JP3647228B2 - Multi-plate brake device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-plate brake device for an automatic transmission, and more particularly to an air vent structure for a piston retainer.
[0002]
[Prior art]
In a brake of an automatic transmission, a friction plate is pressed by a piston that is actuated by hydraulic pressure to be engaged. A piston retainer is provided to form a hydraulic chamber for the piston.
For example, in a brake, a spline is formed on the inner wall of the transmission case to restrain the fixed side friction plates arranged alternately with the rotation side friction plates in the rotational direction and move in the axial direction. It is formed in a cylindrical shape by molding and is arranged adjacent to the spline.
[0003]
A piston is accommodated in the piston retainer so as to be slidable in the axial direction, a hydraulic chamber is formed between the piston retainer and the piston, and a hydraulic valve unit is provided at the lower part of the transmission case for supplying and discharging hydraulic pressure to the hydraulic chamber. This is done through an oil hole formed in the lowest part of the piston retainer so as to communicate with the cylinder.
A similar mounting structure is also shown in, for example, Japanese Patent Publication No. 5-43905.
[0004]
[Problems to be solved by the invention]
As described above, hydraulic pressure is supplied from the bottom to the hydraulic chamber formed between the piston retainer and the piston, and this hydraulic pressure pushes the piston and presses the friction plate. Or air may enter from the piston sliding part.
However, once such air flows in, conventionally, as shown in FIG. 4, there is no escape passage, and therefore, an air pool A is generated above the oil OIL in the hydraulic chamber 61 of the piston retainer 60. As a result, the supplied oil has to compress air, and there is a problem that a time delay occurs in the pressing of the friction plate and the fastening operation as a brake is hindered.
[0005]
SUMMARY OF THE INVENTION Accordingly, in view of the above-described conventional problems, the present invention has an object to provide a multi-plate brake device in which no air pool is generated in a hydraulic chamber formed in a piston retainer of a multi-plate brake of an automatic transmission. And
[0006]
[Means for Solving the Problems]
For this reason, the present invention includes a first friction plate and a second friction plate respectively engaged with a case member and a rotating member that rotates relative to the case member, a piston that presses the friction plate by sliding to one end side in the axial direction, An annular inner peripheral wall portion on which the piston slides, an outer peripheral wall portion, and a connecting wall portion connecting the inner peripheral wall portion and the outer peripheral wall portion on the other end side in the axial direction are formed into a U-shape. A multi-plate brake device for an automatic transmission having a piston retainer that forms a hydraulic chamber of the piston with an inner peripheral wall portion, an outer peripheral wall portion, a connecting wall portion, and a piston, and the piston retainer is fixed to a case member; is provided with the oil holes to the hydraulic chambers on the outer peripheral wall portion, the air vent hole in the hydraulic chamber disposed substantially top portion of the outer peripheral wall portion, the air vent hole is located in the inner diameter surface width of the spline, the hydraulic chamber air Is the outer peripheral wall of the piston retainer It was as those to be discharged through the small gap between the inner diameter surface of the outer peripheral surface and the spline.
[0007]
The case member includes a spline that engages with the first friction plate, and the spline extends to the outer peripheral wall portion of the piston retainer so that the air in the hydraulic chamber is discharged from the air vent hole to the valley space of the spline. be able to.
[0008]
[Action]
Even if air flows into the hydraulic chamber of the piston retainer of the multi-plate brake device, it is discharged from the air vent hole provided in the outer peripheral wall of the piston retainer, so that no air stagnation occurs in the hydraulic chamber. The piston works well.
In particular, an oil hole for supplying hydraulic pressure is provided in the outer peripheral wall of the piston retainer, and an air vent hole is provided at the top of the piston retainer, so that air efficiently gathers at the top of the hydraulic chamber, and this air is discharged quickly and efficiently. be able to.
Then, by positioning the air vent hole within the inner surface width of the spline, a minute gap between the outer peripheral surface of the outer peripheral wall portion of the piston retainer and the inner surface of the spline becomes a choke with respect to the oil, and the oil is prevented from coming off. The air vent hole can be set to a size that can be easily processed, and there is no need to provide a separate member for the choke.
[0009]
In addition, since the air in the hydraulic chamber is configured to be discharged from the air vent hole to the valley space of the spline, there is no need to specially form a discharge passage.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to examples.
FIG. 1 is a longitudinal sectional view of a speed change mechanism portion of an automatic transmission showing the configuration of the embodiment.
In the transmission case 1, a first rotating member 3 that rotates integrally with the main shaft, a second rotating member 4 that can rotate with respect to the main shaft 2, and a planetary gear 5 are sequentially provided in the axial direction around the main shaft 2. It has been. A clutch drum 12 is coupled to the first rotating member 3, and a spline 13 is formed on the inner periphery of the clutch drum 12, and a spline 14 is formed on the outer periphery of the hub portion of the second rotating member 4. The clutch drum 12 and the friction plates 15 and 16 engaged with the splines 13 and 14 of the second rotating member 4 constitute a first clutch CL1. The second rotating member 4 extends between the main shaft 2 and the sun gear 6 of the planetary gear 5 and is connected to the carrier 9 via the carrier plate 10.
[0011]
A hub drum 20 is coupled to the sun gear 6 of the planetary gear 5, and the hub drum 20 has a first drum portion 21 and a second drum portion 23 having splines 22 and 24 on the outer periphery thereof. A second clutch CL2 is configured by the splines 22 of the first drum portion 21 and the friction plates 25 and 26 respectively engaged with the splines 13 of the clutch drum 12. The ring gear 7 of the planetary gear 5 is coupled to the third rotating member 28, and the carrier 9 is connected to the fourth rotating member 29.
[0012]
The second drum portion 23 of the hub drum 20 overlaps the ring gear 7 of the planetary gear 5 in the axial direction, and the carrier 9 extends between the second drum portion 23 and the ring gear 7 toward the fourth rotating member 29.
A spline 30 is formed on the inner wall of the transmission case 1 so as to face the second drum portion 23 of the hub drum 20, and friction plates 31 and 32 that engage with the spline 30 and the spline 24 of the second drum portion 23, respectively. A brake BRK is provided. A retainer plate 33 that supports one end of the friction plate is supported by a shoulder portion 34 formed on one end side of the spline 30 of the transmission case. The friction plate 31 that engages with the spline 30 on the inner wall of the transmission case 1 is the friction plate 32 on the fixed side, and the friction plate 32 that engages with the spline 24 on the second drum portion 23 is the rotation side friction plate.
[0013]
The spline 30 extends to a portion facing the clutch drum 12, and an inner diameter thereof is cut into a diameter-expanded portion 35 in a range facing the clutch drum 12. The enlarged diameter portion 35 has an annular inner peripheral wall portion 40a, an outer peripheral wall portion 40b, and a connecting wall portion 40c that is connected to the end portions on the opposite side to the friction plates 31 and 32 of the wall portions, and has a cross-sectional view. A piston retainer 40 having a U-shape is installed, and is positioned by a snap ring 39 locked in a groove 38 formed in the enlarged diameter portion 35. FIG. 2 shows an enlarged cross section of the piston retainer 40.
[0014]
A ring-shaped piston 45 having a pressing portion 46 is disposed in the piston retainer 40, and a return spring 47 is provided between the piston 37 and the holder 37 provided on the stepped portion 36 of the enlarged diameter portion 35. The piston 45 is urged in a direction in which 46 is separated from the friction plates 31 and 32. A plurality of pressing portions 46 and return springs 47 are provided at intervals in the circumferential direction of the piston 45.
A multi-plate brake device is configured with the above-described brake BRK, piston retainer 40 and piston 45 as main elements.
[0015]
An oil hole 43 is formed in the outer peripheral wall portion 40b of the piston retainer 40 to communicate the bottom portion of the hydraulic chamber 42 with an oil passage 49 communicating with a hydraulic control valve unit (not shown). By supplying hydraulic pressure to the hydraulic chamber 42 through the oil hole 43, the piston 45 slides on the inner peripheral wall portion 40a and the outer peripheral wall portion 40b toward one end in the axial direction, and presses the friction plates 31 and 32, so that the hub drum 20 Fixed.
[0016]
In addition, an air vent hole 44 is formed at the top of the outer peripheral wall 40b of the piston retainer 40 to communicate the top of the hydraulic chamber 42 with the outside of the hydraulic chamber. In particular, as shown in FIG. 3, the piston retainer 40 is secured in the circumferential direction by engaging a positioning stopper 50 welded and fixed to its outer peripheral surface 41 between the spline peaks 52 and 52 of the enlarged diameter portion 35. The air vent hole 44 is positioned at the substantially central portion of the inner diameter surface width S of the spline 30 of the enlarged diameter portion 35, that is, the top surface width of the mountain.
As a result, the top of the hydraulic chamber 42 passes from the air vent hole 44 to the valley space F of the spline 30 of the enlarged diameter portion through a minute gap between the outer peripheral surface 41 of the outer peripheral wall portion 40b of the piston retainer and the inner diameter surface of the spline 30. It leads.
[0017]
The present embodiment is configured as described above, and an air vent hole 44 facing the substantially central portion of the inner diameter surface width S of the spline 30 of the enlarged diameter portion 35 is formed in the hydraulic chamber 42 at the top of the outer peripheral wall portion 40b of the piston retainer 40. Because the air is mixed into the hydraulic chamber 42, the air flows from the air vent hole 44 to the outer peripheral surface 41 of the outer peripheral wall portion 40 b of the piston retainer and the inner diameter surface of the spline 30. Since it is discharged to the outside through a minute gap, there is no effect of air accumulation, and the piston 45 operates reliably and the response as a brake is improved.
In addition, since the air from the air vent hole 44 is discharged to the valley space F of the spline 30 as described above, it is not necessary to form a special discharge passage.
[0018]
In the embodiment, the air vent hole 44 is positioned within the inner surface width S of the spline 30. However, if it is positioned within the inner surface width of the spline, the minute gap between the outer peripheral surface of the outer peripheral wall portion 40b of the piston retainer and the inner surface of the spline becomes a choke with respect to the oil, and air is easily released, but oil is prevented from coming off. Therefore, it is more preferable. Further, as a result, the air vent hole 44 formed in the piston retainer can be set to a large size that can be easily processed as compared with the case where the air vent hole 44 is disposed so as to face the valley space of the spline.
In addition, although the Example demonstrated what provided the air vent hole in the top part of the outer peripheral wall part, it is not necessarily limited to the top part in a strict meaning, Air can be extracted to such an extent that the response of a piston can fully be ensured. The present invention also includes a case where it is provided at a substantially top portion including a range near the top portion that can be formed.
[0019]
【The invention's effect】
As described above, the present invention provides an oil hole for supplying hydraulic pressure to an outer peripheral wall portion of a piston retainer that forms a hydraulic chamber of a piston in a multi-plate brake of an automatic transmission that performs fastening by pressing a friction plate with a piston. At the same time, since the air vent hole is provided at the approximate top, even if air flows into the hydraulic chamber of the piston retainer, air efficiently gathers at the top of the hydraulic chamber, and this air is efficiently and quickly discharged from the air vent hole. Therefore, there is no air accumulation in the hydraulic chamber, and there is an effect that the piston is surely operated and the responsiveness as a multi-plate brake is improved.
Then, by positioning the air vent hole within the inner surface width of the spline, a minute gap between the outer peripheral surface of the outer peripheral wall portion of the piston retainer and the inner surface of the spline becomes a choke with respect to the oil, and the oil is prevented from coming off. The air vent hole can be set to a size that can be easily processed, and there is no need to provide a separate member for the choke.
[0020]
In addition, by configuring the air in the hydraulic chamber to be discharged from the air vent hole to the valley space of the spline extension portion with which the friction plate engages, there is no need to form a special passage for discharging and the processing cost is reduced. It does not take.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a speed change mechanism portion of an automatic transmission according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a piston retainer.
FIG. 3 is a front view showing the arrangement of the piston retainer with respect to the spline of the transmission case.
FIG. 4 is an explanatory view showing an air reservoir in a conventional example.
[Explanation of symbols]
1 Transmission case (case member)
2 Spindle 3 First rotating member 4 Second rotating member 5 Planetary gear 6 Sun gear 7 Ring gear 9 Carrier 10 Carrier plate 12 Clutch drums 13, 14, 22, 24, 30 Splines 15, 16, 25, 26 Friction plate 20 Hub drum ( Rotating member)
21 First drum portion 23 Second drum portion 28 Third rotation member 29 Fourth rotation member 31 Friction plate (first friction plate)
32 friction plate (second friction plate)
33 Retainer plate 34 Shoulder portion 35 Expanded portion 36 Step portion 37 Holder 38 Groove 39 Snap ring 40 Piston retainer 40a Inner peripheral wall portion 40b Outer peripheral wall portion 40c Connecting wall portion 41 Outer peripheral surface 42 Hydraulic chamber 43 Oil hole 44 Air vent hole 45 Piston 46 Pressing portion 47 Return spring 49 Oil passage 50 Stopper 52 Mountain BRK Brake CL1 First clutch CL2 Second clutch S Inner surface width F Valley space

Claims (2)

A first friction plate and a second friction plate respectively engaged with a case member and a rotating member that rotates relative to the case member;
A piston that presses the friction plate by sliding toward one end in the axial direction;
An annular inner peripheral wall portion on which the piston slides, an outer peripheral wall portion, and a connecting wall portion connecting the inner peripheral wall portion and the outer peripheral wall portion on the other end side in the axial direction are formed into a U-shape. A multi-plate brake device for an automatic transmission having a piston retainer that forms an oil pressure chamber of the piston with the inner peripheral wall portion, the outer peripheral wall portion, the connecting wall portion and the piston,
Fixing the piston retainer to the case member;
Is provided with the oil holes to the hydraulic chambers on the outer peripheral wall portion, the air vent hole in the hydraulic chamber disposed substantially top portion of the outer peripheral wall portion,
The air vent hole is located within the inner surface width of the spline, and the air in the hydraulic chamber is discharged through a minute gap between the outer peripheral surface of the outer peripheral wall of the piston retainer and the inner surface of the spline. Multi-plate brake device for automatic transmission. The case member includes a spline that engages with the first friction plate,
The spline extends to the outer peripheral wall of the piston retainer,
2. The multi-plate brake device for an automatic transmission according to claim 1, wherein the air in the hydraulic chamber is configured to be discharged from the air vent hole to a valley space of the spline.

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