JPH0833177B2 - Band brake device for automatic transmission - Google Patents

Description

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 JP-A-61-282653. In the band brake device for an automatic transmission shown in this figure, two pistons for the second speed and the fourth speed are provided for one piston stem. Both pistons are provided with return springs. Further, the second speed piston is provided with a cushion mechanism. That is,
The second speed piston is movable in the axial direction of the piston stem by a predetermined amount, and a cushion spring is provided on the side opposite to the hydraulically operated side of the piston. This alleviates the change in hydraulic pressure during the stroke of the second speed piston against the force of the cushion spring, and 1-2
It is possible to reduce the shift shock of the shift and the 3-2 shift.

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

(D) Means for Solving the Problems The present invention is a one-way clutch that is opened at a high speed stage and is engaged at the time of switching from a high speed stage to a medium speed stage, and is engaged at two speed stages, a low speed stage and a high speed stage. An automatic transmission having a band brake that is in a state of being released and is disengaged at a middle speed between them, and for one low-speed stage independent of one piston stem that exerts a force on the band of the band brake. A cushion for providing a piston and a piston for a high speed stage, at least on the piston side for the high speed stage, enabling the piston to move in the axial direction by a predetermined amount with respect to the piston stem, and facing the hydraulic pressure for fastening the piston. A cushion mechanism configured by providing a spring is provided.

(E) Action For example, when shifting to a high speed stage by fastening a band, hydraulic pressure acts on the piston for the high speed stage.
After the piston and the piston stem have completed their idle strokes, the piston compresses the cushion spring and makes a predetermined stroke. During this time, the force acting on the piston stem gradually increases according to the characteristics of the cushion spring. When the piston for the high speed stage finishes the stroke for the cushion and the piston stem is mechanically connected to the stroke, the maximum force due to the 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 relaxed,
Shift shock is reduced. Also, by releasing the band and engaging the one-way clutch, the cushion spring allows the band brake to be released gently even when shifting to a gear lower than the high-speed stage, so that the one-way clutch is engaged. Since the shock is absorbed, it is possible to prevent sudden torque fluctuations. A cushion mechanism may be provided on the piston side for the low speed stage,
If it is not necessary, it may not be provided.

(F) Embodiment (first embodiment) FIG. 2 shows a skeleton diagram of an automatic transmission (automatic transaxle). The automatic transmission coupled to the engine 10 mounted laterally with respect to the vehicle, that is, in a direction orthogonal to the vehicle front-rear direction, has a torque converter 12, a planetary gear speed change mechanism 14, a differential mechanism 16, and the like. Engine 10
The torque converter 12 to which the rotation from is input has a pump impeller 18, a turbine runner 20, a stator 22, and a lockup clutch 24. Turbine runner 20
Is connected to the input shaft 26 and lockup clutch 24
Pump impeller 18 to the input shaft 26
The rotational force is transmitted to the input shaft 26 via the fluid, and when the lockup clutch 24 is engaged, the rotational force is mechanically input to the input shaft 26. The lock-up clutch 24 operates by a differential pressure between the apply chamber T / A and the release chamber T / R. The torque converter 12 is configured to drive the oil pump 28. The planetary gear transmission mechanism 14 has a first planetary gear set G ₁ and a second planetary gear set G ₂ , and the first planetary gear set G ₁ is
First sun gear S ₁ , first internal gear R ₁ , both gears
S ₁ and R ₁ a first pinion gear P ₁ is composed of a first pinion carrier PC ₁ which supports a, and the second planetary gear set G ₂ which mesh simultaneously with the second sun gear S _2, second Intana _Second gear that engages Lugia R ₂ and both gears S ₂ and R ₂ at the same time
The second pinion carrier PC ₂ supports the pinion gear P ₂ . The first sun gear S ₁ is always connected to the input shaft 26, and the first pinion carrier PC ₁ and the second internal gear R ₂ are always connected to the output shaft 30. The first internal gear R ₁ is a forward one-way clutch F / O and a forward clutch F arranged in series.
It is possible to connect to the second pinion carrier PC ₂ via / C and via the overrun clutch O / C arranged in parallel with these. The second sun gear S ₂ can be connected to the input shaft 26 via the reverse clutch R / C, and the second pinion carrier PC ₂ can be connected to the input shaft 26 via the high clutch H / C. The second sun gear S ₂ can be fixed to the stationary part by a band brake B / B, and the second pinion carrier PC ₂ is a low one-way clutch L / O and a low and reverse brake L & R / B arranged in parallel with each other. It can be fixed to the stationary part via and. An output gear 32 is provided integrally with the output shaft 30. An idler gear 34 is provided so as 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 integrally. The reduction gear 36 meshes with the ring gear 38 of the differential mechanism 16. Differential mechanism 16
Drive shafts 40 and 42 project left and right from this, to which the left and right front wheels are connected.

This planetary gear transmission 14 has clutch F / C, H / C, O / C
And R / C, the brakes B / B and L & R / B, and the one-way clutches F / O and L / O by operating in various combinations, each element of the planetary gear set G ₁ and G ₂ (S ₁ , S ₂ , R ₁ , R ₂ , PC
₁ and PC ₂ ) can be changed in rotation state, whereby the rotation speed of the output shaft 30 with respect to the input shaft 26 can be variously changed. That is, by operating each clutch, brake, etc. in a combination as shown in FIG. 3, it is possible to obtain the fourth forward speed and the first reverse speed. In addition, in FIG.
The mark indicates that the clutch and brake are engaged,
Also, in the case of a one-way clutch, the engaged state is shown. In addition, 2A, 3R and 4A are shown in the band brake B / B column respectively for the second speed apply chamber 2A, the third speed relays chamber 3R and the fourth speed apply of the hydraulic servo device that operates the band brake B / B. The chamber 4A is shown, and the mark ○ indicates that hydraulic pressure is being supplied. Further, α ₁ and α ₂ are the ratios of the number of teeth of the sun gears S ₁ and S _{2 to} the number of teeth of the internal gears R ₁ and R ₂ , respectively, and the gear ratio is the rotation of the input shaft 26 with respect to the rotation speed of the output shaft 30. It is the ratio of numbers.

By the operation of the planetary gear speed change mechanism 14 as described above, the rotation of the input shaft 26 undergoes a predetermined speed change and is output to the output shaft 30.
The rotational force of the output shaft 30 is transmitted to the ring gear 38 of the differential mechanism 16 via the output gear 32, the idler gear 34, and the reduction gear 36. As a result, the left and right front wheels can be driven via the drive shafts 40 and 42. By doing so, it is possible to perform automatic forward four-speed shift 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, a 1-2 shift valve 64, 2-3. Shift valve 66, 3-4 shift valve 68, 3-2 timing valve
70, 4-2 sequence valve 72, 1st speed fixed range pressure reducing valve 74, speed cut valve 76, overrun clutch control valve 78, 1-2 accumulator valve 8
0, kick-down modifier valve 82, overdrive inhibitor solenoid 84, ND accumulator 8
8 and a servo release accumulator 90, these valves are connected to each other as shown in FIG. 4, and the oil pump O / P and torque converter 12 are also provided.
Apply room T / A, release room T / R, clutch R / C, H /
C, O / C and F / C, brake L & R / B, and band brake
The three chambers 2A, 3R and 4A of B / B are also connected as shown. With this configuration, the clutch R / C, H / C, O / C and F can be changed depending on the vehicle speed and the engine throttle opening.
/ C and brakes L & R / B and B / B operate as in the table above.

Fig. 1 shows the band brake B / B in detail. A band 102 is wrapped around the rotatable drum 100. One end 102a of the band 102 is supported by an anchor pin 106 fixed to a casing 104. Anchor pin 1
06 is screwed into the internal thread of the casing 104 by a screw provided on the outer periphery thereof and is fixed by a nut 108 for locking. The tip of the piston stem 110 is pressed against the other end 102b of the band 102. A second speed piston 112 and a fourth speed piston 114 are connected to the piston stem 110 as described later. Second speed piston 1
Reference numeral 12 is a stepped shape having a large diameter portion and a small diameter portion, and the large diameter portion and the small diameter portion are fitted to the large diameter portion and the small diameter portion of the retainer 116, respectively. This allows the retainer 116
The second speed apply chamber 2A is formed between the second speed piston 112 and the second speed piston 112. Further, a third speed release chamber 3R is formed between the inner side of the hole of the casing 104 into which the retainer 116 is inserted and the large diameter portion of the second speed piston 112. The outer diameter portion of the fourth speed piston 114 is fitted to the inner diameter portion of another retainer 118. The retainer 118 is arranged in series with the retainer 116 and is inserted into the hole of the casing 104.
It is locked by 20. A fourth speed apply chamber 4A is formed between the retainer 118 and the fourth speed piston 114. Also, the 4th speed apply chamber 4A for the 4th speed piston 114
A drain chamber 122, which is always drained, is formed on the surface side opposite to the side on which is formed. Retainer 116
Sealing members are provided at two outer diameter portions of the retainer 118 and three outer diameter portions of the retainer 118. Also, the second speed piston 112
Sealing members are also provided on the large-diameter portion and the small-diameter portion, and on the outer-diameter portion of the fourth speed piston 114. Second speed piston 112
The second-speed return spring 124 is provided between the rear side and the inner side of the hole provided in the casing 104. The second speed piston 112 is attached to the piston stem 110 so as to be movable in the axial direction. However, since the end face on the left side of the second-speed piston 112 in the figure is in contact with the stepped portion of the piston stem 110 via the washer 126, when a force to the left in the figure acts on the second-speed piston 112, Piston 112 cannot move relative to piston stem 110,
This force 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. 4 between the spring seat 130 and the second speed piston 112
A speed return spring 132 is provided. Also,
A cushion spring 134 is provided between the spring seat 130 and the fourth speed piston 114. 4
The speed piston 114 is axially movably fitted to the piston stem 110, and is relatively movable with respect to the piston stem 110 by an S dimension shown in the drawing.

Next, the operation of this embodiment will be described. At the first speed, no oil pressure is supplied to any of the oil chambers of the second speed apply chamber 2A, the third speed release chamber 3R, and the fourth speed apply chamber 4A, and the second speed piston 112 and the fourth speed piston. 114 is pushed back to the position shown in FIG. 1 by the second speed return spring 124 and the fourth speed return spring 132, respectively, and the band 102 is in the released state.

When 1-2 shift is performed from this state, hydraulic pressure is supplied to the second speed apply chamber 2A. As a result, a force to the left in the figure acts on the second speed piston 112. The force acting on the second speed piston 112 is applied to the piston stem via the washer 126.
2nd speed piston 112 and piston stem
110 moves to the left in the figure against the force of the second-speed return spring 124, and presses the band 102 against the outer periphery of the drum 100. As a result, the band 102 is brought into the engaged state, and the automatic transmission is brought into the second speed state.

Next, when the gear shift to the third speed is performed, the hydraulic pressure is supplied to the third speed release chamber 3R while the hydraulic pressure supply state to the second speed apply chamber 2A is maintained. Since the hydraulic pressure in the third speed release chamber 3R acts on the large diameter portion of the second speed piston 112 and exerts a force greater than the hydraulic pressure force acting on the second speed apply chamber 2A, the second speed piston 112 Is pushed back to the right in the figure. As a result, the fastening state of the band 102 is released, and the third speed state is established.

Next, when shifting to the fourth speed, the hydraulic pressure is supplied to the fourth speed apply chamber 4A while the hydraulic pressure supply states of the second speed apply chamber 2A and the third speed release chamber 3R are maintained. . The hydraulic pressure in the fourth-speed apply chamber 4A causes the fourth-speed piston 114 to receive a leftward force in the drawing. The fourth speed piston 114 transmits a force to the piston stem 110 via the cushion spring 134 and the spring seat 130, and causes the piston stem 110 to travel by a play stroke. When the idle stroke of the piston stem 110 disappears, the fourth speed piston 114 compresses the cushion spring 134 and moves further to the left in the drawing. 4th speed piston 114
When is stroked to the left by S dimension, the left end of the fourth speed piston 114 comes into contact with the snap ring 128, and the pushing force of the fourth speed piston 114 directly affects the piston stem 1
Transmitted to 10. While the fourth-speed piston 114 strokes this S dimension, the force acting on the piston stem 110 becomes a value determined by the cushion spring 134, and gradually increases in accordance with the compression of the cushion spring 134. That is, the pushing force of the piston stem 110 increases with a gentle inclination, and increases rapidly when the fourth speed piston 114 comes into contact with the snap ring 128.
All the force that the hydraulic pressure in the speed applying chamber 4A acts on the fourth speed piston 114 acts on the piston stem 110.
Therefore, since the pushing force of the piston stem 110 gradually increases at the time when the fastening operation of the band 102 is started, the fastening of the band 102 is smoothly performed and the shift shock is reduced. Further, during the 4-3 gear shift, the hydraulic pressure in the apply chamber 4A is released, the piston stem 110 is pushed back in the opposite direction, and the force acting on the band 102 is first changed by the spring 132.
As the cushion spring 134 gradually extends, the cushion spring 134 gradually decreases near the completion of release of the band brake, and the shock at the time of engaging the one-way clutch F / O is alleviated. In this way, the forward one-way clutch F / O is locked during the 4-3 shift, so that the cushioning action of the cushion spring 134 appears more effectively.

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

(Second Embodiment) FIG. 5 shows a second embodiment. In the second embodiment, a fourth speed return spring 132 is provided between the second speed piston 112 and the fourth speed piston 114 (in the first embodiment, the second speed piston 112 and the spring seat 130 are provided). It is possible to obtain the same operation and effect as those of the first embodiment described above.

(G) Effect of the Invention According to the present invention, it is possible to reduce shift shocks when shifting gears to and from a high speed stage, and especially when shifting from a high speed stage, the engagement shock is higher than that of a normal clutch. Even if it is performed by engaging a one-way clutch having a large size, this shock is absorbed by the cushion mechanism, and it is possible to reliably prevent sudden torque fluctuations when the one-way clutch is engaged.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a skeleton diagram of an automatic transmission, FIG. 3 is a diagram showing a combination of elements that act at each shift stage, and FIG. 4 is a hydraulic circuit. FIG. 5 and FIG. 5 are views showing a second embodiment of the present invention. 102 …… band, 106 …… anchor pin, 110 …… piston stem, 112 …… second speed piston, 114 …… fourth speed piston, 124 …… second speed return spring, 132 …… fourth speed return spring , 134: Cushion spring, 2A: 2nd speed apply chamber, 3R: 3rd speed release chamber, 4A: 4th speed apply chamber.

Claims (1)

[Claims] 1. A one-way clutch that is opened at a high speed stage and is engaged when switching from a high speed stage to a medium speed stage, and an engaged state at two shift stages, a low speed stage and a high speed stage, and a medium speed between them. In an automatic transmission having a band brake which is released from engagement at a gear stage, one piston stem for exerting a force on a band of the band brake is provided with a piston for a low gear stage and a piston for a high gear stage which are independent of each other. Cushion mechanism configured to allow the piston to move in the axial direction by a predetermined amount with respect to the piston stem on at least the high-speed stage piston side, and to provide the piston with a cushion spring in a direction that opposes the fastening hydraulic pressure. A band brake device for an automatic transmission, characterized by being provided with.