JP3465717B2 - Band brake structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band brake structure used as a friction element in an automatic transmission of a vehicle.

[0002]

2. Description of the Related Art Generally, a gear shifting operation of an automatic transmission is performed by fixing each part of a planetary gear or releasing the fixing of each part. One is a band brake. The band brake is composed of a band wound around a drum, an operating piston, and the like, and the band is fastened to the drum or released from the drum by the operation of the operating piston.

As a conventional band brake of this type,
For example there is one described in Japanese Unexamined Utility Model Publication No. 2-6853, which is illustrated in Figure 4.

In FIG. 4 , a band brake 1 is one of friction elements of an automatic transmission (not shown in detail), and a band 5 is drum 6 by a working piston 4 which moves a piston stem 2 toward and away from an anchor pin 3. Is to be concluded and released. The band 5 is wound around a drum 6, and a first bracket 7 is fixed to one end of the band 5 and a second bracket 8 is fixed to the other end.

The first bracket 7 is formed with a first projection 7a which engages with the piston stem 2, and the second bracket 8 is formed with a second projection 8a which is engaged with the anchor pin 3. .

The second bracket 8 is provided with a convex portion 8b, and the convex portion 8b projects toward the first bracket 7 along the outer peripheral friction surface 6a of the drum 6 and is attached to the first bracket 7. It is slidably fitted in the provided recess 7b.

The first bracket 7 and the second bracket 8 in which the concave portion 7b and the convex portion 8b are slidably fitted are restrained from moving in the twisting direction and the bending direction, and the outer peripheral friction surface of the drum 6 is restrained. It is adapted to move relatively along 6a. As a result, the curvature of the band 5 is always maintained to be uniform, the frictional characteristics of the band brake are stabilized, and the shift shock of the automatic transmission is reduced.

[0008]

[SUMMARY OF THE INVENTION However, the present inventor, as a result of intense research experiments, even in the conventional band brake as described above, all operating the shift shock of the automatic transmission as shown in FIG. 5 He found that the situation could not be reduced in a satisfactory manner. That is, FIG. 5 shows the temporal change of the output torque taken on the vertical axis for each throttle opening of the engine shown on the horizontal axis. If there is a gradual change from the start gear shift start point A1 to the gear shift end point A2, a gear shift shock will not occur, but especially when the throttle opening is 3/8 to 5/8, full open and kick down KD occur torque change, it can be seen that extreme <br/> rise is the Ri portion X has occurred. This rise is the <br/> Ri unit X is the discomfort to the occupant become shift shock.

[0009] The start-up is Ri portion X, the second bracket 8
It was found that they are caused by abutting engagement when the second protrusion 8a of the first bracket 7 is engaged with the anchor pin 3 or when the first protrusion 7a of the first bracket 7 is engaged with the piston stem 2. . That is, by the operation of the operation piston 4,
When the piston stem 2 and the anchor pin 3 are relatively close to each other, especially when the throttle opening is high and the load is high,
Since there is no restriction between the bracket 7 and the second bracket 8 and the centers of the projections that engage with each other, a deviation occurs and exerts a twisting or bending direction force on each other, thereby causing the band 5 to behave in the axial direction. I found out that I was not able to hold it down.

The fact that the behavior of the band 5 cannot be reliably suppressed in the axial direction not only causes a gear shift shock, but also causes the band 5 to not hit the entire circumference of the drum 6 uniformly, resulting in partial contact. The oil film formed between the band 5 and the drum 6 may be broken due to the contact with this portion.

Further, in the prior art, the second bracket 8 is provided with a convex portion 8b, and the convex portion 8b is projected toward the first bracket 7 along the outer peripheral friction surface 6a of the drum 6 to form the first convex portion 8b. The recess 7b provided in the bracket 7 is slidably fitted so that the movement of the first bracket 7 and the second bracket 8 in the twisting direction and the bending direction is restricted with respect to each other. The second brackets 7 and 8 are bent to form the concave portions 7b and the convex portions 8b, which makes the structure very complicated.

[0012] The present invention has been made in view of the above problems, Te it does not adversely first and second brackets with each other wrenched the way <br/> direction or bending force to simplify the structure Unishi, the band It is an object of the present invention to provide a band brake structure that surely suppresses the behavior in the axial direction and reduces shift shock.

[0013]

Band brake structure of the present invention In order to achieve the above object, according to the first, as a friction element of an automatic transmission, a band brake is fastened and released by actuating piston to the piston stem spaced closer 及 beauty the anchor pin A drum having an outer peripheral friction surface, a band having facings extending along the outer periphery of the drum, both ends of which face each other with a gap, and a first stem engaging with the piston stem.
A first bracket having a projection formed thereon and fixed to one end of the band and a second bracket formed with a second projection abuttingly engaged with the anchor pin and fixed to the other end of the band are provided. In a band brake provided, a guide portion having a through hole formed in the second protrusion is provided, and a guide convex portion which is inserted into the guide portion and positions the anchor pin is formed by reducing a diameter of a tip portion of the anchor pin. The second protrusion is formed on the shoulder formed on the anchor pin by forming the guide protrusion.
The projections brought into contact engagement, further bored through holes in the flange portion formed on said first bracket, and a structure in which Ru is inserted by extending the guide protrusion into the through hole.

[0014] Second, as a friction element of an automatic transmission, a band brake which is engaged and released by a pair of hydraulic pistons to each other spaced closer 及 beauty a pair of piston stem, and a drum having an outer peripheral friction surface, A band having both ends opposed to each other with a gap and having a facing extending along the outer circumference of the drum, and a first stem engaging at least one piston stem of the pair of piston stems.
A first bracket formed with a protrusion and fixed to one end of the band, and a second bracket abuttingly engaged with the other piston stem
A band brake having a protrusion and a second bracket fixed to the other end of the band.
A guide portion having a through hole is formed on the protrusion, and a guide convex portion that is inserted into the guide portion and positions the other piston stem is formed by reducing the tip end portion of the other piston stem. The second protrusion is brought into abutting engagement with the shoulder portion formed on the other piston stem by forming the convex portion, and a through hole is formed in the flange portion formed on the first bracket, and the through hole is formed. It has a structure in which Ru is inserted by extending the guide protrusion into the hole.

[0015]

According to this structure, the guide protrusion of the anchor pin is formed in the guide portion formed on the second protrusion of the second bracket or the through hole of the flange portion formed on the first bracket. Is inserted to position the anchor pin, and according to claim 2, the guide projection of one piston stem is inserted into the guide formed on the second projection of the other piston stem to position one piston pin. To do. As a result, the anchor pin or the shoulder portion formed on one of the piston stems abuts and engages with the second projection, thereby reliably guiding the behavior of the band in the axial direction.

[0016]

EXAMPLES Next, a first embodiment of the present invention will be describes the <br/> use to FIG.

[0017] Figure 1 is a sectional view showing a band brake structure according to a first embodiment of the present invention.

[0018] In Fig 1, reference numeral 11 is a band brake as a friction element of an automatic transmission, a band brake 11, a band drum 16 by actuating piston 14 to approach and separate the piston stem 12 to an anchor pin 13 15 is to be fastened and released. The working piston 14 receives the working hydraulic pressure from a hydraulic circuit (not shown) to move the piston stem 12 in the axial direction, and the working piston 14 and the anchor pin 13 serve as a case of an automatic transmission (not shown in detail). It is supported by Z. The drum 16 has an outer circumferential friction surface 16a,
The band 15 is wound around the outer periphery of the and extends. The band 15 includes a facing 17a that abuts on the drum 16 and a strap 17b joined to the outer peripheral surface of the facing 17a.
5b are opposed to each other with a gap. A first bracket 18 is fixed to one end 15a of the band 15, and the first bracket 18 is spot-welded or caulked to a strap 17b, for example. A first protrusion 18 a is formed on the first bracket 18, and the first protrusion 18 a abuts and engages with the piston stem 12.

A second bracket 19 is fixed to the other end portion 15b of the band 15, and the second bracket 1
Similarly to the first bracket 18, the reference numeral 9 is spot-welded or caulked to the strap 17b. A second protrusion 19a is formed on the second bracket 19.

The second protrusion 19 of the second bracket 19
transmural hole 20 is provided on a, in the second projection 19a
Formed by bending the tip of the first bracket 18 to face each other.
A through hole 27 is also formed in the formed flange portion 26 to provide an anchor.
The guide protrusion 28 formed by reducing the diameter of the pin 13 penetrates the guide protrusion 28.
It is inserted through the hole 27. It was although I, co the transmural hole 20 constitute a guide portion for positioning Ann <br/> Kapin 13
The through hole 27 is also a plan for positioning the anchor pin 13.
It will constitute the inside . Furthermore, the anchor pin 13
The formation of the guide protrusions 2 8, and shoulder 22 is formed, the shoulder portion 22 are engaged in contact and engaged with the second projection 19a.

When the actuating piston 14 is actuated,
The first protrusion 18a of the first bracket 18 engaged with the piston stem 12 approaches the second protrusion 19a of the second bracket 19 engaged with the shoulder 22 of the anchor pin 13 or is separated from the second protrusion 19a. Band 15 is drum 1
The frictional force between the outer peripheral friction surface 16a of the drum 6 and the outer peripheral friction surface 16a is increased or decreased.
6 is appropriately braked to perform the shifting operation of the automatic transmission.

At this time, the guide projection 28 of the anchor pin 13 is guided by the through hole 20, the shoulder 22 presses the second projection 19a, and the guide projection 28 further penetrates.
By inserting the first bracket 1 into the through hole 27,
8 and the second bracket 19 are constrained from moving in the twisting direction and the bending direction, and move relative to each other along the outer peripheral friction surface 16a of the drum 16.

[0023] The experimental results of the above operating conditions is described by the graph of Figure 3. That is, FIG. 3 is a diagram showing a conventional technique.
Similar to 5 , the horizontal axis represents the time change of the output torque taken on the vertical axis for each throttle opening of the engine. The output torque starts the gear shifting action when the band brake operates. After the gear shift start point B, the rising portion Y is generated at all throttle openings, but it is very small compared to the rising portion X of the prior art, and the output torque changes almost smoothly while suppressing a sudden change in output torque. As a result, shift shock can be reduced.

FIG. 2 shows a second embodiment of the present invention. Instead of the anchor pin 13 of the above embodiment, an operating piston is used.
To the second piston stem 30 operated by the ton 29
With the second piston stem 30
Reduced in diameter, the recess or the through-hole 20 digits set to the second protrusion 19a
Forms a guide convex portion 31 to be inserted. And guidance
The through hole 20 into which the convex portion 31 is inserted is the second piston stem.
A guide portion for positioning 30 will be configured. Further
The second piston stem 30 is formed by forming the guide protrusion 31.
The shoulder portion 32 is formed, and the shoulder portion 32 has the second protrusion 19a.
Since the other configurations are the same as those of the first embodiment, the same reference numerals are given and the description thereof will be omitted.

[0025]

In the band brake structure according to the above-mentioned structure, the anchor pin or the guide protrusion of the piston stem is inserted into the guide portion provided on the second protrusion to position the anchor pin or the piston stem to guide the guide. Since the shoulder portion of the anchor pin or the piston stem formed by forming the convex portion is brought into contact with and engaged with the second protrusion, the guide protrusion of the anchor pin or the piston stem is a guide portion when the piston is operating. Guided to the second shoulder
By pressing the protrusion, the movement of the first bracket and the second bracket in the twisting direction and the bending direction are restrained from each other, and the first bracket and the second bracket relatively move along the outer peripheral friction surface of the drum. As a result, the behavior of the band can be surely suppressed in the axial direction, a rapid change in the output torque can be suppressed during the shift of the automatic transmission, and the output torque can be changed almost gently to reduce the shift shock. Not only that, the band uniformly hits the entire circumference of the drum, so that the oil film breakage due to the partial contact unlike the conventional case does not occur.

Further, the guide portion of the present invention comprises a through hole or a recess provided in the second protrusion, and the guide protrusion is formed by reducing the diameter of the tip of the anchor pin or the piston stem, so that the structure is simple. It can be said that there is a cost advantage.

[Brief description of drawings]

FIG. 1 is a sectional view showing a band brake structure according to a first embodiment of the present invention.

FIG. 2 is a band brake structure according to a second embodiment of the present invention .
FIG .

FIG. 3 is a band brake structure according to the first embodiment shown in FIG .
In relation to the throttle opening when shifting gears
It is a graph which shows the time change of force torque .

FIG. 4 is a sectional view showing a conventional band brake structure .

5 is a view of the conventional band brake structure shown in FIG .
Of output torque in relation to throttle opening during gear shifting
It is a graph which shows time change .

[Explanation of symbols]

11 Band Brake 12 Piston Stem 13 Anchor Pin 14 Working Piston 15 Bands 15a, 15b Both Ends 16 Drum 16a Outer Friction Surface 17a Facing 18 First Bracket 18a First Protrusion 19 Second Bracket 19a Second Protrusion 20 , 27 Through Hole (guide portion) 2 8, 31 guide the projections 22, 3 2 shoulder

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16D 49/06 F16H 63/30

Claims (2)

(57) [Claims] 1. A band brake that is engaged and released by an operating piston that moves a piston stem toward and away from an anchor pin as a friction element of an automatic transmission, the drum having an outer peripheral friction surface and a gap between both ends. A band having facings spaced apart and extending along the outer periphery of the drum; a first bracket formed with a first protrusion that engages with the piston stem; and a first bracket fixed to one end of the band; A second protrusion is formed that abuts and engages with the pin,
In a band brake including a second bracket fixed to the other end of the band, a guide part having a through hole is provided in the second protrusion, and the guide pin is inserted into the guide part to position the anchor pin. A guide protrusion is formed by reducing the diameter of the tip of the anchor pin, and the second protrusion is brought into abutting engagement with a shoulder formed on the anchor pin due to the formation of the guide protrusion. A band brake structure, wherein a through hole is formed in a flange portion formed on the bracket, and the guide convex portion is extended and inserted into the through hole. 2. A band brake that is engaged and released by a pair of working pistons that move a pair of piston stems toward and away from each other as a friction element of an automatic transmission, the drum having an outer peripheral friction surface, and both ends thereof. A band having facings that are spaced apart and extend along the outer periphery of the drum, and a first protrusion that engages at least one piston stem of the pair of piston stems are formed, and one end of the band is formed. A band brake comprising: a first bracket fixed to the second bracket; and a second bracket fixed to the other end of the band, which is formed with a second protrusion that abuts and engages with the other piston stem. a guide portion through hole in the protrusion is formed is provided, the piston guide protrusions of the other which are inserted into the guide for positioning of the other piston stem The distal end portion of the stem is formed to have a reduced diameter, and the second protrusion is brought into abutting engagement with the shoulder portion formed on the other piston stem by the formation of the guide protrusion, and further, the first bracket is attached to the shoulder portion. A band brake structure, wherein a through hole is formed in the formed flange portion, and the guide convex portion is extended and inserted into the through hole.