JP2790566B2 - Control device for power shift transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a power shift transmission.

[0002]

2. Description of the Related Art For example, as a power transmission device for a tractor, the speed of the axle can be changed freely without disconnecting the main clutch, and quickly when the traveling section is overloaded without operating the clutch. There is a power shift transmission that can increase the power, and is used for so-called shuttle (forward / backward) transmission, high / low transmission, and the like (see the new edition of Agricultural Machinery Handbook, pages 282 to 283).

[0003]

In a conventional power shift transmission, a clutch such as a proportional electromagnetic valve is turned on / off by a control device such as a control lever and a pedal, that is, a valve for connecting and disconnecting a clutch element is modulated. It was just doing. However, with only this modulation control, for example, depending on the loader operation by the front loader, forward and backward switching is frequently performed, and depending on the rush operation, lifting operation, etc.
There was a risk that the loader operation could not be adapted.

Therefore, according to the present invention, the control valve which is turned on by the control device is subjected to modulation control,
It is another object of the present invention to adapt the control valve to a work load by performing proportional control of the control valve using a control tool different from the control tool, that is, pressure control in a range from zero pressure to a maximum pressure.

[0005]

According to the present invention, when the first clutch element 35 is connected between the input shaft 3 and the output shaft 44, the first clutch element 35 is connected to the output shaft 44 via the first clutch element 35. A power shift transmission 4 for transmitting forward or high speed power, while transmitting reverse or low speed power from the input shaft 3 to the output shaft 44 via the second clutch element 36 when the second clutch element 36 is connected. And control valves 40A and 40B for switching the operating oil pressure to feed the first and second pistons 31 and 32 connecting the first and second clutch elements 35 and 36, and operating the control valves 40A and 40B. The following technical measures are taken in order to achieve the above-mentioned object in the control device provided with the control device 73.

That is, according to the present invention, when one of the control valves 40A of the first and second clutch elements 35 and 36 is turned on, the other of the first and second clutch elements 35 and 36 is operated by operating a control tool 77 different from the control tool 73. A control circuit 76 for turning off the valve 40A, detecting the operation stroke of the another control device 77, and pressure-controlling the one control valve 40A with the detection signal to turn off. Is what you do.

[0007]

The detector 74 detects that the shuttle lever, which is the control device 73, has been switched to the forward position, and uses this signal to press the first clutch element 35 on the forward side with the first piston 31 for the first control valve.
Modulation control of 40A. At this time, when a pedal, which is another controller 77, is depressed, the stroke is detected by a strain gauge detector 78 such as a potentiometer, and a detection signal is transmitted to the control circuit.

By the arithmetic processing by the control circuit 76, the first control valve 40A is set to P in accordance with the stroke of another controller 77.
WM control and pressure control proportional to the pressure from zero to the maximum pressure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 schematically shows the entire power transmission device of the tractor, in which an input side of a planetary power shift transmission 2 is directly connected to an engine output shaft 1, and a gear which is an output side of the transmission 2. The shaft 3 is extended rearward and is provided with a forward / reverse switching (shuttle) power shift transmission 4 coaxially, and further, on the output side of the transmission 4, coaxially high / low speed switching (high / low). A power shift transmission 5 is provided, and the output side of the casinter shaft 6 is connected to a differential 8 through a two-stage gear transmission 7 in the figure. It is linked to the wheels via a final reduction gear.

The planetary power shift transmission 2 is housed in a clutch housing 9 in which a main clutch is housed,
A transmission case 10 connected to the housing 9 accommodates the following devices such as the shuttle type power shift transmission 4 and the clutch housing 9 and the transmission case 10 together with the engine constitute a tractor body. Referring to FIG. 3, the planetary power shift transmission 2 has an internal gear 11 having a bowl-shaped cross section splined to an engine output shaft 1 and a planetary gear 12 meshing with the gear 11 at a radial position. A planetary gear support 14 rotatably supported by a ball bearing 13 and spline-coupled to the gear shaft 3 on the output side;
A sun gear 15 which is fitted over the boss portion of 14 and in which the planetary gear 12 is engaged, and a ball bearing which is connected to the gear 15 by a spline or the like and fixed to the vehicle body.
A clutch body 18 rotatably supported by 17; a piston 20 and a spring seat 21 which are fitted back-to-back in front of and behind the clutch body 18 and are operatively connected to each other by a connecting shaft 19; A first clutch element 22 interposed between the clutch body 18 and the planetary gear support 14, a second clutch element 23 interposed between the clutch body 18 and the support 16, and a second clutch element 23. A spring 24 that urges in the pressing direction via a spring seat 21
Etc.

The engine output shaft 1 and the gear shaft 3 have a coaxial cylindrical structure, in which a PTO propulsion shaft 25 is inserted. The front end of the PTO shaft 25 is connected to the engine output shaft 1 or the flywheel 26. The rear portion is linked to a PTO shaft (not shown) via a PTO hydraulic clutch 27 as shown in FIG. The support 16 is provided with an oil passage 29 for sending oil, which is switched by the electromagnetic valve 28 shown in FIG.

A shuttle type power shift transmission 4 is provided as a coaxial center on a gear shaft 3 serving as an input shaft for the transmission 4, and a clutch body 30 keyed or spline-connected to the shaft 3; First and second pistons 31 and 32 fitted back and forth in the body 30 as a back-and-forth, and forward rotation (forward) which is rotatably fitted on the gear shaft 3 with a needle bearing and a ball bearing. Gear 33
And idler (reverse) gear 34, and front and reverse first and second gears interposed between clutch body 30 and gears 33 and 34.
The clutch element 35, 36 and one gear 38 on a counter shaft 37 supported in parallel below the gear shaft 3
The other gear 39 is engaged with the idle gear 34 via an intermediate (idle) gear (not shown).

The first and second pistons 31, 32 are respectively provided with return springs by switching the proportional valve 40 shown in FIG.
Oil can be fed against the gears 41 and 42, and therefore, an oil passage 43 is formed in the gear shaft 3. The forward rotation gear 33 is an input shaft of a high-low power shift transmission 5 having a cylindrical structure arranged coaxially with the gear shaft 3.
44 (the output shaft for the shuttle type power shift transmission 4).

Referring to FIG. 1, a tractor steering handle 72 is shown.
The handle post or the like is provided with a shuttle lever (control device) 73 that can be switched from a neutral position N to a forward position F and a reverse position R, and detectors (limit switches) 74 and 75 for detecting the forward / backward position are provided. Have been. The proportional valve 40 is a pressure proportional solenoid valve, and includes a first control valve 40A for forward movement and a second control valve 40B for reverse movement.
Next, the respective detection signals of the detectors 74 and 75 are transmitted to a control circuit 76 exemplified by a CPU to excite and demagnetize the valve, thereby
By modulating 40A and 40B, the hydraulic pressure can be switched and sent to the first piston 31 for advance and the second piston 32 for reverse.

Here, in the embodiment of the present invention, the following control can be performed on the first control valve 40A for forward movement by performing calculations and the like in the control circuit 76. That is, the control device 73
To the forward side to excite the first control valve 40A,
Modulation control of the first piston 31 allows the first
With the clutch element 35 turned on, the operation stroke of another control device 77 (in the figure, the pedal depression stroke) is detected by a detector 78 such as a strain gauge such as a potentiometer,
The first control valve 40A is turned off, that is, demagnetized, through the control circuit 76 by the detection signal.

In this case, the first control valve 40A is subjected to PWM control (pulse width control) by the detection signal of the detector 78, and after proportional pressure control from zero pressure to maximum pressure (for example, 18 kgf / cm ² ), An arithmetic circuit and the like are incorporated in the control circuit 76 to turn off the control valve 40A. Referring to FIG.
The low-type power shift transmission 5 includes a clutch body 45 that is connected to the input shaft 44 by a key or a spline, and the like.
A high fitting which is fitted back and forth around the body 45
The first and second pistons 46 and 47 for low, the first and second gears 48 and 49 for high and low which are relatively rotatably fitted on the input shaft 44, and the coaxial center with the counter shaft 37 for shuttle. And a counter shaft 6 having gears 50 and 51 supported in parallel below the gear shaft (input shaft 44), one of the gears 50 on the counter shaft 6 being connected to the first gear 48, and the other 51 is fitted to the second gear 49.

[0017] Clutch body 45 and high / low gear 4
Between the first and second return springs 52,53.
.First and second clutch elements pressed by two pistons 46 and 47
Oil for the pistons 46 and 47 is supplied to the oil passage 5 formed in the lid 57 by switching the electromagnetic valve 56.
8. The pipes 59 and 60 can be fed via a rotary pipe member 61, an oil pipe 62 formed on the input shaft 44, and the like.

The lid 57 is a mounting base for the various valves 28, 40, 56, and includes an oil passage 58 of the lid 57 and a rotary piping member 61.
6 (A) and 6 (B) are taken in order to connect them with pipes 59 and 60. That is, in FIG. 6A, the lower end of the pipe 59 is connected to the rotary piping member 61 by the screw 59A, and the upper end of the internal
B and an outer seal 59C.

Then, a bolt 59D is screwed into the inner screw 59B, the pipe 59 is held upright, and the lid 57 is positioned.
A blind plug 59E is screwed in place of 59D. FIG.
(B) shows an oil passage 59F formed in a blind plug 59E, and the other parts are common to FIG. 6 (A). 2 and 4, the gear transmission 7 includes a transmission gear 63 connected to the rear end of the counter shaft 6 and a transmission gear 65 which is coaxially disposed on the counter shaft 6 by a bearing 64. Differential drive shaft 66 having a counter shaft 6 and a differential drive shaft 66
And a shift type switching means 67 for switching on and off the
The transmission shaft 70 has transmission gears 68, 69 that mesh with the transmission shafts 63, 65, and is rotatably supported coaxially with the output shaft 44.

In FIGS. 2 and 5, since the planetary power shift transmission 2 is provided with an oil bath, the rotation of the flywheel 26 becomes a resistance. Therefore, the lower part of the flywheel 26 is covered with the oil fence cover 71
And is separated from the oil so that the above-mentioned resistance does not exist. Next, a path from the engine to the differential device 8 will be schematically described.

In the planetary power shift transmission 2,
When the oil of the valve 28 is supplied to the piston 20, the first clutch element 22 is pressed and the planetary action is eliminated, and the rotation of the engine output shaft 1 is transmitted to the gear shaft 3 as it is. On the other hand, when the oil supply is interrupted by switching the valve 28, the tension of the spring 24 presses the second clutch element 23 through the spring seat 21.

As a result, the above-described planetary gear reduction function is achieved, and the gear shaft 3 is rotated under reduced speed. Also, the pistons 31 and 32 of the shuttle type power shift transmission 4
By switching and feeding oil from the valve 40, the shaft 44 on the output side is driven to rotate forward or backward at either high speed or deceleration, and the output of the shuttle type power shift transmission 4 is high / low type. The power is transmitted to the input shaft 44 of the power shift transmission 5 and the first and second pistons are
By switching and sending oil to 46 and 47, the counter shaft 6, which is the output side, has high and
The gear shift is switched to low, and the differential gear 8 is driven through two-stage gear shifting in the figure of the gear transmission 7.

In the above control, in the embodiment of the present invention,
The following control is performed on the forward side of the shuttle type power shift transmission 4. The controller 73 is moved to the forward position F to transmit this signal to the control circuit 76, and by modulating the first control valve 40A, the first clutch element 35 is pressed, that is, turned on, via the first piston 31. For example, when the tractor is moved forward to perform a loader operation, when the operator steps on another control tool 77, the stroke is detected by the detector 78, and the detection signal is transmitted to the control circuit 76.

The control circuit 76 controls the first control valve 40A.
Is pressure-controlled and PWM-controlled in proportion to the pressure from zero to the maximum to turn off the first control valve 40A. Therefore, for example, in loader work, forward and backward movement can be frequently changed automatically, and for example, pressure can be controlled by the intention of the operator according to the load in loader work during forward movement, and the work can be adapted to the work.

The present invention can be applied to one or both of the reverse control of the shuttle type power shift transmission and the high / low control valve of the high / low type power shift transmission. Instead, it can be a lever type. In addition, by arranging various control valves 28, 40, 56 on the lid 57 near the power shift transmission, the distance from the clutch pack is shortened, and the delivery of pump pressure is instantly delivered to each valve. This is advantageous as an automatic control for fighting for milliseconds.

[0026]

The present invention is as described above. Proportional pressure control from zero pressure to maximum pressure can be performed by an operator's intention while performing modulation control, and automatic control according to load can be performed.

[Brief description of the drawings]

FIG. 1A is a sectional view showing an entire embodiment of the present invention, and FIG. 1B is an explanatory view of a proportional valve.

FIG. 2 is a configuration diagram showing an overall outline of an embodiment of the present invention.

FIG. 3 is a side sectional view of a planetary power shift transmission and a shuttle type power shift transmission.

FIG. 4 is a side sectional view of a high / low type power shift transmission.

FIG. 5 is a front view of a flywheel portion.

FIG. 6 is a cross-sectional view showing two examples of oil path formation.

[Explanation of symbols]

 3 Input shaft 4 Power shift transmission 31 First piston 32 Second piston 35 First clutch element 36 Second clutch element 40A First control valve 73 Control device 76 Control circuit 77 Other control device

Claims (1)

(57) [Claims] A first shaft is provided between an input shaft (3) and an output shaft (44).
When the clutch element (35) is connected, forward or high-speed power is transmitted from the input shaft (3) to the output shaft (44) via the first clutch element (35), while the second clutch element (36) is When connected, the output shaft from the input shaft (3) via the second clutch element (36)
(44) is provided with a power shift transmission (4) for transmitting reverse or low speed power, and the first and second clutch elements (35), (36) are provided.
Control valves (40A) and (40B) for switching the working oil pressure and sending liquid to the first and second pistons (31) and (32) connecting the
A control device (73) for operating the control valves (40A) and (40B), wherein one of the control valves (40A) of the first and second clutch elements (35) and (36) is In the ON state, the controller (73)
By operating another control device (77), the one control valve (40
A), and a control circuit (76) for detecting the operation stroke of the another control device (77), and pressure-controlling the one control valve (40A) with the detection signal to turn off the control valve (40A). A control device for a power shift transmission, comprising: