whether the vehicle is light towing or heavy towing based on the actual output value of the draft sensor in this embodiment.

In FIG. 1, the operation of the shift lever 1 is as follows.
The analog output signal 2A of the shift lever potentiometer 2 is transmitted to the shift lever potentiometer 2 via the signal line 1A, and the analog output signal 2A of the shift lever potentiometer 2 is input to the microcomputer 3 to
The analog signal 2A is digitally converted by the / D converter. Draft control device D described later (see FIG. 5)
The output signal dA of the draft sensor d provided in
Input to the sensor controller e
The output eA of is connected to the microcomputer 3 for input. The output of the microcomputer 3 is again converted into a digital signal and an analog signal by the D / A converter in the microcomputer 3, and is connected to the PWM controller 5 as the analog signal 3A.
PWM output electric signal 5A from the PWM controller 5
Is input to the electromagnetic proportional pressure control valve 6. The hydraulic pressure output 6B from the electromagnetic proportional pressure control valve 6 composed of a modulation valve is supplied to three hydraulic clutches 9a in the main transmission unit 9 in the transmission 7 and two hydraulic clutches 9 in the auxiliary transmission unit 10 in the transmission 7. It is transmitted in parallel to the hydraulic clutch 10a. The driving torque from the engine 11 is transmitted to the main clutch 12 via the power line 11B, to the transmission 7 having the main transmission unit 9, the auxiliary transmission unit 10 and the differential device 13, and via the shaft 15 to the rear accelerator. Be transmitted to.

FIG. 2 is a characteristic diagram showing the correspondence between the top link thrust corresponding to the towing load and the draft sensor output corresponding thereto. As shown in the figure, the top link thrust is proportional to the draft sensor output.

FIG. 3 is a comparison of the clutch hydraulic pressure with respect to time in the embodiment of the present invention and the clutch hydraulic pressure versus time boost characteristic of the conventional example. FIG. 3 (a) shows the boost characteristic of the conventional example. 3 (b) shows the boosting characteristic of the embodiment of the present invention. Figure 3
For comparison, in (a) and (b), the boost curves for light and heavy towing have almost the same slope. or,
t _H , t _L , and t _A are the time lags when shifting, P _L is the clutch meet hydraulic pressure during light traction load, and P _H
Is the clutch meet hydraulic pressure under heavy towing load.

In FIGS. 3 (a) and 3 (b), if the meet pressure P _L during light traction load is the same pressure, as long as the clutch hydraulic pressure increase rate with respect to time is the same for the comparison, the conventional example is used after the start. In contrast to the time required for t _L, the embodiment of the present invention requires t _A , and the times t _A and t _L are substantially equal.

[0018] However, in the prior art, after the low-boost curve for light traction, since by means of employing a high boost curve for heavy towing programmatically, time until clutch engagement at the same pressure P _H is As shown in FIG. 3 (a), t _H in the conventional example and FIG. 3 (b) in the embodiment of the present invention.
As shown in, it takes time t _A. Time t _A and time t _L
3A showing the conventional example, it can be seen that it takes time t _H in the conventional example to reach the same high pressure P _H. This is to the same P _H pressure, towards the conventional example, than the present invention embodiment, it is an indication that an effect of delayed time t _HL min.

FIG. 4 is a characteristic diagram showing the output characteristic of the sensor controller e according to the first embodiment of the present invention. 1 and 4
When the towing load increases and the top link thrust increases, the output of the draft sensor d becomes larger than the towing level broken line L ₁ , and the sensor controller e
Causes the output to go high. As a result, the microcomputer 3
Is determined to be under heavy towing, and is controlled by the boosting control curve L ₂ having a large boosting rate indicated by the alternate long and short dash line in FIG. 3 (b). At this time, in order to prevent malfunction due to noise, the output of the sensor controller e is set to the predetermined time t ₁ , t
Delay by ₂ and change.

Therefore, during light towing work such as rotary work, the draft sensor d determines that the work is a light towing work, sets the boost control curve L ₃ having a high boost rate, and during heavy towing work such as plow work. The draft sensor d determines that the work is heavy towing, and sets the boost control curve L ₂ having a low boost rate. Further, in the plow work, the draft sensor d determines that it is a heavy towing work while the tillage work is performed in the field,
When operated gear shifts during該耕Yep working, hydraulic clutches 9a by high boost control curve L _2, 10a is meat, also in the field end, when Kaigyo the tractor, when raising the plow working machine, the draft sensor d is light It determined that towing operations, and this time, when shifting the shifting operation, the hydraulic clutch is meat by low boost control curve L _3, thereby, shift the shift time is kept automatically constant.

Next, another second embodiment of the present invention in which a switching element is used in the draft control device D will be described with reference to FIGS. 5, 6, 7 and 3. Figure 5
FIG. 5 (a) is a side view of the top link bracket assembly, and FIG. 5 (b) is a plan view thereof. In Figure 5 (a),
Reference numeral 101 is a bracket, 102 is a top link bracket, 103 is a leaf spring, and 105 is a feedback link, which transmits the operation of the top link bracket 102 to the control valve. Reference numeral 106 is a draft control stopper, 107 shown in FIG. 5B is a switch support metal, and 110 is a changeover switch which is fixed to the switch support metal 107.

6 (a) and 6 (b) are partially enlarged views showing details of the switching element of the second embodiment of the present invention. In the figure, 101 is a bracket, 102 is a top link bracket, 105 is a draft control stopper,
The top link bracket 102 is joined to the rod 111 by welding. A plate 109 for turning the switch on and off is welded to the rod 111.

Next, FIGS. 5 (a) and 5 (b) and FIGS. 6 (a) and 6 (b)
The operation of the second embodiment of the present invention will be described with reference to FIG. In the figure, when the load (thrust) is applied to the top link and the top link bracket 102 is pushed, the switch is turned off.
Since the N / OFF plate 109 and the rod 111 are welded, they operate as a unit. That is, the switch is turned ON / O in conjunction with the operation of the top link bracket 102.
The FF plate 109 and the rod 111 are separated from the switch 110 in the direction of the arrow shown in FIG. 6A, and the switch 110 is turned on.

By turning on the switch 110, in the second embodiment of the present invention, the curve L ₂ having a high step-up rate in FIG. 3B is selected and controlled, and the first embodiment of the present invention is performed. The same effect as the embodiment will be exhibited.

FIG. 7 shows a block diagram of a power shift wheel according to the second embodiment of the present invention. In the explanatory diagram corresponding to FIG. 1 of the first embodiment, the component elements indicated by numerals 1 to 15 are the same as those in FIG. The switch 110 is shown in FIG.
After the signal for selecting the high boosting rate boosting curve indicated by L ₂ is input to the microcomputer 3 through the signal line fA, the same operational effect as that of the first embodiment described with reference to FIG. 1 is exhibited. The second embodiment of the present invention has a particular effect that the selective controllability of the boosting curve appropriate for the working situation can be obtained by means of directly fixing the changeover switch 110 to the top link bracket 102.

Next, a third embodiment of the present invention for detecting the drawbar towing load based on the change in the internal pressure of the towing rod constituted by a hydraulic cylinder and performing the optimum pressure increase will be described with reference to FIGS. 8, 9 and 3.
Will be described.

FIG. 8 is a partially enlarged view showing the detecting mechanism of the third embodiment of the present invention. In FIG. 8, 201 is a pin,
Reference numeral 202 denotes a bracket, 203 denotes a drawbar cylinder, and the drawbar cylinder 203 is supported by the bracket 202 by a pin 201. 205 is a pressure sensor provided in the drawbar cylinder 203. The drawbar cylinder 203 is configured as a towing rod, and the pressure sensor 205 can sense the hydraulic pressure in the drawbar cylinder 203. A pressure sensor control unit 3 can input an electric signal corresponding to the pressure inside the drawbar cylinder 203 to the microcomputer 3 shown in FIG. 2 in FIG.
07 is a transmission.

Therefore, during heavy towing, the pressure sensor 205
Detects a relatively high voltage and outputs a signal gA from the pressure sensor control unit 206 in FIG. The elements 1 to 15 in FIG.
This is the same as FIG. 1 and FIG. 7 for explaining the second embodiment, and derives the same action and effect as the first and second embodiments.

As described above, in the third embodiment of the present invention,
Since the drawbar towing load is detected by the sensor as a change in the hydraulic cylinder pressure, it can be applied to towing work such as trailer as well as plow work, and this detection result is linked with the full power shift control unit. Heavy towing
Any light towing work has the special effect of shifting with a short time lag.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a first embodiment of the present invention that selects a hydraulic pressure increase rate according to an output from a draft sensor.

FIG. 2 is a diagram showing a relationship between a top ring thrust force and a draft sensor output in the first embodiment of the present invention shown in FIG.

FIG. 3 is a characteristic comparison diagram for comparing control characteristics of a conventional example and first, second, and third embodiments of the present invention.

FIG. 4 is a characteristic diagram for determining whether the vehicle is light towing or heavy towing based on the output value of the draft sensor according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a main part of a second embodiment of the present invention,
(a) is a side view and (b) is a plan view.

6A and 6B are partially enlarged views for explaining the operation around the switch according to the second embodiment of the present invention, in which FIG. 6A is a side view and FIG. 6B is a plan view.

FIG. 7 is a block diagram illustrating a second embodiment of the present invention.

FIG. 8 is a partially enlarged cross-sectional view illustrating a main part of the third embodiment of the present invention.

FIG. 9 is a block diagram illustrating a third embodiment of the present invention.

[Explanation of symbols]

3 Hydraulic control means (microcomputer) 7 Transmission (speed change part) 9a, 10a Hydraulic clutch d, 110, 205 Traction force determination means (draft sensor, switch, drawbar internal pressure sensor) D, 203 Draft control device, drawbar cylinder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasunori Komuro 667 Izuya-cho, Higashi-Izumo-cho, Yatsuka-gun, Shimane Prefecture 1 Mitsubishi Agricultural Machinery Co., Ltd. Address 667 1 Within Mitsubishi Agricultural Machinery Co., Ltd.

Claims (1)

[Claims] 1. In a working vehicle having a speed change portion for switching a power transmission path by a plurality of hydraulic clutches for shifting, a traction force detecting means for detecting a traction force acting from a working machine, and based on the traction force detecting means, Towing force determination means for determining whether the work vehicle is in heavy towing work or light towing work, and when the towing force determination means determines light towing work, the hydraulic pressure supplied to the hydraulic clutch is increased to a relatively low pressure. A hydraulic clutch pressure increasing control device for a working vehicle, comprising: a hydraulic pressure control means for controlling the pressure to be increased at a relatively high pressure increasing rate when it is determined to be heavy towing work. ..