JPS5927464B2 - Automatic transmission hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control system for an automatic transmission for a vehicle, and particularly relates to improvements in the transmission characteristics during downshifting.

In an automatic transmission for a vehicle that includes a hydraulic torque converter and a gear transmission mechanism equipped with a plurality of frictional engagement devices for obtaining several gears, the friction is adjusted depending on the driving state of the vehicle. The operation of the engagement device is switched between various types, and the gear transmission mechanism is automatically controlled to a transmission state most suitable for the driving condition of the vehicle at that time.

Switching control of such a frictional engagement device is normally performed by a hydraulic control device, and this hydraulic control device includes a throttle oil pressure that changes depending on the amount of depression of the accelerator pedal, that is, the intake throttle opening, and a control that changes depending on the vehicle speed. A gear shift valve is built in that is switched depending on the equilibrium relationship of the governor oil pressure, and selects the gear position of the gear transmission mechanism based on the comparative relationship between the throttle oil pressure and the governor oil pressure, that is, the amount of accelerator pedal depression and the vehicle speed. It has become.

In this case, the speed change valve connects one low-speed gear friction engagement device (low clutch) to the line oil pressure supply oil path, and connects one high-speed gear friction engagement device (high franc) to the drain oil path. Switching operation between a first switching position and a second switching position in which the high-speed gear friction engagement device is connected to the line oil pressure supply oil path and the low-speed gear friction engagement device is connected to the drain oil path. In addition, in order to provide an appropriate overramp for switching the hydraulic pressure supply to the frictional engagement device for the low speed gear and the frictional engagement device for the high speed gear, and to perform the gear change smoothly, A low speed accumulator and a high speed accumulator are connected to the hydraulic pressure supply paths of the high speed friction engagement device, respectively.

In a hydraulic control device equipped with such an accumulator,
The set pressure of the high speed accumulator is set to prevent shift shock when shifting from a low speed to a high speed, and to maintain the clutch in a fully engaged state so that the necessary torque can be sufficiently transmitted when driving in a high speed. Therefore, if the set pressure of the accumulator for high speed gear is maintained at the same value even when downshifting from high speed to low speed, during downshifting, the pressure will not reach the same value until just before it is released. In order to maintain the engaged state and therefore not cause shift shock during downshifting, it is necessary to always maintain the correct timing between the release of the equal clutch and the engagement of the low clutch.

Considering that it is extremely difficult to achieve such a goal, the patent application filed on January 4, 1972, filed by the same applicant as the present applicant,
In No. 746, the set pressure of the high-speed accumulator is substantially changed between the amplifier shift and the downshift, and the set pressure is caused to slip to 2. It is proposed to set the pressure to a relatively low level.

Furthermore, a patent application filed in 1972 by the same applicant as the applicant in question
- In No. 14749, a first hydraulic control circuit section is controlled by the hydraulic pressure of the low clutch and reduces the hydraulic pressure of the high flange to a value that causes slippage in the clutch when the hydraulic pressure rises to a predetermined level; and a second hydraulic control circuit unit that is controlled by the hydraulic pressure of the high franchise and increases the hydraulic pressure of the low clutch to a value at which the low clutch is substantially engaged when the hydraulic pressure decreases to a predetermined level. When downshifting, the equal clutch and low clutch are maintained in a slidingly engaged state at the same time, and in the process of sliding engagement between the two, substantially switching the engagement from the equal clutch to the low clutch is achieved. proposed to automatically achieve timing adjustment between the release of the /% engine crunch and the engagement of the low clutch in a downshift.

The present invention, as in the hydraulic control system proposed in the above-mentioned Japanese Patent Application No. 52-1.4746, sets the set pressure of the accumulator for high gear during downshifting to a value that causes slippage at engine launch. In addition, the above-mentioned patent application No. 52-147
By combining the hydraulic control device proposed in No. 49 with a configuration that controls the substantial rise of the low clutch hydraulic pressure in response to a substantial decrease in the low clutch hydraulic pressure, the above-mentioned special feature can be achieved. It is an object of the present invention to provide a hydraulic control device with a simpler structure than the hydraulic control device proposed in Japanese Patent Application No. 14749/1983, and which has an automatic timing adjustment function in downshifting.

According to the present invention, this object is to provide an automatic system that includes a frictional engagement device for a low gear and a frictional engagement device for a high gear and switches gears by switching the engagement between these two frictional engagement devices. In a hydraulic control device for a gear transmission mechanism for a transmission, a first gear is configured to connect the friction engagement device for a low speed gear to a line oil pressure supply oil passage and connect the friction engagement device for a high gear gear to a drain oil passage. A gear shift that switches between a first switching position and a second switching position in which the high-speed gear friction engagement device is connected to the line oil pressure supply oil path and the low-speed gear friction engagement device is connected to the drain oil path. a valve, a low speed accumulator and a high speed accumulator connected to the hydraulic pressure supply paths of the low speed friction engagement device and the high speed friction engagement device, respectively, and a back pressure chamber of the high speed accumulator. a throttle device and a check valve connected in parallel to each other in the middle of an oil passage and a cedar oil passage for supplying hydraulic pressure to the back pressure chamber and discharging hydraulic pressure from the back pressure chamber; When the downshift is switched to the first switching position, the transmission valve changes the hydraulic pressure acting on the high-speed frictional engagement device under the operation of the high-speed accumulator from the first switching position to the When the amplifier is shifted to the second switching position, the high-speed friction engagement device is caused to slip substantially lower than the hydraulic pressure acting on the high-speed friction engagement device under the operation of the high-speed accumulator. a first hydraulic pressure control means that sets the friction engagement device to a predetermined margin value; and a predetermined hydraulic pressure control means that is controlled by the hydraulic pressure of the high-speed friction engagement device during the downshift, and the hydraulic pressure causes the high-speed friction engagement device to substantially release. and a second hydraulic pressure control means for increasing the hydraulic pressure of the low speed friction engagement device to a value that substantially causes the low speed friction engagement device to engage when the low speed friction engagement device is lowered to a level. This is accomplished by a hydraulic control system that

Furthermore, in the hydraulic control device as described above, the present invention sets the set pressure for downshifting of the high-speed accumulator to a value that causes slippage in the bike clutch, and that the throttle opening decreases as the vehicle speed increases. It is proposed that the hydraulic control device be modified to have an automatic downshift timing adjustment function that better adapts to changes in vehicle speed and/or throttle opening by setting the downshift timing to a value that decreases as the vehicle speed and/or throttle opening change.

Such correction is performed in the hydraulic control device as described above, in which the throttle device is controlled by the governor oil pressure, which changes according to the vehicle speed, and the throttle oil pressure, which changes according to the throttle opening.As the vehicle speed increases, the throttle opening changes. The control valve provides a throttle passage whose passage cross-sectional area becomes smaller as the cross-sectional area decreases, and the first hydraulic control means controls the hydraulic pressure of the high-speed friction engagement device under the operation of the high-speed accumulator during a downshift. This is achieved by setting a value that causes slippage in the frictional engagement device for high-speed gears, and that decreases as the vehicle speed increases and as the throttle opening decreases.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a hydraulic circuit diagram showing essential parts of one embodiment of a hydraulic control device according to the present invention.

In the figure, 1 is a friction engagement device for high speed gear (equal clutch), 2 is a friction engagement device for low gear (low clutch), and these are selectively supplied with hydraulic pressure via a gear change valve 3. Alternatively, the engagement bundle is released by discharging the supplied hydraulic pressure.

The speed change valve 3 includes a valve element 5 that is pressed downward in the figure by a compression coil spring 4, and the upper end of the valve element receives throttle oil pressure (Pth) from a port 6, and the lower end receives a throttle hydraulic pressure (Pth) from a port γ. The governor oil pressure (Pgo) is applied, and the switching operation is performed in the vertical direction as shown in the figure based on the balanced relationship between the throttle oil pressure and the governor oil pressure.

When the valve element 5 is in the upward switching position, the line oil pressure (P/,) supplied to the port 8 via the oil passage 9 is supplied from the port 10 to the equalization lunch 1 via the oil passage 11, and When the valve element is switched downward in the figure, the line hydraulic pressure supplied to port 8 is transferred from port 12 to oil passage 13.
It is supplied to the low clutch 2 through the.

Further, when the speed change valve 3 is in the downward switching position, the oil pressure of the bike clutch 1 is drained through the oil passage 11, ports 10 and 16, and the oil passage 1γ, and when the speed change valve 3 is in the upward switching position, The oil pressure of low clutch 2 is oil passage 13
, ports 12 and 19 to drain oil passage 20.

Reference numerals 33 and 34 designate a high-speed gear accumulator and a low-speed gear accumulator connected to the oil passages 11 and 13 for the equal clutch and low clutch, respectively.

Each of these accumulators has a compression coil spring 3
Piston 3 pushed upward in the figure by 5 and 36
γ and 38, and their back pressure chambers 39 and 40
Hydraulic pressure for back pressure is supplied through oil passages 13 and 80.

...A parallel circuit of a throttle element 43 and a check valve 45 is connected to the oil passage 11 for the equal clutch, and a parallel circuit of a throttle element 44 and a check valve 46 is connected to the oil passage 13 for the low clutch. (・ru.

The control valve 61 is a control valve that controls the back pressure drain to the low speed accumulator 34 and also controls a part of the hydraulic pressure supply path to the low clutch.

The control valve 61 includes a valve element γ5 pressed upwardly in the figure by a compression coil spring γ4, and switching of the valve element serves to switch and connect port 8γ to either port 16 or 88, and also connects port 8γ to either port 16 or 88. It is designed to control communication or disconnection between and 95.

Line oil pressure is constantly supplied to the boat γ6 via an oil path 68, and the line oil pressure is supplied to the throttle element 69 (and check valve γ
0) to the high-speed stage accumulator 3 via the oil passage 13 including
It is designed to be supplied to the back pressure chamber 39 of No. 3.

The boat 88 of the control valve 61 is connected to a drain passage 90 that includes a throttling element 89 .

The boat 94 of the control valve 61 has an oil passage 96 including a throttle element 9γ.
It is connected to the upstream side of the throttle element 44 in the oil pressure supply oil passage 13 to the low clutch 2 through the
5 is connected to the oil passage 13 via an oil passage 98 on the downstream side of the throttle element 44 .

The boat 93 of the control valve 61 is connected to the upstream side of the restriction element 91 of the drain oil passage 11 in the speed change valve 3 via an oil passage 92.

Next, the operation of the hydraulic control system shown in FIG. 1 will be described in the case of a downshift with reference to FIG.

When the speed change valve 3 is switched from the upper switching position in the figure to the lower switching position, a downshift is started.

By switching the conversion valve, the hydraulic pressure that had been supplied to the high clutch 1 is now transferred to the oil passages 11, boats 10 and 1.
6. The oil begins to be discharged through the drain oil path 11.

At the beginning of such a downshift, the drain passage 1γ
The oil pressure on the upstream side of the throttle element 91 is sufficiently high, and when this oil pressure acts on the boat 93 of the control valve 61 through the oil passage 92, the control valve 61 is switched to the lower position in the figure. The boat 81 is connected to a drain boat 88.

...When the hydraulic pressure of the equal-crunch 1 begins to be discharged through the drain path as described above, the piston 31 of the accumulator 33 immediately starts upward movement to compensate for the drop in hydraulic pressure, so that the equal-crunch hydraulic pressure is as shown in Figure 2. It takes a course similar to the area α of the high clutch oil pressure curve A, and is almost constant for a while.
The accumulator stays at the oil pressure setting.

This accumulator setting oil pressure is determined by the oil pressure supplied from the oil passage 68 to the back pressure chamber 39 via the throttle element 69 and the oil passage 13, and the land difference of the piston 3γ. It is possible to set the high clutch oil pressure in α to a value that causes the high clutch to slip appropriately.

Meanwhile, during this time, line oil pressure is supplied to the low clutch 2 via the oil passage 13.

The region β of the low clutch oil pressure curve B in Fig. 2 is the region where the low clutch passes through its play area, and after that, when the low clutch passes through the play area, a substantial oil pressure begins to be formed in the low clutch oil pressure. However, at this time, the piston 38 in the low-speed accumulator 34 moves downward in the figure to release the hydraulic pressure, so the low clutch hydraulic pressure remains at the almost constant accumulator setting hydraulic pressure for a while, as in the region γ. maintained.

At this time, the back pressure chamber 40 of the accumulator 38 is
0, the boats 87 and 88 of the control valve 61 are connected to the drain passage 90 via the throttling element 89 and thus the area γ
The accumulator setting oil pressure in the range γ is determined by the degree of restriction of the throttle element 89 and the land difference of the piston 38, and by appropriately designing these, the low clutch oil pressure in the region γ can be adjusted to provide appropriate slippage to the low clutch. It can be set to a value that causes

Thus, in the regions α and γ, both the high clutch and the low clutch are maintained in a slippingly engaged state, and at a point in time t in the middle, engagement of the clutch is substantially switched from the high clutch to the low clutch.

After that, when the piston 31 in the accumulator 33 reaches the end point of its upward movement (point J), the engine launch oil pressure drops significantly, and the oil pressure acting on the boat 93 of the control valve 61 also drops accordingly. The control valve 61 is switched upward in the figure.

When the control valve 61 is switched upward, line hydraulic pressure is supplied to the boat 8γ, the line hydraulic pressure is applied to the back pressure chamber 40 of the accumulator 34, and the low clutch 2 is supplied with the line hydraulic pressure of the control valve 61. 94 and 95, the set pressure varies from a relatively low value in the γ region to a relatively high value in the δ region (corresponding to point j).・The price will increase significantly.

Reliable engagement of the low clutch is achieved at six points along the way.

Thus, in the process where the high clutch oil pressure decreases as shown by curve A and the low clutch oil pressure increases as shown in curve B, a smooth downshift from high gear to low gear is achieved. will be carried out.

In the hydraulic circuit diagram shown in FIG. 1, 99 is an amplifier shift timing valve that controls the timing when the amplifier is shifted from a low gear to a high gear. When the engine oil pressure is still low, the a-clutch oil pressure is drained from the drain oil path passing only through the throttle element 100, and after the engine clutch oil pressure reaches a predetermined level, the low clutch oil pressure is drained through the parallel oil path of the throttle elements 100 and 101. By draining it after...
This is to adjust the release timing of the low clutch relative to the engagement of the high clutch.

Further, P2 and L applied to the shift -9f3 are oil pressures applied in the 2nd range and L range, and Pdet is a detent oil pressure added at the time of kickdown.

Also, as is clear from the above explanation, in the embodiment shown in FIG. 1, the high speed friction engagement device, i.e.
The hydraulic pressure acting on the high-speed gear friction engagement device is substantially lower than the oil pressure acting on the high-speed gear friction engagement device under the operation of the high-speed gear accumulator during amplifier shift, and is a value that causes slippage in the high-speed gear friction engagement device (Fig. 2). The first hydraulic pressure control means for setting the hydraulic pressure in the α range in the graph of is an oil passage section in which a throttle element 69 with a fixed throttle degree acting as the throttle device and a check valve γ0 are connected in parallel. When downshifting, the oil pressure is controlled by the oil pressure of the high speed friction engagement device, that is, the engine launch 1, and the oil pressure is at a predetermined level (j in the graph of FIG. 2) at which the high speed friction engagement device is substantially opened. When the oil pressure decreases to the point of
A control valve 61 is a second hydraulic pressure control means for increasing the hydraulic pressure to a value that substantially engages the low-speed frictional engagement device (hydraulic pressure exceeding point d in the graph of FIG. 2).

By the way, when downshifting, the gear ratio of the automatic transmission increases, so when downshifting, the engine must increase the rotational speed corresponding to the ratio of the gear ratio of the high speed gear and the gear ratio of the low gear. Furthermore, engagement of the clutch is completed just when this increase in rotational speed has been achieved, thereby providing a smooth downshift without any shift shock.

The rate of increase in engine speed during downshifting is approximately given by the following equation.

Ne=ATt-1-BTh+CTt...-(1)
In the above equation, Ne is the rate of increase in engine speed, and T
t is the engine torque, 1゛h is the current torque,
T4 is a low-flanch torque, and AlB and C are coefficients each having a certain value.

Among these, A and C are positive values, and B is a negative value.

As can be seen from the above equation, the larger the throttle opening, the faster the engine speed increases.

On the other hand, even if the rate of increase in engine speed is the same,
For example, when downshifting from 3rd gear with a gear ratio of 100 to 2nd gear with a gear ratio of 150, if the engine speed before downshifting is 2000 rprn, the engine will rotate from about 3000 pm to about 1000 rpm. In contrast, if the engine speed before downshifting is 4000 rpm, the engine speed is 400 rpm.
The rotational speed must be increased by about 2000 rpm from 0 rpm to about 6000 rpm.

Therefore, the absolute value of the increase in rotational speed that the engine should achieve upon downshifting differs depending on the vehicle speed at the time of downshifting, that is, the higher the vehicle speed at the time of downshifting, the greater the increase in rotational speed required. .

FIG. 3 shows the hydraulic control according to the present invention, which has been modified to take into account the effects of vehicle speed and engine torque, ie, accelerator opening, on downshifting, and to achieve downshift characteristics that match the vehicle speed and accelerator opening. 2 is a diagram similar to FIG. 1 showing another embodiment of the device; FIG.

Parts in FIG. 3 corresponding to those in FIG. 1 are designated by the same reference numerals as in FIG.

In the embodiment shown in FIG. 3, the throttle element 69 in the embodiment shown in FIG. is replaced by a control valve 102 which is controlled.

The control valve 102 has a valve element 104 that is pushed upward in the figure by a compression coil spring 103, and has a valve element 104 pushed upwardly in the figure by a compression coil spring 103.
As the governor oil pressure applied to port 5 increases,
As the throttle oil pressure applied to 06 decreases, the degree of restriction between ports 10γ and 108 increases, and vice versa.
As the governor oil pressure applied to port 105 decreases, and as the throttle oil pressure applied to port 106 increases, the degree of restriction between ports 101 and 108 is reduced.

The port 109 has a feedback function that feeds back the raw hydraulic pressure to the port 108 to act on the valve element 104.

As mentioned above, in the α region of the hydraulic pressure curve A shown in FIG. The low clutch is also in sliding engagement.

The oil pressure level in the α region is controlled by the degree of restriction of the control valve 102.

In this case, the back pressure chamber 39 of the high speed accumulator 33
The higher the governor oil pressure applied to the boat 105 of the control valve 102, the lower the oil pressure supplied to the boat 105.
The higher the throttle oil pressure applied to port 106 of No. 2, the higher the oil pressure becomes. Therefore, the oil pressure level in the α region becomes lower as the vehicle speed increases, and increases as the throttle opening degree increases.

Looking at this in relation to the above-mentioned equation (1), it can be seen that the higher the vehicle speed, that is, the engine speed before downshifting, the higher the rate of increase in engine speed Ne required for downshifting; It is understood that the rate of increase in engine speed is achieved by reducing Th, that is, the no-crunch transmission torque, in the term BTh having a negative coefficient B, that is, by lowering the oil pressure level in the α region. Good morning.

On the other hand, when the throttle opening is large, the above formula (1)
The ATt term with positive coefficient A in becomes large.

Therefore, in this case, if the value of Th is increased according to the increase in throttle opening, that is, if the oil pressure level in the α region is increased, the increase in ATL due to the increase in throttle opening can be suppressed by increasing BTh (negative value). It will be appreciated that compensation can be achieved by reduction.

Thus, by providing a control element such as the control valve 102 in the path for supplying hydraulic pressure to the back pressure chamber 39 of the high speed accumulator 33 in the α region, the downshift characteristics can be adjusted in response to changes in vehicle speed and throttle opening. can always be optimally controlled.

FIG. 4 is a diagram similar to FIG. 2, but shows downshift characteristics when the vehicle speed is lower and/or when the throttle opening is larger than in the case of FIG.

As is clear from the comparison of Fig. 4 with Fig. 2, the lower the vehicle speed and/or the greater the throttle opening, the higher the engine launch oil pressure in the α region during downshifting. It will be understood that the piston 31 of the high speed accumulator 33 moves faster and the elapsed time in the α and γ regions becomes shorter.

Although not shown in the figure, if the vehicle speed increases and/or the throttle opening decreases more than the continuous speed and throttle opening conditions shown in Figure 2, α
(in the area)・Ikuratsu oil pressure further decreases from the level shown in Fig. 2, and accordingly, the elapsed time in the α and γ areas becomes longer than the elapsed time in Fig. 2. should be obvious.

Although the present invention has been described above in detail with reference to two embodiments, it will be obvious to those skilled in the art that various modifications can be made to these embodiments within the scope of the present invention. .

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing one embodiment of the hydraulic control device according to the present invention, and Fig. 2 is a hydraulic pressure and engine rotational speed diagram for explaining the operation of the hydraulic control device shown in Fig. 1 during downshifting. and a graph showing changes in output shaft torque, FIG. 3 is a hydraulic circuit diagram showing another embodiment of the hydraulic control device according to the present invention, and FIG. 4 is a diagram similar to the graph shown in FIG. 2, 2 is a graph showing an example of a case where the engine speed and/or throttle opening during downshifting are different from those values in FIG. 1; 1-high crunch, 2-low crunch, 3-shift well, 3
3 - accumulator for high speed stage, 34 - accumulator for low speed stage, 60 - control valve, 99 - amplifier shift timing pulp, 102 - control box.

Claims (1)

[Scope of Claims] 1. For an automatic transmission that includes a frictional engagement device for a low gear and a frictional engagement device for a high gear and switches gears by switching the engagement between these two frictional engagement devices. In a hydraulic control device for a gear transmission mechanism, a first switch that connects the low-speed gear friction engagement device to a line oil pressure supply oil path and connects the high-speed gear friction engagement device to a drain oil path. and a second switching position in which the frictional engagement device for the high speed gear is connected to the line oil pressure supply oil path and the frictional engagement device for the low speed gear is connected to the drain oil path; Hydraulic pressure is supplied to a low speed accumulator and a high speed accumulator connected to the hydraulic pressure supply paths of the low speed friction engagement device and the high speed friction engagement device, respectively, and to a back pressure chamber of the high speed accumulator. The transmission valve further includes an oil passage for discharging hydraulic pressure from the back pressure chamber, and a throttle device and a check valve connected in parallel to each other in the middle of the oil passage, so that the speed change valve moves from the second switching position to the first switching position. When the shift valve is switched to the switching position, the hydraulic pressure acting on the high-speed friction engagement device device under the operation of the high-speed accumulator is changed from the first switching position to the second switching position. to a value that is substantially lower than the hydraulic pressure acting on the high-speed friction engagement device under the operation of the high-speed accumulator when the amplifier is shifted to the high-speed gear position, causing the high-speed friction engagement device to slip. a first hydraulic pressure control means to set the hydraulic pressure of the high-speed friction engagement device during the downshift, and when the hydraulic pressure decreases to a predetermined level that substantially releases the high-speed friction engagement device; A hydraulic control device comprising: second hydraulic pressure control means for increasing the hydraulic pressure of the low-speed frictional engagement device to a value that causes the low-speed frictional engagement device to substantially engage. 2. In the hydraulic control device according to claim 1,
The throttle device is controlled by the governor oil pressure, which changes according to the vehicle speed, and the throttle oil pressure, which changes according to the throttle opening, and provides a throttle passage whose cross-sectional area becomes smaller as the vehicle speed increases and as the throttle opening decreases. The first hydraulic pressure control means is a valve, and the first hydraulic pressure control means controls the hydraulic pressure of the high-speed friction engagement device to a value that causes the high-speed friction engagement device to slip under the operation of the high-speed accumulator. A hydraulic control device characterized in that the value is set to a value that decreases as the vehicle speed increases and as the throttle opening decreases.