JPH0126419B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a shift control device for an automatic transmission for a vehicle, and in particular, in an automatic transmission equipped with an overdrive stage, the present invention relates to a shift control device for an automatic transmission for a vehicle. This invention relates to a speed change control circuit that electrically changes speed to an overdrive stage.

[Prior Art] In a vehicle transmission of this type that includes a hydraulic torque converter and a gear transmission mechanism equipped with a plurality of frictional engagement devices for obtaining several gear stages, Accordingly, the operation of the frictional engagement device is variously switched, and the gear transmission mechanism is automatically controlled to a transmission state most suitable for the operating state of the wheels at that time. Switching control of such a frictional engagement device is normally performed by a hydraulic control device, and the hydraulic control device has a function that changes depending on the amount of depression of the accelerator pedal, that is, the opening degree of the intake throttle, and the vehicle speed. A gear shift valve is incorporated in the gear shift valve that is switched in accordance with the equilibrium relationship between the governor oil pressure and the governor oil pressure, which changes depending on the balance between the throttle oil pressure and the governor oil pressure, that is, the amount of accelerator pedal depression and the vehicle speed. It is becoming more and more selective.

FIG. 1 shows a known example of a vehicle transmission including a hydraulic torque converter of this type and a gear transmission mechanism equipped with a plurality of frictional engagement devices for obtaining several gears, each of which is well known. It is comprised of a torque converter 10, an overdrive mechanism 20, and a planetary gear transmission mechanism 30 with three forward speeds and one reverse speed.

The torque converter 10 includes a pump impeller 12 connected to an engine output shaft 11, a turbine impeller 13 and a one-way clutch 1 opposed to the pump impeller 12 and connected to an overdrive mechanism 20.
The stator 15 is connected to a housing 16 via a stator 15, and a lock-up clutch 18 is provided between the input and output shafts to enable direct connection.

The overdrive mechanism 20 includes a set of planetary gears 21 , which are connected to a carrier 23 connected to the torque converter 10 via a shaft 22 .
A planetary pinion 24 rotatably supported by
and sun gear 2 that mesh with pinion 24, respectively.
5 and a ring gear 26. A multi-disc clutch LO and a one-way clutch FO are provided between the sun gear 25 and the carrier 23, and a multi-disc brake BO is provided between the sun gear 25 and the housing surrounding the overdrive mechanism 20 or the overdrive case 27. It is being

The ring gear 26 of the overdrive mechanism 20 is connected to an input shaft 31 of a planetary gear transmission mechanism 30 with three forward speeds and one reverse speed. Input shaft 31 and intermediate shaft 3
A multi-plate clutch L1 is provided between 2,
Further, a multi-plate clutch L2 is provided between the input shaft 31 and the sun gear shaft 33. sun gear axis 3
A multi-disc brake B1, a multi-disc brake B2, and a one-way clutch F1 are provided between the transmission case 3 and the transmission case 34. This planetary gear mechanism 30 includes two rows of planetary gears 35 and 36, and a multi-disc brake B3 and a transmission case 34 are provided between a carrier 37 that rotatably supports the pinion of the second planetary gear 35 and a transmission case 34. Directional clutch F2
is provided. The sun gear 38 of the second planetary gear 35 and the sun gear 39 of the third planetary gear 44 are connected to the shaft 33.
The ring gear 40 of the second planetary gear 35 and the carrier 4 of the third planetary gear 44 are integrally connected via
1 are both connected to the output shaft 42, and the third planetary gear 3
The ring gear 43 of No. 6 is connected to the intermediate shaft 32.

Switching control of the vehicle transmission consisting of the torque converter 10, overdrive mechanism 20, and planetary gear transmission mechanism 30 with three forward speeds and one reverse speed is performed by the aforementioned throttle oil pressure and governor oil pressure. Since this is well known, the explanation will be omitted. In particular, only the overdrive mechanism 20 that is related to the present invention will be briefly described. FIG. 2 is a hydraulic control system diagram of a conventional automatic transmission for a vehicle that shifts to an overdrive stage.

The oil pumped up from the oil reservoir by the oil pump is sent to the line oil pressure control valve to generate line oil pressure Pli regulated to a predetermined pressure.

The throttle hydraulic pressure control valve generates a hydraulic pressure Pth at its output port, which increases in accordance with the amount of depression of the accelerator pedal, that is, the opening degree of the intake throttle valve. The cabana hydraulic control valve generates cabana hydraulic pressure Pgo according to the speed at its output port.

On the other hand, the overdrive control valve 50 has valve elements 52 and 53 facing each other in the axial direction with a compression coil spring 51 in between. Furthermore, another valve element 54 is provided above the valve element 53. The valve element 52 is a compression coil spring 51
In the figure, a downward pressing force is applied by
Valve elements 53 and 54 are compressed coil springs 51
An upward pressing force is applied in the figure. Governor hydraulic pressure Pgo supplied to port 55 acts on the lower end of valve element 52. Further, a throttle oil pressure Pth is applied to the upper end of the valve element 53 via a port 56, and when this throttle oil pressure Pth exceeds an arbitrary value that overcomes the repulsive force of the compression coil spring 51, the compression coil Valve element 5 with spring 51 compressed
3 directly engages with the valve element 52 and exerts a downward pressing force on the valve element 52 in the figure. When the throttle oil pressure Pth acting on the port 56 is less than the pressure that compresses the compression coil spring 51, the piston element 52 is activated by the downward spring force in the figure applied by the compression coil spring 51 and the governor oil pressure Pgo acting on the port 55. Due to the equilibrium relationship, the switch is appropriately switched between the downward switching position indicated by 50A and the upward switching position indicated by 50B, depending on the vehicle speed. Further, when the throttle oil pressure Pth acting on the port 56 increases while the valve element 54 is biased to the upper end position in the figure, the compression coil spring 51 is compressed and the valve element 53 comes into direct contact with the valve element 52. , valve element 52 is connected to port 5
Throttle oil pressure acting on valve element 53 via 6
The switch is appropriately switched between the switching positions 50A and 50B due to the balanced relationship between the downward pushing force in the figure due to Pth and the upward pushing force in the figure due to the governor oil pressure Pgo acting on the port 55.

A line oil pressure Pli is supplied to the port 57 of the overdrive control valve 50 via an oil path. Line oil pressure supplied to this port 57
When the overdrive control valve 50 is in the downward switching position shown at 50A, Pli is supplied to the clutch LO of the overdrive mechanism via the port 58 and the oil path, and when the overdrive control valve 50 is in the downward switching position shown at 50B. When in the upwardly switched position as shown in FIG.

The upper end surface of the valve element 54 of the overdrive control valve 50 in the figure shows the line oil pressure Pli when the manual switching valve is switched only to the 2 range or L range position, and the shuttle valve 60 and port 6.
It is designed to be supplied through 1. In addition, the line hydraulic pressure can also be connected to this port 61 through another route passing through the solenoid valve 70 and the shuttle valve 60.
Pli is now being selectively supplied.

The solenoid valve 70 communicates with a solenoid 71, an armature 72, a compression coil spring 73, a valve port 74, an inlet port 75, an outlet port 76, and a valve port 74 that are opened and closed by a valve element formed at the tip of the armature 72. It has a drain port 77. When the solenoid 71 is not energized, the armature 72 is displaced downward in the figure by the action of the compression coil spring 73.
Its tip has the valve port 74 closed.
In this state, the line oil pressure Pli supplied to the inlet port 75 via the orifice 78 is directly delivered from the outlet port 76 via the oil path to the shuttle valve 60, and from there is supplied to the port 61 of the overdrive control valve 50 via the oil path. be done. On the other hand, when the solenoid 71 is energized, the armature 72
is displaced upward in the figure against the action of the compression coil spring 73, and the valve port 74 is opened. In this state, the line oil pressure Pli supplied to the inlet port 74 via the oil passage and orifice 78 is released from the valve port 74 to the drain port 77.
The line oil pressure Pli is not effectively transmitted to the outlet port 76 and the oil passage following it.

Excitation current is selectively supplied to the solenoid 71 of the solenoid valve 70 from an arithmetic operation circuit 81 via a manual switch 80. The arithmetic operation circuit 81 includes a speed sensor S/V and a kick-down switch K/V, which generate electric signals according to the speed.
It is configured to operate based on an electric signal emitted by D. The above-mentioned kick down switch K/D
is a throttle sensor that generates an electric signal according to the opening of the intake throttle; it directly detects the opening of the intake throttle valve installed in the engine's carburetor and generates an electric signal, or the It may be a sensor such as a hydraulic switch that detects the detent hydraulic pressure that appears on the throttle hydraulic control valve when the throttle is depressed beyond the degree of depression.
In this type of circuit, the throttle sensor K/
D is configured as a switch that detects whether or not the throttle opening exceeds 85%, and this switch detects whether or not the accelerator pedal is depressed.

Next, an electric control circuit for electrically controlling the overdrive control valve 50, that is, the highest gear shift valve that achieves the highest speed gear among the shift valves will be described. FIG. 3 is a circuit diagram showing an example of a logic circuit in the arithmetic operation circuit 81 in FIG. 2. Kick-down switch K/D output a
is when the throttle opening T does not reach 85% (T
<85%), when the H (high) level is reached and the throttle opening is 85% or more (T≧85%), L (low)
level.

The output b of the vehicle speed sensor S/V is the comparator 82
and 83. The other input terminals of comparators 82 and 83 each have a high-speed reference voltage.
V _H and low speed reference voltage V _L are input. The output c of the comparator 82 becomes L level when the voltage Vb of the output b indicating the vehicle speed is equal to or smaller than the high-speed reference voltage _VH (Vb≦ _VH ), and the voltage Vb is greater than the high-speed reference voltage line oil pressure _VH . Time (Vb
> _VH ) It is set to be at H level.
The high-speed reference voltage takes one of two values, V _H1 and V _H2 = V _H1 = ΔV _H1 , depending on changes in throttle opening and vehicle speed. The comparator 83 compares the voltage Vb with the low-speed reference voltage _VL , and its output d is set to be at the L level when Vb≦ _VL , and to be at the H level when Vb< _VL . The low-speed reference voltage V _L is also designed to take one of two values, V _L1 and L _V2 = V _L1 −△V _L1 , depending on changes in throttle opening and vehicle speed.

The output a of the kickdown switch K/D and the outputs c and d of the comparators 82 and 83 are supplied to an OR circuit 84. Solenoid drive circuit 85
is a circuit for driving the solenoid 71 of the solenoid valve 70, and when the input e is at H level, the solenoid 71 is energized and energized. On the other hand, when the input e is at L level, the solenoid drive circuit 85 does not supply current to the solenoid 71 and de-energizes it. As is clear from this, when the manual switch 80 is in the on state,
When the throttle opening does not reach 85%, that is, when kickdown is not performed, the solenoid 71 is in an excited state regardless of the vehicle speed.

Therefore, for example, when the manual switching valve is switched to the D range, if the vehicle is stopped or running at low speed, the governor hydraulic pressure Pgo generated by the governor hydraulic control valve is low, and the overdrive control valve 50
is in the downward switching position as shown at 50A, and line oil pressure Pli is supplied to clutch LO of the overdrive mechanism. Therefore, in this state, the overdrive mechanism is in a locked state, and the gear transmission mechanism is in the first to third speed states.

When the vehicle is running at high speed, solenoid 71
is excited, and line hydraulic pressure Pli is applied to drain port 77.
is introduced, and the oil pressure at the output port 76 decreases. At this time, overdrive control valve 50 is switched to position 50B, thereby causing its port 57
The hydraulic pressure supplied to the brake BO is switched to the port 58 side and is supplied to the brake BO from the port 59 through an oil path. On the other hand, the hydraulic pressure acting on the clutch LO is discharged from the oil passage and port 58 to the drain port 58. When the line oil pressure Pli is supplied to the brake BO, the overdrive mechanism 20 is activated and an overdrive state is achieved.

The above has explained the switching change that occurs as the governor oil pressure Pgo increases due to an increase in vehicle speed. Of course, such switching change is caused by the governor oil pressure Pgo and the throttle oil pressure acting oppositely on the valve element of each switching valve as described above.
This is done based on the balance of Pth, and the switching point changes depending not only on the vehicle speed but also on the amount of accelerator pedal depression.

At this time, the speed change characteristics of the overdrive control valve 50 in the high speed range are modified compared to the case where only the hydraulic control device is used, as shown in FIG. 4A. In other words, the shift line 3→O/D in a of FIG.
is the upshift characteristic from 3rd gear to overdrive by the electric control circuit, and the shift line O/
D→3 is a downshift characteristic to 3rd speed from overdrive by the electric control circuit.

In this way, the solenoid 71 is
The reason why hysteresis is applied to turn ON and OFF is, for example, due to changes in vehicle speed when climbing a slope, etc.
This prevents frequent switching between high speed and overdrive O/D, and the selection range V _H 1 to V of the high speed reference voltage V _H and low speed reference voltage V _L of the comparators 82 and 83 described above. _H 2, V _L 1~
This is due to V _L 2.

In the conventional shift control circuit of this type of automatic transmission described above, the vehicle cannot run in the overdrive gear unless the manual switch 80 is turned on. That is, when the manual switch 80 is in the OFF state, the line oil pressure Pli is being supplied to the port 61, displacing the valve element 54 downward, and displacing the valve element 54 downward.
Since it is in state A, the clutch LO of the overdrive mechanism is activated, and the vehicle runs under the state shown in the shift diagram of b in Figure 3, i.e., in 1st to 3rd gears, without being led to the overdrive stage. It turns out. In other words, the vehicle runs in an overdrive cancel state. Therefore, for example, in an automatic transmission with three speeds and an overdrive stage, if the vehicle is driven with the overdrive stage canceled, the engine rotational speed may become too high and the engine may overrun. This is particularly noticeable in Europe.

[Object of the Invention] In order to solve the above-mentioned drawbacks, the present invention provides a system in which when the vehicle speed exceeds a certain level, the gear is shifted to the overdrive stage even if the driver does not select the overdrive state, thereby preventing the engine from overrunning. The purpose is to

[Structure of the Invention] The present invention provides a method for changing the speed of an automatic transmission for a vehicle in which driving in the overdrive gear is selected by turning on the power of the vehicle's electrical system using an ignition switch or by selecting overdrive gear driving using an overdrive switch. The control circuit is characterized in that it is configured to be able to shift to an overdrive gear when the vehicle speed exceeds a predetermined speed, regardless of the speed state selected by the overdrive switch.

[Embodiments of the Invention] A specific embodiment of the present invention can be configured as follows. For example, an ignition switch turns on power to the vehicle's electrical system, thereby setting a shift control circuit that electrically shifts gears to an overdrive gear to a state in which the vehicle can run in the overdrive gear. When the overdrive switch is used to set the driving state in which the overdrive stage is not used (cancel state), when the vehicle speed exceeds a predetermined speed, the cancel state is set regardless of the operation of the overdrive switch, even if the driver does not operate the overdrive switch. However, it is configured so that it can be shifted to overdrive gear.

That is, the shift control circuit of the automatic transmission for a vehicle that electrically shifts to an overdrive gear according to the present invention operates as shown in the flowchart shown in FIG. First, when the ignition switch turns on the power to the vehicle's electrical system, the power on-set function sets the vehicle to an overdrive state ready for driving. Thereafter, each time a signal from the overdrive switch is input, the overdrive stage is alternately switched between a runnable state and an overdrive cancel state. When the vehicle is running in the overdrive stage, the kick-down switch is on, that is, it directly detects the opening of the intake throttle valve installed in the engine's carburetor and generates an electrical signal, or the accelerator pedal Activation of a kick-down switch consisting of a throttle sensor that generates an electric signal according to the intake throttle opening, such as a hydraulic switch that detects the detent oil pressure that appears on the throttle oil pressure control valve when the throttle is depressed beyond a predetermined degree. and by releasing the solenoid of the speed change control circuit that changes the speed to the overdrive speed according to the speed condition from the operating state, and setting the speed condition according to the speed change, the speed change control of the overdrive speed is performed. This is what we do.

Examples of the present invention will be described below.

FIG. 5 shows an embodiment of a speed change control circuit for an automatic transmission for a vehicle according to the present invention. In carrying out the present invention, the overdrive control valve 50 and the solenoid valve 70 having the structure of the conventional example described above can be used, so in the drawings, the same reference numerals and symbols indicate the same or equivalent parts as in the conventional example. shall be. E is a power supply, SA is a surge absorber, ZD is a constant voltage diode, D1 to D11, D13 to D18 are diodes, CO1 to CO5 are comparators, R1 to R56
are resistors, C1 to C8 are capacitors, FF is a D flip-flop, I/G is an ignition switch, and O/D is an overdrive switch, which is a momentary type that conducts between terminals only when pressed. K/D is a kick down switch, S/V
is a speed sensor, L is an overdrive cancel lamp, and T1 and T2 are connection terminals of the solenoid 71. Power source E means the output from a vehicle generator or battery. The switching is performed using well-known techniques. The surge absorber SA absorbs surges inserted into the power supply circuit when the power supply E is a generator and due to load fluctuations and the effects of inductive and capacitive loads. Diode D1 prevents reverse connection of the circuit. The capacitor C1, the resistor R1, the capacitor C2, and the constant voltage diode ZD constitute a constant voltage circuit whose output is a constant voltage Ez. These circuits are not directly related to the present invention, and circuits other than those in this embodiment can be used. Note that K/D is a kick-down switch that directly detects the opening of the intake throttle valve installed in the engine's carburetor and generates an electrical signal depending on the predetermined vehicle speed setting. , or a throttle sensor that generates an electrical signal in response to the intake throttle opening, such as a hydraulic switch that detects the detent oil pressure that appears on the throttle oil pressure control valve when the accelerator pedal is depressed beyond a predetermined degree. mechanical switch,
means an electronic switch circuit. Therefore, it is the same as or equivalent to the throttle sensor shown in the known example.

First, when the ignition switch I/G is turned on, charging of the capacitor C4 is started by the resistor R10 forming a time constant circuit. At this time,
The voltage of the capacitor C4 is applied to the base of the transistor Q1 through the resistor R11, and the transistor Q1 is turned on.H level is applied to the set terminal S, and the Q of the D flip-flop FF is set to H.
Set the level to L level. The terminals of flip-flop FF are led to the D input of D flip-flop FF via resistors R15 and R13. Incidentally, the setting of the D flip-flop FF is completed at the initial stage when the ignition switch I/G is turned on.

The H level of the Q output of the D flip-flop FF is
Since the base potential of the transistor Q3 is raised via the resistor R14, the transistor Q3 is turned on and the transistor Q7 is turned off. Therefore, although dark current flows through the overdrive cancel lamp L via the resistor R23, it does not light up. At this time, diode D16 and diode D14 are turned off.

When diode D14 is turned off, it prevents interference in the circuit on the anode side of diode D14 together with diode D16. Therefore, current flows through the diode D13 through the resistors R25 and R26, the resistor R53, and the resistors R50 and R51, and the base potential of the transistor Q6 rises, turning on the transistor Q6. When the transistor Q6 is turned on, the cathode side of the diode D15 becomes approximately at ground potential, and a base current flows through the transistor Q8 by the resistor R52, turning the transistor Q8 on. By turning on the transistor Q8, the power supply voltage E, via the resistor R24, energizes the solenoid 71 of the solenoid valve 70 shown in FIG. 2.

In this way, when the ignition switch I/G is turned on, the D flip-flop FF is set by the power on-set function, the solenoid 71 of the solenoid valve 70 is energized, the armature 72 opens the valve port 74, and the line oil pressure Pli is led to the drain port 77, the oil pressure at the port 61 of the overdrive control valve 50 drops, each valve element becomes like 50B, and the line oil pressure Pli is led to the port 59 side, and the oil pressure of the brake BO of the overdrive mechanism decreases. Therefore, the vehicle can run in the overdrive stage, and the vehicle speed is determined by the torque converter 10.

The output of the vehicle speed sensor S/V, which obtains the number of pulses corresponding to the vehicle speed of a speedometer, etc., is connected to the diode D8.
Since the diode D8 is added to the cathode side of the diode D8, the diode D8 repeatedly turns on and off.

One input of comparator CO2 has a resistor R
A reference voltage determined by the resistor R29 and the resistor R30 is applied, and the potential at the connection point of the resistor R27 and the resistor R28 is applied to the other input. Resistance R
Since a diode D8 is also connected to the connection point between 27 and the resistor R28, the operation of the vehicle speed sensor S/V increases or decreases the reference voltage value determined by the resistors R29 and R30, and the output of the comparator CO2 becomes L level. , H level changes alternately. The number of times the L level and H level change alternately has a value proportional to the vehicle speed. The comparator CO
2 is an open collector type, so when its output is at L level, capacitor C7 is rapidly charged by diode D9 and resistor R33, and when it reaches H level, it is further charged from voltage Ez via resistor R32. The charging voltage of capacitor C7 is raised, raising the potential of the emitter of transistor Q4. Meanwhile, a base resistance R is connected to the base side of the transistor Q4 by a diode D10.
34 is clamped to the emitter side voltage Ez of transistor Q4. The emitter-base voltage increases, turning on the transistor Q4, transferring the charge of the capacitor C7 to the smoothing capacitor C8, and charging it with a constant current. That is, the voltage of the capacitor C8 has a voltage value proportional to the number of pulses of the vehicle speed sensor. Note that resistor R36 is for discharging capacitor C8, and resistor R35 and diode D
11 is for temperature correction. A circuit that obtains a voltage proportional to the number of pulses of this type of vehicle speed sensor is a general f
This corresponds to a circuit called a -V conversion circuit, and the circuit is not limited to the circuit of this embodiment, and a well-known fV conversion circuit can be used. In addition,
If the vehicle speed sensor S/V uses an analog output as its output, this type of circuit can be omitted.

The voltage of the smoothing capacitor C8 becomes an input to a high vehicle speed setting comparator CO3 and a low vehicle speed setting comparator CO4 via a resistor R37. That is,
This is for setting the high vehicle speed V _H 1 and the low vehicle speed V _L 1 in the range c in FIG. 4, which is the range for shifting from the overdrive gear to the third gear when the vehicle is turned down to obtain the vehicle speed while traveling in the overdrive gear. Resistor R38, R
43, R48, R49, R50 and resistor R39 are resistors R38, R39, R39 at low vehicle speed V _L 1.
43 is used to set a reference voltage for low vehicle speed V _L2 . Resistor R40, R42, R44 and resistor R41
is high vehicle speed V _H 1, resistance R40 and resistance R41, R
42 is used to set a reference voltage for high vehicle speed V _H 2.

Now, assuming that the voltage of the smoothing capacitor C8 is higher than the high vehicle speed reference potential V _H 1, the comparator
The output of CO3 becomes L level, the current passing through resistor R45 and the output of comparator CO4 are sucked into the output side of open collector type comparator CO3, and transistor Q5 is in the off state.
The base current of the transistor Q6 is maintained by the current flowing through the resistors R25, R26, R53, the diode D13, and the resistor R50, as well as the current flowing through the resistors R48, R49, and R50.
Transistor Q6 is in an on state. When the transistor Q6 is on, the transistor Q8 is also on, and the solenoid 71 of the solenoid valve 70 is energized, causing the vehicle to run in the overdrive stage.
At this time, the resistor R42 is brought to the ground potential via the diode D15, so the resistor R41 and the resistor R42 are connected in parallel, and the high vehicle speed reference voltage of the comparator CO3 is a voltage _VH2 lower than _VH1 . becomes. Therefore, after reaching the vehicle speed corresponding to the reference voltage V _H 1 for one high vehicle speed, the comparator CO is turned off until the vehicle speed decreases to the reference voltage V _H 2.
The output of No. 3 has hysteresis that does not invert to H level. High vehicle speed reference voltage
When the vehicle speed reaches a speed equal to or higher than V _H 1, diode D13 is turned off even if the kick-down switch K/D remains on until the speed is reduced to a speed equivalent to high vehicle speed reference voltage V _H 2. , the base potential of the transistor Q6 is the resistor R48, R4
Since the transistor Q6 is maintained by the current flowing through R50, the transistor Q6 has no relation to whether the kickdown switch K/D is on or off.

When the voltage of the smoothing capacitor C8 becomes lower than the high vehicle speed reference voltage _VH2 , the comparator CO
The output of No. 3 becomes H level. At this time, since the output of the comparator CO4 is at H level, the potential of the resistor R47 rises, turning on the transistor Q5. Transistor Q6 is connected to resistor R48 and resistor R
49 is pulled to approximately ground potential by transistor Q5, but when kickdown switch K/D is off, resistors R25, R26, R5
3. The on state is maintained by the current flowing through the diode D13 and the resistor R50, and the solenoid 71 is energized to maintain the overdrive stage.

However, while driving in the above-mentioned overdrive stage,
If you press the access to 85% or more for overtaking, etc., and turn on the down switch K/D,
Diode D7 is turned on, and the potential between resistor R25 and resistor R26 becomes approximately ground potential. Therefore, diode D13 is turned off, turning off transistor Q6. When transistor Q6 is turned off, the base voltage of transistor Q8 increases, transistor Q8 is also turned off, and solenoid 71 of solenoid valve 70 is de-energized. At this time, the diode D17 absorbs the back electromotive force of the solenoid 71.

That is, by turning on the kick-down switch K/D, the solenoid 71 of the solenoid valve 70 is de-energized, the armature 72 closes the valve port 74, the line oil pressure Pli is applied to the port 61, and the valve element 54 is placed at the 50A position. As a result, the hydraulic pressure supplied to port 57 is supplied from port 58 to clutch CO of the overdrive mechanism instead of port 59, and from the overdrive stage to the third
is downshifted quickly.

At this time, if there is no hysteresis mentioned above, when the kick-down switch K/D is turned on due to overtaking, etc., chattering will occur around the vehicle speed corresponding to the high vehicle speed reference voltage V _H 1. . The hysteresis prevents this chattering (see a in FIG. 4).

When transistor Q5 is on, resistor R4
Since one end of 3 is at approximately ground potential, and the resistor _R39 and resistor _R43 are connected in parallel, the output of the comparator CO4 is Not reversed. When the voltage of the smoothing capacitor C8 reaches a vehicle speed corresponding to a voltage value lower than the low vehicle speed reference voltage V _L 2, the output of the comparator CO4 becomes L level, and the output of the open collector type comparator CO
The output of 4 sinks current through the output of comparator CO3 and resistor R45, turning off transistor Q5 and turning on transistor Q6. When the transistor Q6 is turned on, the solenoid 71 of the solenoid valve 70 is energized, and even if the kick-down switch K/D is turned on, the solenoid 71 is always energized regardless of the fact that the kick-down switch K/D is turned on, and the solenoid 71 is always energized to shift down from the overdrive stage. never be done. Therefore, even when the vehicle speed sensor malfunctions, for example, when its output drops due to wire breakage or damage to mechanical parts, it is possible to shift to the overdrive stage and prevent the engine from overrunning. Further, at this time, hysteresis is also used to prevent chattering.

Generally, the vehicle will be driven under the above conditions.

However, when passing, downshift and
It is necessary to accelerate the vehicle, and when the vehicle is traveling downhill, it is necessary to downshift and use engine braking. Therefore, depending on the situation, the driver may want to manually downshift from the overdrive gear. At this time, the overdrive switch O/D is used.
It is. By pressing the overdrive switch O/D to turn it on and off, the driveable state of the overdrive stage can be canceled. Next, its operation will be explained.

When overdrive switch O/D is turned on, power supply voltage E is applied to both terminals of resistor R2. While the overdrive switch O/D is on, the power supply voltage E passes through the resistor R3 and the diode D3 and is charged into the capacitor C3. At this time, since the voltage on the cathode side of the diode D2 is lower than the power supply voltage E, when the capacitor C3 is fully charged, the diode D2
It is clamped to the voltage Ez of the constant voltage diode.
The charging voltage of capacitor C3 is led to comparator CO1 via resistor R5, and the reference voltage of comparator CO1, that is, resistor R6 and resistor R7
When the voltage exceeds the voltage determined by , the output of comparator CO1 becomes H level. At this time,
The charging voltage of the capacitor C3 is input to the comparator CO1 through the resistor R5, but since the comparator CO1 is an open collector type, it is brought to the ground potential through the resistor R8 and the diode D4. Therefore, the input to the comparator CO1 is approximately the voltage divided between the resistors R5 and R8.

When the output of the comparator CO1 is at L level, the charging voltage of the capacitor C3 is compared with the approximately divided voltage value of the resistor R5 and the low resistor R8, and the comparator
When the output of CO1 is at H level, voltage Ez is led to the output side of comparator CO1 via resistor R9, and diode D4 becomes reverse biased and turns off. Therefore, when the output of comparator CO1 is at H level, , a voltage equal to the charging voltage of capacitor C3 becomes the input of comparator CO1.
Therefore, comparator CO1 has hysteresis characteristics. This hysteresis characteristic is caused by the time constant circuit of resistor R3 and capacitor C3 as well as the overdrive switch O/D chattering, etc. This prevents the application of taring pulses and reliably detects the number of presses of the overdrive switch O/D. Note that a resistor R4 connected in parallel to the capacitor C3 is for discharging. This type of hysteresis circuit is the same circuit as what is generally called a Schmitt circuit, and it increases the threshold of the rise voltage of capacitor C3 when pressing the overdrive switch O/D to prevent chattering, noise, and pressing errors. In order to prevent this, waveform shaping is performed, and the essence of the present invention is not restricted in any way.

One press of the overdrive switch O/D inputs one pulse to the clock input CL of the D flip-flop FF. Since the L level of the output of the D flip-flop FF is led to the D input of the D flip-flop FF, when the clock input CL is at the L level, the L level of the D input is read, and when the clock input CL becomes the H level, The L level of the read D input is set as the Q output of the D flip-flop FF. Therefore, D
The Q output of the flip-flop FF becomes L level. Accordingly, the output of the D flip-flop FF becomes H level, but the D input of the D flip-flop FF is connected to the resistor R15 by the capacitor C5.
delayed by the time constant determined by capacitor C5,
It becomes H level.

The L level of the output Q of the D flip-flop FF is
Since the base of transistor Q3 is brought to L level via resistor R14, transistor Q3 is turned off. Therefore, the base current of transistor Q7 flows through resistor R20, and transistor Q7
turns on and current flows through diode D16 and transistor Q7, so overdrive cancel lamp L lights up. Incidentally, a dark current flows through the cancel lamp L through the resistor R23 at the same time as the ignition switch I/G is turned on, thereby preventing a rush current from flowing when the transistor Q7 is turned on.

On the other hand, when transistor Q7 is turned on, diodes D13 and D14 are also turned on, and resistor R50
One end of the is pulled to approximately ground potential. The base potential of transistor Q6 is brought to approximately ground potential by resistor R50, and transistor Q6 maintains an off state unless current is supplied from diode D18. The base potential of the transistor Q8 is set to the same potential as the power supply voltage on the emitter side by the resistor R19, and the transistor Q8 is turned off. By turning off transistor Q8, solenoid valve 70
No current flows through the solenoid 71, and the solenoid 71 becomes de-energized.

Therefore, when the vehicle no longer needs to run in the canceled state of the overdrive stage shown in Fig. 4b, when the driver presses the overdrive switch O/D again, the vehicle shifts to D as in the former case.
One pulse is input to the clock input CL of flip-flop FF. At this time, D flip-flop
Since the output H level is guided to the D input of the FF, when one pulse arrives at the clock input CL, the Q output of the D flip-flop FF is inverted and becomes H.
level. That is, the state is the same as the initial state when the ignition switch I/G is turned on, and the solenoid 71 of the solenoid valve 70 is energized.
The vehicle becomes ready to run in the overdrive stage.

Note that when the overdrive switch O/D is further pressed, the previous state of the D flip-flop FF is reversed. That is, by pressing the overdrive switch O/D, the D flip-flop FF reverses its previous state, and the solenoid 71 of the solenoid valve 70 alternately switches between the energized state and the de-energized state, and the overdrive stage is in the ready state. The cancel state can be alternately switched.

However, there are cases where the driver drives the vehicle with the overdrive gear canceled by using the overdrive switch O/D, resulting in the vehicle traveling at a speed higher than the speed originally shifted to the overdrive gear.

At this time, it is assumed that the vehicle speed is in the running state shown in the shift diagram of FIG. 4b. Vehicle speed reference voltage in Figure 4b where vehicle speed is determined by resistor R54 and resistor R55
When the speed corresponding to V _M 1 is reached, the output of the open collector type comparator CO5 changes from the L level to the H level. Comparator CO5
The output of is led to the transistor Q6 via the diode D18, and the base potential of the transistor Q6 rises regardless of the potential on the cathode side of the diode D13 (the potential on the anode side of the diode D14). Therefore, transistor Q6 and transistor Q8 are turned on, energizing solenoid 71, and shifting to overdrive speed. In this embodiment, when the output of the comparator CO5 becomes H level, the kickdown switch K/D
The vehicle speed reference voltage V _M 1 is the high vehicle speed reference voltage because the vehicle will run in the overdrive stage regardless of
It is desirable that V _H is 1 or more.

When the vehicle is decelerated to a speed equal to or less than the vehicle speed of the vehicle speed reference voltage V _M 1, the comparator CO5
The output of the transistor Q6 becomes L level, and the transistor Q6 is turned off. Therefore, at this time, the overdrive stage is canceled. The vehicle travels by changing gears from 1st to 3rd gear. In this way, for example, even if the driver forgets to set the overdrive gear to the shiftable state, the vehicle will be able to drive in the overdrive gear when the speed exceeds a desired speed. Note that in this example, the comparator
In order to provide hysteresis to CO5 and prevent chattering etc., a circuit configuration similar to that of the resistor R8 and diode D4 of the comparator CO1 may be provided between the input and output of the comparator CO5.

Furthermore, in this embodiment, a resistor R24 is inserted in series with the solenoid 71. This constitutes a protection circuit for the solenoid valve 70 system.
Next, I will explain it.

Since the value of the resistor R24 is set small, the current of the normal solenoid 71 is caused by a voltage drop that is caused by the base current flowing between the emitter and the base of the transistor Q2, which is sufficient to turn on the transistor Q2. do not have. However, if the current flowing through the low resistance R24 increases due to, for example, a short circuit between terminals T1 and T2 of the connector of the solenoid valve 70 or a short circuit between the coil terminals or layers of the solenoid 71, the terminal voltage of the resistor R24 increases. is applied between the emitter and base of transistor Q2 and to the series circuit of resistor R18, and
This results in a base current sufficient to turn on 2. When transistor Q2 is turned on, current flows through resistor R17, diode D6, and resistor R21. At this time, the voltage on the anode side of the diode D6 is clamped to the voltage Ez by the diode D5. Since the terminal voltage of the resistor R21 is led to the reset terminal R of the D flip-flop FF by the resistor R16, the terminal voltage of the resistor R21 will reset the D flip-flop FF.
When D flip-flop FF is reset, D
The Q output of the flip-flop FF becomes L level,
Turn off transistor Q3 and turn off transistor Q7.
Raise the base potential of The base voltage flows into the transistor Q7 via the resistor R20, turning it on.
Since the resistor R23, which had been causing a dark current to flow through the cancel lamp L, is short-circuited by the diode D16 and the transistor Q7, the cancel lamp L is turned on. When the D flip-flop FF is in the cancel state, the transistor Q7 is in the on state and draws the cathode side of the diode D14 to approximately ground potential, so the resistors R49 and R50
The potential at the connection point also decreases, transistor Q6 is always off, transistor Q8 is also off, and the current to solenoid valve 70 is cut off. In this state, turn the overdrive switch O/
Even if D is turned on, as long as there is an abnormality on the solenoid valve 70 side, D flip-flop FF will maintain its reset state. Note that since the D flip-flop FF used in this embodiment operates as described above, it is not limited to the D flip-flop, and a JK flip-flop or the like may also be used.

In the above embodiment, the vehicle speed reference voltage is V _M 1≧V _H 1
We have described the circuit in which there is a relationship of
If the circuit is configured as shown in the example shown in the figure, the throttle opening will reach 85% or more and the kick-down switch K/D will reach 85% or more.
The vehicle speed reference voltage VM of the above embodiment can be set even in the range A (see FIG. 4d) in which the overdrive gear is downshifted from the overdrive stage to the third gear by turning on the output. Vehicle speed reference voltage
When V _M 2 is set to V _M 2 ≦ V _H 2 and the output of open collector comparator CO5 is at L level, current is sucked from resistor R56 to the output of comparator CO5, and diode D18 and diode D19 are turned off. So, diode D18
And the cathode side of the diode D19 is made to function as a separate circuit. When the output of the comparator CO5 is at H level, the diode D18 turns on the transistor Q6 and turns on the transistor Q8, thereby exciting the solenoid 71. At this time, when the kick-down switch K/D is turned on, the diode D7 and the diode D19 are turned on, the output of the comparator CO5 becomes L level, and the base potential of the transistor Q6 also becomes L level. Solenoid 71 becomes de-energized. Therefore, the vehicle is shifted down from overdrive speed to third speed. When the vehicle is running at a speed higher than the vehicle speed corresponding to the vehicle speed reference voltage V _H 1, when the kick-down switch K/D is turned on, the diode D18 is turned off, and the transistor Q6 is connected to the The base current will be maintained and the on state will be maintained. In the case of this embodiment, even if you forget to turn on the overdrive switch O/D while driving,
This means that the vehicle can travel approximately in the same manner as shown in the d-shift diagram in FIG.

Further, FIG. 7 shows an embodiment in which an abnormality detection function is provided, and when the diode D19 becomes approximately ground potential due to the transistor Q7 turned on due to abnormality detection, the base potential of the transistor Q6 is also pulled to approximately ground potential and turns off. Therefore, in any state, i.e., transistor Q
6 is turned on, the current path flows from the diode D13 to the resistor R50, and the resistors R48 and R4
9, circuit flowing through R59 or diode D
Even though the base current of transistor Q6 is supplied by the circuit flowing through transistor Q7
By turning on, the vehicle is unable to run in the overdrive stage.

In FIG. 8, the output of a comparator CO6, which inverts the output to L level at an arbitrary speed, is connected to the connection point between the resistor R10 and the capacitor C4, which constitute the time constant circuits of FIGS. 5 and 7. When the output is at L level, the transistor Q1 is turned on by the diode D21, and the D flip-flop FF, which is in the cancel state, is brought into the set state.

In addition, in the present embodiment shown in FIGS. 6, 7, and 8 above, in order to provide hysteresis to the comparator CO5 or the comparator CO6 to prevent chattering, etc., the comparator CO5 or the comparator CO6 must be
5 or between the input and output of comparator CO6,
Resistor R8 and diode D4 of comparator CO1
A circuit configuration similar to that may be used.

The embodiment shown in FIG. 9 performs the same operation as the embodiment shown in FIG. In this embodiment, the vehicle speed is determined by the vehicle speed reference voltage.
When the speed reaches V _H 1, the output of comparator CO3 changes from H level to L level,
Set D flip-flop FF. At this time,
The diode D20 cuts off the output of the comparator CO3 and the output of the comparator CO4, and takes out only the output of the comparator CO3 alone. The diode D22 maintains the function of setting the D flip-flop FF when the ignition switch I/G is turned on. According to this embodiment, it is possible to construct a speed change control circuit for an automatic transmission for a vehicle that achieves the object of the present invention using the least number of parts, and the speed change control circuit becomes inexpensive.

Incidentally, since the present invention can be controlled as shown in the flowchart of FIG. 10, a microprocessor can also be used. If a microprocessor is used, the f-V conversion circuit, vehicle speed reference voltage and hysteresis setting circuit are preferably circuits that can digitally process signals.

[Effects of the Invention] As described above, the first invention provides a shift control circuit for an automatic transmission for a vehicle that includes an overdrive selection means that permits or prohibits shifting to an overdrive gear depending on the state of an overdrive switch. a vehicle speed detecting means for detecting the speed of the vehicle; a high vehicle speed monitoring means for monitoring the vehicle speed detected by the vehicle speed detecting means and emitting a high vehicle speed signal when the detected vehicle speed exceeds a predetermined vehicle speed; Since the automatic transmission is equipped with an overdrive fixing means for forcibly fixing the gear of the automatic transmission to the overdrive gear when a vehicle speed signal is being generated, the driver does not need to select the overdrive gear while driving. However, if this selection is not made and the detected vehicle speed of the vehicle exceeds a predetermined speed, the overdrive fixing means will change the gear position of the automatic transmission regardless of the state of the overdrive switch. can be forcibly fixed to the overdrive stage.

Therefore, even if the vehicle is driven with the overdrive switch canceled, it is possible to shift to the overdrive gear as the vehicle speed increases, so if the driver forgets to press the overdrive switch while driving, the engine speed will decrease. It is possible to prevent it from becoming too high and overrunning. In addition, by fixing the speed to high-speed driving using the overdrive stage, the engine speed can be kept low despite high-speed driving, allowing for quiet driving and extending the life of the engine.

Furthermore, if a predetermined vehicle speed that is the threshold speed of the high vehicle speed monitoring means, that is, a predetermined vehicle speed at which the gear is shifted to the overdrive gear, is set based on the fuel consumption rate, etc., the overdrive gear can be effectively shifted during high-speed driving. can be used, resulting in a good fuel consumption rate and economical operation. In particular, even when the overdrive stage cannot be used appropriately due to lack of user awareness, it is possible to effectively select the overdrive stage and achieve economical operation.

Particularly, in this invention, even if the overdrive cancel switch is pressed by mistake when the overdrive gear is running at a high speed higher than a predetermined speed, the overdrive gear continues to run, so the vehicle cannot shift down. There is no sudden deceleration due to

A second aspect of the present invention is that, in the shift control circuit of the automatic transmission for a vehicle, a vehicle speed detection means for detecting the speed of the vehicle and a vehicle speed detected by the vehicle speed detection means are monitored, and when the detected vehicle speed becomes equal to or higher than a predetermined vehicle speed. a high vehicle speed monitoring means for emitting a high vehicle speed signal; an overdrive fixing means for forcibly fixing a gear position of an automatic transmission to an overdrive stage when the high vehicle speed monitoring means is emitting a high vehicle speed signal; The apparatus includes a kickdown detection means for detecting a kickdown, and an overdrive fixing release means for releasing the fixation of the overdrive fixing means when the kickdown detection means detects a kickdown.

Therefore, this invention can also achieve the same effects as the first invention.

Furthermore, when the kickdown detecting means detects a kickdown, the overdrive fixing means can be released from the overdrive fixing means by the overdrive fixing release means, so that when acceleration is required, the overdrive stage is released by the kickdown. Since driving can be canceled, even if the automatic transmission gear is forcibly fixed to the overdrive gear by the overdrive fixing means, when overtaking or climbing a slope, the necessary acceleration can be achieved by downshifting. can be obtained.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional vehicle transmission including a gear transmission mechanism equipped with a hydraulic torque converter and a frictional engagement device, and Figure 2 is a conventional vehicle automatic transmission that shifts to an overdrive stage. Fig. 3 is a control circuit diagram of a conventional vehicle automatic transmission that shifts to overdrive stage, Fig. 4 is a shift diagram showing the shift control state of the automatic transmission, and Fig. 5 is a hydraulic control system diagram. FIG. 6 is a shift control circuit diagram of an automatic transmission for a vehicle according to a first embodiment of the present invention, FIG. 6 is a shift control circuit diagram of an automatic transmission for a vehicle according to a second embodiment of the present invention, and FIG. FIG. 8 is a shift control circuit diagram of an automatic transmission for a vehicle according to a fourth embodiment of the present invention, and FIG. 9 is a shift control circuit diagram of an automatic transmission for a vehicle according to a fourth embodiment of the present invention. Shift control circuit diagram of automatic transmission for vehicles, Part 1
Figure 0 is a flowchart of the present invention. In the diagram, I/G...ignition switch,
O/D...Overdrive switch, K/D...
…Kickdown switch, S/V…Speed sensor, L…Overdrive cancel lamp,
D1~D23...Diode, CO1~CO6...
Comparator, R1 to R60...Resistance, C1 to C
8...Capacitor, FF...D flip-flop,
T1 and T2... Solenoid connection terminal, 70...
Solenoid valve, 71...In the diagram, the solenoid is
The same reference numerals and symbols indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. In a shift control circuit of an automatic transmission for a vehicle, which includes an overdrive selection means for permitting or prohibiting a shift to an overdrive gear depending on the state of an overdrive switch, a vehicle speed detection means for detecting the speed of the vehicle. and high vehicle speed monitoring means that monitors the vehicle speed detected by the vehicle speed detection means and generates a high vehicle speed signal when the detected vehicle speed exceeds a predetermined vehicle speed, and when the high vehicle speed monitoring means is generating the high vehicle speed signal, A shift control circuit for an automatic transmission for a vehicle, comprising an overdrive fixing means for forcibly fixing a gear of the automatic transmission to an overdrive gear. 2. In a shift control circuit of an automatic transmission for a vehicle, which is equipped with an overdrive selection means for permitting or prohibiting shifting to an overdrive gear depending on the state of an overdrive switch, a vehicle speed detection means for detecting the speed of the vehicle; and the vehicle speed detection means. a high vehicle speed monitoring means for monitoring a detected vehicle speed of the automatic transmission and generating a high vehicle speed signal when the detected vehicle speed exceeds a predetermined vehicle speed; an overdrive fixing means for forcibly fixing the overdrive to the overdrive stage; a kickdown detection means for detecting a kickdown; and an overdrive fixing release for releasing the fixation of the overdrive fixing means when the kickdown detection means detects a kickdown. 1. A speed change control circuit for an automatic transmission for a vehicle, comprising: means.