JP2001173771A - Hydraulic clutch control device for full power shift transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of gear shift shock at a gear shift speed at which a main transmission part and an auxiliary transmission part are simultaneously switched. SOLUTION: When the hydraulic clutches of an auxiliary transmission part and a main transmission part are simultaneously switched, for example, when upshifted from a third speed (L-3) to a fourth speed (M-1) is effected, simultaneously with release of a hydraulic clutch for a low speed L of the auxiliary transmission part and a hydraulic clutch for a third speed of the main transmission part, the oil pressures of a hydraulic clutch for a middle speed (M) of the auxiliary transmission part and the hydraulic clutch for a first speed of the main transmission part are boosted for control. In this case, a given holding pressure Pm is previously fed to the clutch for the middle speed (M) and a delay in engagement of the hydraulic clutch is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power shift transmission in which a power transmission path is switched by a plurality of hydraulic clutches to change gears, and in particular, a power shift transmission including a main transmission section and a sub transmission section each having a plurality of hydraulic clutches. More specifically, the present invention relates to a hydraulic clutch control device for increasing a hydraulic pressure to connect a hydraulic clutch.

[0002]

2. Description of the Related Art In general, a power shift transmission of this type has a main transmission section at first, second, and third speeds while a sub transmission section is maintained at a low speed L. The main transmission is shifted to the first, second, and third speeds while the sub transmission is maintained at the medium speed M to obtain the fourth, fifth, and sixth speeds as a whole, and the sub transmission is driven at a high speed. The 7th, 8th, and 9th speeds are obtained as a whole while holding at H.

[0003] At this time, even in a shift state in which only the main transmission portion is switched, it is necessary to disconnect the currently connected hydraulic clutch and to switch between two hydraulic clutches for connecting a hydraulic clutch corresponding to the shift speed. 3rd speed (L-
3) → 4th speed (M-1), 4th speed (M-1) → 3rd speed (L-
3), 6th speed (M-3) → 7th speed (H-1), 7th speed (H-
1) At the time of shifting from the sixth speed (M-3), a situation occurs in which the hydraulic clutches of both the sub transmission portion and the main transmission portion are respectively switched.

[0004] Conventionally, when a shift lever is operated,
At the same time as the operation, the hydraulic pressure of the corresponding hydraulic clutch is controlled so as to increase.

[0005]

For this reason, the third to fourth speeds at which the sub-transmission and the main transmission are simultaneously switched,
At the 4th to 3rd speed, 6 to 7th speed, and 7 to 6th speed, since the hydraulic pressure needs to be supplied to both the hydraulic clutches of the sub transmission portion and the main transmission portion, the pressurization of these hydraulic clutches is almost delayed,
The gear shift shock is greater than in the gear stage where only the main gear is switched. For example, when upshifting from third gear to fourth gear, when the main transmission is switched to first gear, if the switching of the subtransmission is delayed and remains in the low speed state (L), the gear shifts down to first gear once. Then, the sub-transmission portion shifts to the medium speed state (M) to be in the fourth speed (3 → 1 → 4th speed), and a shift state occurs.
A large shift shock occurs.

Accordingly, an object of the present invention is to provide a power shift transmission which solves the above-mentioned problems by applying a holding pressure in advance to a hydraulic clutch on a sub-shift side to be shifted next. Things.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a main transmission section and a sub transmission section, each of which switches a power transmission path by means of a plurality of hydraulic clutches and performs a speed change. In a power shift transmission that obtains multiple shift speeds by multiplying the shift speeds and the shift speeds of the sub shift unit, respectively, predicts a shift speed of a sub shift unit that operates at least next to the current shift operation. Means, and a holding pressure supply means for previously supplying a holding pressure to such an extent that the clutch is not connected to the hydraulic clutch for achieving the gear position of the auxiliary transmission portion predicted by the prediction means. Hydraulic clutch control device in a full power shift transmission.

[0008]

When the hydraulic clutches of the sub-transmission unit and the main transmission unit are simultaneously switched based on the above-described configuration, for example, the third speed (L-3)
As shown in FIG. 2, when the up-shift from the first gear to the fourth gear (M-1) is performed, the hydraulic pressures of the low-speed (L) hydraulic clutch of the sub-transmission unit and the third-speed hydraulic clutch of the main transmission unit are simultaneously released.
Middle speed (M) hydraulic clutch for sub-transmission and 1 for main transmission
The hydraulic pressure of the speed hydraulic clutch is boosted. At this time, a predetermined holding pressure is given in advance to the hydraulic clutch of the sub-transmission portion to be shifted next, for example, the medium-speed (M) hydraulic clutch, and there is a delay in supplying hydraulic pressure to the hydraulic clutch. There is no pressure and the clutch is connected by increasing the pressure quickly with the predetermined characteristics. As a result, the gear is shifted to the third gear, the fourth gear, and the like without causing a delay in engagement of the hydraulic clutch of the subtransmission portion, and thus without causing a gear shift state such as, for example, the third gear, the first gear, and the fourth gear.

[0009]

As described above, according to the present invention,
Since the predetermined holding pressure is given in advance to the hydraulic clutch of the sub-transmission that is expected to operate at least after the current transmission operation, even when the sub-transmission and the main transmission are simultaneously switched, the hydraulic clutch of the sub-transmission is Engagement delay can be prevented, and large shift shock can be avoided.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 4, a power shift transmission 1 mounted on a tractor includes a main transmission section 2 having a first-speed hydraulic clutch C ₁ , a second-speed hydraulic clutch C _2, and a third-speed hydraulic clutch C _3. And the low-speed hydraulic clutch C
_L , medium speed hydraulic clutch C _M , high speed hydraulic clutch C _H
And includes a secondary shift portion 3, a having a reverse hydraulic clutch C _R. 5 is a wet clutch for transmitting rotation from the engine to the main transmission unit 2, 6 is a neutral brake that operates in neutral, 7 is a front wheel drive clutch, 9 is a rear wheel axle, and 10 is an independent PTO clutch. Reference numeral 11 denotes a PTO transmission unit.

The rotation of the engine is started from the shaft 12 by a wet clutch.
5 and the gears 13, 14, 15 to the main transmission shaft 17.
Is reached. Then, the shift lever (not shown) is in the first speed state
The first-speed hydraulic clutch C₁And low speed hydraulic
Latch C_LAre connected and others are disconnected, so the main change
The rotation of the speed shaft 17 is performed by the gear 19 and the first-speed hydraulic clutch.
C ₁, Gears 20, 21, 22, shaft 23, gears 25, 2
6. Sub-transmission 27, gear 29, low-speed hydraulic clutch
C_L, Shaft 30, gears 31, 32, 33, 35, pinion
36, bevel gear 37 and final gears 39, 40
The power is transmitted to the rear wheel 9. Also, the shift lever is in 2nd gear
In some cases, the low speed hydraulic clutch C of the subtransmission portion 3_LIs connected
In this state, the main transmission unit 2 is in the second-speed hydraulic clutch C_TwoContact
Switch to continue. In this state, the main transmission shaft
The rotation of the gear 17 is performed by the gear 41 and the second-speed hydraulic clutch C._TwoTo
Through the shaft 23. In the 3rd gear state, the sub-shift
The main transmission 2 is in the state of the third-speed hydraulic
Switch C_ThreeIs switched to be connected. In this state,
The rotation of the transmission shaft 17 is performed by the gear 42 and the third-speed hydraulic clutch.
C_ThreeIs transmitted to the shaft 23 via.

[0013] Then, when the shift lever to the fourth speed, the main transmission section 2 together with switched as hydraulic clutch C ₁ is for first-speed connection, such auxiliary transmission section 3 to the hydraulic clutch C _M is medium speed connection Switch to. In this state, the rotation of the shaft 23 which is transmitted via the first-speed hydraulic clutch C ₁ described above is transmitted directly to the shaft 30 via the hydraulic clutch C _M medium speed. And at the 5th and 6th speed,
While the sub-transmission unit 3 maintains the middle-speed hydraulic clutch _CM in the connected state, the main transmission unit 2 operates in the same manner as described above while the second-speed clutch C
To connect the ₂ or 3 speed clutch C ₃ switching switched.

[0014] Then, when the shift lever 7-speed, the main transmission section 2 together with switched as hydraulic clutch C ₁ is for first-speed connection, auxiliary transmission section 3, as a hydraulic clutch C _H is for high-speed connection Switch. In this state, the rotation of the main transmission section 2 of the shaft 23 is transmitted to the pinion shaft 36a via the hydraulic clutch C _H gear 25, 26 and a high speed. Then, in the eighth speed and 9 speed, while auxiliary transmission section 3 has maintained hydraulic clutch C _H for the high-speed connection state, the main transmission section 2 hydraulic clutch C ₂ or hydraulic clutch 3 speed second speed It switched so as to connect the C _3.

Furthermore, when the shift lever to the reverse first speed, the main transmission section 2 together with switched as hydraulic clutch C ₁ is for first-speed connection, auxiliary transmission section 3 to the reverse hydraulic clutch C _R is connected Switch to. In this state, the rotation of the shaft 23 from the main transmission unit 2, the gear 25 is transmitted to the auxiliary transmission unit 27 and the hydraulic clutch C _R for reverse via a gear 29, further through the reverse gear 45 Pinion shaft 3
6a. In the second and third reverse speeds, the main transmission unit 2 maintains the second hydraulic clutch C _R in the connected state while the main transmission unit 2 maintains the second hydraulic clutch C ₂ , It switched so as to connect the C _3.

On the other hand, as shown in FIG.
A rotary potentiometer 50 is provided on the support shaft.
The potentiometer 50 is provided at each shift speed of the shift lever.
Control unit (microcomputer) for analog voltage signal corresponding to position
Send to 51. The control unit 51 is an upper potentiometer
50 to 5 V analog voltage signal input from
To operate among the above-mentioned hydraulic clutches
To the selected outport.
An analog voltage signal of 0 to 5 V is output. And each
The out port communicates with the voltage-current exchange module 52.
The analog voltage signal from each out port is
It is converted into an analog current of 0 to 1 A by Joule 52,
Further, each of the hydraulic clutches C₁, C_Two, C_Three, C
_L, C_M, C_H, C_RElectromagnetic proportional pressure reducing valve V corresponding to₁,
V_Two, V_Three, V_L, V_M, V_H, V _ROutput to

Further, the control unit 51 has a holding pressure supply unit 53 and a next operation auxiliary transmission unit prediction unit 55 incorporated therein. Holding pressure supply means 53 for low-speed auxiliary transmission section 3, the solenoid proportional valve pressure reducing valve V _L for each hydraulic clutch operation for medium and high-speed gear, V _M, and outputs the out port corresponding to the V _H The proportional pressure reducing valves V _L , V _M , V _H are controlled such that a holding pressure is applied to such an extent that each hydraulic clutch does not engage. Further, the next operation subtransmission unit predicting means 55 outputs the hydraulic clutches C _L , C _M , and C _H in the sub transmission unit to be shifted next.
And a selection is made so that the holding pressure supply means outputs the output to an out port corresponding to the hydraulic clutch.

FIG. 3 shows a hydraulic circuit. In the figure, 5
6 is a hydraulic pump, 57 is a low pressure (for example, 15 kg / c
m^Two) A relief valve. Further, C₁, C_Two,
C_Three, C_L, C_M, C_H, C_RIs a hydraulic clutch
And V₁, V_Two, V_Three, V_L, V _M, V_H, V_RIs
Electromagnetic proportional pressure reducing valves that operate each hydraulic clutch
You.

Next, the operation of the above embodiment will be described with reference to FIG.

The shift lever is moved from third speed (L-3) to fourth speed (M
When shifting up to -1), in 3rd gear,
Located auxiliary transmission section 3 of a low speed (L) is hydraulic pressure to the hydraulic clutch C _L for being supplied connected and the hydraulic pressure in the main transmission section 2 of the 3-speed hydraulic clutch C ₃ is in the connected state is supplied. Furthermore, predicting that the following operating auxiliary transmission unit predicting means 55 then medium speed (M) hydraulic clutch C _M for connects, holding pressure supply means the solenoid proportional pressure reducing valve V _M and outputs a predetermined outport The predetermined holding pressure _Pm is controlled so as to rise. In this state, the hydraulic clutch C _M is medium speed, clutch is supplied holding pressure P _m consisting of hydraulic pressure in the immediately preceding advance to engage,
The friction plates are in contact with each other to the extent that no drag torque is generated. Then, from this state, the electromagnetic proportional pressure reducing valves V _L , V ₃
There are operated at the same time the hydraulic pressure to the low-speed hydraulic clutch C _L and the third speed hydraulic clutch C ₃ is released, the solenoid proportional pressure reducing valve V _M, V ₁ is operated, the hydraulic clutch medium for speed C
Hydraulic pressure is supplied at a predetermined characteristic to _M and the hydraulic clutch C ₁ for the first speed. Then, the first-speed hydraulic clutch C ₁ is engaged, and the medium-speed hydraulic clutch C _M is supplied with the holding pressure P _m in advance and is in a state immediately before engagement. Engage without delay. This prevents 3 → 1 → 4-speed bypass shifting by engagement delay in the middle hydraulic clutch C _M for speed is less smooth shifting of the shift shock is performed.

[0021] Similarly, 6 → 7 that auxiliary transmission unit 3 is switched from the hydraulic clutch C _M medium speed to high-speed hydraulic clutch C _H
7 → 6, 4 → 3 when the gear is changed and the sub-transmission is switched
Downshift also smoothly shifting the holding pressure P _m.

[0022] Incidentally, the above embodiment, the following operation auxiliary transmission unit predicting means 55, although the hydraulic clutch to be next operated to act selectively holding pressure P _m by predicting the current engagement in auxiliary transmission section 3 The holding pressure may be supplied in advance to all the hydraulic clutches (except for the reverse drive) other than the engaged clutch. For example, 3 → 4 deceleration time is not limited to the hydraulic clutch C _M for medium speed, it may have been adapted to supply pre-holding pressure P _m to a high speed hydraulic clutch C _H.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a hydraulic clutch control device according to the present invention.

FIG. 2 is a diagram showing the hydraulic pressure of each hydraulic clutch during a 3 → 4 shift.

FIG. 3 is a hydraulic circuit diagram.

FIG. 4 is a schematic diagram showing a full power shift transmission.

[Explanation of symbols]

1 full powershift transmission 2 main transmission section 3 auxiliary transmission section C _1, C _2, C ₃ main transmission section each hydraulic clutch (1
Fast, second speed, _{third-speed) C L, C M, C} H, C R the hydraulic clutches (slower auxiliary transmission section, medium speed, high speed, _{reverse) V 1, V 2, V} 3, V L, V _M , V _H , V _R Electromagnetic proportional control valve 51 Control unit 53 Holding pressure supply unit 55 Next operation auxiliary transmission unit prediction unit P _m Holding pressure

Claims (1)

[Claims] 1. A multi-speed transmission, comprising: a main transmission section and an auxiliary transmission section, each of which changes a power transmission path by means of a plurality of hydraulic clutches and shifts, and multiplies each of the transmission steps of the main variable section and the auxiliary transmission section. In a power shift transmission for obtaining a gear, at least a next operation sub-transmission unit predicting unit that predicts a gear position of a sub-transmission unit that operates next to the current gear shift operation; A hydraulic clutch control device for a full power shift transmission, comprising: a holding pressure supply unit that previously supplies a holding pressure to such an extent that the clutch is not connected to the hydraulic clutch to be achieved.