JP2958957B2 - Engagement control device for friction element for engine brake in automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for engaging a friction element for engine braking of an automatic transmission with good timing.

(Prior Art) Automatic transmissions selectively hydraulically actuate various friction elements such as clutches and brakes to select a predetermined gear position. However, since the transmission train uses a planetary gear set, gear positions other than the highest speed are selected. When the engine brake is selected to make the engine brake effective, it is necessary to separately engage the engine brake friction element.

In the gear train of the RE4RO1A type automatic transmission (see the maintenance procedure) in practical use by the present applicant, the overrun clutch corresponds to a friction element for engine braking. By the way, when the overrun clutch is engaged in the state where the highest speed (4th speed) is selected, the gear transmission train enters an interlock state. Therefore, when the overrun clutch is engaged with the engine brake operating pressure, the engine brake is engaged. It is necessary to engage the overrun clutch after the shift valve for selecting the highest-speed gear (3-4 shift valve) brought to the downshift position by the finger pressure finishes releasing the highest-speed gear selection pressure (fourth-speed servo apply pressure).

For this reason, the applicant of the present application previously provided in Japanese Patent Application No. 62-273219, provided an overrun clutch control valve, and normally received the highest speed stage selection pressure in the highest speed stage selection pressure supply circuit of the highest speed stage selection shift valve. Prohibits the supply of engine brake operating pressure to the engine braking friction element by closing this control valve, and this shift valve is in the downshift position, and the highest speed stage selection pressure is released from the highest speed stage selection pressure release circuit. A technique was proposed in which the control valve was opened and the engine brake working pressure was supplied to the friction element for engine braking to close the valve.

(Problems to be Solved by the Invention) However, in this technique, the following problem occurs because the control valve receives the pressure in the highest-speed stage selection pressure supply circuit of the shift valve as the opening / closing signal pressure. In other words, the pressure of the highest-speed stage selection pressure supply circuit naturally continues to be generated during the selection of the highest-speed stage. However, this pressure is not only used for fastening the corresponding friction element, but also for other reasons.
It is also used as a signal pressure for each part of the two-sequence valve and the lock-up control valve, and originally has a large pressure loss. Thus, when the above technique is used, the pressure of the highest-speed stage selection pressure supply circuit is further used as the signal pressure of the control valve, which is combined with the large signal pressure receiving pressure area of the control valve. , The above-mentioned pressure loss becomes more and more severe. For this reason, the capacity of the friction element for selecting the highest speed stage becomes insufficient, and the pump driving load increases to cover the pressure loss.

The present invention can make the engagement timing of the friction element for engine braking as required even if the pressure in the highest speed stage selective depressurization circuit of the shift valve is used as the signal pressure of the control valve, and the circuit can operate at the highest speed. This idea is embodied from the viewpoint that the above problem does not occur because the highest speed stage selection pressure is not supplied during stage selection.

(Means for Solving the Problems) For this purpose, an engagement control device for an engine brake friction element according to the present invention includes: a shift valve for selecting the highest speed stage which is set to a downshift position by an engine brake command pressure; By switching the highest-speed stage selection pressure supply circuit that connects between the highest-speed stage selection friction element and the highest-speed stage selection pressure input port to the highest-speed stage selection pressure release circuit, the highest-speed stage selection friction element The gear transmission train is provided by removing the high-speed gear selection pressure and selecting a gear other than the highest-speed gear, and supplying the engine brake operating pressure to the engine-braking friction element by a control valve that opens after the highest-speed gear selection pressure is released. The engine brake friction element is engaged without causing the interlock condition of, so that the engine brake can be obtained at speeds other than the highest speed. In the automatic transmission, the signal pressure circuit for opening said control valve, is characterized in that it has connected to the highest speed selection depressurizing circuit.

(Operation) When the driver performs an operation requesting the engine brake,
The engine brake command pressure is generated, and this pressure is used to set the shift valve for selecting the highest speed to the downshift position, and to supply the highest speed selecting pressure supply circuit connecting the shift valve and the friction element for selecting the highest speed to the highest speed. By switching and connecting from the selection pressure input port to the highest speed selection pressure release circuit, the highest speed selection pressure of the friction element for highest speed selection was released, and a speed other than the highest speed was selected for the automatic transmission. State. On the other hand, the engine brake operating pressure generated by the engine brake command reaches the control valve, but this control valve closes in the same way as when the highest speed stage selection pressure is released, and does not direct the engine brake operating pressure to the friction element for engine braking. This state is maintained until the highest-speed stage selection pressure is released. Therefore, it is possible to prevent the frictional element for engine braking from being engaged during the selection of the highest speed stage, thereby preventing the gear transmission from becoming in an interlock state.

When the highest speed selection pressure has been released, the control valve is opened, and the engine brake operating pressure is supplied to the engine brake friction element to be engaged. Therefore, at the same time as the shift speed other than the highest speed, the friction element for engine brake is engaged, and the engine brake at the shift speed can be obtained.

By the way, since the open / close signal pressure circuit of the control valve was connected to the fastest stage selection pressure release circuit of the shift valve that did not conduct the fastest stage selection pressure during the fastest stage selection, the control valve was connected to the highest speed stage selection pressure pressure. It does not cause the capacity shortage of the friction element for selecting the highest speed stage or increase the pump driving load without being involved in the loss.

(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 provided with an engagement control device for a friction element for an engine brake, which is an example of the present invention. FIG. 1 is a shift control hydraulic circuit, and FIG. FIG. 3 is an enlarged sectional view of the run clutch control valve, and FIG. 3 is a skeleton view of the gear transmission train.

First, the transmission train of FIG. 3 will be described.
O1A type automatic transmission and the same as in JP-A-60-62047, wherein rotation from an engine output shaft E is applied 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 described below.

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. The ring gear 5R can be appropriately coupled to the carrier 1C via an overrun clutch OR / C which is a friction element for engine braking, and the carrier 4C can be connected via a forward one-way clutch FO / C and a forward clutch F / C.
Correlate to 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 control valve 38, 3-2 downshift valve 40, first-speed pressure reducing valve 42, kick down modulator valve 44,
And 2-3 a throttle modulator valve 46 which is connected to the frictional elements F / C, OR / C, LR / B, B / B, H / C, R / C and governor valve input GOV / IN, governor valve outlet. GOV / OUT, oil pump O /
P, oil pump feedback chamber O / P FB, lubrication unit LUB,
The chambers 3A and 3R of the torque converter 3 and the oil cooler COOL are connected to each other by a circuit network as shown. 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 a line pressure circuit 52, and the pressure regulator valve 2 regulates the oil to a line pressure corresponding to the pressure from the pressure modifier valve 4 and passes through a torque converter relief valve 12. Lubrication part LUB and torque converter inlet circuit 5
4 to supply excess oil to the oil pump feedback circuit 5.
Return to room O / P FB after 6. 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 (OD) is selected and the fourth speed (OD) is selected and the vehicle pressure is higher than the set vehicle speed and the line pressure is output to the circuit 58, 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 6 II in the II range, or the ports 6D, 6 II and 6 in the I range. I
Then, 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 60 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 an accumulator back pressure.
/ 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, 6 II, 6 I, 6R, and all friction elements F / C.OR / C, LR / B, B / B, H / C, R / C become inactive. Third
The transmission train in the figure does not transmit power, and allows 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) The vehicle speed further increases, and the governor pressure from the circuit 68 to the 3-4 shift valve 20, which is the shift valve for selecting the highest speed, is set for each throttle pressure from the circuit 62 to the 3-4 shift valve 20. When the value becomes equal to or more than the value, the 3-4 shift valve 20 also moves downward from the illustrated downshift position to the upshift position. At this time 3-4
The shift valve 20 outputs the second speed pressure of the circuit 74 as the fourth speed pressure (highest speed stage selection pressure) to the highest speed stage selection pressure supply circuit 86.
Speed is band brake via one way orifice 88
B / B room 4S / A is reached and band brake B / B is engaged. 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 moving the 4S / A accumulation 34, and the one-way orifice 88
In combination with the presence of the gear, the speed of the rise is limited, 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
To try to eliminate from the circuit 104 in FIG. 4 centrals換瞬time t ₁ to 4 speed pressure P _4A had reached from the circuit 86 to chamber 4S / A of the band brake B / B is. Thus, the 4-2 sequence valve 24
80 third speed pressure P ₃ (pressure on chamber 3A / R and high clutch H / C)
Was brought to the up position in the figure, the circuit 104 was passed to the circuit 108, and the 2-3 shift valve was switched to the downshift position, and the circuit 108 was passed to the circuit 110, and Since the relay valve 26 is lowered by the fourth speed P _4A from the circuit 86 in the figure, the circuit 110 is connected to the circuit 74, so the fourth speed pressure to the circuit 104 is not eliminated. -2 instant t ₁ subsequent as shown in FIG. 4 in P _4A by 2 speed pressure (backup pressure) from the circuit 74 via the relay valve 26 and 4-2 sequence valve 24 is also pressed coercive. on the other hand,
2-3 above-mentioned switching to the downshift position shift valve 18 is eliminated without delay from its own drain port as FIG. 4 a 3 speed pressure P ₃ of the circuit 80. 4-2 sequence valve 24 in this exclusion is stroke position shown instantaneously t ₂ which is 3 speed pressure P ₃ from the circuit 106 drops to the set value, 4 speed pressure P to the circuit 104
_4A the draining than instant t _2. Therefore, 4
The high-speed pressure P _4A (pressure in the chamber 4S / A) is removed after the third-speed pressure P ₃ (pressure in the chamber 3S / R and high clutch H / C) is released, and the former 4-speed pressure P _4A is prevented from slipping ahead of the latter 3rd speed pressure P ₃ and shifting from 4 → 3 → 2, ensuring 4 →
By performing two jump shifts, a sufficient acceleration force corresponding to a large depression of the accelerator pedal can be obtained.

(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, and the OD prohibition pressure is transmitted to the 3-4 shift valve 20 via the shuttle valve 92 and the engine brake command pressure circuit 94 by the engine brake command. Pressure, which is returned to the downshift position via plug 96. Therefore, the transmission train
Figure of OD prohibition instant t ₁ to the circuit 86 is the fastest-out stage selection depressurization circuit 10
4 and raise the 4th speed release pressure P _4D of this circuit,
From these circuits 86 and 104, the fourth speed P _4A is connected to the 4-2 sequence valve 24 (the third speed from the circuit 106 at the upper position in the figure) and
Since the valve is removed through the three-shift valve 18 (upshift position lowered in the figure), the state is forcibly returned to the third speed selection state.
Also, at this time, the plug 96 outputs the D range pressure of the circuit 66 to the circuit 98 as the engine brake operating pressure and directs it to the overrun clutch control valve 38. This control valve
38 than a structure which will be described later with reference to Figure 2, 4 in accordance with the pressure P _4D missing fourth speed from the signal pressure circuit 101 through the circuit 104 speed pressure
Opening the fifth drawing instant t ₂ the P _4A has passed through, the engine braking pressure from the circuit 98 via the circuit 100 is supplied with vacuum to overrun clutch OR / C, the operating pressure as shown in FIG. 5
This is concluded by _{POR / C.} Because of this, the transmission train is 3rd
It can be in a state where the engine brake is effective at high speed.
By the way, the overrun clutch control valve 38 receives the fourth speed release pressure from the circuit 104 at the left end in the figure as will be described later, and from the circuit 98 until the fourth speed pressure of the circuit 86 is released and the third speed is reached. The engine brake operating pressure is not output to the circuit 100, and the engagement of the overrun clutch OR / C is delayed. 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 being interlocked.

II Range When the driver desires the second speed engine braking and sets the manual valve 6 to the II range, this manual valve outputs the line pressure from the port 6D in addition to the port 6D, and uses this as the II range pressure. Supply to the circuit 102. This II range pressure is on the one hand to the 2-3 shift valve 18 and on the other hand to the shuttle valve
The shift valves 18 and 20 are supplied to the 3-4 shift valve 20 via a 92 and a circuit 94, respectively, and hold the shift valves 18 and 20 in the illustrated downshift position. 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, manual valve port 6 II to II
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 to draw the II range pressure of circuit 102 and the circuit 104
Through its own drain port to quickly eliminate the fourth speed release pressure P _4D to the circuit 104. As described above, since the fourth-speed release pressure P _4D of the circuit 104 is promptly eliminated, the overrun clutch control valve 38 which receives the pressure at the left end in the drawing is supplied with the II range pressure of the circuit 102 at the right end. In addition, fasten the overrun clutch OR / C. on the other hand,
Switching 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. Thus, even if the fourth speed release pressure P _4D (fourth speed pressure P _4A ) is quickly eliminated as described above, the overrun clutch OR / C is quickly engaged, and the engagement between the overrun clutch OR / C and the band brake B / B is maintained. so,
The power train becomes neutral for a moment, or 4 → 3 → 2
Shifting is reliably prevented, and a desired large engine brake can be obtained by switching the range while compensating for 4 → 2 jump shifting.

I range When the driver wants to perform engine braking in the first speed and sets the manual valve 6 to the I range, this manual valve outputs the line pressure from the port 6 I in addition to the ports 6 D and 6 II, and Is supplied to the circuit 112 as the I range pressure. The D range pressure and the II range pressure from the ports 6D and 6II reach the same places as described above. For the D range pressure, the forward clutch F / C is engaged, and for the II range pressure, the third shift speed and the fourth speed are selected by holding the 2-3 shift valve 18 and the 3-4 shift valve 20 at the illustrated down shift positions, respectively. Ban and sign an overrank rack OR / C. After the I range pressure to the circuit 112 is reduced to an appropriate value by the first speed reducing valve 42, the 1-2 shift valve
16 acts to oppose the governor pressure from circuit 68, and then reaches and engages the low reverse brake LR / B via circuit 114 and shuttle valve 116. When the governor pressure of the circuit 68 is low and the vehicle speed is low, the 1-2 shift valve 16 is maintained at the downshift position shown by the reduced I-range pressure.
The D range pressure of the circuit 66 is not output to the circuit 74, and the engine brake running at the first speed is enabled. Thus, when the governor pressure in the circuit 68 is high, the 1-2 shift valve 16 at high vehicle speed is
Lowers in the figure against the range pressure and becomes the upshift position,
The D range pressure of the circuit 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 the brake, and on the other hand reaches the low reverse brake LR / B via the circuit 118 and the shuttle valve 116 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 overrun clutch control valve 38 according to the engagement control device for an engine brake friction element of the present invention will be described in detail. This valve comprises a plug 151 and a spool 152 which abut each other by springs 153, 154 acting respectively, as is clearly shown in FIG. Plug 151 is large diameter part 151
a and a small diameter portion 151b is inserted into the valve body 156 via the sleeve 155 as a step. Then, the signal pressure circuit 101 leading to the chamber 157 is connected to the circuit 104 shown in FIG. 1 to guide these four-speed release pressure P _4D to the chamber 157, and the engine brake operating pressure circuit 98 is connected to the chamber 158. The small-diameter portion 151b of the plug 151 projects from the sleeve 155 and strikes the spool 152.

The spool 152 has both ends facing the chambers 159 and 160, and the plug 151
The diameter of the end 152a near the end is large, and the pressure regulating (reducing) groove 15 is
Form 2b. The groove 152b is formed in the chamber 15 by the communication hole 152c.
Then, the chamber 160 is connected to the II register pressure circuit 102. An output port 161, an input port 162, and a drain port 163 are formed in the valve body 156. The port 161 is connected to the overrun clutch pressure ( _{POR / C} ) circuit 100, and the port 162 is connected to the engine brake operating pressure circuit 98.

The operation of the overrun clutch control valve 38 will now be described.
_In non-engine braking operation where _{E / B} is not supplied, circuit 1
The overrun clutch pressure _{POR / C} is not output at 00, and the overrun clutch OR / C is deactivated to keep the engine brake ineffective.

Here, when the OD prohibition operation is performed during the fourth speed, or the operation is switched from the D range to the II range or the I range, and the engine brake operating pressure P _{E / B} is output to the circuit 98 as described above. The operation of will be described. 4 speed pressure P _4A of circuit 86 to circuit 104 What changeover above operations in the 3-4 shift valve 20 is in the downshift position of the street shown in the is supplied, rises pressure P _4D missing fourth speed circuit 104 (FIG. 5 in instant t ₁₎ at the same time, usually 4-speed exit pressure P _4D of the in which plug 151 is in the position of FIG. 2 to the chamber 157 is instantaneously against the spring 153 by a spring 154 Figure The spool 152 is moved to the middle right and the spool 152 is set at the rightmost position. Therefore, the overrun clutch OR / C is not yet engaged because the spool groove 152b does not generate the overrun clutch pressure _{POR / C} through the port 161 to the drain port.

Then, the fourth speed release pressure P _4D decreases to the set value (instantaneous t _{2 in} FIG. 5), and when the downshift is performed from the fourth speed, the plug 151 is turned into the engine brake operating pressure P _E reaching the chamber 158. The position is returned to the position shown in FIG. 2 by _{/ B} , and the spool 152 performs a pressure adjusting function described later. As a result, the overrun clutch pressure _{POR / C} obtained by adjusting the engine brake operating pressure _{PE / B} from the port 162 is output to the circuit 100, and this pressure is applied to the overrun clutch OR / C. To apply the engine brake. Incidentally, since the overrun clutch OR / C is engaged after the downshift from the fourth speed is completed, the engagement is performed during the selection of the fourth speed and the transmission train interlocks. Can be avoided. The engagement timing of such an overrun clutch is D
When switching from the range to the II range, the II
It becomes faster because it is supplied to 160, 4-2 sequence valve 2
4 is held at the illustrated position by the II range pressure, so that the shift associated with the range change does not go through the neutral state or the intermediate third speed for a moment, and the shift is surely a 4 → 2 jump. Can be compensated for.

The pressure adjusting function of the spool 152 is as follows. At the time of engine braking accompanying the OD prohibition operation, since there is no II range pressure P _II to the chamber 160, the leftward force in the drawing on the spool 152 is only the spring force of the spring 154. Spool 1 with this spring
When 52 is in the position shown, the overrun clutch pressure _{POR / C} to port 161 is supplied with the engine brake operating pressure _{PE / B} from port 162 and rises. Rising pressure P _{OR / C} is hole 1
Feedback is provided to the chamber 159 by 52c, and the spool 152 is pushed against the spring 154. The pressure P _{OR / C} spring 154 spool 152 when equal to or greater than the value corresponding to the spring force of the pressure was reduced P _{OR / C} through the port 161 to the drain port 163, the overrun clutch pressure P _{OR / C} springs The pressure is adjusted to a value corresponding to the spring force of 154, and the engagement capacity of the overrun clutch OR / C is adjusted appropriately to reduce the shock.

At the time of engine braking accompanying switching to the II and I ranges, the II range P _II is supplied to the chamber 160, and this acts on the spool 152 to assist the spring 154, so that the overrun clutch pressure P _{OR / C} is accordingly increased. By raising the overrun clutch OR / C to increase the engagement capacity. Therefore, the II, I
The overrun clutch engagement capacity is made to correspond to the large engine brake required in the range, thereby preventing the overrun clutch from slipping and deteriorating the effectiveness of the engine brake, and preventing the overrun clutch from burning out.

By the way, the fourth speed release pressure P _4D is led to the signal pressure circuit 101 for determining the pressure adjustment start timing (overrun clutch engagement start timing) of the control valve 38, and this pressure P _4D is used as shown in FIG. (In FIG. 5, OD is prohibited instantly) t ₁
Previously, it was 0 and was not involved in the 4th speed P _4A , so the 4th speed P4A, which was originally leaky during traveling in the 4th speed, did not further worsen the pressure loss and was fastened by the 4th speed P _4A Cause the capacity of the band brake B / B to be insufficient,
It is possible to prevent the pump driving load from increasing.

(Effect of the Invention) As described above, the device of the present invention can
Since the signal pressure circuit 101 of the control valve 3 is connected to the depressurization circuit 104 of the highest-speed stage selecting shift valve 20 for the highest-speed stage selection, the control valve 3
8 is not involved in the pressure loss of the highest-speed stage selection pressure P _{4A, and} the highest-speed stage speed can be achieved without causing the shortage of capacity of the friction element B / B for selecting the highest-speed stage and increasing the pump driving load to be fastened by this pressure. Simultaneous engagement of the friction element for selection and the friction element for engine braking can be reliably prevented, and the interlocking of the gear train can be completely avoided.

[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 cross-sectional view of an over-clutch control valve in the hydraulic circuit, and FIG. 3 is a transmission of the automatic transmission. FIG. 4 is a skeleton diagram showing a row, FIG. 4 is a time chart of various hydraulic pressure changes relating to a 4 → 2 shift associated with depression of an accelerator pedal in a D range 4th speed state, and FIG. 5 is various hydraulic pressures relating to a shift accompanying an OD prohibition. 5 is a change time chart of FIG. 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 (shift valve for selecting the highest speed stage) 22: 3-2 timing valve, 24: 4-2 sequence Valve 26… 4-2 relay valve 28… Accumulation control valve 30… 2 S / A accumulation, 32… 3 S / R accumulation 34… 4 S / A accumulation, 36… ND accumulation 38… Overrun Clutch control 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 prohibited Solenoid, 52 Line pressure circuit F / C Forward clutch OR / C Overrun clutch (friction element for engine brake) LR / B Low reverse brake B / B Band brake H / C … High clutch R / C …… Reverse clutch 86 …… Highest speed stage selection pressure supply circuit 94 …… Engine brake command pressure circuit 98 …… Engine brake operation pressure circuit 101 …… Signal pressure circuit 104 …… Highest speed stage selection pressure Removal circuit 151… Plug, 152… Spool 155 …… Sleeve

Claims (1)

(57) [Claims] A shift valve for selecting the highest speed stage is set to a downshift position by an engine brake command pressure, and a highest speed stage selection pressure supply circuit connecting the shift valve and the friction element for selecting the highest speed stage is selected for the highest speed stage. By switching from the pressure input port to the highest speed stage selection depressurization circuit, the highest speed stage selection pressure of the friction element for highest speed stage selection is released to select a speed stage other than the highest speed stage. By supplying the operating pressure of the engine brake to the friction element for the engine brake by the control valve that opens after the release of the selected pressure, the friction element for the engine brake is fastened without causing the interlocking state of the gear transmission train, and thus the other than the highest speed stage In an automatic transmission capable of obtaining an engine brake at a shift speed, a signal pressure circuit for opening the control valve is provided at the highest speed select pressure release. Characterized in that connected to the circuit, engagement control device of the friction element for engine brake in the automatic transmission.