JPH0582510B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a brake device that prevents rotation of a planetary gear element such as a sun gear in a planetary gear mechanism in order to set a predetermined gear stage in an automatic transmission for a vehicle, and particularly relates to a band brake device. be. BACKGROUND TECHNOLOGY As is well known, automatic transmissions for automobiles use two or three sets of planetary gear mechanisms or differential gear mechanisms. and the carrier and ring gear; in the case of a differential gear mechanism, the ring gear and a pair of side gears that mesh with it)
By fixing one of the elements and using the other two elements as an input member and an output member, an appropriate speed ratio can be obtained. An example of this is shown in the third
The gear transmission shown here is schematically shown in the figure, and is configured to use two sets of planetary gear mechanisms 1 and 2 to obtain four forward speeds and one reverse speed, including overdrive. be. That is, the first clutch C1 is connected between the input shaft 4 connected to the torque converter 3 and the sun gear 5 of the first planetary gear mechanism 1 on the left side in FIG.
is provided, and a second clutch C2 is provided between the second planetary gear mechanism 2 and the carrier 6,
Furthermore, a third clutch C3 is provided between the second planetary gear mechanism 2 and the sun gear 7. Further, the carrier 8 in the first planetary gear mechanism 1 is connected to an output member 9 such as a counter gear, while the carrier 8 in the first planetary gear mechanism 1 is connected to an output member 9 such as a counter gear.
It is connected to the ring gear 10 of the planetary gear mechanism 2, and the ring gear 11 of the first planetary gear mechanism 1 is connected to the carrier 6 of the second planetary gear mechanism 2. Ring gear 11 in first planetary gear mechanism 1
A first one-way clutch F1 is provided between the case 12 and the carrier 6 of the second planetary gear mechanism 2, which is integrated therewith, to prevent reverse rotation (rotation in the opposite direction to the rotation direction of the input shaft 4). A first brake B1, which is a multi-disc brake, is provided in parallel with the first one-way clutch F1. Furthermore, a second brake B2, which is a band brake that prevents rotation of the sun gear 7 of the second planetary gear mechanism 2, is provided between the case 12 and the third clutch B2, which is a band brake that prevents rotation of the sun gear 7 of the second planetary gear mechanism 2. A fourth clutch C4 is provided in parallel with C3, and a second one-way clutch F2 is provided in series with the fourth clutch C4 to prevent the sun gear 7 from rotating relative to the input shaft 4 in the positive direction. The gears set in the automatic transmission equipped with the gear transmission described above are as shown in Table 1.
A mark indicates an engaged state, a blank indicates a non-engaged state, and an (◯) indicates an engaged state during engine braking.

[Table] As shown in Table 1, if the first clutch C1 is engaged and input is applied to the sun gear 5 of the first planetary gear mechanism 1, the accompanying reverse rotation of the ring gear 11 will be caused by the first clutch C1 being engaged.
As a result, the first planetary gear mechanism 1 performs a deceleration action and becomes the first forward speed. In this case, engine braking can be applied by engaging the first brake B1 and fixing the ring gear 11 in either the forward or reverse direction. In the state of the first forward speed, the sun gear 7 of the second planetary gear mechanism 2 rotates in the reverse direction, but if this is fixed by the second brake B2, the second forward speed is established. In addition, when the second clutch C2 is engaged and the second brake B2 is released, the input is from two elements in each planetary gear mechanism 1, 2, so the whole rotates as one, and therefore the speed of increase/deceleration is increased. In other words, the gear ratio is "1", which is the third forward speed. In this state, the fourth clutch C4 is engaged. When the first clutch C1 is released in this third forward speed state, since the fourth clutch C4 is engaged, the second one-way clutch F2 is engaged, and the sun gear 7 is substantially shifted to the input shaft 4. forward third connected to
speed is maintained. Therefore, if the second brake B2 is applied from this state, the second one-way clutch F2 is disengaged and the sun gear 7 is prevented from rotating in the forward direction, and as a result, the gear ratio is greater than "1". It becomes 4th gear (overdrive stage). When going backwards, the third clutch C3 is engaged to receive input from the sun gear 7 in the second planetary gear mechanism 2, and the first brake B1 prevents the forward rotation of the carrier 6, so that the ring gear 10, that is, the output member 9
rotates in the opposite direction and becomes reverse gear. By the way, an important issue in automatic transmissions is to perform smooth gear shifts without so-called gear shifting shocks, and for this purpose, one-way clutches have traditionally been incorporated into gear transmissions, and timing valves and accumulators have been frequently used in hydraulic control circuits. The aim is to optimize the timing of clutch and brake engagement. However, frequent use of one-way clutches, timing valves, etc. increases the number of components of the automatic transmission, leading to an increase in weight and a rise in price. Therefore, the applicant has already proposed a brake device that can effectively eliminate the shift shock without complicating the overall mechanism.
No. 62-101477). In this brake device, a servo cylinder that operates a push rod for tightening the brake band is movable back and forth, and a valve mechanism is built into the servo cylinder, so that the rotating body (that is, the brake drum) moves in the opposite direction to the tightening direction by the push rod. When it rotates, the servo cylinder moves and the valve mechanism opens to exhaust the servo oil pressure and release the brake. Therefore, with this brake device,
Since the brake can be released by rotating the brake drum, a shift shock can be avoided without using a complicated mechanism such as a timing valve. Problems to be Solved by the Invention However, the above-mentioned brake device already proposed by the present applicant may be modified, for example, by the second brake B2 shown in FIG.
When used as a push rod, this second brake B2 brakes the reverse rotation direction in the second forward speed, and brakes the forward rotation direction in the fourth forward speed, so the hydraulic pressure for pressing the push rod and Although it is necessary to appropriately control the hydraulic pressure that presses the servo cylinder according to the braking direction, a suitable hydraulic control device for performing such hydraulic control has not been developed so far. This invention was made against the background of the above-mentioned circumstances, and has a one-way characteristic and can perform braking in either forward or reverse directions depending on the set gear stage, thereby reducing shift shock. It is an object of the present invention to provide a braking device for an automatic transmission that can be easily operated. Means for Solving the Problems In order to achieve the above object, the present invention arranges a brake band on the outer peripheral side of a rotating body arranged in a case, and connects both ends of the brake band to an anchor rod and a push rod. In a brake device that brakes a rotating body by tightening a brake band by bringing the brake bands close to each other, a fluid pressure cylinder that moves back and forth in a tangential direction of the rotating body is disposed in the case at a position opposite to the anchor rod, and the hydraulic cylinder The push rod is attached to the piston of the pressure cylinder, and the hydraulic cylinder and the anchor rod are connected so as to move together, and a first oil chamber is provided on the side of the fluid pressure cylinder opposite to the push rod across the piston. At the same time, a second oil chamber is formed on the opposite side of the push rod with the fluid pressure cylinder in between, and the oil chambers are opened to communicate with each other when the fluid pressure cylinder is retreated toward the second oil chamber. A line hydraulic oil passage for supplying line oil pressure for setting a predetermined gear is connected to the first oil chamber, and the second oil chamber is connected to the second oil chamber. It is characterized in that a switching valve is connected to switch the line hydraulic oil path and the exhaust pressure oil path into communication. Function In the brake device of the present invention, no matter whether hydraulic pressure is supplied to either the first oil chamber or the second oil chamber, a pressing force is generated that pushes the push rod toward the anchor rod, which acts to tighten the brake band. When the cylinder is rotating in the direction opposite to the tightening direction by the push rod (de-energization direction), a load acts on the fluid pressure cylinder in the direction of retracting it, so that the hydraulic pressure in the second oil chamber is discharged. If so, the hydraulic cylinder moves back and the valve mechanism opens, so that the hydraulic pressure in the first oil chamber is exhausted through the second oil chamber, and the brake band is not tightened, that is, braking is not performed. In addition, the second
With the oil chamber communicating with the line hydraulic oil passage,
When line hydraulic pressure is supplied to the line hydraulic oil passage to set a predetermined gear, the hydraulic pressure in the first oil chamber and the second oil chamber increases, and the brake band is tightened by the push rod. Rotation in the direction is also braked. When a shift occurs in this state and the line oil pressure is exhausted, the oil pressure is released from each oil chamber at a speed comparable to that of the line oil pressure that accompanies the gear shift, and the tightening of the brake band is gradually released. Furthermore, when the line hydraulic pressure is supplied to the first oil chamber, if the switching valve is switched to connect the second oil chamber to the exhaust pressure oil passage, for example, a drain, the fluid pressure cylinder can move backward, so the rotating body is de-energized. When rotated in the direction, the valve mechanism opens and pressure is also exhausted from the first oil chamber.
Braking will no longer be applied. When the rotating body starts rotating in the energy direction in this state, the fluid pressure cylinder moves forward and the valve mechanism closes accordingly.
A pressing force is generated to press the push rod, and braking is performed. Therefore, in the brake device of the present invention, when setting a predetermined gear stage, the switching valve is operated to discharge pressure from the second oil chamber, so that the rotating body can be controlled without changing the hydraulic pressure supply state. The brake can be automatically released as the rotation starts in the de-energy direction, and the rotation in the energy direction can be automatically braked. Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the second embodiment of the present invention shown in FIG.
FIG. 3 is a sectional view showing an example applied to brake B2, as seen from the input shaft 4 side. The brake drum 20, which is a rotating body, is connected to the third clutch C3 described above.
This brake drum 20 is connected to the sun gear 7 of the second planetary gear mechanism 2 and housed inside the transmission case 21, and a brake band 2 is provided on the outer circumferential side of the transmission case 21.
2 is placed. Both ends of this brake band 22 are arranged so as to be close to each other and face each other,
One end, ie, the first anchor portion 23, is supported by pressing the tip of the anchor rod 25 against a cap 24 having a spherical or arcuate receiving surface. The anchor rod 25 is housed in a 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 its axial direction, that is, in the tangential direction of the brake drum 20. The rightward movement end) is defined by an adjustment bolt 26, and the outer circumferential side is sealed by an O-ring 27. In addition, anchor rod 25
A radially projecting flange portion 28 is formed at the distal end of the transmission case 21. A connecting rod 29 passes through and is fixed to the flange portion 28, and the distal end of the connecting rod 29 is attached to the transmission case 21. The connecting rod 29 is slidably fitted into a hole 30 formed parallel to the anchor rod 25, so that the tip of the connecting rod 29 serves as a guide pin. Further, the other end of the brake band 22, that is, the second anchor portion 31 presses a push rod 34 attached to a piston 33 of a hydraulic servo cylinder 32 provided in the transmission case 21 at a position substantially opposite to the anchor rod 25. It is maintained by this. The hydraulic servo cylinder 32 is housed in a hollow part 35 formed in the transmission case 21 so as to be able to move back and forth, and has a rear end (an end opposite to the push rod 34 with the piston 33 in between). An annular stopper 36 is disposed in close contact with the inner circumferential surface, and a valve sleeve 37 that protrudes on both front and rear sides in the axial direction is disposed on the inner circumferential side of the stopper 36, and is movable back and forth. A cylindrical portion on the rear end side of the piston 33 is in sliding contact with the inner circumferential surface of the valve sleeve 37 while maintaining liquid tightness. As shown enlarged in FIG. 2, a slight gap is formed between the outer circumferential surface of the valve sleeve 37 and the inner circumferential surface of the stopper 36, forming an oil passage 38. Uchistoppa 3
The portion protruding forward (to the right in FIGS. 1 and 2) from 6 extends outward in the radial direction, and the surface of the extending portion 39 that faces the front of the stopper 36 is the same as the stopper 36. 36, the oil passage 38 between the inner circumferential surface of the stopper 36
It is starting to close. Therefore, here the valve sleeve 37 is used as a valve body, and the stopper 36
A valve mechanism 41 is constructed with a valve seat 40 on the front side. The rear end (left end in FIG. 1) of the hollow part 35 that houses the above-mentioned hydraulic servo cylinder 32 is sealed by a case cover 42, and therefore, inside the hollow part 35, The first oil chamber 43 between the piston 33 and the stopper 36 and the stopper 36
and a second oil chamber 44 between the case cover 42 and the case cover 42 are formed. The length of the valve sleeve 37 protruding toward the second oil chamber 44 is set to such a length that the valve sleeve 37 comes into contact with the case cover 42 within the movable range of the hydraulic servo cylinder 32. The valve is configured to be opened by moving the servo cylinder 32 backward. Further, one end of the connecting rod 29 is attached to the hydraulic servo cylinder 32, and the other end of the connecting rod 29 is fixed to the anchor rod 25 as described above. are adapted to move back and forth in the tangential direction of the brake drum 20 as a unit. Further, in the hydraulic servo cylinder 32, in front of the piston 33, a return spring 45 is arranged to push the piston 33 back toward the left in FIG. A line hydraulic oil passage 46 that supplies line hydraulic pressure when setting the second forward speed and the fourth forward speed is connected to the first oil chamber 43. The line hydraulic oil passage 46 is connected to, for example, a 1-2 shift valve and a 3-4 shift valve (not shown), and is supplied with line hydraulic pressure when the second forward speed is set and when the fourth forward speed is set. The oil passage may be branched from the oil passage. This line hydraulic oil passage 46 is provided with an orifice 47 and an accumulator 48 . On the other hand, the second oil chamber 44 has a switching valve (brake servo valve) 49
It is connected to a portion of the line hydraulic oil passage 46 closer to the first oil chamber 43 than the accumulator 48 via. By moving the spool 50, this switching valve 49 switches the first port 51, which communicates with the second oil chamber 44, with either the second port 52, which connects the line hydraulic oil passage 46, or the drain port 53. The spool 50
A spring 54 that presses the spool 50 is provided at one end of the spring 54.
A control hydraulic oil passage 56 is connected to a port 55 on the opposite side of the spring 54. This control hydraulic oil line 56 may be, for example, an oil line connected to a hydraulic pump (not shown) to constantly generate line oil pressure, or a manual valve (not shown) when set to the drive (D) range. )
It is an oil passage through which line hydraulic pressure is introduced, and is provided with a solenoid valve 57 and an orifice 58 that communicate with the drain. Note that the solenoid valve 57 may be of a type that communicates with the drain when energized or vice versa, but in the following explanation, a type that communicates with the drain when energized is used as the solenoid valve 57. Let me explain with an example. An annular groove 60 is formed in the transmission case 21 corresponding to the small hole 59 formed in the hydraulic servo cylinder 32 to supply and discharge hydraulic pressure to and from the first oil chamber 43, and the line is inserted into the annular groove 60. Although the hydraulic oil passage 56 is in communication with the small hole 59 and the annular groove 60, the widths of the small hole 59 and the annular groove 60 become mismatched when the hydraulic servo cylinder 32 moves backward, and the first oil chamber 43
and the line hydraulic oil passage 46 are set to be cut off. Next, the operation of the brake device configured as described above will be explained. The second brake B2 in FIG. 3, in which the above brake device is used, is engaged at the second forward speed and the fourth forward speed to set the respective gears, as shown in Table 1. The operation of upshifting to the following gears and downshifting from these gears will be explained. The state of the electromagnetic valve 57 for each shift pattern, the port in the switching valve 49 with which the first port 51 communicates, and the presence or absence of braking are shown in Table 2.

[Table] When shifting up from the first speed to the second speed, the second oil chamber 44 is communicated with the line hydraulic oil passage 46 via the switching valve 49. That is, the solenoid valve 57
is energized (ON) to discharge pressure from the control hydraulic fluid path 56, and the spool 50 of the switching valve 49 is set to the upper state shown in FIG. 1 to communicate the first port 51 with the second port 52. In the first forward speed,
Since line hydraulic pressure is not supplied to the line hydraulic oil passage 46, each oil chamber 4 in the hydraulic servo cylinder 32
3 and 44, the push rod 34 is pushed back by the return spring 45, and the brake system is released. In this state, for example, when the 1-2 shift valve operates and the line oil pressure supply path is switched to set the second forward speed, the line oil pressure is supplied to the line oil pressure oil passage 46, so that the first oil chamber 43 The line oil pressure is directly sent to the second oil chamber 44, and the line oil pressure is sent to the second oil chamber 44 via a switching valve 49. Therefore, both the hydraulic servo cylinder 32 and its piston 33 are pushed in the right direction in FIG. As a result, the sun gear 7 of the second planetary gear mechanism 2 shown in FIG. 3 is fixed. In this case, the brake drum 20 is rotating in the opposite direction as indicated by the symbol A in FIG.
The direction of the acting force due to 4 is the same. Line oil pressure is supplied to each of the oil chambers 43 and 44 via the accumulator 48, so the oil pressure increases slowly depending on the characteristics of the accumulator 48. Therefore, sudden torque fluctuations do not occur in the output member 9, and shift shock can be prevented. At this time, the first one-way clutch F1, which was engaged in the first speed, is activated at the optimum timing (the first planetary gear mechanism 1
The ring gear 11 is released at the moment when the ring gear 11 starts rotating forward. On the other hand, when downshifting from second speed to first speed, the solenoid valve 57 may be left ON. In other words, if both the oil chambers 43 and 44 are maintained in a state where they are communicated with the line hydraulic oil passage 46, the oil pressure in the line hydraulic oil passage 46 will operate the shift valve as the gear shifts from second gear to first gear. Since the pressure is exhausted through the accumulator 48, the oil pressure in each oil chamber 43, 44 gradually decreases through the accumulator 48. the result,
As the push rod 34 is gradually pushed back by the return spring 45 and the braking torque decreases, the brake drum 20, that is, the sun gear 7 of the second planetary gear mechanism 2 gradually begins to rotate, causing the ring gear 11 of the first planetary gear mechanism 1 to rotate. When the number decreases and reverse rotation is about to occur, the first one-way clutch F1 is engaged and the first forward speed is set. In the second speed state, the solenoid valve 57 is activated as described above.
It is set to ON, the control oil pressure is exhausted, and rotation of the brake drum 20 is prevented, but when shifting up to 3rd gear from this state,
At the same time as the decision to shift up to 3rd gear is made, the power to the solenoid valve 57 is cut off (turned OFF).
Control hydraulic pressure is supplied to the control port 55 of the switching valve 49. As a result, the spool 50 of the switching valve 49 compresses the spring 54 and moves to the lower state shown in FIG. 1, and the first port 51 communicates with the drain port 53. In other words, the second oil chamber 44 is directly drained, and its oil pressure drops rapidly. Therefore, only the oil pressure in the first oil chamber 43 presses the push rod 34 to perform braking. 2nd gear to 3rd gear
When the hydraulic pressure of the second clutch C2 increases and the torque of the second clutch C2 reaches the turbine torque or higher during the gear shift, the brake drum 20
(Sun gear 7) attempts to rotate in the forward rotation direction (de-energization direction) shown by reference numeral B in FIG. Since the pressure is discharged from the second oil chamber 44, the hydraulic servo cylinder 32 moves to the left in FIG. 1 together with the anchor rod 25. When the hydraulic servo cylinder 32 retreats to a certain extent, the valve sleeve 37 comes into contact with the case cover 42 and its extended portion 39 separates from the valve seat 40 of the stopper 36 as shown in FIG. 60 and the first oil chamber 43 is the line hydraulic oil passage 4.
6, the hydraulic pressure in the first oil chamber 43 is quickly discharged through the oil passage 38 and the second oil chamber 44, and as a result, the pressing force of the push rod 34 is eliminated, so that the braking of the brake drum 20 is reduced. It will be canceled. In other words, when shifting up from 2nd gear to 3rd gear, the brake drum 20 starts rotating and releases its braking. In other words, it acts as a one-way clutch, so the second clutch C2 The timing of engagement and release of the second brake B2 are completely coincident, and there is no possibility of occurrence of shift shock. When shifting from the third forward speed to the second speed, the switching valve 49 is left as it is. That is, the second oil chamber 44 is communicated with the drain. Second
When it is determined that the gear shift has been changed to a higher speed and the line oil pressure starts to be supplied to the line oil pressure oil passage 46, and the oil pressure in the first oil chamber 43 starts to rise in accordance with the characteristics of the accumulator 48, the second clutch C2 is activated. If the brake drum 20 is not sufficiently released, the brake drum 20 is rotating in the forward direction, but in this state, if a frictional force is generated between the brake band 22 and the brake drum 20 due to an increase in the oil pressure in the first oil chamber 43. , the hydraulic servo cylinder 32 is moved backward by the rotational force of the brake drum 20, and as a result, the valve sleeve 37 comes into contact with the case cover 42 and the oil passage 38 is opened. Therefore, at this point, even if the first oil chamber 4
Even if hydraulic pressure is supplied to the brake drum 20 , the brake band 22 contacts the brake drum 20 based on the hydraulic pressure, and the pressure is discharged from the first oil chamber 43 as described above. The brake drum 20 is repeatedly brought into contact with and separated from the brake drum 20, but the brake drum 20 is not braked. When the second clutch C2 is gradually released and its clutch torque decreases, the brake drum 20 begins to rotate in the opposite direction (rotation in the energy direction) as described above. Since the brake band 22 is in contact with the brake drum 20 at this time, the hydraulic servo cylinder 32 is moved to the right in FIG. Therefore, since the oil passage 38 from the first oil chamber 43 to the second oil chamber 44 is closed, the oil pressure in the first oil chamber 43 increases rapidly, tightening the brake band 22 and braking the brake drum 20. . In this case,
When the brake drum 20 is in a coasting state, such as when the engine brake is applied, the brake drum 20 rotates in the normal direction (rotation in the de-energization direction), so a force that moves the hydraulic servo cylinder 32 to the left in FIG. 1 acts on the hydraulic servo cylinder 32. As a result, the hydraulic servo cylinder 32
When the valve moves backward, the valve mechanism 41 is opened as described above, the first oil chamber 43 is communicated with the drain via the second oil chamber 44, and the braking of the brake drum 20 is accordingly released. In addition to being
The line hydraulic pressure will end up being exhausted. Therefore, in order to eliminate this inconvenience, the solenoid valve 57 is closed after the downshift to 2nd gear is completed.
The hydraulic servo cylinder 32
prevent it from moving backwards. In other words, if pressure is exhausted from the second oil chamber 44 and hydraulic pressure is applied to the first oil chamber 43, it functions as a one-way clutch (one-way brake) and allows forward rotation of the brake drum 20 in the third forward speed. At the same time, reverse rotation of the brake drum 20 due to downshifting is automatically prevented without switching the oil path. After downshifting to 2nd gear,
Supply hydraulic pressure to the second oil chamber to cancel the one-way characteristic. Next, to explain the case of shifting up to 4th speed, in the state of 3rd speed, the solenoid valve 57 is
Since the switching valve 49 is in the OFF state and control oil pressure is being supplied to the switching valve 49, the switching valve 49 is in the lower state shown in FIG. 1, and therefore the second oil chamber 44 is evacuated. When it is determined that the shift to the fourth speed is necessary, the solenoid valve 57 is turned on and the control hydraulic pressure is discharged, and as a result, the switching valve 49 is switched to the upper state in Fig. 1, and the second oil chamber is opened. 44 is the line hydraulic oil passage 46
be communicated with. In addition, line hydraulic pressure is supplied to the line hydraulic oil passage 46 from a shift valve or the like to set the fourth speed, so hydraulic pressure is sent to both the first oil chamber 43 and the second oil chamber 44, and therefore the hydraulic pressure is Since the servo cylinder 32 does not move backward, forward rotation (rotation in the de-energy direction) of the brake drum 20 can be prevented. Further, when downshifting from 4th speed to 3rd speed, the solenoid valve 57 is kept ON until the shift is completed, and the switching valve 49 is left unchanged. That is, the second
The oil chamber 44 communicates with the line hydraulic oil passage 46 via the first port 51 and the second port 52 of the switching valve 49, and in this state, when downshifting to the third speed, the line hydraulic oil passage 46 is connected to the oil chamber 44. When the pressure in each oil chamber 43, 44 is exhausted through a shift valve or the like, the oil pressure in each oil chamber 43, 44 is simultaneously exhausted through the line hydraulic oil passage 46. The oil pressure gradually decreases according to the characteristics of the accumulator 48. Therefore, since the brake drum 20 is released slowly, the output shaft torque does not change abruptly, and there is no risk of a shift shock occurring. After the downshift is completed, the solenoid valve 57 is turned on to supply control oil pressure to the switching valve 49. This is to prepare for the occurrence of a downshift from third gear to second gear. Therefore, the above-mentioned brake device can function as both a brake with unidirectional characteristics and a brake without unidirectional characteristics depending on the hydraulic pressure supply state, and as a result, it is possible to function as both a brake with unidirectional characteristics and a brake without unidirectional characteristics. Not only can it be used for braking, but it can also effectively prevent shift shock by optimizing the timing of braking and braking release. In addition, in the above embodiment, an example was explained in which the second brake B2 of the gear transmission shown in FIG. Can be used as a braking means. Further, in the above embodiment, the switching valve is operated by control hydraulic pressure supplied and discharged via a solenoid valve, but the switching valve in this invention may be configured to be electrically switched or operated. You can use the following configuration. Effects of the Invention As is clear from the above description, the brake device of the present invention has a brake with one-way characteristics and a normal brake without one-way characteristics, depending on the state of oil pressure supply to the first and second oil chambers. Since it can function both as a brake and as a brake, the timing control of braking and braking release is performed by the clutch, which simplifies the device by omitting the one-way clutch that was placed in parallel with the brake device. It is possible to achieve reductions in weight, weight, and cost. Furthermore, since the brake device of the present invention can perform timing control by itself, it is possible to omit timing control valves such as upshift timing valves and downshift timing valves that were conventionally used. result,
Effects such as being able to simplify the configuration of the hydraulic control circuit can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a partially enlarged sectional view showing the valve mechanism thereof, and Fig. 3 is a gear transmission for an automatic transmission in which the brake device of the invention can be incorporated. It is a skeleton diagram showing an example. 20... Brake drum, 21... Transmission case, 22... Brake band, 23
...First anchor part, 25...Anchor rod,
29...Connection rod, 31...Second anchor part,
32... Hydraulic servo cylinder, 33... Piston, 34... Push rod, 37... Valve sleeve, 38... Oil passage, 40... Valve seat, 41...
Valve mechanism, 43...first oil chamber, 44...second oil chamber,
46...Line hydraulic oil path, 49...Switching valve, 56
...Control hydraulic oil line.

Claims (1)

[Scope of Claims] 1. A brake band is arranged on the outer circumference side of a rotating body arranged in a case, and both ends of the brake band are brought close to each other by an anchor rod and a push rod to tighten the brake band and stop the rotating body. In a brake device for braking, a fluid pressure cylinder that moves back and forth in a substantially tangential direction of the rotating body is disposed in the case at a position opposite to the anchor rod, the push rod is attached to the piston of the fluid pressure cylinder, and the fluid pressure cylinder is The cylinder and the anchor rod are connected so as to move as one, and a first oil chamber is formed on the opposite side of the hydraulic cylinder from the push rod with the piston in between, and the A second oil chamber is formed on the opposite side of the push rod, and a valve mechanism is provided that opens the oil chambers to communicate with each other when the hydraulic cylinder retreats toward the second oil chamber, and the first oil chamber is A line hydraulic oil passage for supplying line oil pressure for setting a predetermined gear is connected to the second oil chamber, and the second oil chamber is switched to the line hydraulic oil passage and the exhaust pressure oil passage. A brake device for an automatic transmission characterized by connecting a switching valve for communication.