JPH0585789B2 - - 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. Appropriate speed changes can be achieved by fixing one of the elements (sun gear, carrier, ring gear, or in the case of a differential gear mechanism, the ring gear and a pair of side gears that mesh with it), and using the other two elements as the input member and the output member. is configured to obtain the ratio. An example of this is schematically shown in Fig. 4, and the gear transmission shown here uses two sets of planetary gear mechanisms 1 and 2 to obtain four forward speeds and one reverse speed, including overdrive. It is structured like this. 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 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, the first brake B1
By engaging the ring gear 11 and fixing the ring gear 11 in either the forward or reverse direction, engine braking can be applied. In the state of 1st forward speed, 2nd
The sun gear 7 of the planetary gear mechanism 2 is rotating in the opposite direction, but if this is fixed by the second brake B2, the second forward speed is achieved. Furthermore, 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 unit rotates as a unit, 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. The third forward speed is maintained. Therefore, from this state, the second
When the brake B2 is applied, the second one-way clutch F2 is disengaged and the sun gear 7 is prevented from rotating in the forward direction. As a result, the gear ratio is higher than "1" and the fourth forward speed (overdrive stage) is set. become. When going backwards, the third clutch C3 is engaged to receive input from the sun gear 7 of the second planetary gear mechanism 2, and the first brake B1 prevents forward rotation of the carrier 6, so that the ring gear 10, that is, the output member 9 is It 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). The outline of this brake device is explained in Section 5.
As shown in the figure, when hydraulic pressure is sent to the inside of the servo cylinder 100, that is, the first oil chamber 101, the piston 102 moves forward, causing the push rod 10 to move forward.
3 tightens the brake band 105 together with the anchor rod 104 to perform braking. In that case, if the brake drum 106 is rotating in the de-energization direction indicated by the symbol B in FIG. 5, the servo cylinder 100 is integrally moved backward to the left in FIG. The body 107 is pushed to open the first oil chamber 101 and the second oil chamber 1.
Since the oil passage communicating with 08 is opened, the first oil chamber 1
As a result, pressure is removed from push rod 1.
Since there is no force to press 03, braking is not performed. In contrast, the brake drum 106
If the brake drum 106 is rotating in the energy direction indicated by the symbol A in the figure, the brake band 10
5 and the valve body 107 cannot be opened, so braking can be performed. Furthermore, by supplying hydraulic pressure to both the first oil chamber 101 and the second oil chamber 108, the piston 102 is pressurized while the backward movement of the servo cylinder 100 is prevented. It also prevents the rotation of. Therefore, in the above-mentioned brake device proposed by the present applicant, a one-way characteristic occurs depending on the way the hydraulic pressure is supplied, and braking can be released by rotating the brake drum. The shift shock can be reduced without using a complicated mechanism. Problems to be Solved by the Invention However, in the above brake device already proposed by the applicant, if hydraulic pressure is supplied to the first oil chamber 101 and discharged from the second oil chamber 108, braking can be performed in the de-energization direction. However, for example, when line hydraulic pressure is supplied to the first oil chamber 101 and the line hydraulic pressure is applied to the second oil chamber 10,
8 is communicated with the drain to prevent rotation of the brake drum 106 in the energy direction and set a predetermined gear stage.If the brake drum 106 is in an engine braking state, for example, a torque is applied to the brake drum 106 in the de-energization direction. As mentioned above, the servo cylinder 100 retreats and the valve body 107
operates to open the valve, and as a result, the brake drum 106
not only rotates and the braking is not effective, but also the line oil pressure is exhausted through the first oil chamber 101 and the second oil chamber 108. Therefore, in the case of a gear position in which rotation of the brake drum 106 in the energy direction is prevented in a hydraulic pressure supply state exhibiting unidirectional characteristics,
After the shift is completed, it is necessary to supply hydraulic pressure to the second oil chamber 108 to eliminate the one-way characteristic. It is desirable to supply hydraulic pressure to the second oil chamber 108 in order to eliminate the one-way characteristic after completing a shift in which the rotation of the brake drum 106 is almost completely blocked. Completion of gear shifting is determined by detecting the rotational speed of rotating members such as gears or oil pressure in a predetermined oil passage, and based on the results, a solenoid valve or the like is operated to supply oil to the second oil chamber 108. Although it is possible to adopt a configuration in which the path is opened, such a configuration increases the number of components such as detectors and solenoid valves, so it is recommended to simplify the configuration by adding one-way characteristics to the brake device. I end up going against the grain. On the other hand, the switching valve is configured to open the oil passage that supplies line oil pressure to the second oil chamber 108 as the oil pressure in the first oil chamber 101 increases.
It is conceivable to supply hydraulic pressure to the second oil chamber 108 when braking is almost completed by supplying hydraulic pressure to the second oil chamber 108 to eliminate the one-way characteristic. However, in that case, if the cylindrical part 109 that serves as a guide is formed on the rear surface of the piston 102 so as to protrude into the second oil chamber 108, the oil pressure can be supplied to the first oil chamber 101 and the second oil chamber 108. The force with which the push rod 103 is pressed differs greatly between the cases in which the push rod 103 is supplied, and it is necessary to prevent the occurrence of shift shock caused by this. In other words, the piston pressing force when hydraulic pressure Pb is supplied to the first oil chamber 101 is (π/4) x (Dp ² - Dr ² ) x Pb - F Dp: Diameter of the piston Dr: Diameter of the cylindrical part F: Return This becomes the elastic force of the spring 110, and the hydraulic pressure Pb is applied to the second oil chamber 108.
The piston pressing force when supplying is (π/4) x Dc ² x Pb - F Dc: cylinder diameter, and the two are significantly different. Therefore, the second
If oil pressure is supplied to the oil chamber 108, for example, during the inertia phase of a shift transient state, the shift shock becomes large due to a sudden increase in brake torque. The situation is shown in Figure 6, where the accumulator is operating and the oil pressure Ps in the first oil chamber 101 is
In the middle of the inertia phase when Ps1 is slowly rising and the brake is slipping, when hydraulic pressure is supplied to the second oil chamber 108 and its pressure Ps2 increases, the brake torque suddenly increases due to the large pressure receiving area. increases to As a result, the output shaft torque rapidly increases as shown by the chain line in FIG. 6, resulting in a shift shock. Therefore, when the oil pressure supplied to the first oil chamber 101 is used as the control oil pressure of the switching valve for the second oil chamber 108, some kind of device for timing adjustment is required. The present invention was made against the background of the above-mentioned circumstances, and an object of the present invention is to provide a brake device for an automatic transmission that has one-way characteristics and can easily reduce shift shock. It is. Means for Solving the Problems In order to achieve the above object, the present invention improves the above-mentioned brake device proposed by the present applicant, and transfers the hydraulic pressure supplied to the first oil chamber to the second oil chamber. At the same time, when braking by supplying hydraulic pressure only to the first oil chamber is almost completed, the switching valve is operated to control the switching valve that supplies and discharges hydraulic pressure to the first oil chamber.
It is configured to supply hydraulic pressure to the oil chamber.
More specifically, the device of the present invention arranges a brake band on the outer peripheral side of a rotating body placed in a case, and brings the ends of the brake band closer together by an anchor rod and a push rod, thereby tightening the brake band. In a braking device that brakes a rotating body by tightening, a hydraulic cylinder that moves back and forth in a tangential direction of the rotating body is arranged in the case at a position opposite to the anchor rod, and the push rod is attached to the piston of the hydraulic cylinder. and connecting the fluid pressure cylinder and the anchor rod so as to move together,
Further, a first oil chamber is formed on the side of the fluid pressure cylinder opposite to the push rod across the piston, and a pressure receiving area of the fluid pressure cylinder is formed on the side opposite to the push rod with respect to the fluid pressure cylinder. A second oil chamber is formed which is larger than the pressure receiving area in the first oil chamber, and a valve mechanism is provided that opens the oil chambers to communicate with each other when the fluid pressure cylinder retreats toward the second oil chamber. A line hydraulic oil passage for supplying line oil pressure for setting a predetermined gear stage is connected to the first oil chamber, and the second oil chamber is connected to the line hydraulic oil passage and a discharge pressure oil passage. A switching valve is connected to connect the switching valve to the line hydraulic pressure as a first control pressure and a predetermined shift signal hydraulic pressure as a second control pressure opposing the first control pressure. The system is characterized in that it operates against the second control pressure when the control pressure increases to a pressure substantially equal to the second control pressure, thereby communicating the second oil chamber with the line hydraulic oil passage. It is. In addition, in this invention, when the switching valve is a spool valve, and the second control pressure is applied so as to oppose the spring that presses the spool, and the first control pressure is applied to the same side as the spring, each control pressure If the pressure-receiving areas of the first control oil pressure are equal, the elastic force of the spring can be made extremely weak, and if the elastic force of the spring is set to a certain level, the pressure-receiving area of the first control oil pressure can be made narrower. Function In the brake device of the present invention, when line hydraulic pressure is supplied to the first oil chamber with the second oil chamber communicating with the exhaust pressure oil passage, the brake band is tightened by the movement of the piston. In that case, if the brake drum is rotating in the de-energy direction, the hydraulic servo cylinder is moved backward together with the anchor rod, the valve mechanism opens and pressure is discharged from the first oil chamber, and as a result, the tightening force of the brake band is reduced. does not occur, so no braking is performed. On the contrary, if the brake drum is rotating in the energy direction, the brake drum will wrap around the brake band, so braking will be performed and the pressure will not be exhausted from the first oil chamber. In other words, it shows a one-way characteristic, but when braking is performed in this state and the oil pressure in the first oil chamber gradually increases, the first control pressure at the switching valve increases equally, and that pressure becomes almost equal to the second control pressure. When this occurs, the switching valve operates to communicate the second oil chamber with the line hydraulic oil passage, thereby supplying hydraulic pressure to the second oil chamber and eliminating the one-way characteristic. The point at which this state occurs is when the oil pressure in the first oil chamber reaches a pressure that is almost equal to the second control pressure, that is, the line oil pressure, and therefore, the braking, or gear shifting, is almost completed. Therefore, since the pressure receiving area of the hydraulic servo cylinder in the second oil chamber is wide, even if the brake torque increases, the shift shock does not increase. Further, in the device of the present invention, when line hydraulic pressure is supplied to the line hydraulic oil passage in order to set a predetermined gear stage with the second oil chamber communicating with the line hydraulic oil passage by the switching valve, The hydraulic pressure in the first oil chamber and the second oil chamber increases, and the brake band is tightened by the push rod, and rotation in either the forward or reverse direction is braked. In this state, when a shift occurs and the line oil pressure is exhausted, the oil pressure is released from each oil chamber at a speed comparable to the line oil pressure that is exhausted due to the 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 the valve mechanism rotates in this direction, the valve mechanism opens and pressure is also exhausted from the first oil chamber, so that braking is no longer performed. When the rotating body starts to rotate in the energy direction in this state, the fluid pressure cylinder moves forward and the valve mechanism closes accordingly, so that 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 a transmission case 21, and a brake band 22 is arranged on the outer circumferential side of the transmission case 21. Both ends of the brake band 22 are arranged to be close to each other and face each other, and one end, that is, the first anchor part 23, connects the tip of the anchor rod 25 to a cap 24 having a spherical or arcuate receiving surface. Supported by pressing. 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. The tip of the anchor rod 25 has a flange portion 28 projecting in the radial direction.
A connecting rod 29 passes through and is fixed to the flange portion 28, and the tip of the connecting rod 29 is slidably inserted into a hole 30 formed in the transmission case 21 parallel to the anchor rod 25. The connecting rods 29 are fitted together, 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 33a 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 to form an oil passage 38. Among them, Stoppa 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
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. Here, the area where the piston 33 receives pressure from the hydraulic pressure supplied to the first oil chamber 43 is calculated as follows: (π/4)×(Dp ² - Dr ² ) Dp: Diameter of the piston Dr: Diameter of the cylindrical part, and the area where the piston 33 receives pressure when hydraulic pressure is supplied to both the first oil chamber 43 and the second oil chamber 44 is, as a result, (π/4)×Dc ² Dc: Outer diameter of the cylinder (inner diameter of the hollow part) Therefore, compared to the case where hydraulic pressure acts only on the first oil chamber 43, the difference between the first oil chamber 43 and Second oil chamber 44
When hydraulic pressure acts on both piston 3
The pressure receiving area for pressing 3 is increasing. 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, the 1-2 shift valve and the 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
The oil chamber 44 is connected to a portion of the line hydraulic oil passage 46 on the first oil chamber 43 side by an accumulator 48 via a switching valve (brake servo sequence valve) 49 . This switching valve 49 is connected to a first port 51 which communicates with the second oil chamber 44 by moving a spool 50 having two lands.
is switched to communicate with either the second port 52 to which the line hydraulic oil path 46 is connected and the drain port 53, and a spring 54 that presses the spool 50 is arranged on one end side of the spool 50. At the same time, a first control pressure port 55 is formed at the location where this spring 54 is accommodated, and the line hydraulic oil passage 46 is branched and connected to this port. Further, a control hydraulic oil passage 57 is connected to the second control pressure port 56 on the opposite side of the spring 54 for supplying the second control port 56 with a shift signal hydraulic pressure generated, for example, in the second forward speed and the third forward speed. ing. Note that the first of the faces of the spool 50
The diameter d1 of the face that receives the oil pressure applied from the control pressure port 55 is set smaller than the diameter d2 of the face that receives the oil pressure applied to the second control pressure port 56, and the difference in these dimensions is due to the elasticity of the spring 54. With the shift signal hydraulic pressure acting on the second control port 56, the hydraulic pressure applied to the first control pressure port 55 increases to a pressure that is approximately equal to the hydraulic pressure of the second control pressure port 56. When this occurs, the spool 50 is configured to move toward the second control pressure port 56 side. Additionally, a hydraulic servo cylinder 32 is used to supply and discharge hydraulic pressure to and from the first oil chamber 43.
An annular groove 62 is formed in the transmission case 21 to correspond to the small hole 61 formed in the hole 61, and the line hydraulic oil passage 57 is communicated with this annular groove 62. The widths are set so that when the hydraulic servo cylinder 32 moves backward, they become mismatched and cut off the first oil chamber 43 and the line hydraulic oil passage 46. Next, the operation of the brake device configured as described above will be explained. The second brake B2 in FIG. 4, 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. Note that the presence or absence of the shift signal oil pressure to the second control pressure port 56 for each shift pattern, the port with which the first port 51 of the switching valve 49 communicates, and the presence or absence of braking are determined by the second control pressure port 56.
As shown in the table.

[Table] When shifting up from 1st gear to 2nd gear, a shift signal hydraulic pressure is generated in the control hydraulic oil line 57, so a return signal hydraulic pressure acts on the second control pressure port 56 of the switching valve 49, and as a result, the spool 50 moves to the left side in FIG. 1 (the position shown at the bottom in FIG. 1), and the first port 51 communicates with the drain port 53.
That is, the pressure is exhausted from the second oil chamber 44. At the same time, line hydraulic pressure for setting the second speed is generated in the line hydraulic oil passage 46 by switching the 1-2 shift valve (not shown), so that the line hydraulic pressure is applied to the first oil chamber 43. Supplied.
As a result, the piston 33 of the hydraulic servo cylinder 32 moves to the right in FIG.
Begin tightening the brake band 22 via 4.
In that case, the brake drum 20 is rotating (reversely rotating) in the direction indicated by the symbol A, but this rotation direction is the so-called energy direction that coincides with the tightening direction by the push rod 34, and the brake drum 20
A frictional force is generated between the brake band 22 and the hydraulic servo cylinder 32, thereby moving the hydraulic servo cylinder 32 to the right in FIG. Therefore, in addition to the increase in the tightening force by the push rod 34, the so-called winding force of the brake drum 20 causes the brake band 22 to tightly wrap around the brake drum to effect braking. In this case, line oil pressure is supplied to the first oil chamber 43 via the accumulator 48, so the oil pressure increases slowly depending on the characteristics of the accumulator 48. Furthermore, when the hydraulic pressure supplied to the first oil chamber 43 gradually increases, the switching valve 4
The oil pressure of the first control pressure port 55 at 9 also gradually increases, but since the diameter d1 of the face on the first control pressure port 55 side is set small, the pressure acting on the first control pressure port 55 increases to some extent. Until then, the spool 50 remains pushed to the left in FIG. 1 by the shift signal oil pressure (line oil pressure) acting on the second control pressure port 56. When the pressure in the first oil chamber 43 and the pressure in the first control pressure port 55 increase to a pressure approximately equal to the shift signal hydraulic pressure acting on the second control pressure port 56, the spool 50 is moved to the second control pressure port 56. Since the force pushing it to the side becomes greater than the opposing force, the spool 50 moves to the right as shown at the top of FIG. As a result, the first port 51 becomes the second port 5.
2, line oil pressure is supplied to the second oil chamber 43. Therefore, the hydraulic servo cylinder 3
2 is prevented from moving backward by the hydraulic pressure in the second oil chamber 44. Therefore, even if the brake drum 20 attempts to rotate (forward rotation) in the direction indicated by symbol B in FIG. The servo cylinder 32 does not move backward and maintains the braking state of the brake drum 20. FIG. 3 shows temporal changes in the oil pressures Ps1 and Ps2 of the oil chambers 43 and 44, the brake torque, and the output shaft torque during the above-mentioned shift process. That is, when the oil pressure Ps1 in the first oil chamber 43 starts to rise,
Brake torque also increases, but the accumulation rate is 4.
8 begins to act, the increase in the oil pressure in the first oil chamber 43 becomes slow, so the rise in brake torque also becomes slow, and as a result, no large change occurs in the output shaft torque. Immediately before the action of the accumulator 48 ends, the influence of inertial force disappears and the brake drum 2
0 almost completely stops, and the brake torque and output shaft torque decrease slightly accordingly. The shift to the second speed is completed before the action of the accumulator 48 ceases, and at this point, the oil pressure in the first oil chamber 43 increases as the action of the accumulator 48 ends. , since the switching valve 49 switches as described above,
Line hydraulic pressure is supplied to the second oil chamber 44 . When hydraulic pressure acts on both the first oil chamber 43 and the second oil chamber 44, the brake drum 20 is braked with a large clamping force because the pressure receiving area is large. Therefore, the braking force is increased by supplying the line hydraulic pressure to the second oil chamber 44 after the brake drum 20 has stopped and the gear shift has been completed (after the inertia phase has passed and the second speed steady state has been reached). ) Therefore, a sudden increase in braking force will not have an adverse effect on the gear shifting shock. On the contrary, when downshifting from 2nd speed to 1st speed, the shift signal oil pressure is discharged from the control oil pressure oil passage 57, and at the same time, from the line oil pressure oil passage 46, for example, the 1-2 shift valve is switched. The action exhausts line hydraulic pressure. Since the spool 50 of the switching valve 49 was pressed to the first right side in the second speed state, the shift signal hydraulic pressure that was acting on the second control pressure port 56 no longer acts, and the switching valve 49 cannot operate. Therefore, the second oil chamber 44
remains in communication with the line hydraulic oil passage 46 via the first port 51 and the second port 52. Therefore, each oil chamber 4 in the hydraulic servo cylinder 32
The hydraulic pressures 3 and 44 are discharged through the line hydraulic oil passage 46, and the pressing force of the push rod 34, that is, the tightening force of the brake band 22 is eliminated, so the braking of the brake drum 20 is released and the brake drum 20 is released. It begins to rotate in reverse and the first speed is set. In that case, since the accumulator 48 acts, the oil pressure in each oil chamber 43, 44 gradually decreases according to the characteristics of the accumulator 48, and as a result, the braking of the brake drum 20 is slowly released, so that the second speed is reached. The shift shock associated with downshifting from to first gear is reduced. In the second speed state, the shift signal oil pressure is acting on the second control pressure port 56 as described above, but the second
Since the line hydraulic pressure for setting the speed is acting on the first control pressure port 55, the spool 50 is
It has moved to the right side of the diagram, and the brake drum 2
Reverse rotation of 0 is prevented. When a shift to the third forward speed is performed in this state, for example, 2-3
As the shift valve (not shown) operates, pressure is discharged from the line hydraulic oil passage 46, so the oil pressure in each oil chamber 43, 44 gradually decreases according to the characteristics of the accumulator 48. When the pressure in the first control pressure port 55 of the switching valve 49 slightly decreases due to a decrease in the oil pressure in the line hydraulic oil passage 46, the spool 50 is moved to the second It is immediately moved to the left side in FIG. 1 by the shift signal oil pressure acting on the control pressure port 56, and as a result, the pressure is rapidly exhausted from the second oil chamber 44 via the first port 51 and the drain port 53. Ru. In this state, the first oil chamber 43
The brake band 22 is in contact with the brake drum 20 by pressing the push rod 34 only with the hydraulic pressure within the clutch. Therefore, when the clutch torque at the third clutch C3 reaches the turbine torque for setting the third gear, the brake is activated. Drum 20 is the first
The hydraulic servo cylinder 32 begins to rotate forward (rotation in the de-energization direction) in the direction indicated by symbol B in the figure, and along with this, the hydraulic servo cylinder 32 moves backward in the left direction in FIG. I am made to do so.
When the hydraulic servo cylinder 32 retreats to a certain extent,
When the valve sleeve 37 comes into contact with the case cover 42, its extending portion 39 separates from the valve seat 40 of the stopper 36 as shown in FIG. Since the oil chamber 43 is cut off from the line hydraulic oil passage 46, the oil pressure in the first oil chamber 43 is rapidly exhausted through the oil passage 38 and the second oil chamber 44, and as a result, the pressure in the push rod 3
Since the pressing force of 4 is removed, the braking of the brake drum 20 is released. 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,
Shifting shock is greatly improved. Even when shifting from the third forward speed to the second speed, the shift signal oil pressure remains supplied to the second control pressure port 56. Also, the line hydraulic oil passage 46
For example, line oil pressure is supplied by operating a 2-3 shift valve. When line hydraulic pressure begins to be supplied to the line hydraulic oil passage 46 for downshifting to second gear, and the hydraulic pressure in the first oil chamber 43 begins to rise in accordance with the characteristics of the accumulator 48, the second clutch Until C2 is sufficiently released, the brake drum 20 is rotating in the forward direction, but in this state, frictional force is generated between the brake band 22 and the brake drum 20 due to the increase in the oil pressure in the first oil chamber 43. When it occurs, 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 opens the oil passage 38. Therefore, at this point, even if oil pressure is supplied to the first oil chamber 43, the brake band 2
By contacting the brake drum 20,
The pressure is discharged from the first oil chamber 43 as described above, and as a result, the brake band 22 is released from the brake drum 2.
0 is repeatedly brought into contact with and separated from the brake drum 20, and the brake drum 20 is not braked. 2nd clutch C
2 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, and at this time, since the brake band 22 is in contact with the brake drum 20, the hydraulic pressure is increased. Move the servo cylinder 32 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 rapidly increases, tightening the brake band 22 and tightening the brake drum 20.
performs braking. As the oil pressure in the first oil chamber 43 increases, the first control pressure port 5 in the switching valve 49
When the oil pressure of the line oil pressure 5 becomes high to a certain extent, the spool 50 is moved to the right side in FIG. That is, since the backward movement of the hydraulic servo cylinder 32 is prevented, the forward rotation of the brake drum 32 is also prevented, and as a result, the engine brake can be applied in the second speed. In this case as well, the timing at which the spool 50 of the switching valve 49 moves from the left position to the right position in FIG. 1 is due to the difference in the face area of the spool 50 as described above. Therefore, the shift shock will not deteriorate due to an increase in the tightening force of the brake band 22 due to the line hydraulic pressure being supplied to the second oil chamber 44, which has a large pressure receiving area. . That is, in the case of upshifting from 2nd speed to 3rd speed, braking is automatically released as the brake drum 20 starts to rotate forward, and in the case of downshifting from 3rd speed to 2nd speed, When the brake drum 20 attempts to rotate in the opposite direction, the brake drum 20 is automatically braked, and thus functions as a one-way clutch (one-way brake), thereby reliably and easily reducing shift shock. can. After downshifting to the second speed, hydraulic pressure is supplied to the second oil chamber 44 to cancel the one-way characteristic. Next, the case of shifting up to 4th speed will be explained. In this case, the shift signal hydraulic pressure stops acting on the second control pressure port 56 when the shift is determined, and the line hydraulic oil path 46 has a solenoid valve. (not shown) operates to supply line hydraulic pressure. Therefore, the spool 5 of the switching valve 49
0 is located on the right side as shown in the upper side of FIG. 1, the oil pressure is slowly supplied to each oil chamber 43, 44 according to the characteristics of the accumulator 48. In this case, the rotation of the brake drum 20 is in the de-energy direction, but the second oil chamber 4
Hydraulic pressure is also supplied to the hydraulic servo cylinder 32
brake band 2 is prevented from moving backwards.
2 is loosely tightened, and forward rotation of the brake drum 20 is gradually prevented. Furthermore, when shifting down from 4th gear to 3rd gear, the shift signal oil pressure acts on the second control pressure port 56, but the line oil pressure acts on the first control pressure port 55 of the switching valve 49. 1, the spool 50 remains pressed to the right position in FIG. Therefore, the pressure is slowly discharged from each oil chamber 43, 44 via the line hydraulic oil passage 46.
Further, when the hydraulic pressure in the first control pressure port 55 of the switching valve 49 decreases to some extent due to a decrease in the hydraulic pressure in the line hydraulic oil passage 46, the spool 50 is activated by the shift signal hydraulic pressure acting on the second control pressure port 56. As a result, the first port 51 communicates with the drain port 53, so that the second oil chamber 44 is rapidly evacuated. In this state, a load is applied to the hydraulic servo cylinder 32 from the brake drum 20 in a direction that causes it to move backward, so the hydraulic servo cylinder 32 moves backward as pressure is discharged from the second oil chamber 44, and as described above. As in the case of upshifting to the third speed, the valve sleeve 37 is pushed relative to the first oil chamber 43.
communicates with the second oil chamber 44, and as a result, the first oil chamber 4
3 is also rapidly exhausted, the braking of the brake drum 20 is released, and the brake drum 20 begins to rotate forward. In other words, the third speed is set. 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. Furthermore, when line oil pressure is supplied to the second oil chamber 44 in order to eliminate the one-way characteristic, the tightening force of the brake band increases rapidly because the pressure receiving area in the second oil chamber 44 is large, but the timing is the first control pressure port 5 of the switching valve 49
This is the point at which the pressure acting on the second control pressure port 56 becomes approximately equal to the pressure acting on the second control pressure port 56;
Since this is done after the gear shift is completed, it will not have any adverse effect on the gear shift shock. Furthermore, the supply and discharge of hydraulic pressure to perform the above operations is based on the shift signal hydraulic pressure and line hydraulic pressure for setting each gear stage, so there is no need for a special hydraulic control device or braking method, and the equipment and Both control methods can be simplified. In addition, in the above embodiment, the pressure receiving area of each face in the spool 50 (specifically, the diameter d1,
d2), the pressure acting on the first control pressure port 55 in the switching valve 49 becomes different from the second control pressure port 55.
Although the configuration is such that the spool 50 is moved against the pressure acting on the second control pressure port 56 by the pressure being approximately equal to the pressure acting on the control pressure port 56, the present invention is not limited to the above embodiment. Although not limited to this, the point is that if the switching valve performs the switching operation when the hydraulic pressure supplied to the first oil chamber 43 increases to a pressure almost equal to the hydraulic pressure acting on the second control pressure port 56. Therefore, for example, the elastic force of the spring that presses the spool 50 toward the second control pressure port 56 may be made extremely weak. Furthermore, the brake device of the present invention is not limited to the above-described embodiments, and can be used as a brake means for any appropriate gear transmission. Effects of the Invention As is clear from the above description, in the brake device of the present invention, when the second oil chamber is in communication with the drain, the oil pressure supplied to the first oil chamber is increased to a pressure almost equal to the shift signal oil pressure. By doing so, the switching valve is operated and the second oil chamber is communicated with the line hydraulic oil passage, so the timing when the line hydraulic pressure is supplied to the second oil chamber and the braking force by the brake band is increased is the timing at which the shift is completed. Therefore, it is possible to prevent a sudden increase in braking force from having an adverse effect on the shift shock. In addition, this invention can function as both a brake with unidirectional characteristics and a normal brake without unidirectional characteristics, so it is possible to control the timing of braking and braking release at a specific gear position. Therefore, it is possible to omit the one-way clutch disposed in parallel with the brake device, thereby simplifying the device, reducing its weight, and reducing its 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. Effects such as being able to simplify the configuration of the hydraulic control circuit can also be obtained.

[Brief explanation of drawings]

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, and FIG. FIG. 4 is a diagram showing temporal changes in pressure, brake torque, and output shaft torque. FIG. 4 is a skeleton diagram showing an example of a gear transmission for an automatic transmission into which the brake device of the present invention can be incorporated. FIG. FIG. 6 is a schematic diagram showing the principle of the brake device already proposed by the present applicant, and shows the pressure in each oil chamber, brake torque, and output shaft torque in a situation where a gear shift shock occurs due to inappropriate oil pressure supply timing. FIG. 3 is a diagram showing temporal changes. 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, 55
...First control pressure port, 56...Second control pressure port, 57...Control hydraulic oil passage, d1, d2...Diameter of face (of spool).

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 tangential direction of the rotating body is arranged in a position facing the anchor rod in the case, the push rod is attached to the piston of the fluid pressure cylinder, and the hydraulic cylinder and the anchor rod so as to move together, and a first oil chamber is formed on the opposite side of the hydraulic cylinder from the push rod across the piston, and the push rod is connected to the hydraulic cylinder so as to move together. A second oil chamber is formed in which the pressure receiving area of the fluid pressure cylinder on the opposite side is larger than the pressure receiving area of the first oil chamber of the piston, and further, when the fluid pressure cylinder retreats to the second oil chamber side, each oil A valve mechanism is provided that opens the chambers to communicate with each other, 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 A switching valve is connected to switch the second oil chamber to communicate with the line hydraulic oil passage and the exhaust pressure oil passage, and further the switching valve is configured to use the line oil pressure as the first control pressure and to apply a predetermined shift signal oil pressure. A second control pressure is set to oppose the first control pressure, and when the first control pressure increases to a pressure approximately equal to the second control pressure, it operates against the second control pressure to control the second oil chamber to the line. A brake device for an automatic transmission, characterized in that the brake device is configured to communicate with a hydraulic oil path.