JPH01116336A - Band brake device for automatic transmission - Google Patents

Abstract

PURPOSE:To reduce a speed change shock by providing a cushioning spring which makes a piston axially movable on a piston stem by a certain quantity and which applies a force in the direction counteracting a clamping oil pressure, at least on the high-pressure stage piston side. CONSTITUTION:At the time of carrying out speed change to a high-speed stage by clamping a band 102, as an oil pressure is applied to a high speed stage piston 114, when the play stroke between the piston 114 and a piston stem 110 is over, the piston 114 compresses a cushioning spring 134 and travels by a certain quantity. A force which acts on the piston stem 110 during this period is gently increased in accordance with the characteristic of the cushioning spring 134 and, as the high-speed stage piston 114 finishes its cushioning stroke turning into a condition to be mechanically linked to the piston stem 110, the maximum force by the oil pressure acts rapidly on the band 102. Thereby, a force which acts on the band 102 at the first operating time is relaxed, to reduce a speed change shock.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a band brake device for an automatic transmission.

(B) Prior Art As a conventional band brake device for an automatic transmission, there is one shown in FIG. 4 of Japanese Patent Application Laid-Open No. 61-282653. The band brake device for the automatic transmission shown here has two pistons, one for 2nd speed and one for 4th speed, provided for one piston stem. Both pistons are each provided with a return spring. Also, 2
The speed piston is provided with a cushion mechanism.

That is, the second speed piston is movable by a predetermined amount in the axial direction of the piston stem, and a cushion spring is provided on the opposite side of the piston from the hydraulically operated side. This resists the force of the cushion spring.
During the stroke of the speed piston, changes in oil pressure are relaxed, and shift shocks during 1-2 and 3-2 gear shifts can be reduced.

(c) Problems to be Solved by the Invention However, in the band brake device of the conventional automatic transmission as described above, a cushion mechanism is not provided on the 4-speed piston, and the 3-4 speed and 4-speed shift There is a problem in that a shift shock becomes large in a 3-speed transmission or the like. Especially 4-
When a three-speed shift is performed by locking a one-way clutch, a shock is likely to occur when the one-way clutch is engaged. The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention solves the above problems by providing a cushion mechanism on the high-speed piston side.

That is, in the band brake device for an automatic transmission according to the present invention, the piston (114) is connected to the piston stem (
110) in the axial direction by a predetermined distance of 1 t (S), and a cushion mechanism is provided by providing a cushion spring (134) that applies a force to the piston in a direction opposed to the fastening hydraulic pressure. I'm confused. Note that the symbols in parentheses indicate corresponding members in the embodiments described later.

(E) Effect For example, when shifting to a high speed gear by tightening a band, hydraulic pressure acts on the piston for the high speed gear. After the piston and piston stem complete their idle stroke, the piston compresses the cushion spring and strokes a predetermined amount.

During this time, the force acting on the piston stem increases gradually according to the characteristics of the cushion spring.

When the high-speed piston completes its cushioning stroke and the piston stem is mechanically connected to the piston, maximum hydraulic pressure is rapidly applied to the band. In this way, the force acting on the band when the band brake device is first activated is alleviated, so that shift shock is reduced. The same holds true when shifting from a high gear to a lower gear by releasing the band. Note that a cushion mechanism may also be provided on the piston side for the low speed gear, or may not be provided if unnecessary.

(F) Example (First Example) Fig. 2 shows a skeleton diagram of an automatic transmission (automatic transaxle). The automatic transmission connected to the engine IO mounted laterally with respect to the vehicle, that is, orthogonal to the longitudinal direction of the vehicle, includes a torque converter 12, a planetary gear transmission mechanism 14, a differential mechanism 16, and the like. Torque converter 12 whose rotation from engine 1o is manually powered
has a pump impeller 18, a turbine runner 20, a stator 22, and a lock-up clutch 24.

The turbine runner 20 is connected to a human-powered shaft 26, and when the lock-up clutch 24 is released, rotational force is transmitted from the pump impeller 18 to the human-powered shaft 26 via fluid, and the lock-up clutch 24 is engaged. A rotational force is mechanically applied to the human-powered shaft 26. The lock-up clutch 24 is operated by the differential pressure between the apply chamber T/A and the release chamber T/R. Note that the torque converter 12 is configured to drive an oil pump 28. The planetary gear transmission mechanism 14 has a first planetary gear set G1 and a second planetary gear set G2, the first planetary gear set G,
is the 1st Sangia S.

, first internal gear R, both gears 51 and R,
The first pinion gear P, which simultaneously meshes with the
The second planetary gear set G2 includes a second sun gear S2, a second internal gear R2, and a second pinion gear P2 that meshes with both gears 82 and R2 at the same time. 2-binion carrier PC2. The first sun gear S1 is always connected to the human power shaft 26, and the first pinion carrier PCI and the second internal gear R2 are connected to the output shaft 30.
is always connected. 1st internal gear R] is
Forward one-way clutch F10 arranged in series
It can be connected to the second pinion carrier PC2 via the forward clutch F/C and an overrun clutch O/C arranged in parallel thereto. The second sun gear S2 is connected to the input shaft 26 via the reverse clutch R/C.
The second pinion carrier PC2 can also be connected to the input shaft 26 via the high clutch H/C. The second Sankia S2 can be fixed to a stationary part by a band brake B/B, and the second pinion carrier PC2 has a row one-way clutch L10 and a low and reverse brake L&R/B arranged in parallel with each other.
It can be fixed to a stationary part via. Output shaft 30
An output gear 32 is provided integrally with the.

An idler gear 34 is provided to mesh with the output gear 32, and a reduction gear 36 is connected to the idler gear 34 via an idler shaft 35 so as to rotate together with the idler gear 34. The reduction gear 36 meshes with a ring gear 38 of the differential mechanism 16. Drive shafts 40 and 42 protrude left and right from the differential mechanism 16, and left and right wheels are connected to these.

This planetary gear transmission mechanism 14 includes clutches F/C, H/C
, O/C and R/C, brake B/B and L&R/B,
By operating the one-way clutch F10 and Llo in various combinations, each element of the planetary gear set G and G2 (S+, S2, R1, R2, PC+ and Pc
2) can be changed, and thereby the rotational speed of the output shaft 30 with respect to the human power shaft 26 can be variously changed. In other words, each clutch, brake, etc.
Advance 4 by operating the combination as shown in the figure.
You can get 1 speed reverse. Note that in FIG. 3, the O mark indicates that the clutch and brake are engaged, and in the case of a one-way clutch, indicates an engaged state. Also,
2A, 3R, and 4A in the band brake B/B column are 2-speed apply chamber 2A and 3-speed release chamber 3 of the hydraulic servo device that operates the band brake B/B, respectively.
The R and 4th speed apply chambers 4A are shown, and the 0 mark indicates that hydraulic pressure is being supplied. Further, G1 and G2 are the ratios of the number of teeth of sun gears S1 and S2 to the number of teeth of internal gears R1 and R2, respectively, and the gear ratio is
This is the ratio of the rotation speed of the input shaft 26 to the rotation speed of 0.

By the operation of the planetary gear transmission mechanism 14 as described above, the rotation of the human power shaft 26 is changed in a predetermined speed and outputted to the output shaft 30. The rotational force of the output shaft 30 is transmitted to the differential mechanism 16 via an output gear 32, an idler gear 34, and a reduction gear 36.
is transmitted to the ring gear 38. As a result, the drive shaft 40
and 42, the left and right front wheels can be driven.

By doing so, it is possible to perform an automatic shift of four forward speeds with overdrive.

FIG. 4 shows a hydraulic circuit of a hydraulic control device for controlling the power transmission mechanism.

This hydraulic control device includes a pressure regulator valve 50, a manual valve 52, a throttle valve 54, a throttle modifier valve 56, a pressure modifier valve 58, a lockup control valve 60, a governor valve 62.1-2 a shift valve 64.2
-3 shift valve 66.3-4 shift valve 68.3-
2 timing valve 70.4-2 sequence valve 72
, l speed fixed range pressure reducing valve 74, speed cut valve 76, overrun clutch control function, rev 7
8.1-2 It has an accumulator valve 80, a kickdown modifier valve 82, an overdrive inhibitor solenoid 84, an N-D accumulator 88, and a servo release accumulator 90. They are connected as shown in the figure, and also include an oil pump O/P, an apply chamber T/A and a release chamber T/R of the torque converter 12, a clutch R/C,
It is also connected to the three chambers 2A, 3R, and 4A of H/C1O/C and F/C, brake L&R/B, and band brake B/H as shown. With this configuration, the clutches R/C%H/C, O/C and F/C1 and the brakes L&R/B and B/B operate as shown in the table above, depending on the vehicle speed and engine throttle opening. do.

FIG. 1 shows the band brake B/B in detail.

A band 102 is wound around the outer periphery of a rotatable drum 100. One end 102a of the band 102 is supported by an anchor pin 106 fixed to the casing 104. The anchor pin 106 is screwed into the female thread of the casing 104 by a screw provided on its outer periphery, and is fixed by a locking nut 108. The tip of the piston stem 110 is pressed against the other end 102b of the band 102.

A two-speed piston 112 and a four-speed piston 114 are connected to the piston stem 110 as described later. 2
The continuous piston 112 has a stepped shape having a large diameter part and a small diameter part, and the large diameter part and the small diameter part fit into the large diameter part and the small diameter part of the retainer 116, respectively. As a result, there are two
A continuous application chamber 2A is formed. Further, a triple release chamber 3 is provided between the back side of the hole of the casing 104 into which the retainer 116 is inserted and the large diameter portion of the dual piston 112.
R is formed. The outer diameter part of the fourth speed piston 114 is fitted into the inner diameter part of another retainer 118. The retainer 118 is arranged in series with the retainer 116 and inserted into the large direction of the casing 104, and the snap ring 12
Extraction is stopped by 0. A quad application chamber 4A is formed between the retainer 118 and the quad piston 114. Further, a drain chamber 122 that is constantly drained is formed on the side of the 4-speed piston 114 opposite to the side where the 4-speed apply chamber 4A is formed. Note that seal members are provided at two locations on the outer diameter portion of the retainer 116 and at three locations on the outer diameter portion of the retainer 118. Seal members are also provided on the large diameter portion and small diameter portion of the second speed piston 112 and on the outer diameter portion of the fourth speed piston 114.

A dual return spring 124 is provided between the second speed piston 112 and the back side of the hole provided in the casing 104.

Note that the dual piston 112 is assembled to the piston stem 110 so as to be movable in the axial direction.

However, since the end surface of the left-hand side of the second-speed piston 112 in the figure contacts the stepped portion of the piston stem 110 via the washer 126, when a force toward the left in the figure acts on the second-speed piston 112, the second-speed The piston 112 cannot move relative to the piston stem 110, and this is transmitted to the piston stem 110. A spring seat 130 is attached to the piston stem 110 by a stepped portion thereof and a snap ring 128. This spring seat 130 and the dual piston 112
A quadruple return spring 132 is provided between the two. Further, a cushion spring 134 is provided between the spring seat 130 and the quadruple piston 114. Note that the fourth speed piston 114 is fitted to be movable in the axial direction with respect to the piston stem 110, and is movable relative to the piston stem 110 by the dimension S shown in the figure.

Next, the operation of this embodiment will be explained. In 1st gear, 2nd gear apply chamber 2A, 3rd gear release chamber 3R1 and 4
Hydraulic pressure is not supplied to any of the oil chambers in the speed apply chamber 4A, and the 2nd speed piston 112 and the 4th speed piston 1
14 are return springs 124 and 4 for second speed, respectively.
The speed return spring 132 pushes it back to the position shown in FIG. 1, and the band! 02 is in a released state.

When the 1st-2nd gear shift is performed from this state, hydraulic pressure is supplied to the 2nd gear apply chamber 2A. As a result, a force directed to the left in the figure acts on the second speed piston 112. The force acting on the second speed piston 112 is transmitted to the piston stem 110 via the washer 126, and the second speed piston 112 and the piston stem 110 are connected to the second speed return spring 112.
4 to the left in the figure, and presses the band 102 against the outer periphery of the drum 100. This results in band 10
2 is in the engaged state, and the automatic transmission is in poor condition in 2nd gear.

Next, when shifting to the third speed, the oil pressure is supplied to the third speed release chamber 3R while the oil pressure supply state to the second speed apply chamber 2A is maintained. 3rd speed release chamber 3
The hydraulic pressure R acts on the large diameter part of the 2nd speed piston 112,
Since a force greater than the force due to the hydraulic pressure acting on the speed apply chamber 2A is applied, the second speed piston 112 is pushed back to the right in the figure. As a result, the fastened state of the band 102 is released, and the third speed state is entered.

Next, when shifting to the 4th speed, the oil pressure is supplied to the 4th speed apply chamber 4A while the oil pressure supply state of the 2nd speed apply chamber 2A and the 3rd speed release chamber 3R is maintained. . The fourth speed piston 114 receives a leftward force in the figure due to the oil pressure in the fourth speed apply chamber 4A. The fourth-speed piston 114 transmits force to the piston stem 110 via the cushion spring 134 and the spring seat 130, and causes the piston stem 110 to stroke by the idle stroke. Piston stem! When the idle stroke of 10 is exhausted, the fourth speed piston 114 compresses the cushion spring 134 and moves further to the left in the figure. In this way, when the 4th speed piston 114 strokes to the left by the S dimension, the left end of the 4th speed piston 114 comes into contact with the snap ring 128, and the pushing force of the 4th speed piston 114 is directly transmitted to the piston stem 110. Ru. While the quadruple piston 114 strokes this S dimension, the force acting on the piston stem 110 is determined by the cushion spring 134, and gradually increases as the cushion spring 134 is compressed. That is, the pushing force of the piston stem 110 increases with a gentle slope, and the 4th speed piston 11
4 comes into contact with the snap ring 128, the oil pressure in the 4th gear apply chamber 4A increases rapidly and the oil pressure in the 4th gear apply chamber 4A
All the forces acting on piston stem 110 will act on piston stem 110. Therefore, since the pushing force of the piston stem 110 gradually increases when the band 102 starts to be fastened, the band 102 is smoothly fastened and the shift shock is reduced. In addition, during the 4-3 gear shift, the force that the piston stem 110 was acting on the band 102 is initially applied to the cushion spring 13.
It decreases gradually according to the characteristics of 4, so similarly 4
-It is possible to reduce the shock when shifting to 3rd gear. 4-3
Since the forward one-way clutch F10 is locked during gear shifting, the cushioning action of the cushion spring 134 can be more effectively achieved.

In this embodiment, a cushion spring was not provided on the 2nd speed piston 112 side, but this may be provided to reduce the shift shock of 1-2 speed and 2-1 speed.

(Second Embodiment) FIG. 5 shows a second embodiment. In this second embodiment, the 4-speed return spring 132 is connected to the 2-speed piston 112 and 4-speed return spring 132.
It is provided between the continuous piston 114 (in the first embodiment, the second speed piston 112 and the spring seat 13
0), the same operation and effect as in the first embodiment described above can be obtained.

(g) As described in detail, according to the present invention, a cushion mechanism is provided on the piston for the high speed of the band brake device of an automatic transmission that operates at two speeds, so that the piston for the high speed is It is possible to reduce shift shock when shifting and shifting from a high gear. Particularly in the case where a shift from a high speed gear is performed by engaging a one-way clutch, it is possible to reduce the engagement shock of the one-way clutch and prevent the occurrence of sudden torque fluctuations.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the first embodiment of the present invention, Fig. 2 is a skeleton diagram of an automatic transmission, Fig. 3 is a diagram showing the combination of elements that operate at each gear stage, and Fig. 4 is a hydraulic circuit. FIG. 5 is a diagram showing a second embodiment of the present invention. 102... Band, 106... Anchor bin, 11
0... Piston stem, 112... Piston for 2nd speed, 114... Piston for 4th speed, 124... Return spring for 2nd speed, 132... Return spring for 4th speed, 134... Cushion Spring, 2A...
・2nd speed apply chamber, 3R...3rd speed release chamber, 4
A...4-speed application chamber.

Claims (1)

[Claims] A band brake device for an automatic transmission that is engaged in two gears, a low gear and a high gear, in which a single piston stem that applies force to the band is provided with a piston for the low gear and a piston for the high gear that are independent of each other. In a band brake device for an automatic transmission equipped with a piston, at least on the piston side for high gear, the piston can be moved in the axial direction by a predetermined amount with respect to the piston stem, and the piston is provided with hydraulic pressure for fastening. A band brake device for an automatic transmission, comprising a cushion mechanism configured by providing a cushion spring that applies a force in an opposing direction.