JPH0650688Y2 - Actuator of friction element for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic actuator for operating a band brake for shifting gears in an automatic transmission.

(Prior Art) An automatic transmission of a vehicle is generally composed of a combination of a torque converter and a planetary gear type auxiliary transmission. The torque converter is usually composed of three types of impellers, that is, a pump, a turbine, and a stator, transmits the power of the engine to the output shaft via internal fluid, and performs continuous torque conversion according to deceleration. The planetary gear type auxiliary transmission is composed of a sun gear, a pinion that meshes with the sun gear, a planet carrier that supports the pinion, a ring gear, and so on. A shifting element is provided. Further, a hydraulic control device including an oil pump, a pressure regulating valve, a pressure reducing valve and the like is used to control these speed change elements.

By the way, a band brake including a brake drum and a brake band for tightening the brake drum is used for shifting gears in an automatic transmission.
As described in the publication, a hydraulic actuator is provided in a transaxle case, a piston arranged in a cylinder chamber of the actuator is driven, and one end of the brake band is connected to the piston through an integral piston stem. It is known to be configured to operate. In the case of this actuator, one of the cylinder chambers defined by the piston is a servo release chamber that applies hydraulic pressure to the side that releases the engagement of the band brake,
The other chamber is a servo apply chamber that applies hydraulic pressure to the side where the band brake is engaged. The actuator operates in the direction in which the brake band is tightened when the hydraulic pressure in the servo release chamber is released and enters the servo apply chamber, and in the direction in which the brake band is loosened when the hydraulic pressure enters the servo release side. However, this actuator inevitably leaves air in the cylinder chamber when oil is supplied after it is assembled in a factory, etc., and this gradually increases from the seal part as the travel distance increases or due to changes over time depending on the running condition. Go out. Therefore, in the case of the above-mentioned actuator, in particular, the air accumulated in the servo release chamber gradually leaks, and the actual gear shift operation is deviated from the gear shift shock tuning performed in the assembly stage, and the gear shift shock is deteriorated. Occurs.

(Object of the Invention) The present invention has been made in view of the above problems, and provides an actuator of a friction element for an automatic transmission that can perform gear shift shock tuning in a state where air does not accumulate in a servo release chamber. The purpose is to

(Constitution of the Invention) The present invention facilitates the air release from the servo release chamber without increasing the oil leak amount by providing the air vent passage so that the upper part of the servo release chamber and the sliding part of the piston stem communicate with each other. It was found that it could be pulled out. That is, an actuator of a friction element for an automatic transmission according to the present invention has a servo piston for operating a friction element for an automatic transmission arranged in a cylinder chamber, and one of the cylinder chambers defined on both sides of the servo piston. These chambers are used as a servo release chamber that applies hydraulic pressure to the side that disengages the friction elements for the automatic transmission, and the other chamber is a servo apply chamber that applies hydraulic pressure to the side that engages the friction elements. Friction for an automatic transmission configured to operate the servo piston by controlling hydraulic pressure supply to the servo release chamber and the servo apply chamber and operate one end of a brake band of the friction element via a piston stem integrated with the servo piston. In the actuator of the element, an element that connects the upper part of the servo release chamber and the sliding part of the piston stem to each other. The vent passage is characterized in that formed on the casing constituting the actuator.

(Operation) When an automatic transmission is assembled and oil is supplied to the servo release chamber, air in the servo release chamber is pushed out to the air vent passage and escapes to the outside via the sliding portion of the piston stem.
However, the air bleed passage has a structure in which it is sealed against oil by communicating with the sliding portion of the piston stem, so the amount of oil leak from the servo release chamber does not increase. Therefore, the gear shift shock tuning after assembly is performed with the air released from the servo release chamber, and proper shock tuning that does not shift due to aging is performed. Also,
Since the sliding portion of the piston stem that communicates with the air bleed passage also constitutes the oil seal portion, there is no risk that air will flow back into the air bleed passage and enter the servo release chamber when hydraulic pressure is not applied.

(Example) Hereinafter, an example will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an automatic transmission according to an embodiment of the present invention.

In this automatic transmission, a torque converter 2 and a multi-stage transmission gear device 10 described later are sequentially arranged from the engine side coaxially with a crankshaft 1 of an engine which is an input shaft. The torque converter 2 includes a pump 3, a turbine 4, and a stator 5. Pump 3 is crankshaft 1
It is fixed to. The stator 5 includes a fixed shaft 7 that is integrated with a case 11 of a multi-stage transmission gear device 10 via a one-way clutch 6.
Rotate on. The one-way clutch 6 allows rotation of the stator in the same direction as the pump 3, but does not allow rotation in the opposite direction.

The multi-stage speed change gear device 10 includes a central shaft 12 whose base end is fixed to the crank shaft 1 and whose front end extends through the center of the multi-stage speed change gear device and is connected to an oil pump P on the side of the device. There is. A hollow turbine shaft 13 whose base end is connected to the turbine 4 of the torque converter 2 is concentrically provided outside the central shaft 12. A Ravigneaux type planetary gear unit 14 is provided on the turbine shaft 13. This planetary gear unit
The small-diameter sun gear 15 is composed of a large-diameter sun gear 16, a long pinion gear 17, a short pinion gear 18, and a ring gear 19 which are arranged on the side of the small-diameter sun gear 15 on the side farther from the engine.

A forward clutch 20 and a coast clutch 21 are provided on the side of the planetary gear unit 14 farther from the engine.
Are arranged in parallel. The forward clutch 20 is a clutch for forward traveling, and includes the small diameter sun gear 15 and the turbine shaft 13 via the first one-way clutch 22.
The power transmission between is intermittent. The coast clutch 21 also interrupts power transmission between the small-diameter sun gear 15 and the turbine shaft 13. A band type 2-4 brake 23 is arranged radially outward of the coast clutch 21. The 2-4 brake 23 is composed of a brake drum 23a connected to the large-diameter sun gear 16 and a brake band 23b hung on the brake drum 23a. The outside of the forward clutch 20 in the radial direction, and the above 2
A reverse clutch 24 is arranged beside the -4 brake 23. The reverse clutch 24 is a clutch for reverse traveling, and the large diameter sun gear 16 and the turbine shaft 1 are interposed via the brake drum 23a of the 2-4 brake 23.
Power transmission between 3 is intermittent.

A low / reverse brake 25 that disengages the carrier 14a of the planetary gear unit 14 and the case 10a of the multi-stage transmission gear device 10 is arranged outside the planetary gear unit 14 in the radial direction. Also, the above 2-4 brake 23
A second one-way clutch 26 for engaging and disengaging the carrier 14a and the case 10a is arranged between the low reverse brake 25 and the low reverse brake 25 in parallel. A 3-4 clutch 27 that connects and disconnects the power transmission between the carrier 14a of the planetary gear unit 14 and the turbine shaft 13 is arranged laterally on the engine side of the planetary gear unit 14. An output shaft 28 having an output gear 28a is arranged laterally on the engine side of the 3-4 clutch 27, and the output shaft 28 is connected to a ring gear 19. Reference numeral 29 in the figure denotes the turbine shaft 13 and the crankshaft 1.
2 shows a lockup clutch for directly connecting the engine without the torque converter 2.

The multi-stage speed change gear device 10 itself has four forward speed steps and one reverse speed step, and four clutches 20, 21, 24, 27 and two brakes 23, 25 are appropriately operated to achieve the required speed change. You can get steps. Of each clutch and brake,
The 2-4 brake 23 has two oil chambers, an apply side and a release side, as its driving actuator, as will be described later, and supplies hydraulic pressure to the apply side and releases the hydraulic pressure on the release side. Only the 2-4 brake 23 is activated, and in other hydraulic pressure supply modes, the 2-4 brake 23 is released. The remaining clutches and brakes each have only one oil chamber in each actuator, and are engaged when the oil pressure is supplied to this oil chamber, and when the oil pressure in this oil chamber is released. It will be released.

FIG. 2 shows the structure of the 2-4 brake 23 and the 2-4 brake actuator 30. 2-4 Brake 23
The brake band 2 on the brake drum 23a as described above.
3b is applied, and the 2-4 brake actuator 30 is provided at a portion of the case 11 of the multi-stage gear device adjacent to the 2-4 brake. This actuator 30
A servo piston 30b and a servo retainer 30c that covers the rear portion of the cylinder hole 30a are inserted into the cylinder hole 30a, and the servo retainer 30c is held by a snap ring 30d. A servo release chamber 30e is formed between the bottom of the cylinder hole 30a and one end surface of the servo piston 30b, and an oil passage 30f for release side hydraulic pressure supply is opened at a position below the servo release chamber 30e. Further, the servo piston 30b has a small diameter portion 30g concentrically on the other end surface, and the small diameter portion 30g is configured to slide in a cylinder hole 30h formed on the inner end surface side of the servo retainer 30c. And the servo piston 30b
A servo apply chamber 30i is formed between the servo retainer 30c and an inner end surface of the servo retainer 30c, and an oil passage 30j for supplying hydraulic pressure at the apply side opens at a position below the servo apply chamber 30i. Servo piston 3
0b is biased toward the servo retainer 30c by a spring 30k. A piston stem 30l protruding toward the side opposite to the servo retainer 30c is fixed to the servo piston 30b, and the tip of the piston stem 30l is in contact with one end of the brake band 23b via a band strut 31. Also,
The other end of the brake band 23b is supported on the case 11 side via an anchor end rod 32. When the piston stem 30l is pushed out, the brake band 23b is
Tighten 3a.

In the servo release chamber 30e and the servo apply chamber 30i formed on both sides of the servo piston 30b, the former has a larger piston pressure receiving area than the latter. Therefore, the servo piston 30b moves to the left in FIG. 2 against the spring 30k only when the hydraulic pressure is supplied to the servo apply chamber 30i and the hydraulic pressure in the servo release chamber 30e is released. 30l is pushed out and the band brake 23 is engaged.

In this actuator 30, the servo release chamber 30e
An air bleed passage 30n is formed between the upper part of and the sliding portion 30m of the piston stem 30l. After assembly, when oil is supplied to the servo release chamber 30e, the air originally contained in the servo release chamber 30e is pushed out through the air bleed passage 30n, and is then sent to the outside via the sliding portion 30m of the piston stem 30l. Get out.

The present invention is not limited to the above embodiment, but can be implemented in various other modes.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to prevent air from accumulating in the servo release chamber in the actuator of the friction element for the automatic transmission and properly perform gear shift shock tuning. be able to.

[Brief description of drawings]

FIG. 1 is a schematic view of an automatic transmission according to an embodiment of the present invention,
FIG. 2 is a structural view of the essential parts of the same embodiment. 2: Torque converter, 10: Multi-speed gearbox, 11: Case, 23: 2-4 band brake, 23a: Brake drum, 23
b: brake band, 30: 2-4 brake actuator, 30a: cylinder hole, 30b: piston, 30e: servo release chamber, 30i: servo apply chamber, 30l: piston stem, 30
m: sliding part, 30n: air vent passage.

Claims (1)

[Scope of utility model registration request] 1. A servo piston for operating a friction element for an automatic transmission is arranged in a cylinder chamber, and one chamber of the cylinder chamber divided on both sides of the servo piston is provided with a servo piston of the friction element for the automatic transmission. Servo release chamber that applies hydraulic pressure to the side that releases the engagement, and the other chamber as a servo apply chamber that applies hydraulic pressure to the side that engages the friction element, and supply the hydraulic pressure to these servo release chamber and servo apply chamber. In the actuator of the friction element for an automatic transmission, which is configured to operate the servo piston by operating the servo piston and operate one end of the brake band of the friction element via a piston stem integrated with the servo piston, an upper portion of the servo release chamber The air vent passage that connects the piston and the sliding portion of the piston stem to the case that constitutes the actuator. The actuator of an automatic transmission for a friction element, characterized in that it has.