JPS641703B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic control device for an automatic transmission for a vehicle.

In general, automatic transmissions for vehicles often include friction elements that are commonly engaged across multiple gears, and the engagement force (torque capacity) of the friction elements
corresponds to the gear ratio in the gear stage, and in order to reduce drive loss and shift shock of the oil pump, a pressure reduction is provided in an oil path communicating between the hydraulic source and the friction element to reduce the pressure of the oil pressure supplied to the friction element. A valve was installed.

However, in the above configuration, when the friction element is released, the hydraulic pressure supplied to the friction element is discharged via the pressure reducing valve.
Due to some reason such as oil pressure leakage from another hydraulic circuit, the spool valve that makes up the pressure reducing valve stops at the oil pressure adjustment position, making it impossible to discharge oil pressure from the friction element. If the engagement is maintained or air flows into the hydraulic chamber of the servo device that operates the friction element, the air pressure will be compressed and the drop in hydraulic pressure will be delayed when the hydraulic pressure is discharged, causing a delay in the operation of the pressure reducing valve. As a result, the release of the friction element is delayed, resulting in problems such as gear shift shock.

In addition, as disclosed in Japanese Patent Application Laid-open No. 55-60747, a pressure reducing valve (low coast modulator 250) is installed in an oil path that communicates a hydraulic source with a friction element (brake 27) that is engaged at a specific gear stage. Even in a structure in which the hydraulic pressure supplied to the friction element is reduced by disposing the friction element, the same problem as described above occurs when the supplied hydraulic pressure is discharged.

The present invention has been proposed in view of the above, and includes:
Selectively engages and engages with a hydraulic source and hydraulic pressure from the same hydraulic source.
at least one friction element that achieves a gear position by being released; a switching valve that is provided between the friction element and the hydraulic pressure source and controls the supply and discharge of hydraulic pressure to the friction element; and the switching valve and the hydraulic pressure source. a pressure reducing valve provided between the friction element and the pressure reducing valve for reducing the pressure of the hydraulic pressure from the hydraulic pressure source supplied to the friction element, a first oil passage communicating between the pressure reducing valve and the friction element; and a second valve communicating with the pressure reducing valve and the switching valve.
A check valve is provided between the first oil passage and the second oil passage, the check valve being functionally interposed in parallel with the pressure reducing valve and allowing oil to flow only from the first oil passage to the second oil passage. Even if the pressure reducing valve stops at the oil pressure adjustment position or air flows into the servo device of the friction element and delays the operation of the pressure reducing valve, the air will be discharged from the friction element. Since the hydraulic pressure is guided to the switching valve via the check valve without passing through the pressure reducing valve, the hydraulic pressure is discharged smoothly from the friction element, and the friction element is not released or the release is delayed, resulting in gear shift shock. This is something that is prevented from happening.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3. The structure of the present invention is similar to the oil passage 11 in FIG.
This can be achieved by disposing a check valve that only allows oil to flow from the oil passage 119 to the oil passage 109 in functional parallel to the low coast modulator 250 between the oil passage 109 and the oil passage 109. Although it is a thing,
Here, a case in which the present invention is applied to a hydraulic control circuit of an automatic transmission that achieves four forward speeds and one reverse speed will be described.

Equipped with a main transmission and a sub-transmission that achieves two high and low gears, the sub-transmission is shifted only when the main transmission reaches the highest gear, resulting in a total of four forward and reverse gears. This figure shows a case in which the present invention is applied to a hydraulic circuit that supplies and discharges hydraulic pressure to the friction elements of the auxiliary transmission in a vehicle automatic transmission configured to achieve one gear shift.

In FIG. 1, a crankshaft 10 driven by an engine (not shown) is connected to a pump 16 of a torque converter 14 via a casing 12, and a stator 1 of the torque converter 14.
8 is connected to a transmission casing 22 via a one-way clutch 20. Further, the turbine 24 of the torque converter 14 is connected to a clutch 28 and a clutch 30 via an input shaft 26, and the output side of the clutch 28 is connected to an intermediate shaft 32.
The rear sun gear 36 of the first gear transmission mechanism 34 constituted by a Ravigneaux planetary gear device via
The output side of the clutch 30 is connected to a front sun gear 40 of the first gear transmission mechanism 34 via a sleeve shaft 38 fitted onto the intermediate shaft 32, and is also connected to a brake 42. The first gear transmission mechanism 34 includes the rear sun gear 36, the front sun gear 40, a long pinion gear 46 rotatably supported on a rotatably arranged planetary carrier 44, a short pinion gear 48, and a ring gear 50. , the long pinion gear 46 meshes with the front sun gear 40, the short pinion gear 48, and the ring gear 50, and the rear sun gear 36
is meshed with the short pinion gear 48, and a ring gear 50 is connected to the output member 52. The planetary carrier 44 is also connected to the transmission casing 22 via a one-way clutch 54 and to a brake 56.

The output member 52 has a chain sprocket 6.
A chain 66 is wound between the chain 4 and the chain 66.
The second gear transmission 60 includes a ring gear 68,
It is constituted by a simple planetary gear device having a pinion gear 72 and a sun gear 74 rotatably supported on a rotatably arranged planetary carrier 70, and its rotation center axis coincides with the rotation center of the first gear transmission. The input member 62 is arranged parallel to the axis, and the input member 62 is connected to a ring gear 68.
The output shaft 7 is connected to the planetary carrier 70.
6 are connected to each other, and a sun gear 74 is disposed on a sleeve shaft 78 that is fitted onto the output shaft 76 . Further, the sun gear 74 (sleeve shaft 78) is connected to the transmission casing 22 via a one-way clutch 80 and to a brake 82 as a friction element in the present invention, and furthermore, a clutch is connected between the sun gear 74 and the planetary carrier 70. 84 are arranged. Further, the output shaft 76 is provided with a gear 9 that meshes with a final reduction gear 90 for driving a drive axle 86 that is disposed substantially parallel to the coaxial shaft 76 via a differential gear 88.
2 is installed.

In addition, each one-way clutch 54, 80 mentioned above
In this case, it is possible to transmit the driving force that drives the output shaft 76 forward by the input shaft 26, but the output shaft 7
6 to the input shaft 26 (when the vehicle is decelerating), and in the case of reverse drive where the reaction force is in the opposite direction, the conventional structure was such that the driving force could not be transmitted. This is a known mechanical clutch.

Each of the clutches and brakes other than the one-way clutches 54 and 80 is provided with an engaging piston device or a servo device, and is engaged and released by supplying and discharging hydraulic pressure by a hydraulic control device. The first gear transmission 34 is configured to achieve three forward gears and one reverse gear by a combination of the operations of each clutch and brake, and the second gear transmission 60 is configured to achieve three forward gears and one reverse gear by a combination of the operations of each clutch and brake. By engaging the clutch 82 and fixing the sun gear 74, the first gear stage (deceleration) is achieved, and by engaging the clutch 84 and coupling the sun gear 74 and the planetary carrier 70, the second gear stage (direct coupling) is achieved. It is configured to achieve the following. Further, the hydraulic control device operates the clutch 84 of the second gear transmission 60 only when the first gear transmission 34 is in the high speed gear (directly connected), resulting in a total of 4 forward gears and 1 reverse gear.
The vehicle is configured to achieve a number of gears and includes a manual valve for limiting the number of gears achieved.

The table in Figure 2 shows the relationship between the operation of each of the clutches and brakes and the gear status at each position (each range) of the manual valve device. Indicates brake engagement and one-way clutch lock, “-”
Marks indicate their released or unlocked status.

The above-mentioned hydraulic control device includes a manual valve 94 as a switching valve in the present invention shown in FIG. A pump, a conventionally known pressure regulating valve that regulates the hydraulic pressure from the oil pump to a desired value, and a conventionally known pressure regulating valve that generates hydraulic pressure (throttle pressure P _t ) according to the engine load condition represented by the throttle valve opening. throttle valve, hydraulic pressure (governor pressure) according to vehicle speed
P _g ) is operated by the throttle pressure P _t , governor pressure P _g , line pressure P _L, etc., which generates 1st speed (1st) and 2nd speed (2nd speed) in Fig. 2. , and conventionally known 1-2 schematically shown in FIG.
It is comprised of a shift valve 103, a conventionally known 2-3 shift valve 105, and the like.

The line pressure P _L is configured to be guided to various parts of the hydraulic circuit via a manual valve 94, and the manual valve 94 is manually operated by a shift lever provided in the passenger compartment (not shown) to control the valve body. 104 by sliding inside the cylindrical hole 106,
It is equipped with a spool valve 108 that can take seven positions (seven ranges): P, R, N, D ₄ , D ₃ , 2, and L.
In addition to the oil passage 110 to which line pressure P _L is supplied, the cylindrical hole 106 has oil passages 112, 114, 11
6, 118, 120, 122, 124 and oil drain passages 126, 128 are communicated with each other, and a discharge opening 130 is provided, and the spool valve 108 is formed with a land 136 having a smaller diameter than the lands 132, 134 and the cylindrical hole 106. and spool valve 1
The oil passage 110 and each of the other oil passages are connected or disconnected depending on the displacement of the oil passage 08.

Note that, depending on the position of the spool valve 108, the oil passage located to the right of the land 134 in the figure is communicated with the opening 130 through a gap between the land 136 and the cylindrical hole 106. In addition, the P range of the above 7 positions is parking, R range is reverse, N range is neutral, and D ₄ range is 1st to 4th gear.
The _D3 range is an automatic shift drive for 1st to 3rd speeds, the 2nd range is an automatic shift drive for 1st and 2nd speeds, and the L range is selected when the vehicle speed is above a predetermined value. Then, the gear shifts to the second gear or the second gear is held, and when the value becomes lower than a predetermined value, the gear shifts to the first gear and is not shifted to the second gear again. It shows.

The 1-2 shift valve 103 is for switching between 1st speed and 2nd speed, and is used for shifting between D ₄ , D ₃ ,
When the gear is switched to the 2nd speed side due to the balance between the throttle pressure P _t and the governor pressure P _g in the 2nd range, the oil passage 11
8 and an oil passage communicating with the engagement side hydraulic chamber of the brake 42 (not shown in FIG. 3), and 2
-3 Line pressure is guided to the shift valve 105, and in the L range, the line pressure from the oil passage 124 is fixedly held on the 1st speed side, and the oil passage 124 and oil passage 1 are
37, and is configured to guide the line pressure P _L from the oil passage 112 to the oil passage 137 in the R range.

The 2-3 shift valve 105 is for switching between 2nd speed and 3rd speed, and shifts to the 2nd speed position depending on the balance between throttle pressure P _t and governor pressure P _g in the D ₄ and D ₃ ranges. If there is one above, 1-2 shift valve 1
The line pressure P _L from the oil passage 118 supplied through the oil passage 103 is guided to the oil passage 180, and when the gear is switched to the third speed side, the oil passage 118 and the oil passage 138 are connected through the 1-2 shift valve 103. Communication oil passage 138
It is configured to guide the line pressure P _L to the release side hydraulic chambers of the clutch 30 and the brake ₄₂ (not shown in FIG. 3), and to communicate the oil passage 180 with an oil drain passage. Furthermore, in the 2 or L range, the line pressure supplied from the oil passage 122
It is designed to be fixedly held on the second gear side from P _L.

Further, the oil passage 137 communicates with the brake 56 (not shown in FIG. 3) via a branch oil passage (not shown), and also communicates with the brake 82 via the ball valve 102 and the oil passage 139. Oil road 114
is communicated with the clutch 30 and also with a pressure regulating valve (not shown) to supply feedback hydraulic pressure for adjusting the line pressure P during reverse drive. The oil passage 116 communicates with a pressure regulating valve and a throttle valve that generates a throttle pressure _Pt so as to supply a feedback hydraulic pressure for adjusting the line pressure P _L during forward driving, and also communicates with the clutch 28.

Further, the oil passage 120 is communicated with a 3-4 shift valve 96, and the oil passage 122 is communicated with a pressure reducing valve 98. The 3-4 shift valve 96 is a valve device for switching between 3rd speed (3rd) and 4th speed (4th),
Two spool valves 142, 144 that slide in a cylindrical hole 140 bored in the valve body 104, and a spring 14 that presses both spool valves to the right in the figure.
In addition to the oil passages 120 and 138, the cylindrical hole 140 has an oil passage 148 to which the throttle pressure _Pt is supplied, an oil passage 150 to which the governor pressure _Pg is supplied, and a pressure reducing valve 98. An oil passage 152, an oil passage 154 connected to the clutch 84, and drain oil passages 156, 158, and 160 are in communication. The spool valve 142 has two lands 162, 164 having the same pressure receiving area, and both lands 162, 164.
A land 166 with a smaller pressure receiving area is formed, and two lands 168 and 170 with different pressure receiving areas are formed on the spool valve 144.
Both spool valves 142, 144 are moved to the left in the figure by the governor pressure _Pg supplied from the oil passage 150, and to the right in the figure by the throttle pressure _Pt supplied from the spring 146 and the oil passage 148. When the pressure is driven and the communication between the oil passages 138 and 154 is interrupted, and the line pressure P _L is supplied from the oil passage 120, both spool valves 14 are pressed, regardless of the magnitude of the governor pressure P _g .
2,144 is fixedly positioned to the right, the oil passage 138 is closed by the land 164, the oil passage 154 is communicated with the oil drain passage 158, and the line pressure P _L from the oil passage 120 is guided to the oil passage 152. It is configured as follows.

The pressure reducing valve 98 is connected to the 3-4 shift valve 9 from the oil passage 120 when the manual valve 94 is in the _D3 range.
6. This is for making the hydraulic pressure supplied to the brake 82 through the oil passages 152, 178, 139 lower than the line pressure P _L , and the valve body 104
The cylindrical hole 172 includes a spool valve 174 that slides in a cylindrical hole 172 and a spring 176 that presses the spool valve 174 to the right in the figure. An oil passage 178, an oil passage 180, and a drain oil passage 182 communicating with the other ball valve 102 are connected to the spool valve 17.
4 is formed with a land 184 having a large pressure receiving area and a land 186 having a small pressure receiving area.

As described above, the oil passage 180 is configured to be supplied with the line pressure P _L when the manual valve 94 achieves the second speed in the _{D3 range} . By spool valve 17
4 to the left in the figure against the pressing force of the spring 176, the oil passage 152 is closed by the land 186, and the oil passage 178 is communicated with the oil drain passage 182 to discharge the hydraulic pressure in the brake 82. It's getting old. This is achieved by releasing the brake 82 and operating the one-way clutch 80 in the second gear of the _D3 range, and by utilizing the function of the one-way clutch 80, especially from the second gear to the third gear, or from the third gear. This is to reduce shock when shifting from 2nd speed to 2nd speed.

The oil passage 152 and the oil passage 178 communicate with each other via a check valve 100, and the check valve 100 communicates with the oil passage 1.
It is interposed between both the oil passages 152 and 178 so as to allow only the flow of oil from the oil passage 78 to the oil passage 152. In the above configuration, when the manual valve 94 is set to the 2 range or the L range, the oil passage 110 is communicated with the oil passage 122 and furthermore the oil passage 124, and the 2-3 shift valve 105 and the 1-2 shift valve 10 are connected, respectively.
Since the line pressure P _L is supplied to No. 3 and both valves are fixedly positioned on the low-speed side, automatic shifting of only the first and second speeds or a state of being fixed at the first speed is achieved. In this case, line pressure is always applied to the oil passage 120.
Since P _L is supplied, hydraulic pressure is always supplied to the brake 82, but in this case, the oil passage 122
Line pressure P _L is supplied to the pressure reducing valve 98 from
Even if the speed is reached and line pressure is introduced from the oil passage 180, the spool valve 174 will not move to the left due to the pressing force of the spring 176), so the line pressure is not reduced to the oil passage 178 and the brake 82. Pressure P _L is supplied.

Next, when the above manual valve is set to _D3 range,
Oil passages 116, 118 and oil passage 120 are oil passage 110
As a result, the line pressure P _L is supplied to the 3-4 shift valve 96 through the oil passage 120, and both spool valves 142 and 144 are connected to the 3-4 shift valve 96 regardless of the vehicle speed (the magnitude of the governor pressure P _g ). It is fixedly held on the third speed side on the right side in the figure. Therefore, the oil passage 138 is blocked by the land 164 and the oil passage 15
4 is in communication with the oil drain passage 158, the clutch 84 is maintained in the released state, and the second gear transmission 60 is fixed at the deceleration gear, so that each gear is exclusively connected to the first gear transmission 34. This is accomplished by shifting. At this time, the line pressure P _L supplied from the oil passage 120 to the 3-4 shift valve 96 is further
52, pressure reducing valve 98, oil passage 178, ball valve 10
2. The oil is supplied to the brake 82 through the oil passage 139 to engage the brake 82 (however, when the second speed is achieved, the oil passage 180 is supplied as described above).
Since the line pressure P _L is supplied and the spool valve 174 is displaced to the left, the oil passage 178 is connected to the oil drain passage 18.
2, and the brake 82 is released. ), the line pressure P _L supplied to the brake 82 is reduced by the pressure reducing valve 98 so that the following relationship holds. That is, the hydraulic pressure supplied to the oil passage 178 is P, the pressure receiving area of the land 184 is S ₁ , and the land 18
When the pressure receiving area of the spring 176 is S ₂ and the pressing force of the spring 176 is F, the line pressure P _L is reduced to a hydraulic pressure P that satisfies the relationship F=P(S ₁ −S ₂ ).

For this reason, since the brake 82 is engaged with a relatively small torque capacity, especially the above-mentioned
The shift shock when shifting the manual valve 94 to the D ₃ range to achieve the 3rd speed from the state where the 4th speed is achieved in the D ₄ range is reduced, and the brake 82 does not have a torque capacity higher than necessary. This prevents increased wear on various parts of the transmission due to holding the gear. Further, since the driving force can be transmitted from the output shaft 76 to the input shaft 26, an engine braking effect can be obtained in the third speed.

In this case, since the torque capacity of the brake 82 is small, there is a possibility that the torque capacity of the brake 82 is insufficient especially during acceleration when the first speed is achieved, but the one-way clutch 80 is locked during the same acceleration. It can handle the driving force without any problems. Furthermore, the oil pressure P in the oil passage 178 that is supplied to the brake 82 is
The pressure becomes lower than the line pressure P _L in the check valve 100.
Since the check valve 100 maintains the closed state, the check valve 100 does not affect the supply of the hydraulic pressure P to the brake 82, the pressure reducing function of the pressure reducing valve 98, etc.

When the manual valve 94 is moved to the _D4 range from the state where the third speed of the _D3 range has been achieved,
The oil passage 120 is communicated with the opening 130 through the space between the land 136 of the spool valve 108 and the cylindrical hole 106, and the line pressure P _L supplied to the left end of the 3-4 shift valve 96 is discharged. . Therefore, when the vehicle speed is equal to or higher than a predetermined value, the spool valves 142 and 144 are moved to the left by the action of the governor pressure P _g , so that the oil passage 138 and the oil passage 154 are communicated, and a line is connected to the clutch 84. In addition to being supplied with the pressure P _L , the oil passage 152 and the oil discharge passage 156 are communicated with each other, and the hydraulic pressure that has been supplied to the brake 82 is discharged. In this case, the hydraulic pressure supplied to the brake 82 is
Since the oil is discharged through the oil passage 139, the ball valve 102, the check valve 100, and the oil passage 152, the spool valve 174 of the pressure reducing valve 98 may become stuck for some reason, or there may be a delay in the operation of the pressure reducing valve 98. Even if this occurs, the hydraulic pressure is discharged extremely smoothly by the action of the check valve 100, and the brake 8
2 remains in the engaged state, or a shift shock occurs due to a delay in release. Also, if the vehicle speed is below a predetermined value,
Even when the spools 142, 144 of the -4 shift valve 96 are not moved to the left fourth speed position, the oil passage 152 communicates with the opening 130 of the manual valve 94 via the 3-4 shift valve 96 and the oil passage 120. Because it is done,
Similarly to the above, the hydraulic pressure within the brake 82 is smoothly discharged.

When the manual valve 94 is set to the _D4 range, the oil passage 110 is communicated with the oil passages 116 and 118.
1-2 shift valve 103 and 2-3 shift valve 10
5, the line pressure P _L is selectively supplied to the clutches 28, 30 and brake 42 of the first gear transmission 34, and the transmission 34 is shifted, thereby shifting from the first to third speeds. gear is achieved,
During this time, the brake 82 and clutch 84 of the second gear transmission 60 are released, and the one-way clutch 80 (not shown) is locked to achieve a deceleration gear position where driving force can be transmitted, so that no gear change is performed. . Then, a state in which the first gear transmission 34 has achieved a high speed (third speed) gear position (a state in which the 2-3 shift valve 105 is displaced to the high speed side and line pressure P _L is supplied to the oil passage 138 ), when the vehicle speed further increases, the spool valves 142, 1 of the 3-4 shift valve 96 shift due to the pressing force of the governor pressure P _g .
44 is displaced to the left and the oil passages 138 and 144 are communicated with each other, line pressure P _L is supplied to the clutch 84 and the clutch 84 is engaged, thereby changing the gear stage directly connected to the second gear transmission 60. is achieved and the highest speed (4th speed) is achieved. In addition, in the _D4 range, simply releasing the clutch 84 from the 4th gear state causes the one-way clutch 80 to become locked again, allowing the gear position such as 3rd gear or 2nd gear to be achieved. There is no hydraulic pressure supplied to the brake 82 when each gear stage is achieved.

When the manual valve 94 is set to the R range, oil path 1
10 is communicated with oil passages 112 and 114, and the line pressure
P _L is supplied to the brake 82 via the oil passage 112, 1-2 shift valve 103, oil passage 137, ball valve 102, and oil passage 139, and is also supplied to the brake via an oil passage (not shown) branched from the oil passage 137. 56
Since the brakes 82, 56 and the clutch 30 are engaged, a reverse gear stage is achieved. In this case, the line pressure P _L supplied to the brake 82 is not reduced.

When the spool valve 108 of the manual valve 94 is set to the P range or the N range, the oil passage for supplying hydraulic pressure to each brake and clutch is connected to the oil drain passage 128, the opening 130, and the oil drain of other valves (not shown). Since all the brakes and clutches are released, the transmission enters a neutral state in which transmission of power from the input shaft 26 to the output shaft 76 is cut off.

As is clear from the above, according to the present invention, in a hydraulic control device for a vehicle automatic transmission configured to supply hydraulic pressure to a friction element via a pressure reducing valve, the oil passages upstream and downstream of the pressure reducing valve are connected to each other. Communication is made through the check valve, and when the hydraulic pressure is discharged from the friction element, it is configured to be performed through the check valve, so that there is no possibility that the pressure reducing valve may malfunction due to some reason such as stopping of operation. Also, since the hydraulic pressure of the friction element is reliably and smoothly discharged through the check valve, it is possible to reliably prevent the occurrence of a shift shock due to a delay in releasing the friction element.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the schematic structure of a power transmission section of an automatic transmission provided in one embodiment of the present invention, and FIG.
The figure is a table showing the relationship between the operation of each friction element in the power transmission section and the gear position status, and FIG. 3 is a hydraulic circuit diagram showing the configuration of the main part of an embodiment of the present invention. 82... Friction element, 96... 3-4 shift valve (switching valve), 98... Pressure reducing valve, 100... Check valve, 152...
Second oil passage, 178...first oil passage.

Claims (1)

[Claims] 1 A hydraulic source, a friction element that achieves at least one gear stage by selectively engaging with hydraulic pressure from the hydraulic source, and a friction element provided between the friction element and the hydraulic source and providing a friction element to the friction element. A switching valve that controls the supply and discharge of hydraulic pressure, and a pressure reducing valve that is provided between the switching valve and the frictional element and reduces the pressure of the hydraulic pressure from the hydraulic pressure source supplied to the frictional element, A first oil passage that communicates between the pressure reducing valve and the friction element, and a second oil passage that communicates between the pressure reducing valve and the switching valve.
A check valve is provided between the first oil passage and the second oil passage, the check valve being functionally interposed in parallel with the pressure reducing valve and allowing oil to flow only from the first oil passage to the second oil passage. Hydraulic control system for automatic transmissions for vehicles.