JP2842719B2 - Work vehicle clutch hydraulic pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power shift work vehicle having a transmission portion for changing a power transmission path by using a plurality of hydraulic clutches, for example, a tractor having a full power shift transmission, and more particularly to a hydraulic clutch. The present invention relates to a hydraulic clutch pressure increasing control device for appropriately controlling hydraulic pressure increasing.

[0002]

2. Description of the Related Art Generally, the above-mentioned power shift transmission is used when shifting from a first speed to a second speed, for example.
It is necessary to disengage the second-speed hydraulic clutch and to connect the second-speed hydraulic clutch. Further, when shifting the sub-transmission at the same time, in addition to switching the two hydraulic clutches of the main transmission, the two-speed It is necessary to shift the number of hydraulic clutches simultaneously. For this reason, if the engagement timings of the two switched hydraulic clutches are different, a problem such as a shift shock occurs, but the meet range of the clutch largely differs due to a change in the axle load torque based on the traction resistance.

The applicant of the present invention has made it possible to improve the response at the time of shifting and improve the shock at the time of shifting in both light towing work such as rotary plowing and heavy towing work such as plow tillage. As shown in FIG. 3 (a), in order to reduce
A method has been proposed in which two or more types of different clutch pressure rise curves are continuously set with respect to a time axis within a clutch meet range.

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

[0005]

However, according to the above-mentioned means, the heavy traction load control curve for controlling the increase rate of the clutch oil pressure relatively high with respect to the time axis is, as described above, a curve of the clutch oil pressure increase rate. since the program control after the end of the relatively low light traction control area, in FIG. 4 (a), in order to clutch engagement at low pressure value P _L, whereas it takes time t _L, meat at a high pressure value P _H This requires time t _H.

Accordingly, the conventional clutch control device includes a case for meat at low pressure value P _L, in the case for meat at a high pressure value P _H is t _H -t _L, i.e., cause the time difference between the time t _HL component, At the time of the high pressure meet, there is a problem that a time t _HL delay occurs.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a hydraulic clutch press-up control device structure for a power shift work vehicle that can shift without a delay as compared with a clutch shift during light towing even if the clutch is shifted during heavy towing. With the goal.

[0008]

SUMMARY OF THE INVENTION The present invention comprises means for selectively controlling and using both control curves without a program control of a curve having a high increase rate with respect to time of a hydraulic pressure after a curve having a low increase rate. Is a basic feature.

According to the present invention, a draft control device (2) for controlling the towing load of a working machine to be substantially constant, and draft control releasing means (21), (27) for stopping the function of the draft control device.
Wherein the draft control release means (21), (27) is provided with a clutch hydraulic pressure control device for a working vehicle, comprising: When the draft control device (2) is in the operating state, the towing operation is a heavy towing operation such as a plow operation, and when the draft control device is in the stopped state, the towing operation is a light towing operation such as a rotary operation. Means (42),
(60), (61), when the towing selecting means is a light towing operation, the hydraulic pressure supplied to the hydraulic clutches (51), (52) is increased at a relatively low increasing rate, and In the case of the towing work, a hydraulic control means (46) for controlling the pressure to increase at a relatively high rate of pressure increase is provided.

[0010]

When the operator operates the draft control canceling means (21), (27) to activate the draft control device (2) based on the above-mentioned structure, the selecting means (42), (60), (6)
1) As a heavy towing operation, the hydraulic control means (46) is set to a high pressure increasing rate. In this state, the working vehicle is generally performing heavy towing work such as plowing work, and has a large axle load torque and therefore a high clutch pressure meet pressure (P _H ). At (t _A ), the hydraulic clutch meets.

Further, the draft control releasing means (2)
When the draft control device (2) is released in (1) and (27), the selecting means (42), (60), (6)
1) sets the hydraulic control means (46) to a low pressure increase rate as light traction. In this state, the working vehicle is generally performing light towing work such as rotary work, and its axle load torque is small, and accordingly, the meet pressure of the clutch hydraulic pressure is also low (P _L ). (T
_{In A} ), the hydraulic clutch meets.

[0012]

As described above, according to the present invention,
Draft control device release means (21), (27)
Operation, the hydraulic pressure control means is selected to a high boosting rate or a low boosting rate, so that it is possible to judge very easily and reliably whether heavy towing work or light towing work, and to shift the clutch during heavy towing work. However, there is an effect that a large time delay does not occur as compared with the clutch shift during the light towing operation.

Reference numerals in parentheses refer to the drawings, but do not limit the configuration of the present invention.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a front view of a draft control stopper release device according to an embodiment of the present invention, and FIG.
FIG. 2 is a side view of FIG.

The tractor has a driver's seat at the rear of the fuselage. A lever portion including a position control lever (hereinafter abbreviated as a PC lever) and a draft control lever, which will be described later, is disposed on the side of the driver's seat.
A hydraulic housing having a hydraulic control valve is arranged below the driver's seat, and a draft control device is arranged behind the hydraulic housing. Further, the draft control stopper release device 1 is substantially constituted by the lever member and the draft control device.

The draft control device 2 is shown in FIG.
As shown in FIG. 1 (b), a fixing plate 3 is provided, and a top link mounting bracket 6 is pivotally supported by a pin 5 below the fixing plate 3, and is fixed to the top link mounting bracket 6. Is formed by welding two rising portions 9 to the connecting plate 7 and welding bosses 10 over the rising portions 9, 9. A feedback rod 11 is rotatably supported on one side of the connection plate 7 via a support shaft 12 and a rod bracket 13. The feedback rod 11 is connected to a hydraulic control (not shown) via a multi-link. Connected to the valve.

Further, a through hole 7a is provided in the upper portion of the connecting plate 7.
The restriction bolt 16 fixed to the fixing plate 3 with the nut 15 is inserted through the hole 7a. The bolt 16 is connected to the connecting plate 7 by its washer 16a.
The amount of rotation in the counterclockwise direction is limited. A leaf spring 19 is fixed to the lower end of the fixed plate 3 by a bolt 17, and the leaf spring 19 urges the connecting plate 7 in a counterclockwise direction.

A stopper plate 21 is rotatably supported on the upper end of the fixed plate 3 via a pin 20 which is vertically mounted on the fixed plate 3. It is urged toward 16. The spring 22 is connected to the stopper plate 2
1 and a support plate 3 fixed to an upper portion of the fixed plate 3
b. When the stopper plate 21 is interposed between the connection plate 7 and the fixed plate 3, the draft control is not operated.

A wire plate 21a is fixed substantially above the center of the stopper plate 21. An outer wire 23 is fixed to the support plate 3b, and an inner wire 25 is slidably inserted into the outer wire 23. One end of the wire 25 is connected to the wire plate 21a, and the other end of the wire 25 is a support portion 27 of the draft control lever 27 in the lever portion.
a through a wire connection portion 29, the draft control lever 27 is fixed to the boss 30a,
It is rotatably supported.

Then, the draft control lever 27
Is in the draft operation range (between the position A and the position B), the stopper plate 21 also rotates from the position A 'to the position B', and the draft control can be used. Further, when the draft control lever 27 is in the draft release range (between the position B and the position C), the stopper plate 21 is also rotated from the position B 'to the position C' to release the draft control. ing.

As shown in FIG. 1 (b), a PC lever 31 is disposed on one side of the draft control lever 27. The PC lever 31 is fixed to a boss 30b and is rotatably supported. Have been. The PC lever 31 is connected to a hydraulic control valve via a power arm and a link (not shown), and controls the hydraulic control valve by the link to arbitrarily set the height of the work implement. Further, the draft control lever 27 is set so that the traction force of the work machine becomes a predetermined value, and controls the hydraulic control system so that the work machine such as a plow has a predetermined traction force. The lever portion has a lever guide 32, and the guide 32 is fixed to a side surface of the fender 33. Two long grooves are formed in the lever guide 32, and guide the movement of the draft control lever 27 and the PC lever 31, respectively.

In a first preferred embodiment of the hydraulic clutch pressure increasing control device for a power shift work vehicle according to the present invention, as shown in FIG. 2, a limit switch 42 is provided and the draft lever 27 is moved to the position shown in FIG. When the stopper plate 21 is moved between B and C as shown, the stopper plate 21 also moves between B 'and C' and the draft control is released. Thus, the limit switch 42 that is turned on and off by the operation of the draft lever 27 is provided, and the limit switch 42 is turned on when the draft lever 27 is moved between B and C.

Then, when the limit switch 42 is ON, that is, when the draft control device 2 is in the inactive state, the control unit determines that the operation is a light traction operation, and the hydraulic clutch is moved with respect to time as shown in FIG. _The voltage is boosted at a relatively low boost rate shown in FIG.
When is set to OFF, i.e., if the draft control apparatus 2 is in operation, it is judged that the heavy traction work, boosting the oil pressure at the curve L ₁ of a relatively high step-up ratio.

FIG. 4 is a block diagram showing a clutch hydraulic pressure control device. In FIG. 4, the operation of the shift lever 43 is transmitted to a shift lever potentiometer 45 via a signal line 43A, and an analog output signal 45A of the shift lever potentiometer 45 is input to the microcomputer 46, and A The analog signal 45A is digitally converted by the / D converter. The output signal 42A of the limit switch 42 is connected to be input to the microcomputer 46. The output of the microcomputer 46 is a D / A converter in the microcomputer 46, which converts the digital signal into an analog signal again, and converts the digital signal into an analog signal 46A.
Is connected to The PWM output electric signal 47A from the PWM controller 47 is input to the electromagnetic proportional pressure control valve 49. The hydraulic output 49B from the electromagnetic proportional pressure control valve 49 is
It is transmitted in parallel to a number of hydraulic clutches 51 in the main transmission section in the transmission 50 and similarly to the hydraulic clutch 52 in the sub transmission section in the transmission 50 via a switching valve (not shown). The driving torque from the engine 53 is transmitted to the main clutch 55 via the power line 53B, and is transmitted to the predetermined hydraulic clutch 51 of the main transmission unit, the predetermined hydraulic clutch 52 of the auxiliary transmission unit, and the transmission 50 having the differential device 56. ,
Further, it is transmitted to the rear wheels 59 via the axle 57.

As described above, as a first embodiment of the present invention, by disposing the limit switch 42 in a part of the draft control stopper releasing mechanism 1, it is possible to reliably determine whether a heavy towing operation or a light towing operation is being performed. In conjunction with the full power shift control unit,
When it is determined that the work is a heavy towing operation, the control is performed by increasing the pressure increase rate, so that there is an effect that the shift can be performed with the same time lag as the light towing operation.

Next, as a second embodiment of the present invention, a hydraulic clutch control device for a power shift working vehicle, which is controlled using a draft control stopper releasing mechanism, as in the first embodiment, will be described. FIG. 5 is a block diagram illustrating a clutch hydraulic pressure control device according to a second embodiment of the present invention.
Reference numerals 43 to 59 are the same as those in the embodiment of FIG. 5 and 6, the potentiometer 60 operates in response to the movement of the draft lever 27, and the potentiometer 60
Has the effect of outputting the voltage shown on the vertical axis in FIG. 7 in proportion to the operation angle of the draft lever 27. The voltage output shown on the vertical axis is taken into the microcomputer 46 via the signal line 60A to reliably determine whether the draft has been released, that is, to determine whether the operation is a heavy towing operation or a light towing operation.
The same operation and effect as those of the embodiment can be achieved.

Next, a description will be given of a third embodiment of the hydraulic clutch pressure increasing control apparatus for a power shift working vehicle according to the present invention, in which a limit switch is directly operated by a draft control stopper plate 21. Fig. 8 (a)
FIG. 6 is a plan view illustrating a third embodiment of the present invention. Fig. 8 (b)
FIG. 9 is a side view of FIG. In the figure, 3 is a bracket, 6 is a top link mounting bracket, 11 is a feedback rod, 19 is a leaf spring, 21 is a stopper plate, and 61 is a limit switch provided on the bracket. 8 (a) and 8 (b), when the stopper plate 21 is removed, the limit switch 61 is turned off, and the control unit determines that the operation is heavy towing.

A clutch hydraulic pressure control apparatus according to a third embodiment of the present invention will be described with reference to a block diagram shown in FIG.
In FIG. 9, reference numerals 43 to 59 are the same as those of the first and second embodiments of the present invention shown in FIGS. In FIG. 9, when the limit switch 61 is turned off, the microcomputer 46 detects through a signal line 61A that the operation is a heavy towing operation, and selects a control curve having a high hydraulic pressure increase rate. When the limit switch 61 is turned ON, the microcomputer 46 detects through the signal line 61A that the operation is a light towing operation. When the operation is detected as a heavy towing operation, the microcomputer 46 uses a control curve having a high boosting rate, and is therefore larger than the light towing operation. This has the effect of not causing a time lag.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a draft control release device according to a first embodiment of the present invention, wherein (a) is a front view and (b) is a side view.

FIG. 2 is an enlarged side view of a main part explaining the switch part.

FIGS. 3A and 3B are graphs showing a boosting characteristic of a clutch hydraulic pressure, wherein FIG. 3A shows a proposed example and FIG. 3B shows a boosting characteristic according to the present invention.

FIG. 4 is a block diagram showing a clutch hydraulic pressure control device according to the first embodiment of the present invention.

FIG. 5 is a block diagram similar to FIG. 4, illustrating a second embodiment of the present invention.

FIG. 6 is an enlarged side view of a main part of a second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing characteristics of the potentiometer according to the second embodiment of the present invention.

FIG. 8 is a front view showing a mechanism according to a third embodiment of the present invention.

FIG. 9 is a block diagram showing a clutch hydraulic pressure control device according to a third embodiment of the present invention.

[Explanation of symbols]

1 Draft control stopper release device 2 Draft control device 21, 27 Draft control release means (stopper plate, draft control) 42, 60, 61 Selection means (limit switch, potentiometer, limit switch) 46 Hydraulic control means (microcomputer) 51, 52 Hydraulic clutch

──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A-58-137652 (JP, A) JP-A-57-53154 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16D 25/00-25/14 A01B 63/112

Claims (1)

(57) [Claims] 1. A draft control device for controlling a towing load of a work machine to be substantially constant, and a draft control release means for stopping a function of the draft control device, wherein a power transmission path is controlled by a plurality of hydraulic clutches. A clutch hydraulic control device for a working vehicle having a shift portion that switches and shifts, wherein the draft control device is connected to the draft control releasing means, and when the draft control device is in an operating state, a heavy tow operation such as a plow operation is performed. When the device is in a stopped state, towing selection means for light towing work such as rotary work, and when the towing selection means is light towing work, the hydraulic pressure supplied to the hydraulic clutch is set to a relatively low pressure increasing rate. If heavy towing work is performed, increase the pressure at a relatively high rate. Clutch hydraulic control device of a working vehicle, characterized by comprising comprises a hydraulic control unit, the controlling so.