JPH0613902B2 - Hydraulic control of automatic transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a hydraulic control device for an automatic transmission, and in particular, it includes a main transmission capable of automatically switching a plurality of shift stages and an auxiliary transmission capable of switching at least a low speed side and a high speed side. TECHNICAL FIELD The present invention relates to an improvement in a hydraulic control device for an automatic transmission that achieves a multi-speed shift by a combination of shifts including simultaneous shifts of a transmission and an auxiliary transmission.

[Prior art]

With the rapid spread of automatic transmissions for vehicles in recent years, main gearboxes that can automatically shift gears in relation to vehicle speed and throttle opening mainly aiming at improving fuel economy have a reduction ratio of 1 or less. A so-called overdrive device that is attached in series as an auxiliary transmission has been widely used. Also, paying attention to the function as an auxiliary transmission capable of switching between a high speed stage and a low speed stage like such an overdrive device, this is positively tuned to the shift of the main transmission, and the main transmission and the auxiliary transmission are connected. It is already known that a shift control as shown in FIG. 4 is performed by simultaneously or alternately shifting to achieve a multistage shift of six forward gears. In this way, by arranging the auxiliary transmissions that can switch between the high speed side and the low speed side with respect to the main transmission in a serial relationship, the existing automatic transmission can be used as a basis for reducing the design changes and manufacturing. While advantageous, it is possible to easily realize a multi-speed shift, and it is possible to obtain many advantages such as an improvement in fuel consumption, an improvement in power performance, and a reduction in the load on the friction engagement device due to the multiple speeds.

[Problems to be Solved by the Invention]

However, for an automatic transmission that achieves a multi-speed shift by such a combination of shifts including simultaneous shifts of the main transmission and the sub-transmission, for example, from the second speed to the third speed in FIG. When the automatic transmission as a whole is upshifted by shifting the main transmission to a high gear and shifting the auxiliary transmission to a low gear, such as shifting to the fourth speed or shifting from the fourth speed to the fifth speed. However, in this case, if the acting force on the auxiliary transmission side is rapidly released, there is a problem that a large shift shock occurs. In order to deal with this problem, it is necessary to moderate the low gear shift of the auxiliary transmission in such a case, that is, to reduce the speed at which the high speed hydraulic servo mechanism of the auxiliary transmission releases. As a means used in such a case, it is general to provide a restriction (orifice) in the oil passage. However, if an orifice is provided, this not only prolongs the time lag when the accelerator is stepped on and the auxiliary transmission shifts to a low gear (so-called "down gear"), but it also causes a problem that the gear shift at that time becomes worse. To do.

[Object of the Invention]

The present invention has been made in view of such a conventional problem, and while maintaining a good gear shift shock at the time of a multi-speed gear shift, a time lag at the time of a downshift does not become long, and the gear shift shock is not deteriorated. An object of the present invention is to provide a hydraulic control device for such an automatic transmission.

[Means for Solving the Problems]

The present invention includes a main transmission capable of automatically switching a plurality of shift stages and an auxiliary transmission capable of switching at least a low speed side and a high speed side, and each shift including simultaneous shifts of the main transmission and the auxiliary transmission. In a hydraulic control device for an automatic transmission that achieves multi-speed shift by a combination of the above, when the main transmission shifts to a high gear and the auxiliary transmission shifts to a low gear, the entire automatic transmission shifts up. In the case where the entire automatic transmission is downshifted by a means for slowing the release speed of the high speed friction engagement device of the auxiliary transmission and a low gear shift of the auxiliary transmission due to a depression of the auxiliary transmission, The above object is achieved by providing a means for increasing the release speed of the high speed friction engagement device of the auxiliary transmission, compared with the above case. Further, in the embodiment of the present invention, the degree at which the release speed is moderated or increased is determined according to at least one of the vehicle speed, the engine load, and the accelerator depression speed,
For example, the gear shift shock can be improved more finely according to the running state of the vehicle, such as the gear shift shock at the time of a partial down.

[Action]

In the present invention, the disengagement speed of the high-speed frictional engagement device of the auxiliary transmission is not merely slowed down, but the disengagement speed is increased when the accelerator is depressed and the auxiliary transmission undergoes a low gear shift. By doing so, it is possible to maintain the shock during the multi-speed shift satisfactorily, and at the same time, to prevent the time lag during the downshift from being short and to prevent the shift shock during the downshift from deteriorating.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a skeleton diagram of an FF (front engine / front drive) automatic transmission to which the present invention is applied. The automatic transmission includes a torque converter 120 and a transmission unit 140 that are provided coaxially with the engine 9.
Have. The transmission unit 140 includes a main transmission 160 and an auxiliary transmission 18 connected in series with an output shaft of the main transmission 160.
It consists of 0 and. The main transmission 160 is here an underdrive device and has three forward gears, and the auxiliary transmission 180 is an overdrive device here, and there are two forward gears including a low gear with a reduction ratio of 1 and a high gear with overdrive. have. The main transmission 160 includes a common sun gear 161, ring gears 162a and 162b, a planetary pinion 164.
a, 164b, and Kiyariya 166a, a front side consisting 166b, includes a planetary gear unit in the second column of the rear side, respectively clutch _C 1, _{C 2,} the brake _{B 1, B} 2,
The rotation is controlled by B ₃ and the one-way clutches F ₁ and F ₂ . On the other hand, the auxiliary transmission 180 is
1, a planetary gear unit including a ring gear 182, a planetary pinion 184, and a carrier 186 are provided, and rotation is controlled by a clutch C ₀ , a brake B ₀ , and a one-way clutch F ₀ . Since the specific coupling configuration of the main transmission 160, the sub transmission 180, and each friction engagement device is well known, only the skeleton is shown in FIG. 2, and the detailed description is omitted. In this automatic transmission, each element such as a brake and a clutch is controlled as shown in FIG.
0 and the auxiliary transmission 180 are gear-shifted as shown in FIG. FIG. 1 is a partial view of a hydraulic control circuit for controlling the automatic transmission. The oil pump 10 sucks and pressurizes the oil in the oil sump 1 to project. The other hydraulic control circuit 12 includes various pressure regulating valves such as a primary regulator valve, and
A shift valve for controlling the shift of the main transmission 160 is included, and the configuration and operation of these are well known, so description thereof will be omitted. The 3-4 shift valve 14 is a valve that controls the shift of the auxiliary transmission 180. In the state on the left side of the drawing, the port 14d and the port 14e communicate with each other and the line pressure is supplied to the clutch C _{0. When 0} is engaged, the auxiliary transmission becomes the low speed stage (see FIG. 4). Also, when the 3-4 shift valve 14 is in the state on the right side of the drawing, the ports 14d and 14c are
DOO are communicated, since the line pressure to the brake B ₀ is supplied, the auxiliary transmission 180 the brake B ₀ is engaged becomes high gear. The state and switching of the 3-4 shift valve 14 on the right side and the left side in the drawing are turned on by an electromagnetic solenoid valve (not shown) which is driven according to an instruction from the microcomputer 24 to which the throttle opening, vehicle speed, etc. are input. OFF
Thus, it is performed depending on whether or not the control oil pressure is applied to the port 14a. The B ₀ release control solenoid 16 is provided in the B ₀ drain oil passage from the port 14b of the 3-4 shift valve 14, and includes a valve body 16b, a solenoid 16c, and a spring 16d that pushes back the valve body 16b. There is. The solenoid 16c is controlled by an electric signal from the microcomputer 24. When the B ₀ release control solenoid 16 is in the OFF state, the port 16a is closed, so the drain of the brake B ₀ is throttled by the orifice 18, and the release of the brake B ₀ becomes gradual. Also, B0 release control solenoid 16
Is ON, the port 16a is opened, so most of the drain of the brake B ₀ is drained from the drain port 16e of the B ₀ release control solenoid 16 and the brake B ₀ is released quickly. FIG. 5 shows the characteristics when the entire automatic transmission shifts up from the second speed to the third speed. In this shift, the main transmission 160 shifts to a high gear and the sub transmission 18
Since 0 shifts to a low gear, it is necessary to moderate the low gear shift of the auxiliary transmission 180 in order to improve the shift shock. Therefore, it is necessary to appropriately maintain the B ₀ hydraulic pressure by means such as an orifice. However, if the B ₀ hydraulic pressure is left only by the orifice, not only the time lag at the time of the downshift becomes long, but also the gear shift shock at the time of the downtime deteriorates. In this embodiment, in order to prevent such a problem,
When the main transmission 160 shifts to a high gear and the auxiliary transmission 180 shifts to a low gear (the automatic transmission becomes an upshift as a whole), the B ₀ hydraulic pressure is retained by the orifice (slowly released). However, the B ₀ hydraulic pressure is quickly drained at the time of a downshift to prevent an increase in the time lag and aggravation of the shift shock at the downtime. FIG. 6 shows a gear shift characteristic at the time of a downshift (corresponding to gear shift from the sixth speed to the fifth speed of the automatic transmission as a whole) according to this embodiment. Before the time t ₀ , the 3-4 shift valve 14 is in the state on the right side of the drawing in FIG. 1, the port 14d and the port 14c communicate with each other, and the line pressure is supplied to the brake B _0. B ₀ is engaged, and the auxiliary transmission 180 is on the high speed stage side. At time t ₀ , the port 14 a of the 3-4 shift valve 14
The control oil pressure that had been operating is drained, and the 3-4 shift valve 14 is switched to the state on the left side in the drawing. Accordingly, the port 14d and the port 14e communicate with each other, the line pressure is supplied to the clutch C ₀ , and the port 14c and the port 14e are connected.
The B ₀ hydraulic pressure is drained because it communicates with b, but at this time, the B ₀ release control solenoid 16 is set to the ON state by the microcomputer 24, so that the drain of the brake B ₀ becomes quick, The release of B ₀ becomes faster. At time t ₁ , the input shaft rotation speed of the auxiliary transmission 180 increases to the synchronous rotation of the clutch F ₀ , so that the auxiliary transformer 180 enters the low speed stage state. FIG. 7 is a control flow chart of this embodiment. First, in step 30, the flag F and the timer T are reset as initialization. In step 32, the instructed shift speed is calculated from the vehicle speed, the intake throttle opening degree, and the like. If there is no speed change, F = 0 at step 34 and NO at step 36, and the B ₀ release control solenoid is turned off (step 38). However, when the auxiliary transmission 180 depresses the accelerator and downshifts, a YES determination is made in step 36, so the B ₀ release control solenoid 16 is turned on (step 40) and the flag F in step 42. Is set to 1, the timer starts counting at step 44. Step 5
In step 4, the shift control solenoid valve is drive-controlled based on the commanded shift speed determined in the main routine in step 32. When the auxiliary transmission 180 is downed, the flag F is set to 1 set, and therefore the determination at step 34 is F.
= 1 and the timer value is compared with the predetermined time Ta in step 46, and if T <Ta, that is, the predetermined time T
If a has not elapsed, nothing is done (step 54
To T ≧ Ta, the B ₀ release control solenoid 16 is turned off (step 48) and the flag F and the timer T are reset (step 50,
52). It should be noted that in the above embodiment, the B ₀ release control solenoid 16 is turned on when the downshift is performed in the low speed range, for example.
By using the FF, it is possible to improve the shift check at the time of so-called personal downshift. This control is performed by B ₀ release control solenoid 1
6, the set time of the timer Ta, or ON / OFF
The duty ratio can be changed according to the vehicle speed, the throttle opening, or the accelerator pedal depression speed.

【The invention's effect】

As described above, according to the present invention, a shift shock at the time of a multi-speed shift, in particular, a shift shock at the time of an upshift of the entire automatic transmission due to the main gear shifting to a high gear and the auxiliary transmission shifting to a low gear. While maintaining good, the auxiliary transmission reduces the time lag at the time of downtime achieved by the low gear shift, and
It is possible to obtain an excellent effect that it is possible to prevent the gear shift shock during the downshift from being deteriorated.

[Brief description of drawings]

FIG. 1 is a hydraulic control circuit diagram showing a part of an embodiment of a hydraulic control device for an automatic transmission for a vehicle according to the present invention, and FIG. 2 is a skeleton of an automatic transmission for a vehicle to which the above embodiment is applied. FIG. 3 is a diagram showing an engagement / combination state of the friction engagement device of the automatic transmission, and FIG. 4 is a diagram showing a combination of gear shifts of the main transmission and the auxiliary transmission. FIG. 5 is a shift characteristic diagram when the entire automatic transmission is upshifted from the second speed to the third speed, and FIG. 6 is a similar shift characteristic when the entire automatic transmission is downshifted from the sixth speed to the fifth speed. 7 is a flow chart showing the control routine used in the above embodiment. 160 ...... main transmission, 180 ...... auxiliary transmission, 14 ...... 3-4 shift valve, 16 ...... _{B 0} release control solenoid, 18 ...... orifice, 24 ...... microcomputer.

Claims (2)

[Claims] 1. A main transmission capable of automatically switching between a plurality of shift speeds, and an auxiliary transmission capable of switching at least a low speed side and a high speed side, each including simultaneous shifting of the main transmission and the auxiliary transmission. In a hydraulic control device for an automatic transmission, which achieves a multi-speed shift by a combination of shifts, the main transmission shifts to a high gear and the auxiliary transmission shifts to a low gear, whereby the entire automatic transmission upshifts. In this case, the means for slowing down the disengagement speed of the friction engagement device for the high speed stage of the auxiliary transmission and the case where the entire automatic transmission is downshifted by depressing the accelerator to shift the auxiliary transmission to a low gear ,
A hydraulic control device for an automatic transmission, comprising: a means for increasing a release speed of a friction engagement device for a high speed stage of the auxiliary transmission, which is faster than the above case. 2. The hydraulic pressure for an automatic transmission according to claim 1, wherein the degree of slowing or speeding up the release speed is determined according to at least one of a vehicle speed, an engine load, and an accelerator pedal speed. Control device.