JPS6231751A - Device for controlling down-shift timing and engine brake for automatic speed change gear - Google Patents

Abstract

PURPOSE:To make it possible to electronically control down-shift timing and engine brake, by using only one solenoid valve for controlling the above- mentioned timing and engine brake. CONSTITUTION:There is provided a shuttle valve 5 which responds to line pressure increasing in proportion to engine load, and which takes a first position when the line pressure is lower than a predetermined value but takes a second position when the line pressure is higher than another set value. Further, at the first position, an engine brake control valve 7 may be controlled by a solenoid valve 9, and a down-shift timing valve 6 is held is a condition in which timing control is impossible. Further, at a second position, the down-shift timing valve 6 may be controlled by the solenoid valve 9, and the engine control valve 7 is held in a condition in which frictional elements OR/C for engine brake are inoperative. With this arrangement, the electronic control can be made with no restriction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device that performs downshift timing control and engine brake control for an automatic transmission.

(Prior Art) An automatic transmission is configured to automatically change gears by switching a power transmission path by selectively operating various friction elements (clutches, brakes, one-way clutches, etc.).

By the way, when downshifting, a sudden change in engine speed occurs due to a change in gear ratio before and after the downshift.
Such a sudden change in the engine rotational speed, together with the fact that the shift is mainly performed during power-on driving with a large engine load (accelerator pedal depression amount), causes a large shift shock.

The automatic transmission also includes a one-way clutch as a reaction force element for the rotating member, and its operation receives the reaction force from the rotating member to enable the above-mentioned power transmission. Because of this,
When a reverse drive torque is applied to the rotating member, it can be cut off by releasing the one-way clutch and the occurrence of shock, rattling, etc. can be prevented, but the one-way clutch makes engine braking ineffective.

To solve the former problem, it is common practice to set a so-called neutral interval by controlling the timing to delay the downshift until the engine speed reaches the value required to prevent shift shock. To deal with this, it is common practice to provide an engine braking friction element in parallel with the one-way clutch and operate this as appropriate to effect engine braking.

Conventionally, downshift timing control and engine braking friction element operation control have been performed as shown in the 3-2 downshift control and over-launch launch operation control of the THM-700 type transmission manufactured by General Motors Corporation in the United States, respectively. , or RN4FO2A type (RL4FOZA type) and RNaFO manufactured by Nissan Motor Co., Ltd.
As seen in the IA type automatic formatic transaxle shift control and low reverse brake operation control, the former control is performed by governor pressure corresponding to vehicle speed, and the latter control is performed by switching a manual valve. It was usually carried out.

(Problem to be Solved by the Invention) However, in such a conventional configuration, when attempting to electronically control an automatic transmission, the electronic control would eliminate the need for governor pressure, and a governor valve to generate this would be required. Although it can be omitted, governor pressure must still be generated for timing control of the downshift. Furthermore, since engine brake control is performed by switching manual valves, there is little flexibility in implementing electronic control. Furthermore, in electronically controlling both of these controls, a solenoid that responds to vehicle speed information creates governor pressure and uses this to control downshift timing, and a solenoid that responds to manual valve switching controls engine brake command pressure. However, such control requiring individual solenoids is disadvantageous in terms of space and cost.

(Means for Solving the Problems) The present invention has the following features: (a) the engine brake friction element is arranged in parallel to the one-way clutch as described above;
During power-on driving, the operation or non-operation of the engine brake friction element does not affect the power transmission state and can be kept in the non-operation state; (c) Of the above two controls, engine brake control is required during coasting, and downshift timing control is required during power-on driving. In other words, based on the fact that these two controls have different required timings and can be executed by a common solenoid valve, timing control is performed to delay the downshift until the engine speed reaches the value required to prevent shift shock. In an automatic transmission equipped with a downshift timing valve that operates a downshift timing valve to provide engine braking, and an engine brake control valve that appropriately operates an engine braking friction element to obtain engine braking, the automatic transmission responds to line pressure that increases in proportion to the engine load. A shuttle valve is provided that is in a first position when the line pressure is below a certain line pressure and is in a second position when the line pressure is above another set line pressure higher than the certain line pressure, and the engine brake control valve is controlled by a solenoid valve in the first position. and maintains the downshift timing valve in a state in which the timing control is disabled, and in a second position, the downshift timing valve is controllable by the electromagnetic valve, and the engine brake control valve is controlled for the engine brake. The shuttle valve is configured to maintain the friction element in a deactivated state.

(Function) The shuttle valve is in the first position below a certain line pressure, that is, below the corresponding engine load, and in this first position the engine brake control valve is controlled by the solenoid valve, and the engine brake friction element is activated as appropriate. can be activated to obtain engine braking. In this first position, the downshift timing valve is kept in a state in which the timing of downshift speed change is not controlled, but there is no problem because downshift timing control is not required during coasting due to a low engine load.

Above another set line pressure, i.e. above the corresponding engine load, the shuttle valve is in the second position, and in this second position the downshift timing valve is controlled by the same solenoid valve as above, and the downshift is controlled by the engine speed. The shift shock can be reduced by controlling the timing to delay the number until the number reaches a value required for preventing shift shock.

In this second position, the engine brake control valve is kept in a state in which the engine brake friction element is not activated, but the engine brake friction element does not participate in power transmission during power-on driving where the engine load is higher than the engine load. Therefore, there is no problem.

Therefore, it is possible to perform both engine brake control and downshift timing control using a common solenoid valve, which is advantageous in terms of space and cost.In addition, these controls can be freely controlled electronically, and the governor valve can be controlled from these controls. Can be omitted.

In addition, since hysteresis is set between the positive line value that puts the shuttle valve in the first position and the positive line value that puts the shuttle valve in the second position, the change in line pressure near the positive line value for position switching of the shuttle valve is prevented. This prevents hunting from occurring, and prevents abnormal noise from occurring and line pressure fluctuations from being exacerbated. The hysteresis described above results in instantaneous, snap-action switching of the shuttle valve from one position to the first or second position, making it possible to reduce the size of the spring that must act against the line pressure, and to The storage space can be reduced, contributing to downsizing of the shuttle valve.

(Example) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

The drawing shows an embodiment of the control device of the present invention, and an automatic transmission to which this device is applied includes a forward clutch F/C, band brake B/B, high clutch H/C, and overrun clutch (friction element for engine braking) OR. /C, the first speed is selected by the operation of the forward clutch F/C,
With this and the operation of the band brake B/B, 2nd speed is selected, and the operation of the forward clutch F/C and the high clutch H/
It is assumed that the third speed is selected by the operation of C. The band brake B/H is activated or deactivated by the band servo B/S.
When supplying pressure to the servo apply chamber S/A, the servo B/S operates the brake B/B, and when supplying pressure to the servo release chamber S/R, the servo apply chamber S/A operates. It is assumed that the servo B/S deactivates the brake B/B depending on the magnitude of the piston pressure receiving area regardless of the presence or absence of pressure. It is assumed that by operating the overrun clutch OR/C in the first, second, and third speed selection states, the automatic transmission can obtain engine braking at the corresponding gear position.

The automatic transmission also has a manual valve 1 and a pilot valve 2.
．． 1-2 speed change valve 3. In addition to providing the 2-3 speed change valve 4, a solenoid 9 as a solenoid valve that constitutes a main part of the control device of the present invention is provided.
, a shuttle valve 5.3-2, a timing valve (downshift timing valve) 6, and an overrun clutch control valve (engine brake control valve) 7 are provided.

Manual valve 1 is spool 1 when the driver wishes to park.
a to the P range, spool la to the R range when you wish to reverse, and spool 1a to the N range when you wish to stop.
When you want forward automatic shifting, set spool 1a to D range.
When 2nd speed engine braking is desired, press spool 1a■
range, and when 1st speed engine braking is desired, the spool 1a is set to the R range.In each range, the output port I R is set.

LD, III, and II are line pressure P from the line pressure circuit.
Assume that L is output as shown in the following table.

Table 1 In this table, the O mark indicates a boat that is outputted with line pressure, and the unmarked boat indicates a boat that is released to the atmosphere. Also, line pressure P1-
As described in "Automatic Trans Axle RN4FO2A Type, RL4FO2A Type Maintenance Manual J (A261CO6)" published by Nissan Motor Co., Ltd., it changes depending on the throttle opening and vehicle speed, and is relatively low during coasting and is relatively low when driving with power on. The price shall be relatively high.

The pilot valve 2 includes a spool 2b elastically supported by a spring 2a at the upper half position in the figure, and at this spool position outputs the line pressure PL from the circuit to the pilot pressure circuit 8 in order to increase the biloft pressure thereto. , the pilot pressure is fed back to the chamber 2c, and as the pilot pressure increases, the spool 2b is moved to the right in the figure. When the pilot pressure exceeds the value corresponding to the spring force of the spring 2a, the spool 2
b The circuit 8 is cut off from the circuit, and the pilot pressure is lowered through the drain port 2d, whereby the spool 2b
When it returns to the lower half position in the figure, the reduction in pilot pressure is stopped. The pilot valve 2 thus maintains the pilot pressure in the circuit 8 at a constant value corresponding to the spring force of the spring 2a.

The 1-2 speed change valve 3 and the 2-3 speed change valve 4 are connected to the spool 3, respectively.
a, 4a are elastically supported by springs 3b, 4b in the downshift positions shown in the right half and left half, and in this spool position, the boats 3c, 4c are moved to the drain boats 3d, 4.
d, and when the spools 3a, 4a are brought to the upshift positions shown in the left half and the right half by a shift pressure P to the chambers 3e, 4e, the boats 3c, 4c are shifted to the boat 3f.

4f.

The shuttle valve 5 is constructed by elastically supporting a spool 5a at the right half position in the figure by a spring 5b. At this spool position, the boat 5C is connected to the drain boat 5d and the boat 5e is connected to the boat 5f, and when the spool 5a is brought to the right half position in the figure against the spring 5b due to the pressure inside the chamber 5g,
port) 5c to port 1-5f, and boat 5e to boat 5.
h.

In order to force the spool 5a upward in the figure by the pressure inside the chamber 5g, the spool land 51 that opens and closes the boat 5d is always fitted into the land guide 51 between the drain port 5d and the chamber 5j, and the spool 5a, a land 5k with a smaller diameter than the land 51 and a land 51 with an even smaller diameter are arranged on the side of the land 51 far from the spring 5b.
will be established sequentially. Land guides 5m and 5n for land guides 51 are installed on these lands 5, and their arrangement relationship is determined as follows.

That is, when the spool 5a is at the left half position in the figure, the land 5k fits into the guide 5m, and as the spool rises, the tend 5k
When the land 51 comes off the guide 5m, the land 51 just comes off the guide 5n.
so that it starts mating. Therefore, when the spool 5a is in the right half position in the figure, the land 51 is fitted into the guide 5n, and just when the land 51 is removed from the guide 5n due to the lowering of the spool, the land 5k begins to fit into the guide 5m.

Then, with the land 5k fitted to the guide 5m, the spool 5a has a land 5i, and the pressure receiving area difference between the land 5i and the chamber 5g
An upward force in the figure is applied to the spool 5a with the land 51 fitted into the guide 5n, which is the product of the pressure receiving area difference between the lands 5i and 51 and the pressure of the chamber 5g. An upward force in the figure, represented by , acts.

3-2 The timing valve 6 is configured such that the spool 6a is elastically supported in the left half position in the figure by a spring 6b, and the spool 6a is appropriately moved to the right half position in the figure by pressure applied to the chamber 6c. It is assumed that this valve 6 opens the circuits 10 and 11 at the left half position of the spool 6a in the figure, and shuts off the circuits 10 and 11 at the right half position of the spool 6a in the figure.

The overrun clutch control valve 7 is connected to the spool 7a.
The spring 7b is elastically supported in the left half position in the figure, and the spool 7a is appropriately switched to the right half position in the figure by applying pressure to the chamber 7c. This valve 7 communicates the boat 7d to the boat 7e at the left 4' position of the spool 7a in the figure, and communicates the boat 7d to the drainboard 7f at the right half position of the spool 7.3 in the figure.

The pilot pressure circuit 8 is connected to both shuttle valve boats 5f and 5h, and an orifice 12 is inserted in the middle of the pilot pressure circuit 8 connected to the shuttle valve boats 5f. 2:(,,.

A drain bow 1-13 is provided downstream of the orifice 12, and a solenoid 9 is provided opposite thereto. The solenoid 9 is composed of a coil 9a, a plunger 9b, and a spring 9c. When the coil 9a is OFF (de-energized), the spring force of the plunger 9b or spring 9c closes off the drain boat 13 and makes the pressure on the boat 5r the same as the pilot pressure. However, when the coil 9a is turned ON (energized), the plunger 9b or the spring 9c moves downward against the spring force to open the drain boat 13 and drain the boat 5.
Assume that the pressure on f is reduced to O by draining from the drain boat 13.

The boat 5c of the shift valve 5 is connected by a circuit 14 to the chamber 6c, and the boat 5e is connected by a circuit 15 to the chamber 7c.

The boat ID of the manual valve 1 is connected to the forward clutch F/C by the circuit 16, and among the circuits 17 to 20 branched from the circuit 16, the circuit 17 is connected to the boat 17e, the circuit 18 is connected to the chamber 5g, and the circuit 19 is connected to the boat 3. D, circuit 2o is baud 1
Connect to 4f respectively.

The boat 3c of the 1-2 speed change valve 3 is connected to the servo apply chamber S/A by the circuit 21, and the boat 4c of the 2-3 speed change valve 4 is connected to the servo apply chamber S/A by the circuit 21.
The circuit 10 is connected to the servo release chamber S/R, and the circuit 11 is connected to the servo release chamber S/R. Circuit 10. A one-way orifice 22 is separately connected between the circuit 11 and the circuit 10, and is configured by a check valve 22a and an orifice 22b arranged in parallel to function for oil flow from the circuit 11 to the circuit 10. A circuit 23 branching from this is provided in the circuit 1o,
This circuit 23 is connected to the high clutch (1/c).

The remaining boat 7d of the overrun clutch control valve 7 is connected to the overrun clutch OR by the circuit 24.
Connect to /C.

The operation of the above embodiment will be explained next.

While the driver desires forward automatic gear shifting and places the spool 1a of the manual valve 1 in the D range position as shown in the figure, the circuit 16
The line pressure Pl is output from the circuit, and this line pressure is supplied to the forward clutch F/C to continue operating it, and also reaches the connection points of these circuits via circuits 17 to 2o.

Here, the shift pressure P is low and 1.1-2 shift valves 3 and 2-3
When both the spools 3a and 4a of the speed change valve 4 are in the downshift position, the servo apply chamber S/A is connected to the drain port 3d via the circuit 21 and bow h3c, and the band brake B/B is deactivated and the high clutch is activated. 11/c is also circuit 2
3,10, it connects to the drain boat 4d via the boat 4c and is inactive. In this case, the automatic transmission selects the first speed by operating the forward clutch F/C.

From this state, when the spool 3a of the 1-2 speed change valve 3 is switched to the upshift position shown in the left half due to an increase in the speed change pressure P, the line pressure from the circuit 9 is passed through the circuit 21 to the servo apply chamber S/ A is reached and band brake B/B is activated. At this time, the automatic transmission is forward clutch F/C.
The second speed is selected by the operation of the band brake B/B and the operation of the band brake B/B.

As the shift pressure P further increases, the spool 4a of the 2-3 shift valve 4 is also switched to the upshift position shown in the right half.
The line pressure from circuit 20 reaches the high clutch H/C via circuit 10.23, actuating it, and also
Line pressure from 0 is circuit 1o, check pulse 7'22a
, reaches the servo release chamber S/R via circuit 11 and deactivates the band brake B/B. At this time, the automatic transmission operates the forward clutch F/C and the high clutch H.
3rd speed is selected by operating /C.

Thereafter, when the spool 4a of the 2-3 speed change valve 4 switches to the downshift position shown in the left half due to a decrease in the speed change pressure P,
The boat 4c connects to the drain port 4d, and the high clutch 1
(By removing the pressure supplied to the servo release chamber S/C, it is rendered inactive, and at the same time, the pressure supplied to the servo release chamber S/R is appropriately removed while controlling the speed as described later. The automatic transmission can be downshifted from the third speed to the second speed under appropriate downshift timing control.

Line pressure from circuit 18 reaches chamber 5g of shuttle valve 5 to stroke control spool 5a as follows. That is, at the left half position of the spool 5a in the figure, as described above, there is a pressure receiving area difference between the lands 5i, 5 and the chamber 5g.
An upward force in the figure acts, which is expressed as the product of the line pressure within. When the line pressure increases here, this force increases and the spool 5a is raised from the left half position in the figure. As a result, the land 5k comes off the guide 5m, and when the land 51 reaches the spool position where it fits into the guide 5n, the spool 5
As mentioned above, an upward force in the figure, expressed as the product of the pressure receiving area difference between the lands 5i and 51 and the line pressure in the chamber 5g, acts on a, and the latter's pressure receiving area difference is the former's pressure receiving area. Since the area difference is greater than the area difference, the spool 5a instantly changes to the right half position in the figure. Then, the spool 5a is held at the same position while the line pressure is equal to or higher than the pressure at this time (first set line pressure).

When the line pressure to the chamber 5g decreases from this state, the upward force in the figure, which is represented by the product of this and the pressure-receiving area difference between the lands 5i and 51, decreases, and the spool 5a moves toward the right half of the figure. It is lowered from this position by a spring 5b. As a result, when the land 51 comes off the guide 5n and the land 5k reaches the spool position where it fits into the guide 5m, the spool has a pressure expressed by the product of the pressure receiving area difference between the lands 5i and 5 and the line pressure in the chamber 5g. As shown in the figure, an upward force acts on the spool 5a, and as the pressure receiving area decreases, the spool 5a instantly switches to the left half position in the figure. Then, the spool 5a is held at the same position while the line pressure is below the pressure at this time (second set line pressure).

The first set line pressure is higher than the second set line pressure, and hysteresis can be set between the two.

By the way, as mentioned above, the line pressure is relatively low during coasting, and the shuttle valve spool 5a is set to the left half position in the figure when it is below the second set line pressure, and is relatively high during power-on running, and when it is above the first set line pressure. Move the shuttle valve spool 5a to the right half position in the figure.

First, to explain the operation when the shuttle valve 5 is in the left half state in the figure during coasting, the overrun clutch control valve 7 is in a state where the stroke can be controlled by the solenoid 9 due to communication between the boats 5e and 5f. Become. In other words, there is an engine brake command from the driver via a switch or the like, or an automatic engine brake command based on the determination result of the road surface gradient, etc., and when the solenoid coil 9a is turned on, the plunger 9b is activated by the drain boat 13.
By opening, the pressure on the boat 5f, and hence the pressure in the chamber 7c, becomes zero, and the overchin clutch control valve 7 is placed in the left half state in the figure. As a result, line pressure from circuit 17 reaches overrun clutch OR/C via circuit 24, activating it. In this case, the automatic transmission can provide engine braking during automatic gear shifting in selected gears, ie, first, second, or third gear.

By the way, during the coasting, the chamber 6c of the 3-2 timing valve 6 communicates with the drain boat 5d due to the state of the shuttle valve 5 in the left half in the figure, and the spool 6a of the valve is in the left hand position in the figure. In this case, the pressure in the servo release chamber S/R is quickly removed almost entirely through the circuit 11.10, without passing through the orifice 22b, and from the third speed to the second speed.
To immediately complete a downshift to a higher speed without timing control. However, there is no problem because downshift timing control is not required during the coasting as described above.

Next, when the shuttle valve 5 is in the right half state in the figure during power-on running, the 3-2 timing valve 6 is in a state where its stroke can be controlled by the solenoid 9 due to communication between the boats 5c and 5f. By the way, at this time, the solenoid coil 9a is turned off at a predetermined vehicle speed or higher, and the pressure is supplied to the chamber 6c via 5f, 5c and the circuit 14, and the 3-2 timing valve 6 is turned off. Put it in the middle right half state. Thus 3-2 timing valve 6 is connected to circuit 10.1
1, and the pressure in the servo release chambers S/R is removed while the speed is controlled by the orifice 22b. It can be done under control. Therefore, the shift can be completed when the engine speed increases to a value commensurate with the vehicle speed and the gear ratio after the shift, and shift shock can be reduced.

Note that the solenoid coil 9a is not kept OFF, but is turned ON when the engine speed reaches the above value, and at this point, the 3-2 timing valve 6 is set to the downshift timing control discontinued state shown in the left half. It goes without saying that the above purpose can be achieved even more completely by doing so.

By the way, during the power-on running, the pilot pressure from the circuit 8 reaches the chamber 7c via the circuit 15 due to the shuttle valve 5 being in the right half state in the figure, causing the overrun clutch control valve 7 to be in the right half state in the figure. I keep it. In this case, the circuit 24 connects to the drain port 7f and holds the overrun clutch OR/C inactive, keeping the engine brake in a state where it cannot be obtained, but engine braking is not required during the power-on driving, and as described above. As the overrun clutch OR/C (frictional element for engine braking) operates or deactivates, it does not affect power transmission, so there is no problem.

Incidentally, if the driver particularly desires to maintain the engine brake state in the second speed or the engine brake state in the first speed, the driver sets the manual valve spool 1a to the ■ range or ■ range. ■In the range, as shown in Table 1 above, the line pressure of the circuit is also output to Baud 1-Ill, and in the I range, the line pressure
As shown in the table, in addition to that, the line pressure of the circuit is also output to port II. The line pressure from port 1 reaches a predetermined location via a circuit network not shown, and the forward clutch F/C and handbrake B/B are activated to lock the second gear, and the overrun clutch OR/C is activated. The engine brake condition is maintained through operation. The line pressure from port 1■ reaches a predetermined location via a circuit network not shown, and locks the first gear by prohibiting the operation of friction elements other than the forward clutch F/C (however, if the engine overspeeds, (at vehicle speeds such as 1 to 2), the engine brake state is maintained by operating the overrun clutch OR/C.

The driver requests manual valve spool 1a to drive in reverse.
When set to R range, the line pressure from the circuit becomes the first
Baud (as shown in the table) is output only to the IR.

This line pressure reaches a friction element (not shown) for reverse selection and activates it, allowing the vehicle to travel in reverse.

(Effects of the Invention) Thus, the control device of the present invention can perform downshifts (
In the illustrated example, timing control (3-2 downshift) and engine brake control are performed by one common solenoid valve (solenoid 9), which is advantageous in terms of space and cost, and allows these controls to be performed freely. It has various features such as being able to be electronically controlled and eliminating the need for a governor valve from these controls.

In addition, since hysteresis is set for the set line pressure for switching the position of the shuttle valve 5, the shuttle valve will not hunt due to fluctuations in line pressure near the set line pressure, which may cause abnormal noise or line It is possible to prevent pressure fluctuation from being promoted. Moreover, the above hysteresis causes the position of the shuttle valve 5 to be changed in a snap-action manner, and the spring 5b, which is supposed to act against the line pressure, can be made smaller, and the storage space thereof can be reduced, and the shuttle valve can be made smaller. Contribute to

[Brief explanation of the drawing]

The drawing is a hydraulic circuit diagram showing an embodiment of the control device of the present invention. 1...Manual valve 2...Pilot valve 3.
...1-2 speed change valve 4...2-3 speed change valve 5...
Shuttle valve 6...3-2 Timing valve (downshift timing valve) 7... Overrun crunch control valve (engine brake control valve) Line pressure circuit 9... Solenoid (electromagnetic valve) 12. ... Orifice 13... Drain boat 22... One-way orifice F/C... Forward clutch B/B... Handbrake B/S... Band servo 11/C... High clutch OR/C・・・Oper run crunch (friction element for engine brake)

Claims (1)

[Claims] 1. A downshift timing valve that controls the timing to delay downshift until the engine speed reaches a value required to prevent shift shock; and a downshift timing valve that controls engine braking by appropriately operating an engine braking friction element. In an automatic transmission equipped with an engine brake control valve, the control valve responds to a line pressure that increases in proportion to the engine load, and is set to a first position below a certain line pressure, and to a first position higher than this certain line pressure. A shuttle valve is provided that is in a second position when the pressure is higher than another set line pressure, and in the first position, the engine brake control valve can be controlled by a solenoid valve, and the downshift timing valve is maintained in a state where the timing control is disabled. and the shuttle valve is configured to allow the downshift timing valve to be controlled by the electromagnetic valve in the second position and to maintain the engine brake control valve in a state in which the engine brake friction element is deactivated. A downshift timing control and engine brake control device for an automatic transmission, characterized by: