JPH0112979B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in a hydraulic control system for an automatic transmission, and is intended to reduce shift shock caused by a friction element using a band brake. In conventional automatic transmissions for vehicles, different gears can be obtained by selectively operating a torque converter 1 and a plurality of friction elements, as schematically shown in FIG. It is comprised of a planetary gear transmission mechanism 2 configured as above, and a hydraulic control device for controlling these. As this planetary gear transmission mechanism 2, for example, the first
There is a Ravigneaux planetary gear set shown in the figure, and an input shaft 4 connected via a torque converter 1 to a crankshaft 3 driven by an engine (not shown) is connected to a clutch 5 and a clutch 6, and the output side of the clutch 5 is It is connected to a rear sun gear 8 via an intermediate shaft 7. Further, the output side of the clutch 6 is connected to a front sun gear 10 via a sleep shaft 9 fitted onto the intermediate shaft 7, and to a brake 11 constituted by a band brake equipped with a servo device. Furthermore, this Lavigneau type planetary gear device 2 is composed of a long pinion gear 13, a short pinion gear 14, and a ring gear 15, which are rotatably supported on a rotatably arranged planetary carrier 12. The front sun gear 10 meshes with the short pinion gear 14 and the ring gear 15, and the rear sun gear 8 meshes with the short pinion gear 1.
4, and the ring gear 15 is engaged with the output shaft 16.
is connected to. Also, planetary carrier 1
2 is connected to the transmission casing 18 via an unway clutch 17 and also to a brake 19, and furthermore, a brake 20 is provided on the input shaft 4 to stop the rotation of the input shaft 4. . By combining these clutch and brake operations, it is possible to achieve three forward speeds and one reverse speed as shown in Table 1. In addition, the ○ mark in the same table indicates engagement of the clutch or brake.

[Table] As is clear from the table, the brake 11 is engaged when the second speed is achieved, and the brake 11 is released when the third speed is achieved.The sleeve shaft 9 that is braked by the brake 11 When shifting from third speed to second speed, the brake drum 21 connected to the vehicle is decelerated from rotating in one direction and rotates in the completely opposite direction. For this reason, for example, when shifting from 3rd gear to 2nd gear, that is, when shifting from a high gear to a low gear while stepping on the accelerator, the characteristics of the band brake depend on the winding direction of the band brake and the rotating direction of the brake drum. Since the self-locking effect sometimes occurs and sometimes does not occur, it is difficult to determine the timing for engaging the brake 11. That is, if the brake 11 is engaged before complete synchronization, the shift shock will be large, and conversely, if the brake 11 is engaged after complete synchronization, the engine will overrun. Therefore, as shown in FIG. 2, by utilizing the fact that the reaction force applied to the brake band 11 is greatly different between the self-locking action and the anti-self-locking action that occur due to the relationship between the rotational direction of the brake band 11 and the brake drum 21, a completely synchronized state is achieved. A system has been proposed that detects this reaction force and controls the brake servo device (USP 3251245). In this device, an anchor part 22 and a servo part 23 are arranged so that the band brake 11 that brakes the brake drum 21 produces a self-locking action when the brake is engaged when shifting to a low gear. That is, in the illustrated example in which the brake drum 21 rotates counterclockwise in the third speed state and rotates clockwise after the second speed fully synchronized state, the brake band 11 is wrapped around the brake drum 21 from above. Sometimes brake band 11
The lower left end is used as an anchor part 22, while the lower right end is provided with a servo part 23. This anchor portion 22 has an anchor rod 25 that is slidable within a cylinder 24 and is urged by a spring 26 to protrude forward. The spring force of this spring 26 is set to be larger than the reaction force of the anti-self-locking action acting on the anchor rod 25, and smaller than the reaction force due to the self-locking action. The cylinder 24 also has an oil drain hole 27 and an oil supply hole 28 that open and close each other as the anchor rod 25 slides.
is formed. On the other hand, the servo section 23 has a servo piston 30 mounted in a servo cylinder 29, and a regulator valve 31 for hydraulic control is interposed between the anchor section 22 and the servo section 23. This regulator valve 31 is composed of a spool 32 with three lands and a spring 33 that urges it to the right, and a constant pressure of hydraulic oil (line pressure P _l ) is supplied between the two lands. At the same time, it is supplied to the right end surface of the spool 32 facing the spring 33 and sent to the engagement side hydraulic chamber 34 of the servo section 23, and further branched before the servo section 23 and sent to the oil supply hole 28 of the anchor section 22 via an orifice 35. It communicates with the spool 32 and acts on the spool 32 in cooperation with the spring 33. Therefore, for example, when a shift command is issued from the state in which the third speed is achieved to the second speed, the counterclockwise rotational speed of the brake drum 21 gradually decreases due to the operation of other friction elements, and the regulator valve 31
is supplied with line pressure P _l . In this state, an anti-self-locking action occurs in the brake band 11, so the anchor rod 25 is pushed forward, the oil drain hole 27 is opened, and the oil pressure downstream of the orifice 35 is approximately zero. Therefore, the hydraulic pressure supplied to the engagement-side hydraulic chamber 34 of the servo section 23 is low and regulated by the balance between the spring 33 and the hydraulic pressure acting on the spool 32, and the servo piston 30 reaches the initial engaged state position. be advanced. Then, when the rotational speed of the brake drum 21 decreases, passes through 0, and reverses (clockwise), a self-locking action occurs on the brake band 11 at this moment, and a large reaction force is applied to the anchor rod 25. Therefore, the anchor rod 25 is pushed against the spring 26 and the oil drain hole 2
7 is closed, the pressure downstream of the orifice 35 becomes the same as that upstream, and the line pressure P _l is also supplied to the engagement side hydraulic chamber 34 of the servo section 23, and the brake is engaged in a completely synchronized state to achieve the second speed. be done. In this way, a change in the rotational direction of the brake drum 21 is detected from a change in the reaction force acting on the brake band 11, and this moves the spool 32 of the regulator valve 31 to operate the servo piston 30, thereby controlling the speed change shock and the engine. Shifting without overrun can be achieved. However, in this conventional device, the servo piston 3
The supply of hydraulic oil to 0 is controlled by the balance between the spring 33 and the hydraulic pressure acting on the left and right end surfaces of the spool 32, and a large flow valve is used, which is large and has a complex structure. becomes. This poses an obstacle to miniaturization of the hydraulic control device of an automatic transmission, and has the disadvantage that the pressure regulation value is difficult to be influenced by the supply pressure and flow rate to the servo section. The present invention aims to eliminate such conventional drawbacks and provide a hydraulic control device for an automatic transmission which has a simple structure and does not cause overrun of the shift shock or engine. A brake band that engages the brake drum when a gear is achieved; an anchor portion that is connected to one end of the brake band; and an anchor that is connected to the other end of the brake band that uses hydraulic pressure to connect the band to the brake drum. a servo section having an engagement-side hydraulic chamber supplied with hydraulic pressure, and a first servo section communicating with a hydraulic pressure source.
A part of the oil in the first oil passage is disposed between the oil passage and a second oil passage communicating with the engagement side hydraulic chamber, and when the oil pressure in the first oil passage exceeds a predetermined value, a part of the oil in the first oil passage is a pressure regulating valve that discharges oil into a discharge oil passage and regulates the oil pressure of the second oil passage to a predetermined value, and a reaction force detection means that detects a reaction force of the brake band, and the reaction force detection means detects the reaction force of the brake band. In an automatic transmission configured such that when a reaction force of the band is detected, the hydraulic pressure supplied to the engagement side hydraulic chamber becomes equal to or higher than the predetermined value, when the reaction force detection means detects the reaction force, the oil pressure is discharged from the discharge oil path. valve means for closing the pressure regulating valve and stopping the pressure regulating function of the pressure regulating valve;
An orifice disposed in the first oil passage. Another object of the present invention is to provide a hydraulic control device for an automatic transmission that can reliably and quickly change gears in accordance with the gear shift timing, and has a structure in which the hydraulic control device is wound around a brake drum and is a brake band that engages the brake drum;
An anchor part connected to one end of the brake band, an engagement-side hydraulic chamber connected to the other end of the brake band to which hydraulic pressure is supplied when the band is engaged with the brake drum, and hydraulic pressure is discharged. a servo section having a release side hydraulic chamber; a first oil path disposed between a first oil path communicating with the hydraulic pressure source and a second oil path communicating with the engagement side hydraulic chamber; and the second oil passage communicate with each other, and a first hydraulic chamber for urging the valve body in a direction in which both the oil passages and the discharge oil passage communicate with each other, and the first and second oil passages. and a second hydraulic chamber provided with a biasing means for biasing the valve body in a direction in which communication with the discharge oil passage is cut off, when the hydraulic pressure of the first oil passage exceeds a predetermined value. a pressure regulating valve that discharges a portion of the oil in the first oil passage to a discharge oil passage and regulates the oil pressure in the second oil passage to a predetermined value; and a reaction force detection means that detects a reaction force of the brake band. In the automatic transmission, the automatic transmission is configured such that when the reaction force detection means detects the reaction force of the brake band, the hydraulic pressure supplied to the engagement side hydraulic chamber becomes equal to or higher than the predetermined value. Valve means for closing the discharge oil passage and stopping the pressure regulating function of the pressure regulating valve when the means detects a reaction force, and a third oil passage communicating between the release side hydraulic chamber and the second hydraulic chamber. and an orifice disposed in the first oil passage. Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 3 is a schematic diagram of an embodiment of the hydraulic control device for an automatic transmission according to the present invention. The brake drum 40 to be braked rotates counterclockwise in a high speed gear, and rotates clockwise after passing through a stop position when shifting to a low gear. The lower left end is an anchor part 42 so that a self-locking action occurs after the stop position during gear shifting.
On the other hand, the lower right end portion is a servo section 43. The anchor portion 42 is an anchor rod 44.
is slidably mounted within the cylinder 45, and the spring 4
6, it is urged to protrude forward.
The spring force of the spring 46 is set to a value greater than the reaction force generated by the anti-self-locking action of the brake band 41 and smaller than the reaction force caused by the self-locking action. Also,
The cylinder 45 is formed with an oil drain hole 47 and an oil supply hole 48, which are opened and closed by sliding of the anchor rod 44. On the other hand, the servo section 43 has a servo piston 50 mounted in a servo cylinder 49, and a relief type pressure regulating valve 51 is interposed between the anchor section 42 and the servo section 43. This relief valve 51 includes a spool 52 having two lands with different diameters and a third land.
The valve body is configured with a spring 53 that urges it to the right in the figure, and an oil drain passage communicates with the right end of the valve body.
A supply oil passage 55 is provided between the two lands and communicates with a hydraulic pressure supply source (for example, line pressure P _l ) via an orifice 54 . They are communicated through an oil passage 57. Further, an oil passage 58 communicating with the oil supply hole 48 of the anchor portion 42 is provided at a position that is opened and closed depending on the balance between the biasing force of the spring 53 acting on the spool 52 and the hydraulic pressure due to the difference in area between the two lands. With this configuration, for example, when the third speed is achieved and the brake drum 40 is rotating counterclockwise, when a shift command is issued to the second speed, the operation of the other friction elements and The rotational speed of the brake drum 40 gradually decreases. At the same time, line pressure P _l is supplied to the supply oil passage 55 of the relief valve 51 via the orifice 54.
This line pressure _Pl is regulated by the balance between the hydraulic pressure due to the area difference between the two lands and the biasing force of the spring 53, and the spool 52 is moved to the left to adjust the pressure. The oil is supplied to the engagement side hydraulic chamber 56 of the servo section 43 via the oil passage 57. Furthermore, in this state, only a small reaction force is generated in the anchor portion 42 due to the anti-self-locking action on the brake band 41, and since the anchor rod 44 is pushed forward by the spring 46, the oil supply hole 48 and the oil drain hole 47 are connected to each other. is in communication, and all the oil in the oil passage 58 is discharged. Therefore, low-pressure oil is supplied to the engagement side hydraulic chamber 56 of the servo piston 50 via the relief valve 51 due to the balance between the hydraulic pressure due to the area difference of the spool 52 and the biasing force of the spring 53, and the initial engagement position is reached. The servo piston 50 is moved toward. At the moment when the rotational speed of the brake drum 40 decreases from this state, stops, and then reverses (rotates clockwise), a self-locking action occurs on the brake band 41, and a correspondingly large reaction force is generated on the anchor portion 42. work. Therefore, the anchor rod 44 is connected to the spring 46.
The hydraulic pressure in the oil passage 58 increases to the line pressure P _{l, and the line pressure P l is} also applied from the oil passage 57 to the engagement side hydraulic chamber 56 of the servo piston 50. is supplied and the brake is immediately engaged. In this way, the rotational direction of the brake drum 40, that is, the completely synchronized state, is detected by the reaction force acting on the brake band 41, and the brake servo piston 50 is actuated thereby, so that the brake is engaged the moment the completely synchronized state is achieved. It is possible to smoothly shift from 3rd gear to 2nd gear without causing a shift shock or engine overrun. In addition, in this device, a relief valve is used as the pressure regulating valve 51, and the supply of hydraulic oil to the servo piston 50 is performed by this pressure regulating valve 51.
Since the pressure is regulated by discharging from the anchor portion 42 without allowing the inside to pass through, there is no need for a conventional large-flow type regulator valve, and the valve can be made smaller.
That is, while conventional large flow rate pressure regulating valves require at least nine elements on the valve body side, the pressure regulating valve 51 of the present device requires only seven elements, making it compact and lightweight, and requiring only a small installation space. Next, another embodiment of the present invention shown in FIG. 4 will be described. As described above, the device of the present invention can be made smaller and lighter by using a relief valve as the pressure regulating valve 51. Therefore, the pressure regulating valve 51 is housed in the servo piston 50 of the servo section 43 of the band brake instead of being installed in the valve casing 59 in which the hydraulic control device of the automatic transmission is incorporated. That is, a spool mounting hole 60 is formed perpendicular to the sliding direction of the servo piston 50, and the spool 52 is mounted therein, and an oil passage 57 is also formed in the servo piston 50. Further, the oil passage 58 that communicates the pressure regulating valve 51 and the oil supply hole 48 of the anchor part 42 is formed by forming a groove in the side surface of the valve casing 59 and covering this with a cover plate. Since it has the same configuration as the embodiment shown in FIG. 3, the same reference numerals will be used and the explanation will be omitted. With this configuration, it is possible to prevent overrun of the gear shifting shock and engine and achieve smooth operation by just slightly changing the servo piston 50, etc., without making major changes to the structure of the conventional automatic transmission or the structure of the hydraulic control device. Can change gears. Changes in the oil pressure P of the servo section, the output shaft torque T, the drum rotation speed N, and the piston stroke S in the first device of the present invention shown in the above two embodiments are shown in Fig. 5 a, b, and c. It becomes as shown in . That is, when a shift command is issued during a shift from 3rd speed to 2nd speed, the pressure P _O in the release side hydraulic chamber of the servo piston 50 gradually decreases from the high pressure state of line pressure P _l , and the pressure in the engagement side hydraulic chamber decreases. The pressure P _I is supplied as a low pressure by the action of the relief valve 51 described above, and after the oil pressure decreases with the stroke S of the servo piston 50, the pressure P _S corresponds to the strength of the spring 53 of the relief valve 51. On the other hand, the output shaft torque T decreases as the pressure P _O in the disengagement side hydraulic chamber decreases, and the rotational speed N of the brake drum 40 changes from the third speed rotation direction through a stopped state and reverses, but in the engagement side hydraulic chamber The supply pressure P _I to the relief valve 51
The line pressure is maintained at a low pressure and brought into an initial engagement state, and immediately after the anchor portion 42 detects the reversal, the line pressure is increased to P _l and the second speed is achieved. In such a device, if the amount of oil supplied to the engagement-side hydraulic chamber, which is regulated to a low pressure, is small, the amount of oil (i.e., the oil pressure and the time for which it is supplied) necessary for the initial engagement state cannot be secured. After the reversal at the anchor part 42, the brake drum 40 is immediately applied as line pressure.
The brake may not be applied in time and overrun may occur. This is because the accelerator is depressed for a kickdown, so if the braking of the brake drum is delayed, the planetary gear transmission shown in FIG. 1, for example, will be in the first speed state and overrun will occur. That is,
These are caused by a delay in the movement of the servo piston 50 because the pressure P _O in the release side hydraulic chamber decreases with a temporal gradient and the pressure P _I in the engagement side hydraulic chamber is also low. Therefore, as in the second device of the present invention shown in FIG. 6, a spring 53 of a relief valve type pressure regulating valve 51 is interposed between the brake anchor part 42 and the servo part 43. A hydraulic chamber is formed on the left end side of the spool 52, and this and the release side hydraulic chamber 61 of the servo cylinder 49 of the servo section 43 are communicated through an oil passage 62. The pressure P _O in the release side hydraulic chamber of the piston 50 is applied. Note that the other configurations are the same as in each of the above embodiments, so the same numbers are given to the same parts and the explanation will be omitted. With this configuration, the changes in the oil pressure P of the servo section, the output shaft torque T, the rotational speed N of the drum, and the piston stroke S are as shown in Fig. 7a,
It becomes as shown in b and c. That is, when a shift command is issued from the state in which the third speed is achieved to the second speed, the pressure P _O in the release side hydraulic chamber 61 of the servo piston 50 increases.
gradually decreases from the high pressure state of the line pressure P _l , and the pressure P _I in the engagement side hydraulic chamber 56 is supplied as a low pressure by the action of the relief valve 51. The pressure P _O on the release side pushes the spool 52 to the right. As a result, the pressure P _I on the engagement side gradually decreases to a value equal to the pressure P _O on the release side plus the pressure increase due to the biasing force of the spring 53, and the servo piston 50 is quickly stroked to the initial engagement state. After that, the pressure becomes equal to the strength of the spring 53 of the relief valve 51. On the other hand, the output shaft torque T is the pressure on the release side as in FIG.
The rotational speed N of the drum decreases as P _O decreases, and the rotational speed N of the drum reverses from the rotational direction of the third speed through a stopped state, but this reversal is detected by the anchor part 42 and the oil drain hole 47 is opened by the anchor rod 44. In order to close, the relief action at the relief valve 51 is stopped, and the pressure P _I on the engagement side rises to the line pressure, causing the brake band 41 to close.
is tightened to effect engagement. At the time of this engagement, a sufficient amount of oil (hydraulic pressure and holding time) is already supplied to stroke the servo piston 50 to the initial engagement position.
The brake is immediately engaged due to this oil pressure increase, and the second speed is achieved without causing overrun. In particular, with engines equipped with a turbocharger, the speed at which the engine revs up varies depending on the operating state of the turbocharger, but since the brakes are applied immediately after detecting a fully synchronized state, good shifting is achieved in all operating ranges. You get a feeling. In the device of the present invention, as in the embodiment shown in FIG. 4, the spool 52 may be installed in the spool device hole 60 in which the relief valve 51 is formed in the servo piston 50, which greatly changes the conventional structure. The device of the present invention can be constructed without the need to do so. Furthermore, the fourth
62 in the figure is an oil passage to be added. As described above in detail with the embodiments, according to the present invention, unnecessary oil is removed when the pressure introduced from the first oil path is regulated to a predetermined value and supplied to the second oil path. When the reaction force detecting means detects the reaction force of the brake band, the valve means closes the discharge oil passage that discharges the brake band, thereby stopping the pressure regulating function of the pressure regulating valve. Therefore, it is impossible for the pressure regulating valve to regulate the hydraulic pressure to the second oil path to a predetermined value, and as a result, the hydraulic pressure supplied to the engagement side hydraulic chamber of the servo section can be increased to engage the brake. . Further, since only the minimum amount of oil required is guided to the discharge oil path, there is no wastage of oil, and the servo section can be operated efficiently. Furthermore, according to the invention, the first
Since an orifice is installed in the first oil passage, the amount of oil introduced to the pressure regulating valve is relatively small, which not only allows the pressure regulating valve to be made smaller, but also prevents fluctuations in the oil pressure upstream of the orifice in the first oil passage. Even if this occurs, it is possible to more stably control the hydraulic pressure to the second oil passage leading to the engagement side hydraulic chamber of the servo unit. Furthermore, by providing a third oil passage that cooperates with the urging means between the release side hydraulic chamber of the servo part and the pressure regulating valve, the brake can be engaged more quickly and the shift feeling can be improved. .

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an automatic transmission, FIG. 2 is a schematic configuration diagram of a conventional hydraulic control device for an automatic transmission, and FIGS. A schematic configuration diagram and a sectional view of an embodiment of the control device, FIGS. 5a, b, and c are explanatory diagrams showing temporal changes in each part of the present invention shown in FIGS. FIGS. 7a, 7b, and 7c, which are schematic configuration diagrams of an embodiment of the hydraulic control system for the second automatic transmission of the present invention, are explanatory diagrams of changes over time in various parts of the embodiment shown in FIG. 6. In the drawing, 40 is a brake drum, 41 is a brake band, 42 is an anchor part, 43 is a servo part, 4
4 is an anchor rod, 47 is an oil drain hole, 50 is a servo piston, 51 is a pressure regulating valve, 52 is a spool, 53
54 is a spring, 54 is an orifice, 57 and 58 are oil passages, and 62 is an oil passage.

Claims (1)

[Scope of Claims] 1. A brake band that is wrapped around a brake drum and engages the brake drum when a specific gear is achieved, an anchor portion connected to one end of the brake band, and the other end of the brake band. a servo section having an engagement-side hydraulic chamber connected to the brake drum and to which hydraulic pressure is supplied when coupling the band to the brake drum; and a first oil passage communicating with the hydraulic pressure source communicating with the engagement-side hydraulic chamber. A part of the oil in the first oil passage is disposed between the second oil passage and the second oil passage when the oil pressure in the first oil passage exceeds a predetermined value. a pressure regulating valve that regulates the hydraulic pressure of the brake band to a predetermined value, and a reaction force detection means that detects the reaction force of the brake band, and when the reaction force detection means detects the reaction force of the brake band, the engagement side hydraulic chamber In the automatic transmission configured to make the hydraulic pressure supplied to the hydraulic pressure equal to or higher than the predetermined value, when the reaction force detection means detects a reaction force, the discharge oil passage is closed and the pressure regulation function of the pressure regulation valve is stopped. 1. A hydraulic control device for an automatic transmission, comprising: a valve means for controlling the oil pressure; and an orifice disposed in the first oil passage. 2. The hydraulic control device for an automatic transmission according to claim 1, wherein the pressure regulating valve is mounted within a servo piston of the servo section. 3. A brake band that is wrapped around a brake drum and engages the brake drum when a specific gear is achieved, an anchor that is connected to one end of the brake band, and an anchor that is connected to the other end of the brake band. a servo section having an engagement-side hydraulic chamber to which hydraulic pressure is supplied when the brake drum is engaged with the brake drum, and a disengagement-side hydraulic chamber from which the hydraulic pressure is discharged;
The first oil passage is disposed between a first oil passage communicating with the hydraulic pressure source and a second oil passage communicating with the engagement side hydraulic chamber.
a first hydraulic chamber for urging the valve body in a direction in which the oil passage and the second oil passage communicate with each other, and both oil passages and the discharge oil passage; a second hydraulic chamber provided with a biasing means for biasing the valve body in a direction in which communication between the oil passage and the discharge oil passage is cut off; A pressure regulating valve that discharges a portion of the oil in the first oil passage to a discharge oil passage and regulates the oil pressure in the second oil passage to a predetermined value when the oil pressure reaches a predetermined value; and a reaction force that detects the reaction force of the brake band. detecting means, and configured to increase the hydraulic pressure supplied to the engagement-side hydraulic chamber to the predetermined value or more when the reaction force detecting means detects the reaction force of the brake band. Valve means for closing the discharge oil passage and stopping the pressure regulating function of the pressure regulating valve when the reaction force detection means detects a reaction force, and a third valve means for communicating the release side hydraulic chamber and the second hydraulic chamber.
A hydraulic control device for an automatic transmission, comprising: an oil passage; and an orifice disposed in the first oil passage. 4. The hydraulic control device for an automatic transmission according to claim 3, wherein the pressure regulating valve is mounted within a servo piston of the servo section.