JPH07113403B2 - Shift shock reduction device for automatic transmission - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing shift shock of an automatic transmission in which a band brake is involved in opening and closing a friction element.

(Prior Art) As a conventional automatic transmission, for example, there is an RL4F0ZA type automatic transmission described in the Nissan Motor Maintenance Manual (1984). Second
The figure is an enlarged view of the servo band piston part. In the figure, 1 is the transmission case of the automatic transmission, 2 is the brake drum, 3 is the servo band wrapped around the drum 2, and 3a and 3b are the servo band 3. Retainers fixed to both ends, 4 are anchor stems attached to the transmission case 1 for fixing one end of the servo band 3 by colliding with one of the retainers 3b,
Reference numeral 5 is a stem for operating the other end of the servo band 3 by colliding with the other retainer 3b, and reference numeral 1a is a servo piston cylinder integrally formed with the transmission case 1 for operating the stem 5. Ports A, B and C are opened on the side wall of the cylinder 1a.

Port A is a port to which line pressure is constantly supplied, port B is a servo piston apply pressure port, and port C is a servo piston release pressure port. 6
Is a lid that closes the open end of the cylinder 1a, and the servo piston 7 and the accumulator piston 8 that are slidable in a liquid-tight manner are housed in the chamber of the cylinder 1a via a seal ring. 9 is a spring retainer attached to the stem 5, 10a is a servo piston return spring provided between the servo piston 7 and the wall of the cylinder 1a, 10b
Is a servo piston return spring provided between the servo piston 7 and the spring retainer 9, 11 is a spring retainer fixed to the central projection of the lid 6, and 12a and 12b are accumulator pistons 8 and spring retainers.
It is the Accu-Mu piston return spring that is provided between 11 and. The stem 5 has a structure that can move with the movement of the servo piston 7. When the stem 5 moves to the left in the figure, the stem 5 presses the retainer 3a of the servo band 3 and the other retainer of the servo band 3 is pushed. Since 3b is fixed by the anchor stem 4,
The servo band 3 is pressed against the drum 2 to generate a braking force.

(Problems to be Solved by the Invention) However, in such a conventional automatic transmission, when the servo band 3 is fastened, the position at which the stem 5 starts the crimping of the servo band 3 of the band brake to the drum 2. There is a problem in that a large surge pressure is generated at the moment when the gear moves to a point, and this surge pressure acts on the pressing force of the stem 5 and the anchor reaction force, resulting in a large gear shift shock during gear shifting involving the fastening of the band brake. It was

(Means for Solving Problems) In order to solve the above problems, the present invention provides
In an automatic transmission having a speed change means composed of a planetary gear, having at least one or more band brakes as a means for controlling the engagement and release of each member of the planetary gear,
In the one having a servo piston that can move integrally with the stem that presses the band brake, an elastic member is inserted between the stem and the transmission case, and the elastic force of the elastic member is exerted immediately before the start of braking by the band brake. Is applied to the stem as a reaction force to configure a shift shock reducing device for an automatic transmission.

(Operation) As described above, according to the present invention, the elastic member is provided between the stem for pressing the band brake and the transmission case, and the elastic member is provided on the stem immediately before the start of braking by the band brake. Since the spring retainer is brought into contact with the spring retainer so as to have a buffering effect on the surge pressure, it is possible to reduce the surge pressure, suppress a rapid rise of the output shaft torque, and reduce shift shock.

Embodiment An embodiment of the first invention will be described below with reference to FIG. In the figure, the same reference numerals as those in FIG. 2 denote the same components.

In this embodiment, a disc spring 13 is inserted between the spring retainer 9 provided on the stem 5 that presses the band brake and the transmission case 1 that faces the stem 5, so that the stem 5 serves as the retainer 3a of the servo band 3. By pushing, the elastic force of the disc spring 13 acts on the stem 5 as a reaction force immediately before the start of braking by the band brake.

Next, the operation will be described.

The state of shifting by pressing the servo band 3 onto the drum 2 and braking will be described. In this case, the servo piston apply pressure P _C flows from the port A into the servo piston apply chamber 14, and the servo piston 7 receives F = P _C
× A _ap (A _ap : effective cross-sectional area of servo piston apply chamber 14) acts to the left in Fig. 1, and this force F acts on the spring reaction force of servo piston return springs 10a and 10b, The piston 7 is moved to the left in the figure.
Along with that, the stem 5 also moves to the left in the figure. Immediately before the top 5a of the stem 5 contacts the retainer 3a of the band 3, the disc spring 13 hits the end surface 1d of the servo piston cylinder 1a, and the elastic reaction force acts as a buffering action against the force F acting on the servo piston 7. easy. In this way, the top 5a of the stem 5 presses the retainer 3a of the servo band 3, and when the servo band 3 is pressed against the drum 2, the movement of the stem 5 is stopped and the pressure P _C in the servo piston chamber 14 increases, and the accumulator return Springs 12a, 12b
In cooperation with the spring reaction force of, the force applied in the accumulator chamber 15, P _L × A _ac (P _L ; line pressure, A _ac effective sectional area of the accumulator chamber 15), and the accumulator piston 8 Move to the right in the figure.

FIGS. 3 and 4 compare the hydraulic pressure transient change and the output shaft torque transient change in the above-described process with the conventional case. FIG. 3 shows the case of the conventional case, and FIG. 4 shows the case of the present invention. is there.

Here, in the conventional specification, since there is no elastic member such as a disc spring as in the present invention, the stem 5 is the band retainer 3a.
When it comes into contact with, a large surge pressure is generated as shown by E in FIG. 3, and this appears as a sharp waveform in the output shaft torque waveform, which causes a shock at the time of shifting and deteriorates the feeling. On the other hand, according to the present invention, the disc spring 13
As a result of the elastic members such as the cushioning effect and the above-mentioned sirsi pressure being suppressed to a low level as shown in FIG. 4, a sharp waveform does not occur in the output shaft torque waveform, and the shift shock is reduced and the feeling is also improved. improves.

(Effect of the Invention) As described above, according to the first aspect of the present invention, the elastic member is inserted between the stem that presses the band brake and the transmission case, and the elastic member is inserted from immediately before the start of braking by the band brake. Abuts a spring retainer provided on the stem so as to have a buffering effect on the surge pressure. Therefore, the surge pressure is reduced, the rapid rise of the output shaft torque is suppressed, and the shift shock is reduced. The effect that can be obtained is obtained.

(Means for Solving Problems) FIG. 5 shows a second means for solving the above-mentioned problems. In this case, an automatic transmission having a speed changing means composed of a planetary gear is shown. Among these, at least one or more band brakes are provided as a means for controlling engagement / disengagement of each member of the planetary gear, and a servo piston movable integrally with a stem pressing the band brakes, and the servo piston In one having an accumulator piston having an accumulator function against such hydraulic pressure, a first spring member for regulating the movement amount of the accumulator piston and a second spring member for regulating the movement amount only in a predetermined accumulator movement amount region. A member is provided to configure a shift shock reducing device for an automatic transmission.

(Operation) As described above, according to the second invention, in addition to using the compression coil spring as the accumulator piston return spring as the first spring member that regulates the movement amount of the accumulator piston, Since a disc spring member that generates a spring reaction force only within the range of the predetermined movement amount of the accumulator piston is added as the second spring member, the surge pressure generated at the start of the movement of the accumulator is suppressed, and after that, The hydraulic characteristics are the same as the conventional ones, and the shift shock caused by the surge pressure can be reduced and the deterioration of the feeling can be eliminated.

(Embodiment) An embodiment of the second invention will be described below with reference to FIG. In the figure, the same symbols as the above-mentioned symbols indicate the same items.

That is, in the figure, 1 is a transmission case of an automatic transmission, 2 is a brake drum, 3 is a servo band wound around the drum 2, 3a and 3b are retainers fixed to both ends of the servo band 3, and 4 is one Anchor stem 5, which is attached to the transmission case 1 for abutting against the retainer 3b of FIG. 3 and fixing one end of the servo band 3, abuts with the other retainer 3b to activate the other end of the servo band 3. 1a is a servo piston cylinder integrally formed with the transmission case 1 for operating the stem 5,
Ports A, B and C are opened on the side wall of the cylinder 1a.

Port A is a port to which line pressure is constantly supplied, port B is a servo piston apply pressure port, and port C is a servo piston release pressure port. A servo piston retainer 16 and an accumulator piston retainer 17 are inserted in the servo piston cylinder 1a, and further, a servo piston 18 and an accumulator piston 19 are provided inside the retainers 16 and 17 through a seal ring, respectively. It is installed so that it can slide closely. A spring retainer 20 is fitted in the intermediate portion of the stem 5. 21 is a servo piston return spring inserted between the inner wall surfaces of the transmission case 1 facing the servo piston 18, 22 is a spring retainer 20 attached to the stem 5, and the servo piston
Cushion springs inserted between the recesses 18a of the 18 and 23a and 23b are accumulator piston return springs inserted between the accumulator piston 19 and the retainer 24 fixed to the accumulator piston retainer 17 with a bolt. Is.

In this embodiment, two disc springs 25 are superposed and incorporated between the end surface 16a of the servo piston retainer 16 and the end surface 19a of the accumulator piston 19.

Next, the spring member of the device shown in FIG.
The operation during shifting will be described. At the time of 1-2 shift, 1
By the operation of the -2 switching valve (not shown), the hydraulic pressure is guided to the apply pressure chamber 26 via the port B. At this time, the release pressure chamber 28 communicates with the drain, and the line pressure P _{L is} guided to the accumulation back pressure chamber 27. Then, the apply pressure chamber 26
The hydraulic pressure introduced into the cylinder is gradually increased, and the servo piston 18 is moved to the left in FIG. 5 against the spring force of the servo piston return spring 21 and the cushion spring 22, and at the same time, the stem 5 is also moved to the left. To do. Further, the hydraulic pressure in the apply pressure chamber 26 rises, the servo piston 18 and the stem 5 move to the left, and the stem 5 presses the retainer 3a which is the stopper of the band 3 of the band brake, and the servo band 3 When the stem 5 is stopped to move to the left by pressing it so as to wind it around the drum 2, the apply chamber pressure PA starts to rise rapidly and a surge pressure is generated, but the apply pressure PA becomes PA ≧ (P _L A ₂ −K _X0 −k _D δ ₀ ) / A
_When it becomes ₁ or more, the accumulator piston 19 starts moving to the right. Here, A _{1 is} the effective sectional area of the apply chamber 26, kx _{0 is} the initial load of the two accumulator return springs 23 a and 23 b, and k _D δ ₀ is the initial load of the disc spring 25. The hydraulic pressure in the apply pressure chamber 26 immediately after the accumulator piston 19 starts moving to the right is the spring constant k of the two accumulator return springs 23a, 23b.
When it will have the sum of the spring the number k _s of the disc spring 25, the oil pressure increase gradient in proportion to k + k _s. After the accumulator piston 19 has moved to the right by more than a predetermined amount, the disc spring
25 is in the free state (the state of the lower half sectional view shown below the center line of the stem 5 in FIG. 5), and the hydraulic pressure increase gradient of the hydraulic pressure PA in the apply pressure chamber 26 is proportional to the spring constant k. It will be what you did. On the other hand, in the conventional method, that is, in the state where the disc spring 25 is not inserted, the apply pressure PA at which the accumulator piston 19 starts moving to the right is PA ≧ (P _L A ₂ −kx ₀ ) / A ₁ or more. Therefore, the surge pressure is higher than that of the present invention, and the surge pressure rises accordingly, which causes an increase in the torque of the output shaft to increase the shift shock and deteriorate the feeling. Furthermore, in order to suppress this surge pressure rise, if the initial load KX ₀ of the accumulator return springs 23a, 23b is made small, the surge pressure rise can be suppressed, but the apply of the accumulator piston 19 while moving to the right side can be suppressed. The absolute value of the pressure PA is also lowered, and as a result, the brake is dragged, and the band brake is burned, and the inertia torque at the time of a high opening shift is increased.

FIG. 6 shows hydraulic transient characteristics (curve PA) and output shaft torque waveform (curve T) in the case of the conventional structure.
The figure shows the hydraulic transient characteristics (PA) and the output shaft torque waveform (T) when the structure of the present invention is used,
FIG. 8 shows the hydraulic transient characteristic (PA) and output shaft torque waveform (T) at the time of a high opening shift when the initial setting load kx ₀ of the accumulator return springs 23a, 23b is reduced with the conventional specifications. is there.

(Effect of the Invention) As described above, according to the second invention, the compression coil springs 23a and 23b are used as the accumulator piston return springs as the first spring member that regulates the movement amount of the accumulator piston 19. In addition to the above, since a disc spring 25, which generates a spring reaction force only within the range of the predetermined movement amount of the movement amount of the ammulator piston 19, is added as a second spring member, it occurs when the movement of the accumulator piston 19 starts. It is possible to suppress the surge pressure that occurs, and to make the hydraulic characteristics thereafter equal to those of the related art, reduce the shift shock caused by the surge pressure, and remove the deterioration of feeling.

[Brief description of drawings]

FIG. 1 is a sectional view of a servo piston portion of an automatic transmission equipped with the device of the present invention, FIG. 2 is a sectional view of a conventional device, and FIGS. 3 and 4 are hydraulic transient characteristics and output shaft torque characteristics by each method. FIG. 5 is a sectional view of a servo piston portion of an automatic transmission equipped with the device of the present invention, and FIGS. 6 to 8 are diagrams showing hydraulic transient characteristics and output shaft torque characteristics by each method. is there. 1 ... Transmination case 2 ... Brake drum, 3 ... Servo band, 4 ... Anchor stem, 5 ... Stem, 6 ... Lid, 7 ... Servo piston, 8 ... Accumulator piston, 9 ... Spring retainer, 10a , 10b …… Servo piston return spring 11 …… Spring retainer 12a, 12b …… Accum piston return spring 13 …… Disc spring 14 …… Servo piston retainer 17 …… Accum piston retainer 18 …… Servo piston 19 …… Accumulator piston 20 …… Spring retainer 21 …… Servo piston return spring 22 …… Cushion spring 23a, 23b …… Accumulator piston return spring 24 …… Retainer, 25 …… Disc spring

Claims (2)

[Claims] 1. An automatic transmission having a speed change means composed of a planetary gear, wherein at least one band brake is provided as a means for controlling engagement / disengagement of each member of the planetary gear. In a servo piston that is movable integrally with a stem that presses, the elastic member is inserted between the stem and the transmission case, and the elastic force of the elastic member is applied to the stem immediately before the start of braking by the band brake. A gear shift shock reducing device for an automatic transmission characterized by being applied as a reaction force. 2. An automatic transmission having a shift means composed of a planetary gear, wherein at least one or more band brakes are provided as means for controlling engagement / disengagement of each member of the planetary gear. In a servo piston that is movable integrally with a stem that presses and an accumulator piston that has an accumulator function for the hydraulic pressure applied to the servo piston, a first spring member that regulates the movement amount of the accumulator piston And a shift shock reducing device for an automatic transmission, characterized in that a second spring member for restricting a movement amount only in a predetermined accumulation piston movement amount region is provided.