JPH0533863A - Band brake device for automatic transmission - Google Patents

Abstract

PURPOSE:To provide a device wherein its use can be classified in trailing and leading directions by a band brake so that fine control can be performed. CONSTITUTION:Two sets (A, B) of band servos, respectively providing a servo piston 4, are opposedly provided relating to a band 2. In these servos, the band can be tightened independently of each other by supplying pressure oil to respective 2-speed servo apply chambers 9, 9. When a direction of rotation is (b), leading tightening is obtained, when the band is tightened by a side of the one set (A), and trailing tightening is obtained when the band is tightened by a side of the other set (B). In the case of the direction of rotation being (a), a mode is reversed. A control system has a control unit 30 and switching valves 23, 24. In the control unit 30, control is executed so as to tighten the band in a trailing side, in the case of low capacity fine control such as LFUS required, and in a leading side in the case of large capacity control required. In the switching control, compatibility can be obtained in preventing shock worsening and ensuring capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band brake device for an automatic transmission, and more particularly to an improvement in the device structure and a control system using the band brake device.

[0002]

2. Description of the Related Art An automatic transmission selects a corresponding shift speed by selectively engaging and disengaging various friction elements and shifts.
The band brake is used as one of the frictional elements in such a case. For example, "RE4R01A Automatic Transmission Maintenance Manual" (A261C07) issued by Nissan Motor Co., Ltd.
The construction is used in a gear train as a fastening element or a release element, as in the automatic transmission described. Here, it is assumed that the second and fourth speed selection friction elements are engaged by a band servo, and a combination of engagement / disengagement switching of other clutches or the like changes the speed from the first speed to the second speed (band brake). Is engaged control), shifting from the second speed to the third speed (release control for the band brake), and shifting from the third speed to the fourth speed (engagement control for the band brake). It is possible (see the comparative example in FIG. 4).

[0003]

However, in the above,
The direction of the force that tightens the band is one direction set in advance with respect to the rotating brake drum, and when fixing or releasing the drum by tightening the band, the reading is performed regardless of the drum rotation direction. It does not have a function such that it can be selectively used in either direction or trailing direction. If the fastening direction (state) of the band brake can be switched and used in the above two modes, for example, in the case of low-capacity fine control (such as 1-2 foot release), the trailing should be adapted accordingly. It is possible to perform precise control such as selectively using the engagement to further reduce the shift shock, but even in the case of a low capacity, such control is difficult to perform even if the band-leading engagement mode is uniform.

An object of the present invention is to provide an automatic transmission which can be used in both the leading direction and the trailing direction, and can be used for widening the control range to enhance the adaptability and easily improve the function as a band brake. To provide a band brake device for a machine.

[0005]

According to the present invention, the following band brake device is provided. It is a band brake device in an automatic transmission that fastens and releases a rotary brake drum in a speed change mechanism with a tightening force by a band, and the band tightening operations can be performed independently of each other. When the leading direction is fastened with respect to the rotation direction, the other one of the trailing directions is fastened with respect to the rotation direction of the drum. It is a band brake device of an automatic transmission provided with a servo piston. Further, according to the present invention, the means for controlling the first and second servo pistons is a fastening mode on the trailing side for low capacity control and on the leading side for large capacity control. There is provided a band brake device for an automatic transmission, which is obtained by combining the band brake fastening direction switching control device.

[0006]

According to the first aspect of the present invention, the first servo piston and the second servo piston can perform band tightening operation independently of each other, and in the case where the rotation direction of the brake drum is the same in a predetermined rotation direction. Even if there is one, the fastening in the leading direction and the fastening in the trailing direction can be used properly depending on which of the two is used. This allows
When fastening or releasing by the brake band, it is possible to perform either band reading or trailing, so that the control range of the band brake can be expanded and the adaptability can be improved.

According to a second aspect of the present invention, the band brake fastening direction switching control device uses the first and second servo pistons, and at the time of low displacement control, fastening on the trailing side,
In the case of a large capacity, it is selectively switched to the fastening on the leading side. As a result, the respective functions of trailing engagement and leading engagement can be effectively exerted, and when fine control with low capacity such as foot-shifting is required, engagement is performed on the trailing side so as to better meet such requirements. on the other hand,
When a large capacity is required, the leading side can be fastened to meet the demand, and it is easy to prevent deterioration of gear shift shock and secure capacity.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an embodiment of the present invention, which is an example applied to a configuration in the case of operating for selection of second speed and fourth speed.
More specifically, it shows a case where it is applied to a band brake portion in the transmission mechanism described in the above document. In the figure, in the apparatus of the present embodiment, two (one) band servo groups are provided facing each other with respect to a common brake band 2 wound around the brake drum 1. The drum 1 is a reverse clutch drum in this example, and the band brake operates (engages) as a friction element for selecting 2nd speed and 4th speed to fix the rotating drum.

The basic construction in the case where two servo pistons are provided facing each other in the band, and their proper use will be described below with reference to FIG. 2 as follows. In FIG. 2, the band 2 for the brake drum 1 is shared by the servo piston A and the servo piston B, and the tightening of the band 2 causes the servo piston A to operate or the servo piston B to operate. You can do this depending on whether you use it or not.

When the band brake is selected as the friction element to be engaged in the shift control, and the drum rotation direction is the direction shown in the figure, the engagement is performed by pushing one end of the band 2 by the servo piston A. , Leading fastening, and fastening in which the servo piston B pushes the other end of the band 2 is trailing fastening. The fastening of the leading side and the trailing side is suitable for the former when a large capacity is required and for the latter when a smaller capacity is not required but a more detailed control is required. The mechanism to have a pair is
As a band brake device for an automatic transmission (A / T), it is possible to use either the leading direction or the trailing direction. The above relationship can be expressed as follows if shown in a table (in Table 1, the mark ◯ means that it is more suitable than the mark Δ).

[0011]

With the above-mentioned mechanism, when the gear shifts to a control symmetrical element during shifting, the trailing side is fastened when fine control of low capacity is required, and the leading side is fastened when large capacity is required. It is of course possible to realize such a use with a single tightening force of the brake band (that is, common to the two servo pistons), and further, as a usage thereof, for example, the servo piston until the end of the gear shift. Even if it is operated with B, it switches to the servo piston A side after the shift is completed, such as further switching to reading that can secure capacity during steady running, or switching to trailing before shifting to release the band, smooth It is possible to easily introduce a method such as realizing various gear shifts. The selective use of the leading fastening and the trailing fastening can be performed by controlling the supply of the working pressure to the two servo pistons together with the drum rotation direction.

In FIG. 1, the two opposing band servo sets A and B are shown as having substantially the same structure,
The configuration of the control system is also shown in the figure. One set A side (lower side in the figure) will be described. This is provided with a piston stem 3, a servo piston 4, a servo piston retainer 5, an OD servo piston 6, and return springs 7 and 8 and three hydraulic pressures. It has rooms 9, 10, and 11. In this example, the band brake is disengaged at the first speed, the engagement element when the second speed is selected, and the disengagement element when the third speed is selected, and the engagement element when the fourth speed is selected. There are a hydraulic chamber 9 as a working chamber (second speed servo apply chamber), a hydraulic chamber 10 as a third speed releasing chamber (third speed servo release chamber), and a hydraulic chamber 11 as a fourth speed working chamber (fourth speed servo apply chamber). Prepare

The stem 3 is attached to one end side of the brake band 2 and elastically supports the return springs 7 and 8 at a position shown in the drawing due to a difference in spring force between them, and the band brake is deactivated (released) at the stem position. To do. Each hydraulic chamber 9-11
In the first speed, the operating pressure is not supplied, so that the released state is maintained.

On the other hand, regarding the second speed, the third speed, and the fourth speed, when the hydraulic pressure (second speed servo apply pressure P ₂ ) is supplied to the hydraulic chamber 9,
When the working pressure acts on the servo piston 4, the stem 3 is advanced (pushed up) to tighten the brake band, and the brake band is fastened to fix the drum 1, and the hydraulic pressure is also supplied to the hydraulic chamber 10 in this state. The brake band 2 is released by retracting (pushing down) the stem 3 depending on the size of the servo piston pressure receiving area.
When supplying hydraulic pressure to 11, the operating pressure is OD servo piston 6
Then, the stem 3 is advanced (pushed up) by the piston 6, and the brake band 2 is tightened and fastened again to fix the drum 1.

The other set B side (upper side in the figure) can also have a similar structure. The piston stem 3 is attached to the other end side of the brake band 2, and similarly, the stem 3 is advanced (pushed down) from the illustrated stem position (non-actuated state, released state) so that the drum 1 is fastened. Can also be fixed, or can be released from the fastened state by retracting (pushing up).

With the above construction, therefore, two independent sets of band servos are provided for the brake drum 1, so that which side is used depending on the direction of rotation a or b, and the combination thereof are also used. Various possibilities,
Also when the band is fastened, it is possible to use a device which can be used depending on whether the fastening is done by trailing or leading. Table 2 shows the correspondence table.

[0018]

From Table 2 above, when the rotation direction is a, the set A
If the side is fastened, the trailing is fastened, and conversely, if the group B is fastened, the leading is fastened. When the rotation direction is B, the mode is opposite to the above. Thus, in the present band brake, when it becomes a fastening side friction element, either trailing side servo fastening or leading side servo fastening can be used. When the band is fastened in the trailing direction, as mentioned earlier, it is suitable for fine control of low capacity, so if you want to control the low capacity accurately, use the servo on the trailing side. Side, the direction of rotation B can be used on the band servo B side) to reduce shock and achieve smooth gear shifting. Further, since the reading direction is suitable for a large capacity, the leading side servo may be used (the band servo B side is used for the rotation direction a and the band servo A side is used for the rotation direction b) to secure the capacity.

Also, when fixing the drum 1,
It can also be used to fasten the trailing side servo and then switch to the leading side servo. For example, in the case of the drum rotation direction (b), first fasten the trailing side servo by the set B side and then fasten it by the set A side. It can also be used by switching to the reading side servo (or by using both at the same time), and in this sense also finer control can be realized.

Furthermore, although the above is the case of fastening,
The friction element on the disengagement side can be used properly in the same manner, and the disengagement can be performed by the servo on the trailing side for smooth disengagement. The existence of two sets of band servos is to release band 2 if either of them, A or B, was engaged on the leading side when it was released during shifting. It is also possible to switch to be performed by B or A, which is the other one of the above, so that the trailing side servo can release the gear so that a smooth gear shift can be realized.

As described above, this device can be used in various ways, the range of control can be expanded, the adaptability can be improved, and the function of the band brake can be improved. 3 to 4, an example of the control method will be described in more detail. FIG. 1 also shows an example of a control system for the band brake device. Here, a configuration in which an electromagnetic switching valve for selection is used for the second speed selection circuit portion in the shift control hydraulic circuit is shown. There is.

That is, each hydraulic chamber 10 of the band servo A and B groups
The (second speed servo apply chamber) is connected to electromagnetic switching valves 23 and 24 via oil passages 21 and 22, respectively. In the normal state, the switching valves 23 and 24 respectively communicate the oil passages 21 and 22 to the drain, and are switched by the operation of the respective solenoids (A) and (B) to switch the oil passages 21 and 22 to two.
It is assumed that the oil passages 25 and 26 are supplied with the _high speed servo apply pressure P ₂ . Here, the servo apply pressure as the operating pressure
The source pressure of P ₂ can be common. Solenoid switching valve 23,
The control unit 30 controls the switching by the A / T control unit 30, and the control unit 30 controls the shift control such as a signal from the TVO sensor 31 for detecting the throttle opening and a signal from the vehicle speed sensor 32 for detecting the vehicle speed. And the information used for line pressure control, etc.
Input the signal from.

The control unit 30 carries out shift control and line pressure control based on required input information. Regarding the shift control, the optimum shift stage for the operating condition is judged from the throttle opening and the vehicle speed, and the shift control shift solenoid in the hydraulic control circuit is turned on and off so that this shift stage can be obtained.
The F combination is commanded, and the adjusted line pressure is supplied as the working hydraulic pressure to the corresponding friction element so that the corresponding shift stage is selected, and shift control is executed. Further, in this case, when the band brake is selected as the engagement element, the control unit 30 performs a low capacity fine control such as LFUS (foot release shift) according to a control program as an example of which is shown in a flowchart in FIG. If required, the control for the band brake is executed so that the trailing side is engaged, and if the large capacity is required, the leading side is engaged.

In step 101, first, when a shift command for fastening the band is made, it is determined based on the shift signal whether or not the shift is a leading shift. Specifically, the type of shift is determined when the band brake is the engagement-side friction element, and more specifically, here, it is determined whether the shift is a 1-2 shift. FIG. 4 also shows, as a comparative example, the state of the band in each gear in the automatic transmission using the band brake device described in the above-mentioned document. Looking at this, in the relationship between the band fastening direction and the drum rotation direction, In the case of upshift 1-2 shift, it is engaged by leading (in other cases, it is rotated by trailing, and if trailing is engaged, release and engagement can be smoothly performed). Therefore, including the above-mentioned 1-2 shift, 2-3 shift related to the band, 3-
Focusing on four shifts, the correspondence between these shifts and the band servo operation in the automatic transmission is as follows in the comparative example. (1) 1-2 shift Leading (2) 2-3 shift Trailing (3) 3-4 shift Trailing Therefore, for the shift control of the band shift in such an automatic transmission, the band configured as shown in FIG. When using a brake device and performing control with switching control of the band fastening direction according to this program, perform step 10 above.
The determination processing in 1 may be performed by specifically determining whether or not 1-2 shift.

However, if NO in step 101, that is, if fastening is performed in the trailing direction, fastening is performed by trailing as in the case of the above-mentioned literature control. In the third speed released state, the band servo A side is used, and the operating pressure acts on the hydraulic chambers 9 and 10 as described above.
The hydraulic pressure is also supplied to the hydraulic chamber 11, which is the speed servo apply chamber,
Fastening is done by the trailing servo (step 102). As a result, at the time of the 3-4 gear shift, it is possible to perform the smooth gear shift by engaging with the trailing.

On the other hand, if the answer in step 101 is YES, step 103 is performed in order to avoid a large shift shock during LFUS 1-2 shift or coast 1-2 shift even in 1-2 shift, in order to shift gears. Below, switching control for selectively using the band servos A and B is executed. Therefore, first, in step 103, the idle SW signal is read, and in step 104, the throttle opening is checked. These are the processes for checking whether or not both the LFUS 1-2 and the coast 1-2 are in such a state because the driver is releasing his / her foot from the accelerator pedal. Depending on the judgment result in
Selectively advance the processing to 105 or step 108 (note that the TVO sensor output may be read in step 103)
.

That is, if the answer in step 104 is NO, this means that the driver is depressing the accelerator pedal. Therefore, at this time, since it is necessary to output the capacity, the leading side servo is engaged in step 105, and after the shift is completed, step 106 selects step 107 in this program example, and this program ends. .
Here, the processing in step 105 can be performed by using the band servo A side when the drum rotation direction in FIG. 1 is B. Therefore, in this case, the electromagnetic switching valve 23 is turned on. As a result, the second speed servo apply pressure P ₂ is supplied to the hydraulic chamber 9 on the side of the band servo A. In this way, 1 with the accelerator pedal depressed
The -2 shift can be performed by band-leading engagement while securing the capacity.

On the other hand, when it is determined in step 104 that the throttle opening is 0/8, it means that the foot has been released. Therefore, if the foot is released, tighten the band slowly with a smooth force. Fasten the trailing side servo so that it can go (step 108). Therefore, in step 108, the electromagnetic switching valve 24 is turned ON to use the band servo B side opposite to the case of step 105, and the second speed servo apply pressure P ₂ is applied to the hydraulic chamber 9 via the oil passage 22. It is supplied as an operating pressure, and hydraulic pressure control during shifting is performed until the end of shifting is determined in step 109, thereby increasing the engaging hydraulic pressure to fix the drum 1 in the rotation direction b. As a result, when the band is fastened with the feet separated, it can be tightened in a light direction, and the low capacity can be accurately controlled and finely controlled.
-Suitable for control in the case of -2 shift. It is possible to prevent the shift shock from becoming worse due to the band-leading engagement even though the capacity is not required such as LFUS1-2 shift.

As described above, when fine control such as LFUS is performed, the stem on the band servo B side is advanced and fastened on the trailing side until the shift is completed. The control is switched to advance the stem of. That is, if it is determined in step 109 that the shift has been completed, the process proceeds to step 107 and switches to the leading side that can secure the capacity during steady running. The switching control can be performed by turning off the electromagnetic switching valve 24 on the band servo B side and turning on the electromagnetic switching valve 23 on the band servo A side. By further switching from the trailing side to the leading side as described above, the following situation can be avoided. That is, when the shift is completed by the engagement on the trailing side, if it is left as it is, the engine may be blown off and the vehicle may start to slip. Therefore, in consideration of this, in order to secure the capacity after the engagement, it was decided to switch to the leading servo so that the capacity can be earned. Even in such cases, it is possible to avoid situations such as slipping out.

The present invention is not limited to the above embodiment. For example, if the present invention is used as a countermeasure against a shock at the LFUS1-2 shift, a small servo dedicated to the LFUS1-2 trailing may be provided as one of the paired band servos. In particular,
When space is emphasized, such as when the low one-way clutch L / OWC is removed from the gating lane described in the above document to make the automatic transmission compact,
You may do so. In addition, although the brake bands are shared in FIGS. 1 and 2, the present invention can be implemented with a structure in which the bands are used individually.

[0032]

According to the first aspect of the present invention, the band brake used in the automatic transmission is selected from the leading direction and the trailing direction regardless of the drum rotation direction. It is possible to obtain a device that can be used, and the use thereof can expand the controllability and enhance the adaptability and improve the function. In claim 2, trailing engagement and leading engagement can be selectively switched, and when performing fine control such as foot release gear shifting, the former engagement is accurately controlled to reduce gear shift shock, In the case of a large capacity, it is possible to secure the capacity by fastening the latter, and it is possible to perform more detailed control by effectively exerting the functions of both. In addition, the switching control also enables control such that the trailing side is used during the shift and the leading side is switched to secure the capacity after the shift is completed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the basic configuration of the apparatus.

FIG. 3 is a flowchart showing an example of a control program executed by a control unit.

FIG. 4 is an explanatory diagram showing a state of bands in each gear in the applied automatic transmission including the case of the comparative example.

[Explanation of symbols]

1 brake drum 2 brake band 3 piston stem 4 servo piston 5 Servo piston retainer 6 OD servo piston 7,8 Return spring 9 hydraulic chamber 10 hydraulic chamber 11 Hydraulic chamber 23, 24 Solenoid switching valve 30 A / T control unit 31 TVO sensor 32 vehicle speed sensor 33 Idle SW

Claims (2)

[Claims] 1. A band brake device in an automatic transmission for engaging and releasing a rotary brake drum in a speed change mechanism with a band tightening force, wherein band tightening operations can be performed independently of each other. When one of them is in a leading mode of engagement with respect to the rotating direction of the drum, the other is in a trailing direction of engagement with respect to the rotating direction of the drum. A band brake device for an automatic transmission, comprising a second two servo pistons. 2. The means for controlling the first and second servo pistons according to claim 1, wherein the trailing side is engaged when the displacement is low, and the leading side is engaged when the displacement is large. A band brake device for an automatic transmission that is combined with a band brake fastening direction switching control device.