JPH0718485B2 - Brake device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brake device used in an automatic transmission, and more particularly to a band brake.

BACKGROUND ART As is well known in the art, an automatic transmission for an automobile uses two or three pairs of planetary gear mechanisms and differential gear mechanisms, and has three elements (that is, a sun gear and a planetary gear mechanism in the case of a planetary gear mechanism). An appropriate gear shift is achieved by fixing any one of the carrier, the ring gear, and in the case of a differential gear mechanism, the link gear and a pair of side gears meshing with the link gear and the other two elements serving as an input member and an output member. Configured to obtain the ratio. An example thereof is schematically shown in FIG. 9, and the automatic transmission shown here is configured so as to obtain a shift speed of three forward speeds and one reverse speed by using two sets of planetary gear mechanisms 1 and 2. .

That is, the input shaft 3 connected to the engine (not shown) is integrated with the pump impeller 5 of the torque converter 4, and the turbine runner 7 that faces the pump impeller 5 with the stator 6 in between is connected to the automatic transmission. It is connected to the input shaft 8. The input shaft 8 includes a ring gear 9 in the rear planetary gear mechanism 2, a first clutch C1 and an intermediate shaft 10.
While being connected via the second clutch C2, the sun gear shaft 11 is connected via the second clutch C2. The sun gear shaft 11 is the one to which the sun gears 12 and 13 of each planetary gear mechanism 1 and 2 are attached, and the sun gear shaft 11 rotates in a fixed direction between the sun gear shaft 11 and a fixed part such as a transmission case. In order to prevent the above, the first one-way clutch Oc1 and the first brake B1 are arranged in series. In order to selectively prevent the rotation of the sun gear shaft 11, a second brake B2, which is a band brake, is arranged on the outer peripheral side of the clutch drum of the second clutch C2, which is integral with the sun gear shaft 11. Further, the ring gear 14 in the front planetary gear mechanism 1 and the carrier 15 in the rear planetary gear mechanism 2 are connected, and the output shaft 16 is connected to these. The carrier 17 of the front planetary gear mechanism 1 is connected to a second one-way clutch Oc2 that blocks rotation in a fixed direction and a third brake B3 that is a band brake that selectively blocks both forward and reverse rotations. Has been done.

The gears set by the above-mentioned automatic transmission are as shown in Table 1. In Table 1, a circle mark indicates an engaged state, a blank column indicates a disengaged state, and (○ ) Indicates that the engine is in an engaged state during braking.

As shown in Table 1, at the first forward speed, the first clutch C1 is engaged and input from the ring gear 9 of the rear planetary gear mechanism 2. In this case, the carrier 17 of the front planetary gear mechanism 1
In the reverse rotation direction (direction opposite to the rotation direction of the input shaft 8)
However, since the second one-way clutch Oc2 blocks rotation in that direction, the carrier 17 becomes a fixed element, and as a result, the gear ratio becomes a large value. However, in this state, for example, when trying to apply the engine brake by narrowing the accelerator opening on a downhill, the torque in the forward rotation direction acts on the carrier 17 because it is input from the output shaft 16 side, and the engine 17 is free to move. Since it can rotate, the ring gear 9 of the rear planetary gear mechanism 2 becomes a fixed element accordingly, and the engine braking does not work.
Therefore, the third brake B3 is engaged to make the carrier 17 a fixed element, and the ring gear 9 of the rear planetary gear mechanism 2 is engaged.
The engine brake is activated with the output element.

In the second forward speed, the first clutch C1 is engaged to input from the ring gear 9 of the rear planetary gear mechanism 2, and the first brake B1 is engaged to rotate the sun gear shaft 11 in the reverse rotation direction. Prevent. Therefore, the carrier 15 of the rear planetary gear mechanism 2 rotates in the forward rotation direction with the rotation of the pinion gear attached thereto, and the gear ratio becomes smaller than the first forward speed. In this case, when there is an input from the output shaft 16 side, a torque in the forward rotation direction acts on the sun gear shaft 11, and the sun gear shaft 11 rotates at an increased speed in the forward rotation direction. The ring gear 9 of the planetary gear mechanism 2 becomes a fixed element. Therefore, during engine braking, the second brake B2 is engaged to prevent the sun gear shaft 11 from rotating in both forward and reverse directions.

Further, in the case of the third forward speed, the first and second clutches
Engage C1 and C2. In this case, the rear planetary gear mechanism 2
The gear ratio becomes "1" because the whole is integrated.

In the case of reverse travel, the second clutch C2 is engaged to input from the sun gear shaft 11, and the third brake B3 is engaged to fix the carrier 17 of the front planetary gear mechanism 1. Therefore, the rotation of the sun gear 12 in the front planetary gear mechanism 1 is reversed and transmitted to the ring gear 14, so that the vehicle is decelerated in accordance with these gear ratios to be in the reverse traveling state.

By the way, in the above-mentioned automatic transmission, as is apparent from Table 1, the second brake B2 is engaged only during engine braking at the second forward speed, and this is provided with the first one-way clutch Oc1. Therefore, it is conceivable that the second brake B2 substitutes the first one-way clutch Oc1 and the first one-way clutch Oc1 and the first brake B1 are omitted. Figure 10 is an example of that,
The operation table of the automatic transmission shown here is as shown in Table 2.
There is no difference from the automatic transmission shown in FIG. 9 except that the second brake B2 is always engaged in the second forward speed.

Problems to be Solved by the Invention Generally, in an automatic transmission, it is a major technical problem to perform a shift as smoothly as possible. To solve such a problem, it is sufficient to increase the number of shift stages. However, for that purpose, the number of planetary gear mechanisms required increases, and other problems such as increase in weight and size of the automatic transmission occur. Therefore, as shown in FIGS. 9 and 10, the one-way clutch Oc
Using 1 and Oc2, the disengagement during gear shifting is automatically generated to prevent gear shift shock. However, since the one-way clutch only engages in one direction as its name suggests, the one-way clutch does not function when the torque is reversed as in the case of applying the engine brake, and therefore the one-way clutch does not function. In the configuration shown in, the second brake
It requires B2, which is one of the causes of the increase in weight and price.

On the other hand, in the configuration shown in FIG. 10, the first shown in FIG.
Although the one-way clutch Oc1 and the first brake B1 can be omitted to reduce the weight and the cost, the second
As shown in the table, the second brake B2 is released when shifting from the second forward speed to the third forward speed, which makes it difficult to set the timing, which complicates the configuration and adjustment of the hydraulic circuit. There is a problem such as becoming.

By the way, in an automatic transmission using a band brake such as the second brake B2 and the third brake B3 described above, a shock absorbing mechanism is incorporated in order to reduce a shock at the time of shifting due to engagement of the band brake. A brake is proposed by No. 62-124742. this is,
The support stem that holds one end of the brake band and the cylinder tube of the hydraulic servo cylinder that generates the fastening force are arranged so as to move back and forth in the tangential direction of the rotating body, and both of them are connected and integrated. An elastic body is interposed between the casing and a fixed portion such as a casing. Therefore, with such a configuration, when the hydraulic servo cylinder is operated and the brake band is tightened for braking, the support stem and the cylinder tube move integrally due to the rotational force of the rotating body, and Since the elastic body exerts a cushioning action, it is possible to avoid sudden braking and reduce shift shock. However, it is a buffer when the brake is engaged, and it is not possible to absorb the shock at the time of gear shift accompanied by the release of the brake.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brake device that also has a function of a one-way clutch in order to simplify the configuration and reduce the cost.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention exhausts a fluid pressure that causes a braking force by applying a reaction force from a rotating body accompanying braking, or applies a fluid pressure. A valve device for reducing the braking force is provided, and as a result, the braking is released depending on how the force acts. More specifically, the present invention relates to a brake device for an automatic transmission, which performs braking by tightening an outer periphery of a rotating body with a brake bunt, wherein one end of the brake band is connected to a piston rod of a fluid pressure cylinder and the brake is applied. The other end of the band is connected to an anchor rod that can move back and forth, and the cylinder tube of the fluid pressure cylinder is held so as to move back and forth, and the cylinder tube and the anchor rod move back and forth as a unit. Further, a valve device is provided for opening or closing the valve by receiving a force in a certain direction from the brake band to move the cylinder tube and for applying or exhausting fluid pressure in a direction to reduce the tightening force by the brake band. It is characterized by being present.

Operation In the brake device of the present invention, braking is performed by supplying pressurized fluid such as hydraulic pressure to the fluid pressure cylinder and tightening the brake band to the rotating body. In that case, the fluid pressure is changed depending on the rotating direction of the rotating body. The cylinder tube of the cylinder moves in a predetermined direction together with the anchor rod. If the direction is the direction to operate the valve device, the valve device is operated with the movement of the cylinder tube,
The fluid pressure, which pressurizes the brake band against the rotating body, is drained from the cylinder tube, so that braking of the rotating body is released. If the moving direction of the cylinder tube is opposite to the above case, the valve device does not operate, so that the tightening force of the rotating body is maintained and the braking is continuously performed. That is, depending on the rotating direction of the rotating body, the braking is automatically released in accordance with the force acting on the fluid pressure cylinder, and eventually it functions as a one-way clutch.

Embodiment Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example in which the present invention is applied to the above-mentioned second brake B2, and is a view seen from the input shaft 8 side.
The brake drum 20, which is a rotating body, is the second clutch described above.
This brake drum also doubles as the C2 clutch hub.
20 is connected to the sun gear shaft 11 and is housed inside the transmission case 21, and a brake band 22 slightly shorter than the outer peripheral length is arranged on the outer peripheral side thereof. Both ends of the brake band 22 are arranged so as to closely approach each other, and one end, that is, the first anchor portion 23, has a cap 24 having a spherical or arcuate receiving surface and a tip portion of the anchor rod 25. It is supported by pressing. The anchor rod 25 is housed in the hollow portion formed in the transmission case 21 in the tangential direction of the brake drum 20 so as to move back and forth in the axial direction thereof, that is, in the tangential direction of the brake drum 20, and its retracted end (left in FIG. 1). The moving end in the direction is defined by the adjusting bolt 26, and the outer peripheral side is sealed by the O-ring 27. A flange portion 28 protruding in the radial direction is formed at the tip end portion of the anchor rod 25, and the flange portion 28 is provided with a guide pin 30 fitted in a hole 29 formed in the transmission case 21. .

Similarly to the first anchor portion 23, a cap 32 having a spherical or arc-shaped receiving surface is attached to the other end portion of the brake band 22, that is, the second anchor portion 31, so that the transmission case 21 can be secured. Among them, a hydraulic servo cylinder provided at a position substantially facing the anchor rod 25.
By pressing the piston rod 34 of 33 against the cap 32, the second anchor portion 31 is held.

The hydraulic servo cylinder 33 has a configuration in which a cylinder tube 35 is housed inside a hollow portion 36 formed in the transmission case 21 so as to be movable back and forth.
Has a bottomed cylindrical shape integrally formed with an end plate penetrating the piston rod 34, and a piston 37 having a rear end portion of the piston rod 34 mounted therein is housed inside the cylinder tube 35 so as to be movable back and forth, and Piston in front of piston 37
A return spring 38 for pushing back 37 to the right in FIG. 1 is arranged, and an annular stopper 39 is fixed to the rear end of the cylinder tube 35. This stopper
On the inner peripheral side of 39, a valve sleeve 40 projecting to the front and rear sides in the axial direction is movably arranged back and forth, and on the inner peripheral surface of the valve sleeve 40, a cylindrical portion on the rear end side of the piston 37 is formed. 37a is in sliding contact while maintaining liquid tightness.

A small gap is formed between the outer peripheral surface of the valve sleeve 40 and the inner peripheral surface of the stopper 39 to form an oil passage 41, as shown in an enlarged view in FIG. A portion of the stopper 39 that projects forward from the stopper 39 extends outward in the radial direction, and a surface of the extended portion 42 that faces the front surface of the stopper 39 is intimately contacted with the stopper 39 so that the inside of the stopper 39 The oil passage 41 with the peripheral surface is closed. Therefore here valve sleeve 40
Is a valve body, and the stopper 39 has a valve seat 43 on the front surface thereof.

A rear end portion (right end portion in FIG. 1) of the hollow portion 36 accommodating the hydraulic servo cylinder 33 is sealed by an end plate 45, and therefore, inside the hollow portion 36,
There are three oil chambers, a first oil chamber 46 on the front side of the piston 37, a second oil chamber 47 between the piston 37 and the stopper 39, and a third oil chamber 48 between the stopper 39 and the end plate 45. Has been formed. The structure for supplying and discharging hydraulic pressure to and from these oil chambers 46, 47 and 48 will be described. As shown in FIGS. 1 and 3, the first oil chamber 46 is provided on the peripheral wall of the cylinder tube 35.
An oil hole 49 opening to the second oil chamber 47 and an oil hole 50 opening to the second oil chamber 47 are formed. On the other hand, a long groove 51 is formed within the stroke range of each oil hole 49, 50 on the inner surface of the cylinder tube 35. , 52 are formed respectively, and oil passages 53, 54 penetrating the transmission case 21 communicate with these oil holes 51, 52, respectively. Further, an oil passage 55 communicating with the third oil chamber 48 is formed so as to penetrate the transmission case 21. The oil passage 53 is communicated with a predetermined switching valve (not shown), the oil passage 54 is communicated with another switching valve (not shown) via an accumulator 56 and an orifice 57, and the oil passage 55 is further connected. Further, it is connected to another switching valve (not shown).

The cylinder tube 35 of the hydraulic servo cylinder 33 configured as described above and the anchor rod 25 are connected to each other via the connecting rod 58 and the flange portion 28 so as to integrally move back and forth.

By the way, the above-mentioned brake device performs the same action as a one-way clutch as will be described later, and in order to ensure the action, the piston rod when the hydraulic pressure is supplied to the second oil chamber 47 is described. The oil pressure by 34 and the pressing force by the anchor rod 25 are configured to be substantially equal. That is, in order to perform braking and braking release according to the rotation direction at the optimum timing, when the direction of the rotation moment of the brake drum 20 is the deenergizing direction (the direction of arrow B in FIG. 1), the cylinder tube 35 moves backward ( The valve sleeve 40 is opened by moving it to the right in FIG. 1), and the cylinder tube 35 moves forward when the rotational moment of the brake drum 20 is in the energy direction (arrow A in FIG. 1). (Move to the left in Fig. 1) is required. When the hydraulic pressure is supplied to the second oil chamber 47, the pressing force by the piston rod 34 (the pressing force toward the left in FIG. 1) is Fa, and the pressing force by the anchor rod 25 toward the right in FIG. Pressure (connecting rod 58
Tensile force) Fb, end plate 45 is valve sleeve 40
Fa ′ is the force that presses the adjustment bolt 26
^Let Fb 'be the force pushing in the right direction in Fig. 1. From the above conditions, e ^{μ β} (Fa + Fa') = Fb + Fb 'where e is the base of the natural logarithm and μ is the friction between the brake band and the brake drum. The coefficient β is the winding angle of the brake band, Fa ′ = 0 and Fb ′> 0, so e ^μβ · Fa> Fb Fb / Fa <e ^μβ (1). Further, from the above conditions, Fa> e ^μβ · Fb 1 / e ^μβ <Fb / Fa (2), and therefore 1 / e ^μβ <Fb <e ^μβ holds from equations (1) and (2). Will be required. Then, considering the sliding resistance of each fitting portion, Fa≈Fb is optimal.

Therefore, in the above brake device, the pressure receiving surface mark S1 (= π (D2-D3) of the piston 37 when the hydraulic pressure is supplied to the second oil chamber 47.
^2/4) is configured so that the pressure receiving area S2 of the stopper 39 is equal. Here, D2 is the outer diameter of the piston 37, and D3 is the outer diameter of the cylindrical portion 37a of the piston 37, as shown in FIG. The outer diameter of the cylinder tube 35 is indicated by D1.

Next, the operation of the brake device configured as described above will be described.

FIG. 1 shows a state in which no braking is applied, and the first to third oil chambers 46, 47, 48 are exhausted, so that the anchor rod 25 is retracted to the leftward retracted end in the figure. At the same time, the piston 37 of the hydraulic servo cylinder 33 is pushed back by the return spring 38 to the right in the figure,
As a result, the brake band 22 opens and the brake drum 20
Can rotate freely. This state is
When it is used for the second brake B2 of the automatic transmission configured as shown in FIG. 10, it is in a state of being set to each of the first forward speed, the third forward speed, and the reverse speed.

On the other hand, FIG. 4 shows the second forward speed state in which the brake drum 20 is being braked. In this state, oil passages 54, 55 are provided in the second oil chamber 47 and the third oil chamber 48.
The hydraulic pressure is supplied via each. In this case, since the valve sleeve 40 has a wide pressure receiving area on the side of the second oil chamber 47, the valve sleeve 40 is pressed rightward in the drawing, and the extending portion 42 thereof is brought into close contact with the valve seat 43 so that the oil passage 41 is closed. Seal tightly. Further, since the piston 37 also advances in the state where the cylinder tube 35 has advanced to the left in the figure, the second anchor portion 31 becomes the first anchor portion.
23, and as a result, the brake band 22 tightens the brake drum 20 to brake the brake drum 20 and prevent its rotation. In this state, torque acts on the brake drum 20 in the direction of arrow A.

Here, if the hydraulic pressure in the third oil chamber 48 is set sufficiently high,
Even if the brake drum 20 rotates in the direction of the arrow indicated by the arrow B in the figure, the cylinder tube 35 does not retreat to the right in the figure, so that the braking of the brake drum 20 is continued and therefore the engine braking can be activated. it can.

When shifting from the second forward speed to the third forward speed, in the automatic transmission shown in FIG. 10, the second clutch C2 is engaged and the second brake B2 is released, but in that case, the shift to the third speed is performed. First, an oil passage communicating with the third oil chamber 48 based on the instruction signal.
55 is switched to a drain and is made to communicate, and hydraulic pressure is slowly supplied to the second clutch C2 shown in FIG. 10 via an accumulator or the like. At the same time, the pressure is discharged from the oil passage 54 communicating with the second oil chamber 47. Since the accumulator 56 and the orifice 57 communicate with the oil passage 54, the pressure drop in the second oil chamber 47 is slow. Therefore, the brake band 22 tightens the brake drum 20 for a while. Continue the braking. When the hydraulic pressure in the second clutch C2 gradually rises and the transmission torque becomes a clutch torque capable of sufficiently transmitting the engine torque, the torque in the direction of arrow B acts on the brake drum 20. At this time, while the tightening by the brake band 22 is performed, the cylinder tube 35 receives the force from the brake drum 20 because the pressure is exhausted from the third oil chamber 48, and the anchor rod 25 is moved to the right in the figure. Along with that, they move without receiving any resistance. FIG. 5 shows the state after the movement, and in this state, the rear end portion (the right end portion in the drawing) of the valve sleeve 40 contacts the end plate 45, so that the valve sleeve 40 moves in the left direction with respect to the stopper 39. It is moved relatively, and its extended portion 42 separates from the valve seat 43 to open the oil passage 41. As a result, the hydraulic pressure of the second oil chamber 47 is rapidly discharged through the oil passage 41, the third oil chamber 48, and the oil passage 55, so that the piston
37 is pushed by the return spring 38 and retracts to the right in the figure, and the tightening by the brake band 22 is released accordingly, so that the brake drum 20 is released and rotates freely. That is, in the above braking device, the braking of the brake drum 20 is released automatically by its rotation direction and torque. In other words, since it acts as a one-way clutch, the timing of the exhaust pressure for releasing the braking is particularly high. It is possible to perform a smooth gear shift without accurate control.

By the way, in the above-described embodiment, since it is necessary to continue tightening the brake drum 20 by the brake band 22 until the valve device 44 acts and the pressure is exhausted from the second oil chamber 47, the accumulator 56 and the orifice are provided in the oil passage 54. 57 was connected and provided. Therefore, the brake release timing changes depending on the characteristics of the accumulator 56 and the orifice 57. In other words, the accumulator 56 and the orifice 57 need to be adjusted. However, if the configuration shown in FIG. The influence of the accumulator 56 on the timing of brake release can be avoided.

That is, FIG. 6 is a cross-sectional view showing a second embodiment of the present invention, in which the brake device shown here is an improvement of the device of the above-mentioned embodiment to supply hydraulic pressure to the second oil chamber 47. At the end of the oil passage 54 on the cylinder tube 35 side, the long groove 52
Not directly through the inner surface of the hollow portion 36, and its opening area is made substantially equal to the oil hole 50 formed in the cylinder tube 35, and the opening position of the cylinder tube 35 is advanced to the left in the figure. The position where the oil hole 50 communicates with the oil hole 50 is established.

Therefore, with the configuration shown in FIG. 6, the brake band
When the brake drum 20 receives the torque in the direction of arrow B with 22 being tightened, and the cylinder tube 35 retracts to the right in the figure accordingly, the oil hole 50 and the oil passage 54 opening to the second oil chamber 47 are Since the position of is shifted and the second oil chamber 47 is closed,
The oil pressure in the second oil chamber 47 is maintained, and then the valve sleeve
The valve 40 is opened to discharge the pressure from the second oil chamber 47.
Therefore, external factors such as the accumulator do not influence the timing of releasing the brake, and the work such as adjusting the characteristics of the accumulator becomes unnecessary.

In the configuration described above, neither of the anchor portions 23 and 31 of the brake band 22 is fixed, and it is possible to move within a certain range together with the anchor rod 25 and the cylinder tube 35. Therefore, for example, the release shown in FIG. In this state, the anchor rod 25 and the cylinder tube 35 may move due to vibrations and the like caused by traveling, and rattling noise may be generated. In order to eliminate such an inconvenience, it is preferable to supply the hydraulic pressure to the third oil chamber 48 even in the released state. By doing so, the cylinder tube 35 moves forward in the left direction in the drawing. Since the anchor rod 25 is pressed against the retracted end via the connecting rod 58, the anchor rod 25 and the cylinder tube 35 are substantially fixed, and the rattling noise is prevented. In that case, the third oil chamber
In order to prevent the piston 37 from advancing due to the hydraulic pressure supplied to 48, the hydraulic pressure is similarly supplied to the first oil chamber 46.

Each of the embodiments described above is an example in which the automatic transmission that performs three forward gears and one reverse gear is used to set the second forward speed by stopping the rotation in the energy direction. As mentioned above, the above-mentioned brake device is used in the third oil chamber.
By increasing the oil pressure of 48, the one-way characteristic is lost, but the rotation in the dinage direction can also be stopped. Therefore, the four forward gears and one reverse gear shown in FIG.
It can also be used in an automatic transmission that shifts gears. That is, the automatic transmission shown in FIG. 8 is mainly composed of two sets of planetary gear mechanisms 60, 61, the input shaft 63 connected to the torque converter 62, and the first planetary gear mechanism 60 on the left side in FIG.
In the second planetary gear mechanism 61, and a second clutch C2 in the second planetary gear mechanism 61, and a second clutch C2.
The third clutch C3 is provided between the sun gear 66 and the sun gear 66. Further, the carrier 67 in the first planetary gear mechanism 60
Is connected to an output member 68 such as a counter gear, and is also connected to a ring gear 69 of the second planetary gear mechanism 61, and a ring gear 70 of the first planetary gear mechanism 60 is connected to a carrier 65 of the second planetary gear mechanism 61. It is connected. First planetary gear mechanism
A first one-way clutch F1 for preventing reverse rotation of the ring gear 70 in 60 and the carrier 65 of the second planetary gear mechanism 61 integral therewith (rotation in the direction opposite to the rotation direction of the input shaft 63).
Is provided between the case 71 and the case 71, and a first brake B1 which is a multi-plate clutch is provided in parallel with the first one-way clutch F1. Further, a second brake B2, which is a band brake that blocks the rotation of the sun gear 66 of the second planetary gear mechanism 61, is provided between the case 71 and the sun gear 66 and the input shaft 63.
Between the third clutch C3 and the fourth clutch
A clutch C4 and a second one-way clutch F2 that is in series with the fourth clutch C4 and blocks relative rotation in the forward rotation direction with respect to the input shaft 63 are provided.

The operation table of the above automatic transmission is shown in Table 3. It should be noted that in Table 3, the mark ◯ indicates the engaged state,
A blank column indicates a non-engaged state, and a mark (◯) indicates an engaged state during engine braking.

If the brake device is used as the second brake B2 in the above automatic transmission, the rotation in the energy direction is stopped at the second forward speed, and the rotation in the deenergization direction is stopped at the fourth speed. That is, when shifting from the first speed to the second speed, or when shifting from the third speed to the second speed, if the hydraulic pressure is supplied to the second oil chamber 47 as described above, the piston rod 34 and the anchor rod 25 are separated from each other. Press the anchor portions 23, 31 in a direction in which they approach each other, the brake band 22 tightens the brake drum 20, and in that case, the valve mechanism 44 does not open in the cylinder tube 35.
Is moved by the rotation of the brake drum 20, and as a result,
The brake drum 20 is braked and the second forward speed is set. If you want to shift up from that state to the 3rd speed,
By engaging the second clutch C2, the brake drum 20
When the cylinder starts to rotate in the deenergizing direction, the cylinder tube 35 moves backward as described above, and as a result, the valve sleeve 40 comes into contact with the end plate 45 to open the valve, so that the pressure is discharged from the second oil chamber 47. , Braking of the brake drum 20 is released. That is, the braking can be released without switching the hydraulic pressure supply / discharge state, and thus the one-way characteristic is exhibited.

When setting the fourth forward speed, the second oil chamber 47 and the third oil chamber 47
Hydraulic pressure is supplied to both oil chambers 48. As a result, the entire hydraulic servo cylinder 33 moves forward against the load caused by the brake drum 20 rotating in the deenergizing direction, and the anchor rod 25 abuts the adjustment bolt 26 and receives a pressing force, The piston rod 34 presses the second anchor portion 31 to tighten the brake band 22, and accordingly, the rotation of the brake drum 20 in the deenergizing direction is stopped and the fourth forward movement is performed.
The speed is set.

The pressure receiving area of the hydraulic servo cylinder 33 by the hydraulic pressure supplied to the second oil chamber 47 and the third oil chamber 48 is set as follows in order to ensure the braking in the deenergizing direction. That is, assuming that the force by which the piston rod 34 is pressed by the hydraulic pressure supplied to the third oil chamber 48 is Fc and the pressing force by the anchor rod 25 is Fd, in order to stop the rotation in the deenergizing direction, e ^μβ (Fa + Fc) = Fb + Fd (3) is required to be satisfied, and since Fa ≈ Fb as described above, Fb + Fd ≤ 0 and Fa + Fc> 0 are required for the equation (3) to be stably satisfied. Therefore, when used as the second brake B2 in the automatic transmission shown in FIG.
When the hydraulic pressure is supplied to 47 and the third oil chamber 48, the pressure receiving area S4 (−π in the third oil chamber 48 for the hydraulic servo cylinder 33)
(D1-D3) ^2/4) (than Figure 7 refer) is the second pressing force of the anchor rod 25 of the case of supplying the oil pressure to the oil chamber 47 (pressure receiving area S2 to generate a tensile force) of the connecting rod 58 It is set to be large.

By the way, when the brake drum 20 is braked at the second speed and when the brake drum 20 is braked at the fourth speed, the supplied hydraulic pressure is the same, and at the same time, the load torque, the transmission torque capacity, and the pressure receiving area are Each will be different. Therefore, in order to reduce the shift shock at any gear, the hydraulic pressure is supplied to the second oil chamber 47 to set the second speed, and the hydraulic pressure is supplied to the second oil chamber 47 and the third oil chamber 48. When the fourth speed is set by setting the fourth speed, the pressure receiving area of the piston 37 for setting the respective shift speeds, that is, the pressure receiving area S1 (= π (D2 -D3) ^2/4) (see FIG. 7), the second
Receiving area at the time of supplying the oil pressure to the oil chamber 47 and the third oil chamber 48 (S1 + S3) (= π (D2-D3) 2/4 + π · D3 2/4) ( see FIG. 7), but, each shift speed The area is set so as to produce a transmission torque commensurate with the load torque at.

That eighth gear ratio of the first planetary gear mechanism 60 shown in FIG. (Ratio between the number of teeth of the sun gear of the ring gear) [rho _r, second
Assuming that the gear ratio of the planetary gear mechanism 61 is ρ _f and the turbine torque is T _t , the load torque T ₂ at the second speed is T ₂ = ρ _f · T _t / (1 + ρ _f ) ρ _r On the other hand, the load torque T ₄ at the fourth speed is T ₄ = ρ _f · T _t / (1 + ρ _f ). That is, the brake load torque T ₂ at the second speed is 1 / ρ _r times the brake load torque T ₄ at the fourth speed,
Further, during the upshift to the 2nd speed and the upshift to the 4th speed, an inertia torque corresponding to the engine speed change rate (decrease rate) is also added to the load torque, and each tooth number ratio ρ _f · Since ρ _r is generally about 0.3 to 0.7, the load torque T ₂ at the second speed is larger than the load torque T ₄ at the fourth speed. Therefore, if the brake transmission torque during shifting is maintained at a torque that is a little higher than the steady-state torque of the next shift stage and the shifting is completed, a sudden decrease in engine speed does not occur, and the output shaft torque due to inertia torque does not increase. Since it is possible to prevent a sudden change and to improve the shift shock, the brake transmission torque at the time of upshifting to the second speed is set to the first value, provided that the hydraulic pressure supplied to the hydraulic servo piston 33 is constant. The structure may be set to be about 1 / ρ _r times the brake transmission torque when upshifting to the 4th speed.

On the other hand, the brake drum 20 when upshifting to second gear
Since the rotation direction of is the energy direction, the piston rod
The transmission torque capacity T ₂ ′ of the brake band 22 with respect to the hydraulic pressure that generates the pressing force by 34 is T ₂ ′ = (Sp−F) R (e ^μβ −1) where S is the pressure receiving area p is the hydraulic pressure F is the return spring 38 The elastic force R becomes the radius of the brake drum 20. On the other hand, when the fourth gear is upshifted, the brake drum 20 rotates in the deenergizing direction, so that the transmission torque capacity T ₄ ′ of the brake band 22 is T ₄ ′ = (Sp−F) R (e ^μβ − 1) / e ^μβ . Therefore, under the conditions of the same pressure receiving area and the same hydraulic pressure, the brake transmission torque capacity T ₂ ′ at the time of upshifting to the second speed
Is the brake transmission torque capacity during upshift to 4th speed
It becomes e ^μβ times T ₄ ′.

That is, in the above braking device, the pressure receiving area where the hydraulic pressure is supplied to the second oil chamber 47 when setting the second speed becomes S1, and when setting the fourth speed, the second oil chamber 47 and the third oil chamber The pressure receiving area where the hydraulic pressure is supplied to the chamber 48 becomes (S1 + S3), but these areas are different from the same hydraulic pressure in consideration of the difference in the load torque and the difference in the transmission torque capacity at each gear described above. The transmission torque is set so as to correspond to the load torque at each gear. As a result, the shift shock becomes good both when shifting to the second speed and when shifting to the fourth speed. In other words, since it is not necessary to control the back pressure of the accumulator according to the shift speed, the configuration can be simplified and the cost can be reduced accordingly.

As described above, in the basic structure of the present invention, in the brake device for an automatic transmission that tightens the outer periphery of the rotating body with the brake band to perform braking, one end of the brake band is connected to the piston rod of the fluid pressure cylinder. In addition, the other end of the brake band is connected to an anchor rod that can move back and forth, and the cylinder tube of the fluid pressure cylinder is held so as to move back and forth. A valve device that is connected to each other so that the cylinder tube moves by receiving a force in a certain direction from the brake band to open the valve to apply or exhaust fluid pressure in a direction to reduce the tightening force by the brake band. It is characterized in that it is provided, but if the more specific modes are listed, It is as of.

The valve device is configured to have a valve body having one end protruding from the cylinder tube to one side in the moving direction, and the fixing portion for contacting the protruding end of the valve body with the moving direction of the cylinder tube. It may be configured such that it is provided on one side apart from the cylinder tube.

The valve device may be arranged between the oil chamber and an oil chamber in a fluid pressure cylinder adjacent to the oil chamber. In this case, the valve body is provided between these oil chambers, and one end of the valve body is projected toward the end plate side, and one end portion of the valve body comes into contact with the end plate as the cylinder tube moves toward the end plate side. It can be configured to open the valve.

If the valve device is configured as described above, the valve element itself also has a function of transmitting an external force for opening the valve to the valve element, so that the timing of opening the valve is accurate, and the total length is shortened and the component members are shortened. Compactness can be achieved by reducing the number. That is, FIG. 11 is a schematic view of a conventional poppet valve 80, in which the poppet 81 is pressed against the opening of the first oil passage 83 by the spring 82, the hydraulic pressure supplied increases, and the poppet 81 springs.
The opening of the first oil passage 83 is opened by retracting against the elastic force of 82, and as a result, the first oil passage 83 and the second oil passage 84 are communicated with each other, and the end portion of the spring 82 is supported. Movable plate
By moving 85 along with the movement of the external member such as the cylinder tube 35, the timing of opening the valve by the poppet 81 is appropriately adjusted. In the poppet valve 80 having such a configuration, a space for accommodating the poppet 81, the spring 82, and the like is required, and since the movement of the external member is not directly transmitted to the poppet 81, the timing of opening the valve does not change as expected. It may not be On the other hand, in the valve device 44 described above, since the movement of the cylinder tube 35 is directly transmitted to the valve sleeve 40,
Accurate valve opening timing.

Further, FIG. 12 is a schematic view of a conventional general spool valve 86, in which the movement of an external member such as the cylinder tube 35 is transmitted to the spool 87 to connect the first oil passage 88 and the second oil passage 89. Also, it is designed to be non-communication. With such a configuration, the movement of the external member can be directly transmitted to the spool 87, but for that purpose, some kind of connecting member is required, and in addition to this, a space portion for housing the spool 87 is required. The overall size increases. On the other hand, in the valve device 44 described above, no special accommodation space is required, and
Since the valve sleeve 40 directly connects the second oil chamber 47 and the third oil chamber 48, the oil passage as described above is unnecessary, and the size can be reduced in this respect as well.

The fluid pressure cylinder is housed in a hollow portion formed in the transmission case so as to be movable back and forth, and the open end of the hollow portion is sealed by an end plate, so that hydraulic pressure can be supplied and discharged between the end plate and the fluid pressure cylinder. It is possible to form a different oil chamber, supply hydraulic pressure to the oil chamber, and press and fix the cylinder tube toward the anchor rod side. According to this structure, it is possible to prevent unnecessary movement of the cylinder tube and prevent rattling noise.

An oil hole that opens to the oil chamber in the fluid pressure cylinder is formed in the cylinder tube, and an oil passage that opens to the oil hole is formed in the transmission case to provide an oil chamber that supplies the hydraulic pressure for tightening the brake band. The opening oil hole may be configured to be displaced from the oil passage and closed as the cylinder tube moves. According to this structure, the tightened state of the brake band can be maintained until the valve device operates without requiring any special device or adjustment.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the brake device of the present invention, the valve device operates due to the movement of the cylinder tube by receiving the force from the rotating body, and thereby the fluid pressure that tightens the brake band. The brake can be released automatically according to the direction of the torque of the rotating body because it releases the pressure. Therefore, it works like a one-way clutch. Can be omitted to smoothly shift the gears. As a result, the structure of the automatic transmission can be simplified, the weight can be reduced, and the cost can be reduced.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a partial sectional view showing the valve device thereof, FIG. 3 is a partial sectional view showing an oil passage structure, and FIG. 4 is a sectional view in an engaged state. 5 and 5 are sectional views in a released state due to the operation of the valve device, FIG. 6 is a sectional view showing another embodiment of the present invention, and FIG. 7 is a view showing dimensions of each part in the hydraulic servo cylinder. Partial view, FIG. 8 is a skeleton diagram showing a gear train of an automatic transmission capable of setting four forward gears and one reverse gear, FIG. 9 is a configuration diagram showing an example of an automatic transmission in skeletons, and FIG. 10 is an automatic transmission. FIG. 11 is a schematic diagram showing another example of the above with a skeleton, FIG. 11 is a schematic diagram of a conventional poppet valve, and FIG. 12 is a schematic diagram of a conventional general spool valve. 20 …… Brake drum, 22 …… Brake band, 23 ……
1st anchor part, 25 ...... anchor rod, 31 ...... second anchor part, 33 ...... fluid pressure cylinder, 34 ...... piston rod, 35 ...... cylinder tube, 37 ...... piston, 40 ......
Valve sleeve, 41 ... Oil passage, 43 ... Valve seat, 44 ... Valve device, 46 ... First oil chamber, 47 ... Second oil chamber, 48 ... Third oil chamber, 58 ... Connecting rod .

Claims (1)

[Claims] 1. A brake device for an automatic transmission, wherein an outer circumference of a rotating body is tightened by a brake bunt for braking, wherein one end of the brake band is connected to a piston rod of a fluid pressure cylinder and the other end of the brake band is connected. A portion is connected to an anchor rod that can move back and forth, and is held so as to be able to move back and forth from a cylinder tube of the fluid pressure cylinder, and the cylinder tube and the anchor rod are connected so as to move back and forth integrally, and A valve device is provided for opening or closing the valve when the cylinder tube moves in response to a force in a certain direction from the brake band and for applying or exhausting fluid pressure in a direction to reduce the tightening force by the brake band. Brake device for automatic transmission.