JP2666423B2 - Line pressure control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a line pressure control device for an automatic transmission.

2. Description of the Related Art An automatic transmission selects and operates a variety of friction elements such as a clutch and a brake by a line pressure to select a predetermined gear, and shifts to another gear by changing the operated friction element. If the engagement capacity of the friction element to be actuated, that is, the line pressure, does not correspond to the transmission power, the friction element slips and burns out or causes power loss, or a large engagement shock during shifting. Is generated.

Therefore, in general, for example, "RN" issued by Nissan Motor Co., Ltd.
As described in “4F02A and RL4F02A Automatic Transaxle Maintenance Manual” (A261C06), a pressure modifier valve that uses the engine load signal pressure (normal throttle pressure) as the base pressure is provided, and this valve reduces the engine load signal pressure. Normally, the pressure regulator valve was made to respond to the pressure modifier pressure thus produced, and this valve was used to regulate the line pressure to an appropriate value.

However, the line pressure adjusted in this manner is a pressure substantially proportional to the opening degree of the engine throttle, and becomes the minimum value at the time of requesting engine braking when the accelerator pedal is released. On the other hand, when the engine is braked, a large reverse driving torque may be input from the wheels. In this case, the friction element slips and the effect of the engine brake deteriorates, and the friction element is burned. This tendency becomes more remarkable because the band brake is engaged as a friction element at the time of the second speed engine braking, and this brakes the member rotating in the trailing direction.

Therefore, as described in the above document, the source pressure of the pressure modifier valve is switched from the throttle pressure to the line pressure in the engine brake range, so that the pressure regulator valve keeps the line pressure at a high constant value regardless of the engine load. Technology has been proposed.

(Problems to be Solved by the Invention) However, in such a conventional line pressure control device, the line pressure at the time of engine braking is defined by the other normal line pressure maximum values, and it is possible to freely change the line pressure independently. Can not. Therefore, if you want to change the line pressure during engine braking by changing the vehicle type, you must also change the line pressure to the maximum value during normal operation, and review the overall design of all elements on which line pressure acts. I'm sorry.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem by allowing the line pressure during engine braking to be freely changed without such a significant design change by changing the structure of the pressure modifier valve.

(Means for Solving the Problems) For this purpose, the present invention is to output the engine load signal pressure created by reducing the line pressure in the automatic transmission range of the automatic transmission, and to output the engine load signal pressure in the automatic transmission range of the automatic transmission. A switching valve that outputs an engine brake range pressure having the same value as the line pressure generated in the engine braking range, and an output of the switching valve as a base pressure, which is adjusted to a value corresponding to a pressing force of the elastic member. A pressure modifier valve that outputs as a pressure modifier pressure,
In an automatic transmission in which a line pressure created by a pressure regulator valve in response to the pressure modifier pressure is used as an operating pressure, a first pressure receiving surface for applying a source pressure in the same direction as a pressing direction of the elastic member; A second pressure receiving surface for applying the engine brake range pressure in a direction opposite to a pressing direction is provided on the pressure modifier valve. In the automatic transmission range, the second pressure receiving surface acts on the pressing force of the elastic member and the first pressure receiving surface. In the engine brake range, the pressure value determined by the pressing force based on the engine load signal pressure, the pressing force of the elastic member and the pressing force of the line pressure acting on the first pressure receiving surface and the second pressure receiving surface, respectively. The pressure modifier pressures are each adjusted to a constant value determined by.

(Operation) In the automatic transmission range, the pressure modifier valve uses the engine load signal pressure output from the switching valve as the original pressure,
The pressure modifier pressure is adjusted to a pressure adjustment value determined by the pressing force of the elastic member and the pressing force based on the engine load signal pressure acting on the first pressure receiving surface. In this case, the pressure modifier pressure depends on the engine load, and the line pressure regulated by the pressure regulator valve responsive to the pressure can be made to correspond to the engine load as required.

On the other hand, in the engine brake range, the line pressure is input to the pressure modifier valve as the original pressure, and in the engine brake range, the pressure modifier valve has an engine brake having the same value as the line pressure generated in the engine brake range output by the switching valve. With the range pressure as the original pressure, the pressure modifier pressure is adjusted to a constant value determined by the pressing force of the elastic member and the pressing force of the line pressure acting on each of the first pressure receiving surface and the second pressure receiving surface. In this case, the pressure modifier pressure corresponds to the line pressure, and the pressure regulator valve responsive thereto can maintain the line pressure at a high constant value as required.

The line pressure at the time of the engine braking has no effect on the line pressure at the normal time by changing the pressure receiving area on the second pressure receiving surface for applying the engine brake range pressure in the direction opposite to the pressing direction of the elastic member. Can be changed without any changes. Therefore, the line pressure during engine braking can be freely changed only by changing the dimensions of the pressure modifier valve partially, and at this time, there is no change in the normal line pressure, and the engine pressure is changed without any significant design change. The line pressure during braking can be changed, and the applicable range of the automatic transmission can be widened.

Also, by changing the pressure receiving area on the first pressure receiving surface for applying the original pressure in the same direction as the pressing direction of the elastic member,
The output pressure characteristic of the pressure modifier pressure changes, and the line pressure created by the pressure regulator valve in the automatic transmission range can be changed in accordance with various automatic transmissions.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 to 3 show an automatic transmission having a line pressure control device according to an embodiment of the present invention. FIG. 1 is a shift control hydraulic circuit, and FIG. 2 is a pressure modification for line pressure control in the same circuit. FIG. 3 is an enlarged sectional view of the valve, and FIG. 3 is a skeleton diagram of the gear transmission train.

First, the power train of FIG. 3 will be described.
-62047, a torque converter 3 for transmitting rotation from an engine output shaft E to an input shaft I, a first planetary gear set 1, a second planetary gear set 5, an output shaft O,
And various friction elements to be described later.

The torque converter 3 is driven by an engine output shaft E, and is also used for driving an oil pump O / P. A pump impeller 3P, which is fluid-driven by the pump impeller through an internal working fluid and transmits power to the input shaft I It is a normal lock-up torque converter that is constituted by a stator 3s placed on a fixed shaft via a runner 3T and a one-way clutch 7 to increase torque to the turbine runner 3T, and a lock-up clutch 3L is added to this. The torque converter 3 receives the supply of the working fluid from the release chamber 3R, and releases the lock-up clutch 3L and removes the engine power via the pump impeller 3P and the turbine runner 3T while the working fluid is removed from the apply chamber 3A ( In the converter state), the torque is transmitted to the input shaft I while increasing it.
Lock-up clutch while working fluid is removed from 3R
3L is engaged, and the engine power is transmitted to the input shaft I through the lock-up clutch (in a lock-up state) as it is. In the latter lock-up state, the slip of the lock-up torque converter 3 (relative rotation of the pump impeller 3P and the turbine runner 3T) is arbitrarily controlled (slip control) by reducing the working fluid rejection pressure from the release chamber 3R. can do.

The first planetary gear set 1 is a normal simple planetary gear set including a sun gear 1S, a ring gear 1R, a pinion 1P meshing with the sun gear 1S, and a carrier 1C rotatably supporting the pinion 1P,
The second planetary gear set 5 is also a simple planetary gear set including a sun gear 5S, a ring gear 5R, a pinion 5P, and a carrier 5C.

Next, the various friction elements will be described. The carrier 1C can be appropriately coupled to the input shaft I via the high clutch H / C,
The sun gear 1S can be appropriately fixed by a band brake B / B, and can be appropriately connected to the input shaft I by a reverse clutch R / C. The carrier 1C can be appropriately fixed by a multi-plate low reverse brake LR / B, and also prevents reverse rotation (rotation in the opposite direction to the engine) via a low one-way clutch LO / C. The ring gear 1R is integrally connected to the carrier 5C and is drivingly connected to the output shaft O, and connects the sun gear 5S to the input shaft I.
To join. Ring gear 5R is overrun clutch OR / C
Can be connected to the carrier 1C as appropriate, as well as a forward one-way clutch FO / C and a forward clutch F / C.
To the carrier 4C via. The forward one-way clutch FO / C connects the ring gear 5R to the carrier 4C in the reverse rotation direction (the direction opposite to the engine rotation) in a state where the forward clutch F / C is connected.

The high clutch H / C, the reverse clutch R / C, the low reverse brake LR / B, the overrun clutch OR / C, and the forward clutch F / C are each operated by supply of hydraulic pressure to perform the above-mentioned appropriate coupling and fixing. However, as shown in FIG. 1, the band brake B / B is a band having three chambers of a 2-speed servo apply chamber 2S / A, a 3-speed servo release chamber 3S / R, and a 4-speed servo apply chamber 4S / A. It shall be appropriately operated by the servo. That is, this band servo deactivates the band brake B / B when no hydraulic pressure is supplied to any of the three chambers, and activates the band brake B / B when hydraulic pressure is supplied only to the chamber 2S / A. When hydraulic pressure is also supplied to the 3S / R, the band brake B / B is deactivated, and when hydraulic pressure is also supplied to the room 4S / A, the band brake B / B is activated.

The power transmission train in FIG. 3 includes friction elements B / B, H / C, F / C, OR / C, L
By operating R / B, R / C in various combinations as shown in the following table, along with the appropriate operation of the friction elements FO / C, LO / C,
By changing the rotation state of the elements constituting the planetary gear sets 1 and 5, the rotation speed of the output shaft O with respect to the rotation speed of the input shaft I can be changed. As shown in the following table, four forward speeds and one reverse speed Gears can be obtained. In the following table, ○ indicates operation (inflow of hydraulic pressure), while △ indicates a friction element to be operated when engine braking is required. And while the overrun clutch OR / C is actuated as indicated by the △ mark,
The forward one-way clutch FO / C juxtaposed thereto is inactive, and the low one-way clutch LO / C juxtaposed thereto is inactive while the low reverse brake LR / B is operating.

FIG. 1 shows a hydraulic circuit for controlling the speed of the transmission train.
Pressure regulator valve 2, pressure modifier valve 4, manual valve 6, throttle valve 8, lock-up control valve 10, torque converter relief valve 12,
4-speed speed cut valve 14, 1-2 shift valve 16, 2-3 shift valve 18, 3-4 shift valve 20, 3-2 timing valve 22,
4-2 sequence valve 24, 4-2 relay valve 26, accumulation control valve 28, 2S / A accumulation 30, 3S / R accumulation 32, 4S / A accumulation 34, ND accumulation 36, overrun clutch pressure reducing valve 38, 3-2 Downshift valve 40, 1
Speed reducing valve 42, kick down modulator valve 44, and 2-
A three-throttle modulator valve 46, which is provided with the friction elements F / C, OR / C, LR / B, B / B, H / C, R / C and the governor valve inlet GOV.
/ IN, governor valve outlet GOV / OUT, oil pump O / P, oil pump feedback chamber O / P FB, lubrication unit LUB, torque converter 3 chambers 3A, 3R, oil cooler COOL Connect and configure. The network further includes an idle solenoid 48 and an OD inhibiting solenoid 50.

The oil pump O / P is driven by the engine as described above, but is of a variable displacement type having an oil pump feedback chamber O / P FB. The oil from the oil pump O / P is output to the line pressure circuit 52, and the pressure regulator valve 2 adjusts the oil to the line pressure according to the pressure modifier pressure from the pressure modifier valve 4 and the torque converter. Lubrication part via relief valve 12
The oil is supplied to the LUB and torque converter inlet circuit 54, and the excess oil is returned to the chamber O / P FB via the oil pump feedback circuit 56. Excess oil returned to this chamber reduces the capacity of the oil pump O / P, and minimizes this capacity to reduce the pump drive load.

The line pressure of the circuit 52 is the lock-up control valve 10,
It is supplied to the manual valve 6 and the kick down modulator valve 44. The lock-up control valve 10 is normally in the position shown in the drawing, and the oil of the circuit 54 is supplied to the chamber 3 of the torque converter 3.
After flowing through R and 3A, the torque converter 3 is set to the converter state by being directed to the oil cooler COOL. When the fourth-speed speed cut valve 14 selects the fourth speed (OD) and outputs the line pressure to the circuit 58 because the vehicle speed is higher than the set vehicle speed, the lock-up control valve 10 is raised in FIG. After flowing through the chambers 3A and 3R of the third unit, the torque converter 3 is locked to the oil cooler COOL. At this time, when the internal pressure of the torque converter is going to be higher than the set pressure, the torque converter relief valve 12 drains the circuit 54 to prevent breakage of the hydraulic circuit and deformation of the torque converter.

The manual valve 6 has a parking (P) range, a reverse (R) range, a neutral (N) range, an automatic shift (D) range, a second speed engine brake (II) range, or a first speed according to a driving mode desired by the driver. The engine is manually operated in the high speed engine brake (I) range, and the line pressure of the circuit 52 is output to the ports 6D, 6II, 6I, 6R according to the selected range. That is, in the P and N ranges, no line pressure is output to any of these ports, and only the port 6D in the D range, the ports 6D and 6II in the II range, and the ports 6D, 6II and 6I in the I range. Further, the line pressure is output only to port 6R in the R range.

The kick down modulator valve 44 sets the upper limit of the line pressure from the circuit 52 and outputs the line pressure to the circuit 60, which is input to the throttle valve 8. The throttle valve 8 outputs a throttle pressure (engine load signal pressure) corresponding to a spring force corresponding to the depression of an accelerator pedal to a circuit 62, and outputs the throttle pressure to a 2-3 throttle modulator valve 46, an accumulation control valve 28, and a shuttle valve 64 (pressure). Modifier valve 4) and 1-2
Supply to shift valve 16.

The line pressure output to the port 6D in the forward travel ranges D, II, and I of the manual valve 6 passes through the circuit 66, and the governor valve inlet GOV /
Supply to IN and accumulation control valve 28. The governor valve rotates with the transmission output shaft, and its rotation speed (vehicle speed)
Governor pressure corresponding to the
Output to the circuit 68 from V / out. The accumulator control valve 28 regulates the line pressure from the circuit 66 to a value corresponding to the throttle pressure (engine load) from the circuit 62, and uses this as the accumulator back pressure by means of the circuit 70 for the 2S / A accumulator 30,
4S / A accumulation 34 and ND accumulation 36.
The line pressure from the circuit 66 is used as the accumulator back pressure of the 3S / R accumulator 32.

Next, the shift operation will be described briefly.
Or any manual valve port 6 in the N range
No line pressure is output to D, 6II, 6I, and 6R, and all friction elements F / C, OR / C, LR / B, B / B, H / C, and R / C are deactivated. The transmission train of FIG. 3 does not transmit power, and enables parking and stopping.

D range In the state where the manual valve 6 is set to the D range in order to request automatic shifting traveling, automatic shifting is performed as follows.

(1st speed) In this D range, manual valve 6 is connected to port 6D and circuit 66
Only the line pressure is output as the D range pressure. This line pressure is supplied to the forward clutch F / C via the one-way orifice 72 and is engaged. The operating oil pressure is restricted by the ND accumulator 36 at the rising speed, and the engagement shock of the forward clutch F / C (select shock)
Can be alleviated. On the other hand, when the D range was initially selected, the vehicle speed was low, and the governor pressure of the circuit 68 was low, so that the shift valves 16, 18,
20 cannot be lowered from the illustrated downshift position in the figure.
Thus, all other friction elements are deactivated, and the transmission train of FIG. 3 can select the first speed and start the vehicle as is evident from Table 1.

(Second speed) When the vehicle speed increases after the start and the governor pressure from the circuit 68 to the 1-2 shift valve 16 exceeds the set value for each throttle pressure from the circuit 62 to the 1-2 shift valve 16, 1-2 The shift valve 16 is lowered from the illustrated downshift position to the upshift position in the figure. At this time, the 1-2 shift valve 16 outputs the D range pressure of the circuit 66 to the circuit 74 as a second speed, which is passed through the one-way orifice 76 and the 2S / A accumulator 30 to the band 2B of the band brake B / B. / A is supplied and the band brake B / B is engaged. Therefore, in the transmission train of FIG. 3, the band brakes B / B are engaged in the forward clutch F / C engagement state,
The shift from the high speed to the second speed can be performed. At this time, the band brake engagement pressure is limited in the ascending speed by the one-way orifice 76 and the 2S / A accumulator 30, so that the shift shock accompanying the engagement of the band brake can be reduced.

(Third speed) The vehicle speed further increases, and the governor pressure from the circuit 68 to the 2-3 shift valve 18 changes from the circuit 62 to the 2-3 shift valve 18 via the 2-3 throttle modulator valve 46 and the circuit 78. When the pressure exceeds the set value for each pressure, the 2-3 shift valve 18 also moves downward from the illustrated downshift position to the upshift position. At this time, the 2-3 shift valve 18 outputs the second speed pressure of the circuit 74 as the third speed pressure to the circuit 80, and the third speed pressure is connected to the high clutch H / C via the one-way orifice 82 and is engaged. , On the other hand, one-way orifices 82, 84 and 3
Through the S / R accumulation 32, the band brake B / B is released to the room 3S / R of the band brake B / B. Therefore, in the transmission train of FIG. 3, the forward clutch F / C is engaged, the high clutch H / C is engaged, and the band brakes B / B are released.
The shift from the third speed to the third speed can be performed. At this time, the band brake release pressure is limited in rising speed by the one-way orifice 82 and the 3S / R accumulator 32, so that shift shock can be reduced.

(Fourth speed) When the vehicle speed further increases and the governor pressure from the circuit 68 to the 3-4 shift valve 20 exceeds the set value for each throttle pressure from the circuit 62 to the 3-4 shift valve 20, the 3-4 shift is performed. The valve 20 is also lowered from the illustrated downshift position to the upshift position in the figure. At this time, the 3-4 shift valve 20 outputs the second speed pressure of the circuit 74 to the circuit 86 as the fourth speed pressure, and this fourth speed pressure passes through the one-way orifice 88 to reach the band 4S / A of the band brake B / B and the band Engage brake B / B. Therefore, in the transmission train shown in FIG. 3, the band brake B / B is also engaged in a state where the forward clutch F / C and the high clutch are engaged, so that the shift from the third speed to the fourth speed can be performed. At this time, the band brake engagement pressure rises while the 4S / A accumulator 34 is being stroked, and the rising speed is limited by the presence of the one-way orifice 88, so that the shift shock can be reduced.

The 4 → 2 downshift when the driver depresses the accelerator pedal greatly in the fourth speed selection state and the throttle pressure from the circuit 62 is increased thereby will be described.
The throttle pressure which has become high when the pedal is depressed reaches the 2-3 shift valve 18 and the 3-4 shift valve 20 from the circuits 62 and 78, and switches these shift valves from the upshift position to the downshift position shown in the figure. By this switching, the 3-4 shift valve 20
Tries to eliminate the fourth speed pressure from the circuit 104 to the chamber 4S / A of the band brake B / B from the circuit 86. So 4
-2 sequence valve 24 directs third speed of circuit 80 (pressure to chamber 3S / R and high clutch H / C) by circuit 106,
In the figure, the circuit 104 is connected to the circuit 108, the 2-3 shift valve 18 is switched to the downshift position, the circuit 108 is connected to the circuit 110, and the 4-2 relay valve 26 is connected.
Is lowered by the fourth speed pressure from the circuit 86 in the figure, so that the fourth speed pressure to the circuit 104 is not eliminated because the fourth speed pressure to the circuit 104 is not eliminated. -2
The pressure is maintained by the second speed pressure from the circuit 74 via the sequence valve 24. On the other hand, the switching of the 2-3 shift valve 18 to the above-described downshift position allows the third speed pressure of the circuit 80 to be removed without delay from its own drain port. With this elimination, the 4-2 sequence valve 24 is no longer supplied with the third speed pressure from the circuit 106 and strokes to the position shown in the drawing to drain the fourth speed pressure to the circuit 104. Therefore, in the shift, the fourth speed (pressure of the chamber 4S / A) is eliminated after the third speed (pressure of the chamber 3S / R and pressure of the high clutch H / C) is released. Prevents the gear from slipping out of the latter pressure and shifting from 4 → 3 → 2, making sure that the 4 → 2 jump shift is performed, enabling sufficient acceleration corresponding to a large depression of the accelerator pedal I do.

(OD prohibition) While driving in the 4th speed, the driver desires to prohibit the 4th speed (OD) and turns on the OD prohibition solenoid 50 by turning on the OD prohibition switch.
When it is turned on and closed, the D range pressure of the circuit 66 is output to the circuit 90 as the OD prohibition pressure. The OD prohibition pressure reaches the 3-4 shift valve 20 via the shuttle valve 92 and the circuit 94, and is connected to the plug 96. Return to downshift position via Thus, the transmission train is
Is connected to the circuit 104, and the fourth speed pressure is supplied from the circuits to the 4-2 sequence valve 24 (upper position in the figure at the third speed pressure from the circuit 106).
And the gear is removed via the 2-3 shift valve 18 in the upshift position, so that it is forcibly returned to the third speed selection state. At this time, the plug 96 outputs the D range pressure of the circuit 66 to the circuit 98, and then supplies this D range pressure to the overrun clutch OR / C under reduced pressure via the overrun clutch pressure reducing valve 38 and the circuit 100. To conclude. As a result, the transmission train may be in the third speed and the engine brake may be effective. By the way, the overrun clutch pressure reducing valve 38 receives the fourth speed pressure of the circuit 104 at the left end in the figure, and does not output the D range pressure from the circuit 98 to the circuit 100 until the fourth speed pressure is completely removed and the third speed is reached. Delay the execution of the run clutch OR / C. Therefore, it is possible to prevent the overrun clutch from being engaged before the shift from the fourth speed to the third speed is completed, thereby preventing the transmission train from interlocking.

II range If the driver wants to run the engine in the 2nd speed and drives the manual valve 6 to the II range, this manual valve outputs the line pressure from port 6II in addition to port 6D,
This is supplied to the circuit 102 as the II range pressure. This II range pressure is supplied to the 2-3 shift valve 18 on the one hand and to the 3-4 shift valve 20 via the shuttle valve 92 and the circuit 94 on the other hand, and these shift valves 18 and 20 are moved to the downshift position shown in the figure. To hold. As a result, the transmission train selects the second speed or the first speed according to the position of the 1-2 shift valve 16, and prohibits the high speed stages higher than the third speed. Then, at this time, the plug 96 of the 3-4 shift valve 20 engages the overrun clutch OR / C in the same manner as described above for OD prohibition, thereby enabling the engine brake running at the second speed.

Here, a description will be given of a 4 → 2 downshift when the driver needs abrupt engine braking in the fourth speed selection state and switches the manual valve 6 from the D range to the II range. At the time of this switching, the manual valve port 6
The range pressure switches the 2-3 shift valve 18 and the 3-4 shift valve 20 from the upshift position to the illustrated downshift position, respectively, as described above. By this switching, the 3-4 shift valve 20
Passes the fourth speed pressure from the circuit 86 to the chamber 4S / A of the band brake B / B to the circuit 104 and to the 4-2 sequence valve 24. The 4-2 sequence valve 24 is now in the position shown, conducting the II range pressure of the circuit 102 and passing the circuit 104 through its own drain port to quickly relieve the 4th pressure to the circuit 104. . In this way, the fourth-speed pressure in the circuit 104 is quickly eliminated, and the over-clutch pressure-reducing valve 38 receiving this at the left end in the figure is supplied with the II range pressure of the circuit 102 at the right end. Fasten the overrun clutch OR / C. On the other hand, the switching of the 2-3 shift valve 18 to the above-described downshift position allows the third speed pressure of the circuit 80 to be removed without delay from its own drain port, and the band brake B / B is maintained in the engaged state. Therefore, even if the fourth speed pressure is quickly removed as described above, the overrun clutch OR / C is quickly engaged, and the transmission train is momentarily neutralized by this and the holding of the band brakes B / B. Thus, it is possible to reliably prevent a shift from 4 to 3 to 2 and to compensate for a 4 to 2 jump shift to obtain a desired large engine brake by switching the range.

I range When the driver wants to perform engine braking at the first speed and sets the manual valve 6 to the I range, the manual valve outputs the line pressure from the port 6I in addition to the ports 6D and 6II, and outputs the line pressure from the port 6I. It is supplied to the circuit 112 as a range pressure. The D range pressure and the II range pressure from ports 6D and 6II reach the same locations as described above. D range pressure is forward clutch
F / C is engaged and II range pressure is 2-3 shift valve 18 and 3-
The fourth shift valve 20 is held at the illustrated downshift position to prohibit selection of the third speed and the fourth speed, and the overrank rack OR / C is engaged. After the I range pressure to the circuit 112 is reduced to an appropriate value by the first speed pressure reducing valve 42, the 1-2 shift valve 16 acts to oppose the governor pressure from the circuit 68, and
Thereafter, the low reverse brake LR / B is reached via the circuit 114 and the shuttle valve 116 and is engaged. 1-2 shift valve 16
At low vehicle speed when the governor pressure of the circuit 68 is low,
The circuit is maintained at the downshift position shown by the range pressure.
The D range pressure of 66 is not output to the circuit 74, and the engine brake running at the first speed is enabled. Thus, the 1-2 shift valve 16 at the time of high vehicle speed where the governor pressure of the circuit 68 is high is lowered in the figure to the upshift position against the reduced I-range pressure.
The D range pressure of 66 is output to the circuit 74 as the second speed pressure, and the second speed is selected to prevent the engine from over rotating.

R Range When the driver desires the reverse and sets the manual valve 6 to the R range, this manual valve outputs the line pressure to only the port 6R as the R range pressure. This R range pressure reaches the reverse clutch R / C via the circuit 118 and the one-way orifice 120 on the one hand and engages it, and reaches the low reverse brake LR / B via the circuit 118 and the shuttle valve 116 on the other hand and engages it. By doing so, the reverse gear can be selected. Note that the engagement pressure of the reverse clutch R / C reaches the 4S / A accumulation 34 by the circuit 122, and the stroke speed thereof is limited, so that the ascending speed is limited, so that the select shock accompanying the engagement of the reverse clutch R / C can be reduced.

Next, the pressure modifier valve 4 according to the line pressure control device of the present invention will be described in detail. As shown in FIG. 2, this valve is constituted by abutment of a plug 151 and a spool 152. The plug 151 is inserted into the valve body 154 via an exchangeable sleeve 153, and the spool 152 is connected to the valve body.
Insert directly into 154. Plug 151 is a stepped with a feedback pressure receiving surface diameter portion 151 _a (the diameter d ₁₎ and the second large diameter part 151 _b (diameter d ₄₎ is a pressure receiving surface, pressure modifier is output to the small diameter portion feeding back the pressure P _MF, circuit 102 with the step portion between the small-diameter portion 151 _a and the large diameter portion 151 _b
The line pressure P _L (II range pressure) to act in the same direction presses the plug 151 to the spool 152. This reacted with the spring 155 to the spool 152 so as to face the spool 152 to the large diameter portion (diameter d ₂₎ the end 152 _a close to the plug 151 is a first pressure receiving surface, the remainder (diameter d ₃₎ to form a spool groove 152 _b. The spool groove 152 _b output circuit 15 to output circuit 156 through the original pressure circuit 157 according to the stroke of the spool 152
The pressure modifier pressure P _MF from 6 is increased, or the pressure modifier pressure P _MF is decreased by passing the output circuit 156 to the drain port 158. Circuit 157
The original pressure exerts the pressing direction in the same direction of the spring 155 from the circuit 159 to the large diameter portion 152 _a.

1, the main pressure circuit 157 is connected to the output port of the shuttle valve 64, and the input port of the shuttle valve 64 is connected to the II range pressure circuit 102 and the throttle pressure circuit 6 as described above with reference to FIG.
Connect 2.

The operation of the pressure modifier valve will be described next. The line pressure P _L (II range pressure) is not output to the circuit 102 outside the II and I ranges (engine brake range). Therefore, only the throttle pressure P _TH from the circuit 62 is input to the circuit 157 as the original pressure to the pressure modifier valve 4, and the balance equation of the force is obtained by applying the spring force of the spring 155 to F _M
Then Becomes Since the throttle pressure P _TH is as shown by the dotted line in FIG. 3, this equation (1) is expressed as shown by the one-dot chain line in FIG. Therefore, the pressure modifier pressure P _MF output from the circuit 156 is as shown by the solid line in FIG. 4 except for the engine brake range.

This pressure P _MF corresponds to the pressure regulator valve 2 in FIG.
While being subjected to the control of the supplied line pressure in, wherein the modifier in the pressure regulator valve 2 A pressure P _MF
The pressure receiving area A _M of the spring force F _L of the pressure regulating spring acting in the direction of cooperation with this, the pressure receiving area of the line pressure P _L to be fed back to the opposing direction when the A _L, the line pressure P _L Is Substituting equation (1) into equation (2), the line pressure P _L
Can be obtained by the following equation.

Accordingly, the line pressure P _L is as shown by a two-dot chain line in FIG. 4, and the engagement capacity of the friction element can be kept within a suitable range by approximating the engine output characteristic with respect to the throttle opening.

In other words, by changing the pressure receiving area of the large-diameter portion 152 _a (the diameter d _2), pressure modifier pressure P output pressure characteristics of the _MF are changed, particularly I, II range pressure regulator valve in addition (braking range) 2 can be modified to suit a is produce line pressure P _L to the various automatic transmissions.

In the II and I ranges (engine brake range), the line pressure P _L (II range pressure) is output to the circuit 102. Since this line pressure P _L is higher than the throttle pressure P _TH ,
The shuttle valve 64 is switched and supplied to the circuit 157 as the original pressure, and also supplied to the circuit 159.
Also supplied to 51 _b. At this time, the balance formula of the force applied to the pressure modifier valve 4 is Becomes Therefore, the line pressure P _L is assumed (4) (2) such as the following equation by substituting the equation.

Therefore, the line pressure P _L in the engine braking range becomes as shown by the two-dot chain line in FIG. 5, becomes as shown by a solid line in FIG pressure modifier pressure P _MF to source pressure it. For this reason, a sufficient line pressure is secured even during the engine braking operation performed by releasing the accelerator pedal (throttle opening 0), and at this time, the band brake B / B which needs to brake the member rotating in the trailing direction is also provided. All the friction elements, including the one, can secure a sufficient fastening capacity and do not slip.

Also, (5) a method of changing the line pressure during engine braking a diameter d ₄ that is not involved in the normal line pressure at the time indicated by (3) represented by the formula, it can be freely changed. Therefore, normal line pressure whatever can change the line pressure level during engine braking without affecting, can be implemented by only this change changes significant design without changing the diameter d _4, the automatic transmission The range of application of the machine can be widened. As this time the second view, and set to the spool 152 and a separate plug 151 parts of pressure regulating diameter d _4, the valve body 1 via an exchangeable sleeve 153 the plug
If interposed 54, the valve body by exchanging the plug 151 and sleeve 153 with items of different diameters d ₄ a set
The 154 is advantageous because the line pressure can be changed during engine braking as it is.

In the hydraulic circuit of FIG. 1, the line pressure is maintained at the characteristic shown in FIG. 5 in the engine brake range, and the line pressure during the 1 → 2 shift after engine braking in the range is too high, causing a large shift shock. There are concerns. However, during the shift, the accumulator back pressure of the 2S / A accumulator 30 corresponding to the accumulator control valve 28 is set to a value corresponding to the throttle pressure, and the 2S / A accumulator 30 performs the same 1 → 2 shift as the D range. Therefore, no large shift shock occurs. Moreover, the accumulation control valve
28 is not specially added, N → D accumulation
This is originally necessary in connection with the 36, 4S / A accumulation 34, etc., and does not substantially increase the number of valves.

On the other hand, in the automatic transmission described in the above-mentioned document “Maintenance manual for automatic transaxle of RN4F02A type and RL4F02A type,” the first time in the engine brake range,
When the speed is increased, a special backup valve is added to return the original pressure of the throttle modifier valve from the line pressure to the throttle pressure, thereby returning the line pressure to the normal line pressure control and shifting from 1 to 2 in the engine brake range. Measures were taken to mitigate the shock. For this reason, conventionally, it has been necessary to add a dedicated valve for this measure. However, in the hydraulic circuit of FIG. 1, it is not necessary to add a dedicated valve as described above, and the number of valves can be reduced.

(Effects of the Invention) Thus, as described above, the device of the present invention uses the source pressure of the pressure modifier valve as the engine load signal pressure output from the switching valve in the automatic transmission range,
The pressure modifier pressure is adjusted to a pressure adjustment value determined by the pressing force by the engine load signal pressure acting on the first pressure receiving surface. In the engine brake range, the line pressure generated in the engine brake range output by the switching valve and the line pressure generated by the switching valve are adjusted. Using the same value of the engine brake range pressure as the original pressure, the pressure modifier pressure is set to a constant value determined by the pressing force of the elastic member and the pressing force by the line pressure acting on each of the first pressure receiving surface and the second pressure receiving surface. Since the pressure is adjusted, the line pressure during engine braking affects the line pressure during normal operation by changing the pressure-receiving area on the second pressure-receiving surface that applies the original pressure in the direction opposite to the pressing direction of the elastic member. Can be freely changed without the need for a major design change, and the range of use of the automatic transmission can be expanded. .

Also, by changing the pressure receiving area on the first pressure receiving surface for applying the original pressure in the same direction as the pressing direction of the elastic member,
The output pressure characteristic of the pressure modifier pressure changes, and in particular, the line pressure created by the pressure regulator valve in the automatic transmission range can be changed according to various automatic transmissions.

According to the configuration of the second aspect, the line pressure at the time of the engine braking can be changed without changing the valve body only by replacing the plug and the sleeve as a set, and the operation can be easily performed. Cost reduction can be achieved by using a common valve body.

[Brief description of the drawings]

FIG. 1 is a shift control hydraulic circuit diagram of an automatic transmission showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a pressure modifier valve in the hydraulic circuit, and FIG. 3 is transmission of the automatic transmission. FIG. 4 and FIG. 5 are diagrams showing line pressure control characteristics of the device of the present invention for each range. 2 Pressure regulator valve 3 Torque converter 4 Pressure modifier valve 6 Manual valve 8 Throttle valve 10 Lock-up control valve 12 Torque converter relief valve 14 4-speed speed cut Valve 16: 1-2 shift 18: 2-3 shift valve, 20: 3-4 shift valve 22: 3-2 timing valve, 24: 4-2 sequence valve 26: 4-2 relay valve 28 Accumulation control valve 30 Accumulation 2S / A, 32 Accumulation 3S / R 34 Accumulation 4S / A, 36 Accumulation 38 ND Accumulation 38 Overrun clutch pressure reducing valve 40 3-2 Downshift valve 42 ... 1st speed reducing valve 44 ... Kick down modulator valve 46 ... 2-3 Throttle modulator valve 48 ... Idle solenoid 50 ... OD prohibiting solenoid, 52 ... Line pressure circuit F / C ... … Forward clutch OR / C …… Overrun clutch LR / B …… Low reverse brake B / B …… Band brake, H / C …… High clutch R / C …… Reverse clutch 62 …… Throttle pressure circuit, 64… ... Shuttle valve 102 ... II range pressure circuit, 151 ... Plug 152 ... Spool, 153 ... Sleeve 154 ... Valve body

Claims (2)

(57) [Claims] In an automatic transmission range of an automatic transmission, an engine load signal pressure generated by reducing a line pressure is output,
In the engine brake range of the automatic transmission, a switching valve that outputs an engine brake range pressure having the same value as the line pressure generated in the engine brake range, and the output of the switching valve is used as a base pressure, which is used as a pressing force of the elastic member. A pressure modifier valve that regulates the pressure to a value corresponding to the pressure modifier and outputs the pressure as a pressure modifier pressure, wherein the automatic pressure and the line pressure created by the pressure regulator valve in response to the pressure modifier pressure are used as the operating pressure. A first pressure receiving surface for applying an original pressure in the same direction as the pressing direction of the elastic member, and a second pressure receiving surface for applying the engine brake range pressure in a direction opposite to the pressing direction are provided on the pressure modifier valve. In the automatic transmission range, the pressing force of the elastic member and the first
In the engine brake range, the pressure applied to the elastic member and the first pressure receiving surface and the second pressure receiving surface act on the pressure adjustment value determined by the pressing force by the engine load signal pressure acting on the pressure receiving surface. A line pressure control device for an automatic transmission, wherein a pressure modifier pressure is adjusted to a constant value determined by a pressing force based on a line pressure. 2. The pressure modifier valve according to claim 1, wherein said pressure modifier valve applies a pressing force of said elastic member to a spool provided with said first pressure receiving surface, and causes said spool to return to said pressure modifier pressure feedback pressure receiving surface and said second pressure receiving surface. 2. A line pressure control device for an automatic transmission according to claim 1, wherein said plug is inserted into said valve body via a replaceable sleeve, while being abutted against said plug provided with said pressure receiving surface. .