JPH0517430B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a hydraulic pressure control device for an automatic transmission, and more particularly to a hydraulic pressure control device in which control hydraulic pressure is obtained by duty-controlling a solenoid valve provided in a hydraulic circuit. Regarding equipment. BACKGROUND OF THE INVENTION In recent years, various functions have been added to automatic transmissions in order to improve their performance, such as torque converter slip control performance, creep prevention function, shift shock prevention function, etc. When various functions are added in this way, it becomes advantageous to control the hydraulic pressure by electronic control. In this electronic control, a solenoid valve is provided in the hydraulic pressure circuit of the control device, and by controlling the duty of the solenoid valve, the desired control hydraulic pressure is obtained. It is known from Publication No. 59-47552. Specifically, an orifice is interposed in a hydraulic pressure supply circuit that supplies hydraulic pressure from a hydraulic pressure source to various control elements such as various valves and clutches, and a drain passage is connected to the downstream side of the orifice. and this drain passage is connected to the control pulse signal.
A solenoid valve is installed that opens and closes in response to ON and OFF. The duty ratio of the control pulse signal output from the control unit is variably controlled based on vehicle operating conditions such as engine speed, throttle opening, and gear position. Therefore, by draining a portion of the hydraulic pressure in accordance with the duty ratio, it is possible to generate a hydraulic pressure, that is, a control pressure, in accordance with the vehicle operating state on the downstream side of the orifice. Problems to be Solved by the Invention Oil is generally used as the hydraulic fluid in the above-mentioned hydraulic pressure control device, but this hydraulic fluid has the characteristic that the viscosity changes with temperature changes, and the viscosity increases at low temperatures. There is. When the viscosity of the hydraulic oil increases in this way, in the type of hydraulic oil that controls the hydraulic pressure by draining the hydraulic oil as described above, the drain generally does not go smoothly, so the increase in hydraulic pressure is prevented. arise. On the other hand, if the viscosity becomes extremely low at high temperatures, the fluid is quickly drained, which tends to lower the fluid pressure. Therefore, improvements have been made in the past in which various means are used to compensate for the drop in line pressure at extremely high temperatures. However, in the conventional hydraulic control device,
Since there is an orifice with a relatively small diameter on the upstream side of the solenoid valve, if the viscosity increases at low temperatures, the flow through the orifice will be obstructed. Conversely, the hydraulic pressure downstream of the orifice tends to decrease. FIG. 9 shows characteristic changes in the control pressure downstream of the orifice obtained for each duty ratio depending on the oil temperature. For example, when the temperature is 30° C. or lower, the hydraulic pressure decreases significantly. Therefore, if we were to apply the above-mentioned correction for high temperatures as is and correct the duty ratio so that the drain period ratio increases as the temperature decreases, the problem would be that the drop in fluid pressure would become even worse. It was hot. Means for Solving the Problems Therefore, in the present invention, the drain period ratio, that is, the open period ratio of the solenoid valve is corrected to be small when the temperature is low. That is, as shown in FIG. 1, the present invention includes a control means b for controlling the duty ratio of a control pulse signal based on the operating state, and a control means b for supplying hydraulic pressure from a hydraulic pressure source through a control element heorifice such as a valve. a drain passage (not shown) connected to the downstream side of the orifice of the hydraulic pressure circuit; a solenoid valve a that is interposed in the drain passage and opens and closes the drain passage in response to the control pulse signal; A fluid pressure control device for an automatic transmission c, comprising: a fluid temperature sensor d for detecting the fluid temperature of a control hydraulic fluid; and a fluid temperature sensor d for detecting the fluid temperature, and based on the detected fluid temperature, the open period ratio of the solenoid valve a is small at low temperatures. The present invention is characterized in that a duty correction means e is provided for correcting the duty ratio of the control pulse signal so that the following equation is obtained. Effect When the viscosity of the control hydraulic fluid increases at low temperatures and the flow through the orifice becomes obstructed, the control pressure obtained on the downstream side of the orifice tends to decrease. On the other hand, based on the temperature of the working fluid detected by the fluid temperature sensor d, the duty ratio of the control pulse signal is corrected so that the open period ratio of the solenoid valve a becomes small when the temperature is low. Therefore, the increase in passage resistance at the orifice and the decrease in the drain period are offset, and a decrease in control pressure at low temperatures is avoided. Examples Examples of the present invention will be described in detail below with reference to the drawings. That is, FIG. 2 shows the entire circuit of a hydraulic pressure control device showing one embodiment of the present invention, and the power transmission train of an automatic transmission controlled by this hydraulic pressure control device is, for example, the one shown in FIG. There is something like the one shown in the schematic diagram. That is, this power transmission train includes a torque converter 3 that transmits rotation from the engine output shaft 1 to the input shaft 2, a first planetary gear set 4, a second planetary gear set 5,
It is composed of an output shaft 6 and various friction elements described below. The torque converter 3 is driven by the engine output shaft 1 and includes a pump impeller 3P that is also used to drive the oil pump O/P, and a turbine that is fluidly driven by the pump impeller via internal working fluid and transmits power to the input shaft 2. placed on a fixed shaft via a runner 3T and a one-way clutch 7,
It consists of a stator 3s that increases the torque to the turbine runner 3T, and a lock-up clutch 3 is attached to this stator 3s.
This is a normal lock-up torque converter with L added. The torque converter 3 is supplied with working fluid from the release chamber 3R, and while the working fluid is removed from the apply chamber 3A, the lock-up clutch 3L is released and the engine power is pumped through the impeller 3P and the turbine runner 3T ( (in the converter state) torque is transmitted to the input shaft 2 while increasing, and while the working fluid is supplied from the apply chamber 3A and the working fluid is removed from the release chamber 3R, the lock-up clutch 3L is engaged and the engine power is increased. is transmitted as is to the input shaft 2 via this lock-up clutch (in the lock-up state). 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 displacement pressure from the release chamber 3R. be able to. The first planetary gear set 4 is a normal simple planetary gear set consisting of a sun gear 4S, a ring gear 4R, a pinion 4P that meshes with these gears, and a carrier 4C that rotatably supports the pinion 4P.
Sun gear 5S, ring gear 5R, pinion 5P
and carrier 5C. Next, the various friction elements mentioned above will be explained. The carrier 4C can be appropriately connected to the input shaft 2 via a high clutch H/C, and the sun gear 4S can be appropriately fixed by a band brake B/B, and can also be appropriately connected to the input shaft 2 by a reverse clutch R/C. . The Carrier 4C can be fixed appropriately with a multi-plate low reverse brake LR/B, and
Reverse rotation (rotation in the opposite direction to the engine) is prevented via the row one-way clutch LO/C. Ring gear 4R is integrally connected to carrier 5C and output shaft 6
The sun gear 5S is coupled to the input shaft 2. Ring gear 5R is an overrun clutch
In addition to being able to connect to carrier 4C as appropriate via OR/C, forward one-way clutch FO/C
and the carrier 4C via the forward clutch F/C. The forward one-way clutch FO/C connects the ring gear 5R to the carrier 4C in the reverse direction (the direction opposite to the engine rotation) when the forward clutch F/C is engaged. High clutch H/C, reverse clutch R/
C, low reverse brake LR/B, overrun clutch OR/C and forward clutch F/
C is operated by hydraulic pressure supply to perform the above-mentioned appropriate coupling and fixing, and band brake B/B is connected to 2-speed servo apply chamber 2S/A,
When the 3rd speed servo release chamber 3S/R and the 4th speed servo apply chamber 4S/A are set and the 2nd speed selection pressure P ₂ is supplied to the 2nd speed servo apply chamber 2S/A, the band brake B/B is activated. In this state, when the 3rd speed selection pressure _P3 is also supplied to the 3rd speed servo release chamber 3S/R, the band brake B/B becomes inactive, and then the 4th speed servo apply chamber 4S/A is also supplied with the 3rd speed selection pressure P3.
When the speed selection pressure _P4 is supplied, the band brake B/B is activated. Such a power transmission train includes friction elements B/B, H/
By operating C, F/C, OR/C, LR/B, and R/C in various combinations as shown in the table below,
Together with the appropriate differential of the friction elements FO/C and LO/C, the rotational state of the elements constituting the planetary gear sets 4 and 5 is changed, thereby changing the rotational speed of the output side 6 relative to the rotational speed of the input shaft 2. As shown in the table below, it is possible to obtain four forward speeds and one reverse speed. In addition, the ○ mark in the following table is activated (hydraulic inflow)
, where the cross symbol indicates the friction element that should be activated when engine braking is required. Then, while the overrun clutch OR/C is operated, the forward one-way clutch FO/C placed in parallel with it is inactive, and while the low reverse brake LR/B is operated, the forward one-way clutch FO/C is placed in parallel with it, as shown by the mark. Of course, the row one-way clutch LO/C becomes inoperative.

[Table] By the way, the hydraulic side control device shown in FIG. 2 includes a pressure regulator valve 20, a pressure modifier valve 22, a duty solenoid 24 as a solenoid valve, and a pilot valve 2.
6, torque converter regulator valve 28, lockup control valve 30, shuttle valve 32,
Duty solenoid 34, manual valve 36,
first shift valve 38, second shift valve 40, first shift solenoid 42, second shift solenoid 44,
Forward clutch control valve 46, 3-2
Timing valve 48, 4-2 Relay valve 50, 4-2
Sequence valve 52, I range pressure reducing valve 54, shuttle valve 56, overrun clutch control valve 58, third shift solenoid 60, overrun clutch pressure reducing valve 63, 2nd speed servo apply pressure accumulator 64, 3rd speed servo release pressure accumulator 66, 4-speed servo apply pressure accumulator 68 and accumulator control valve 7
The main components are the torque converter 3, forward clutch F/C, high clutch H/C, band brake B/B, reverse clutch R/C, and low reverse brake LR/C.
Connect to B, overrun clutch OR/C, and oil pump O/P as shown. The pressure regulator valve 20 includes a spool 20b elastically supported in the left half position in the figure by a spring 20a, and a plug 20 that abuts against the lower end surface of the spool in the figure.
Basically, the oil pump O/P regulates the oil discharged to the circuit 71 to a certain pressure determined by the spring force of the spring 20a, but the plug 20c applies an upward force to the spool 20b in the figure. When the line pressure is increased, the above pressure is increased accordingly to reach a predetermined line pressure. For this purpose, the pressure regulator valve 20 transfers the pressure in the circuit 71 via the damping orifice 72 to the pressure receiving surface of the spool 20b.
0d, which urges the spool 20b downward, and ports 20e to 20h are provided which are opened and closed depending on the stroke position of the spool 20b. Port 20e is connected to circuit 71, and is arranged so that as spool 20b descends from the left half position in the figure, it communicates with ports 20h and 20f. As the spool 20b descends from the left half position in the figure, the port 20f becomes a drain port.
The arrangement is such that communication with port 20e is started when communication with 0g is reduced and communication with this is cut off. And bleed 73 in the middle of port 20f
It is connected to the capacity control actuator 75 of the oil pump O/P via a circuit 74 in which there is a. The oil pump O/P is a variable capacity vane pump driven by the engine as described above, and the eccentricity is reduced when the pressure toward the actuator 75 exceeds a certain value, so that the capacity becomes smaller. The plug 20c of the pressure regulator valve 20 receives the modifier pressure from the circuit 76 on its lower end face in the figure, and receives the retreat selection pressure from the circuit 77 on the pressure receiving surface 20i, and the plug 20c receives the modifier pressure from the circuit 77 on its pressure receiving surface 20i, and the plug 20c receives the modifier pressure from the circuit 77 on its lower end face in the figure. Assume that a force of 2 is applied to the spool 20b. The pressure regulator valve 20 is normally in the left half state in the figure, and when oil is discharged from the oil pump O/P, this oil flows into the circuit 71. Circuit 7 at the left half position of spool 20b
The oil in No. 1 is not drained at all, and the pressure increases.
This pressure acts on the pressure receiving surface 20d through the orifice 72, pushes up the spool 20b against the spring 20a, and connects the port 20e to the port 20h. As a result, the above pressure is partially drained from the port 20h and lowered, and the spool 20b is pushed back by the spring 20a. By repeating this action, the pressure regulator valve 20 basically operates in the circuit 71.
The pressure inside (hereinafter referred to as line pressure) is set to a value corresponding to the spring force of the spring 20a. By the way, plug 2
An upward force from the modifier pressure from the circuit 76 acts on 0c, causing the plug 20c to come into contact with the spool 20b as shown in the right half of the figure, and this upward force is applied to the spool 20b to assist the spring 20a, and As will be described later, the modifier pressure is generated when the vehicle is not in reverse mode and increases in proportion to the engine load (engine output torque), so the above-mentioned line pressure increases as the engine load increases other than when the reverse mode is selected. When reversing is selected, an upward force is applied to the plug 20c by the retracting selection pressure (same value as the line pressure) from the circuit 77 instead of the modifier pressure described above, and this is applied to the spool 20b, so that the line pressure is kept at a desired constant value when reversing is selected. becomes. When the oil pump O/P reaches a certain rotational speed or higher (the engine rotates at a certain rotational speed or higher), the oil discharge amount that increases accordingly becomes excessive, and the pressure within the circuit 71 exceeds the pressure regulation value. This pressure lowers the spool 20b further from the pressure regulating position in the right half of the figure, communicates the port 20f with the port 20e, and blocks it from the drain port 20g. As a result, some of the oil in port 20e is removed from port 20f and bleed 73, but feedback pressure is generated within circuit 74. This feedback pressure increases as the rotational speed of the oil pump O/P increases, and reduces the eccentricity (capacity) of the oil pump O/P via the actuator 75. In this way, the capacity of the oil pump O/P is controlled so that the discharge amount remains constant while the rotational speed exceeds a certain value, and the power loss of the engine is prevented from increasing due to discharging more oil than necessary. . As mentioned above, the line pressure generated in the circuit 71 is transferred to the pilot valve 26, the manual valve 36, and the accumulator control valve 70 by the line pressure circuit 78.
and a third-speed servo release pressure accumulator 66. The pilot valve 26 includes a spool 26b elastically supported in the upper half position in the figure by a spring 26a, and the end face of the spool 26b far from the spring 26a is connected to a chamber 26c.
The pilot valve 26 is further provided with a drain port 26d, and a pilot pressure circuit 79 having a strainer S/T is maintained. and,
A communication hole 26e is provided in the spool 26b to guide the pressure of the pilot pressure circuit 79 to the chamber 26c, and the circuit 79 is switched and connected from the circuit 78 to the drain port 26d as it moves to the right in the figure. The pilot valve 26 is normally in the upper half state in the figure, and when it is supplied with line pressure from the circuit 78, it increases the pressure in the circuit 79. The pressure in the circuit 79 reaches the chamber 26c through the communication hole 26e, causing the spool 26b to move to the right in the figure, and when the spool 26b exceeds the pressure regulating position shown in the lower half, the circuit 79 is cut off from the circuit 78, and at the same time, the drain port 26
Leads to d. At this time, the pressure in circuit 79 is reduced,
This pressure drop causes the spool 26b to spring 26a.
When pushed back, the pressure in the circuit 79 rises again. In this way, the pilot valve 26 can reduce the line pressure from the circuit 78 to a constant value determined by the spring force of the spring a, and output it to the circuit 79 as pilot pressure. This pilot pressure is applied to the pressure modifier valve 22 and the duty solenoid 2 through a circuit 79.
4, 34, lockup control valve 30, forward clutch control valve 46, shuttle valve 32, first, second, third shift solenoid 4
2, 44, 60, and the shuttle valve 56. The duty solenoid 24 as a solenoid valve consists of a coil 24a, a spring 24, and a plunger 24b, and connects a circuit 81 connected to a pilot pressure circuit 79 via an orifice 80 to a drain port 24c when the coil 24a is turned on (energized).
communicate with. The duty solenoid 24 has a coil 24a turned on and off at a constant cycle by a computer (not shown), and the ratio of the ON time to the constant cycle (duty ratio) is controlled. generates control pressure. The duty ratio is made smaller as the engine load (for example, engine throttle opening) increases except when the reverse is selected, so that the above-mentioned control pressure is made higher as the engine load increases. Further, when selecting reverse, the duty ratio is set to 100%, and the above control pressure is set to 0. The pressure modifier valve 22 has a spring 22a.
The pressure modifier valve 22 further includes an output port 22c to which the circuit 76 is connected, and an input port to which the pilot pressure circuit 79 is connected. Port 22d and drain port 2
2e is provided, and the spool 22b is far from the spring 22a.
A circuit 76 is connected to the chamber 22f facing the end face. These ports are arranged so that the port 22c is exactly blocked from the ports 22d and 22e at the left half of the spool 22b in the figure. The pressure modifier valve 22 has a spring 22
The spool 22b receives the spring force from a and the force from the control pressure from the circuit 81 downward in the figure, and the spool 22b receives the force due to the output pressure from the port 22c that has reached the chamber 22f upward in the figure. The spool 22b is stroked to a balanced position. If the output pressure from the port 22c is insufficient to compensate for the downward force, the spool 22b descends beyond the pressure regulating position shown in the left half. At this time, the port 22c communicates with the port 22d, and receives supplementary pilot pressure from the circuit 79 to increase the output pressure. Conversely, if this output pressure is too high to match the downward force mentioned above, spool 2
2b rises toward the right half position in the figure. At this time, the port 22c communicates with the drain port 22e, and the output pressure is reduced. By repeating this action, the pressure modifier valve 22 regulates the output pressure from the port 22c to a value corresponding to the sum of the spring force of the spring 22a and the force due to the control pressure from the circuit 81.
This is supplied as a modifier pressure to the plug 20c of the pressure regulator valve 20 from the circuit 76. By the way, as mentioned above, the control pressure increases as the engine load increases except when reverse is selected, and is 0 when reverse is selected, so the modifier pressure is also a value obtained by amplifying this control pressure by the spring force of the spring 22a. It increases as the engine load increases except when the reverse is selected, and becomes 0 when the reverse is selected, allowing the pressure regulator valve 20 to control the line pressure described above. Torque converter regulator valve 28 has spring 2
8a, the spool 28b is elastically supported in the right half position in the figure, and the port 28
c to the port 28d, and as the spool 28b rises from the left half position in the figure, the port 28c
The degree of communication is decreased for port 28d, port 2
It is assumed that the degree of connectivity is increased relative to 8e. In order to control the stroke of the spool 28b, a chamber 28f facing the spool end face far from the spring 28a is communicated with the port 28c through a communication hole 28g provided in the spool 28b. The port 28c is connected to a predetermined lubricating part via a relief valve 82 and connected to the lockup control valve 30 via a circuit 83, and the port 28d is connected to the port 20 of the pressure regulator valve 20 via a circuit 84.
h, and port 28e is connected by circuit 85 to lockup control valve 30. circuit 8
5 has an orifice 86 in the middle, and the orifice and port 28c are connected to a circuit 83 via an orifice 87, and are communicated to an oil cooler 89 and a predetermined lubricating section 90 by a circuit 88. The torque converter regulator valve 28 is normally in the right half state in the figure, where oil flows from the port 20h of the pressure regulator valve 20 to the circuit 8.
4, this oil is directed from circuit 83 to torque converter 3 as described below. When supply pressure to the torque converter is generated, this torque converter supply pressure is applied to the communication hole 2.
8g, the chamber 28f is reached, and the spool 28b is raised against the spring 28a in the figure. When the spool 28b rises from the left half position in the figure due to an increase in the torque converter supply pressure, the port 28e opens and a portion of the torque converter supply pressure is removed through the port 28e and the circuit 88, thereby reducing the torque converter supply pressure. The pressure is adjusted to a value determined by the spring force of the spring 28a. The oil removed from the circuit 88 is cooled by an oil cooler 89 and then directed to a lubricating section 90. In addition, the torque converter regulator valve 28
If the torque converter supply pressure exceeds the above value even with the above-mentioned pressure regulating action, the relief valve 82 opens and the excess pressure is released to the corresponding lubricating part, thereby preventing deformation of the torque converter 3. The lock-up control valve 30 is connected to the spool 3
0a and the plug 30b coaxially butted,
When the spool 30a is at the limit position shown in the right half, the circuit 83 is connected to the circuit 91 from the torque converter release chamber 3R, and when the spool 30a is lowered to the left half position in the figure, the circuit 83 is connected to the circuit 85. When the spool 30a further descends, the circuit 91 is connected to the drain port 30c. In order to control the stroke of the spool 30a, the end face of the spool 30a far from the plug 30a faces the chamber 30d, and the orifice 9 is placed in the chamber 30e facing the end face of the plug 30b far from the spool 30a.
2 to lead the pressure of the circuit 91. Note that the circuit 93 from the torque converter apply chamber 3A is connected to the circuit 85 at a location closer to the lockup control valve 30 than the orifice 86. Further, the pilot pressure from the circuit 79 is applied to the plug 30b through the orifice 94 to continue applying a downward force in the figure, thereby preventing pulsation of the spool 30a. The lock-up control valve 30 controls the stroke of the spool 30a by the pressure supplied to the chamber 30d, and while this pressure is sufficiently high, the spool 30a
maintains the right half position in the figure. At this time, the oil from the circuit 83 flows through the circuit 91, the release chamber 3R, the apply chamber 3A, the circuit 93, and the circuit 85 under pressure regulation by the torque converter regulator valve 28.
Excluded from 8. Thus, the torque converter 3 transmits power in the converter state. As the pressure within chamber 30d decreases, spool 30a is forced to close plug 30 by pressure from orifices 92, 94.
b, and further descends from the left half position in the figure, the pressure regulating oil from circuit 83 flows to circuits 85, 93, apply chamber 3A, relay chamber 3R, circuit 91, and drain port 30c. The torque converter 3 transmits power in a slip control state in which the slip decreases as the pressure in the chamber 30d decreases. Room 3 from this state
When the pressure inside 0d is further reduced, the spool 30
Due to the further fall of a, the circuit 91 is connected to the drain port 3.
0c, the pressure in the release chamber 3R becomes 0, and the torque converter 3 transmits power in a locked-up state. The shuttle valve 32 controls the stroke of the lockup control valve 30 together with a forward clutch control valve 46, which will be described later.
A spool 32b is elastically supported by 2a in the lower half position in the figure, and this spool is appropriately switched to the upper half position in the figure by the pressure inside the chamber 32c. The shuttle valve 32 connects the circuit 95 of the chamber 30d to the pilot pressure circuit 7 when the spool 32b is in the lower half position in the figure.
9 and extending from chamber 46a of forward clutch control valve 46.
is connected to a circuit 97 from the duty solenoid 34, and when the spool 32b is in the upper half position in the figure, the circuit 95 is connected to the circuit 97, and the circuit 96 is connected to the circuit 71. The duty solenoid 34 is a plunger 34 elastically supported in the closed position by a coil 34a and a spring 34d.
A circuit 97 connected to the pilot pressure circuit 79 through an orifice 98 is connected to the coil 34a.
When it is ON (energized), it shall be connected to the drain port 34c. This duty solenoid 34 is controlled to turn ON and OFF the coil 34a at a constant cycle by a computer (not shown), and also controls the ratio of the ON time to the constant cycle (duty ratio), so that a circuit 97 is connected to the coil 34a in accordance with the duty ratio. Generate control pressure. When the control pressure of the circuit 97 is used to control the stroke of the lock-up control valve 30 with the shuttle valve 32 in the upper half state in the figure, the duty ratio of the solenoid 34 is determined as follows. In other words, under high load and low rotation speeds of the engine where the torque increasing function and torque fluctuation absorbing function of the torque converter 3 are absolutely necessary, the duty ratio is set to 0.
%, thereby making the control pressure of circuit 97 the same as the pilot pressure of circuit 79, which is the source pressure. At this time, the control pressure maintains the spool 30a in the right half position in the figure in the chamber 30d, and maintains the torque converter 3 in the converter state to meet the above requirements. As the requirements for both of the above-mentioned functions of the torque converter 3 become lower, the duty ratio is increased and the control pressure is lowered.
The torque converter 3 is operated in a slip control state that matches the demand through The torque converter 3 is maintained in the locked-up state as required via the lock-up control valve 30 by reducing the pressure to zero. Note that when the control pressure of the circuit 97 is used to control the stroke of the forward clutch control valve 46 with the shuttle valve 32 in the lower half state in the figure, the duty ratio of the solenoid 34 reduces the N→D selection shock as described later. or to prevent creep. The manual valve 36 is operated by the driver to select the parking (P) range, reverse (R) range, neutral (N) range, forward automatic shift (D) range, forward 2nd gear engine brake () range, and forward 1st gear range. Spool 3 stroked to high speed engine brake () range
6a, and the line circuit 78 is connected to ports 36D and 36 according to the selected range of the spool as shown in the following table.
, 36, 36R. Note that in this table, ○ marks indicate ports that communicate with the line pressure circuit 78, and no marks indicate ports that are drained.

[Table] The first shift valve 38 includes a spool 38b elastically supported in the left half position in the figure by a spring 38a, and this spool is switched to the right half position in the figure when pressure is supplied to the chamber 38c. . When the spool 38b is in the left half position, the first shift valve 38 changes the port 38d to the drain port 38e and the port 38f to the drain port 38e.
to port 38g, port 38h to port 38i
When the spool 38b is in the right half position in the figure, the port 38d is connected to the port 38j, and the port 3 is connected to the port 38j.
8f to port 38k, port 38h to port 3
8l each. The second shift valve 40 includes a spool 40b elastically supported by a spring 40a in the left half position in the figure, and this spool assumes the right half position in the figure when pressure is supplied to the chamber 40c. and second shift valve 40
When the spool 40b is in the left half position in the figure, the port 40d is connected to the drain port 40e, the port 40f is connected to the port 40g, and the port 40h is connected to the drain port 40i with an orifice, and the spool 40
When b is in the right half position in the figure, port 40d is connected to port 40j, and port 40f is connected to drain port 40e.
Assume that each port 40h is connected to a mote 40k. The spool positions of the first and second shift valves 38 and 40 are controlled by a first shift solenoid 41 and a second shift solenoid 44, respectively, and these shift solenoids are connected to coils 42a and 44a, respectively.
and plungers 42b, 44b, spring 42
d, 44d. 1st shift solenoid 4
2 is connected to the pilot pressure circuit 79 via the orifice 99, and connects the circuit 100 to the chamber 38c.
Drain port 4 when coil 42a is ON (energized)
2c to make the control pressure in the circuit 100 the same value as the pilot pressure, which is the source pressure.
It is assumed that the shift valve 38 is switched to the right half state in the figure. Further, the second shift solenoid 44 is connected to the pilot pressure circuit 79 via the orifice 101, and the circuit 102 leading to the chamber 40c is connected to the coil 44a.
When turned on (energized), the drain port 44c is shut off to make the control pressure in the circuit 102 the same value as the original pilot pressure, thereby switching the second shift valve 40 to the right half state in the figure. Turn on these shift solenoids 42 and 44,
The first to fourth forward speeds can be obtained by combinations of the OFF states and, therefore, the states of the shift valves 38 and 40, which are summarized in the table below.

[Table] In this table, the ○ marks indicate the right half of the shift valve in the figure (ascending), the × marks indicate the left half of the shift valve in the figure (descending), and the shift solenoid 42,
44 is determined to correspond to a suitable gear position based on the vehicle speed and engine load based on a gear shift pattern set in advance by a computer (not shown). The forward clutch control valve 46 includes a spool 46b on which the pilot pressure from the circuit 79 guided through the orifice 103 is applied downward in the figure to prevent pulsation of the spool, and further includes a orifice 10
4, the operating pressure of the forward clutch F/C in the circuit 105 is fed back and applied downward in the figure. The spool 46b is stroked to a position where the downward force in the figure due to these pressures and the force due to the pressure inside the chamber 46a are balanced.
When the spool 46b is in the right half position in the figure, the circuit 105
is connected to the drain port 46c, and when in the left half position in the figure, the circuit 105 is connected to the circuit 106, and the circuit 105 has a one-way orifice 107 that exerts a throttling effect only on the hydraulic pressure directed to the forward clutch F/C. The circuit 106 is connected to the port 36D of the manual valve 36. The 3-2+ timing valve 48 includes a spool 48b elastically supported at the left half position in the figure by a spring 48a, and at this spool position, a port 48c and a port 48d with an orifice 48f communicate with each other, and the chamber 48
It is assumed that when the pressure in e is high and the spool 48b is at the right half position in the figure, the ports 48c and 48d are shut off. 4-2 The relay valve 50 includes a spool 50b elastically supported at the left half position in the figure by a spring 50a, and at this spool position, the port 50c is connected to the drain port 50b with an orifice, and pressure is supplied into the chamber 50e. It is assumed that when the spool 50b is at the right half position in the figure, the port 50c communicates with the port 50f. 4-2 The sequence valve 52 includes a spool 52b elastically supported in the right half position in the figure by a spring 52a, and in this spool position, the port 52c is connected to the drain port 52d with an orifice, and the pressure inside the chamber 52e is high and the spool is closed. It is assumed that when 52b is in the left half position in the figure, port 52c communicates with port 52f. The range pressure reducing valve 54 includes a spool 54b biased toward the right half position in the figure by a spring 54a,
Ports 54 communicating with each other at this spool position
c, 54d, and a drain port 54 that starts communicating with the port 54c when the spool 54b rises to the left half position in the figure and finishes closing the port 54d.
Provide e. Spool 54b far from spring 54a
The chamber 54f facing the end face is connected to the port 54c via the orifice 108. Thus, the range pressure reducing valve 54 is normally in the right half state in the figure, and when pressure is supplied to the port 54d, pressure is output from the port 54c. This output pressure is
08 on the lower end surface of the spool 54b in the figure, and as the output pressure increases, the spool 54b is raised in the figure. When the spool 54b rises above the left half position in the figure, the port 54c is connected to the drain port 54.
e to reduce the output pressure from port 54c. When the spool 54b descends beyond the left half position in the figure due to this decrease in output pressure, the port 54c communicates with the port 54d, increasing the output pressure from the port 54c. By repeating this action, port 5
The output pressure from 4c is reduced to a constant value determined by the spring force of spring 54a. The shuttle valve 56 includes a spool 56b elastically supported in the left half position in the figure by a spring 56a, and this spool is held in this position when there is a pressure supply to the chamber 56g; When the upward force in the figure due to the pressure from the port 56c exceeds a certain value, it is stroked to the right half position in the figure. The port 56d is connected to the circuit 109 from the third shift solenoid 60 at the left half position in the figure, and the port 56e is connected to the drain port 56f, and the port 56d is connected to the pilot pressure circuit 79 at the right half position in the figure. 56e is connected to the circuit 109. The third shift solenoid 60 includes a coil 60a, a plunger 60b, and a spring 60d.
Pilot pressure circuit 79 via orifice 110
Turn on the circuit 109 connected to the coil 60a.
(When energized), the drain port 60c is cut off, and the control pressure in the circuit 109 is set to the same value as the pilot pressure, which is the source pressure. Note that whether the third shift solenoid 60 is turned on or off is determined by a computer (not shown). It is assumed that the overrun clutch control valve 58 includes a spool 58b elastically supported in the left half position in the figure by a spring 58a, and this spool is switched to the right half position in the figure when pressure is supplied to the chamber 58c. In addition, the spool 58b is located at the left half position in the figure, and the port 58d is connected to the drain port 58e, and the port 58f is connected to the drain port 58e.
are connected to the port 58g, and at the right half position in the figure, the port 58d is connected to the port 58h, and the port 58f is connected to the drain port 58e. The overrank clutch pressure reducing valve 62 has a spring 62
The spool 6 is supported at the left half position in the figure by a.
2b, and this spool also has a port 62c.
When there is pressure from the spool 62b, this applies a downward force in the figure to hold the spool 62b in this position.
While there is no pressure inflow from port 62c, port 6
When pressure is supplied to 2d, this pressure is applied to port 6
Increase the output pressure from 2e. This output pressure is
f, and when the spool 62b reaches a value corresponding to the spring force of the spring 62a, the spool 62b is moved to the right half position in the figure to cut off the connection between the ports 62d and 62e, and the overrun clutch pressure reducing valve 62 transfers the output pressure from the port 62e to the spring force. It is assumed that the pressure is increased to a constant value determined by the spring force of 62a. The 2-speed servo apply pressure accumulator 64 is constructed by elastically supporting a stepped piston 64a at the left half position in the figure by a spring 64b, and a chamber 64c defined between both ends of the stepped piston 64a is opened to the atmosphere. The small-diameter end face and the variable-diameter end face of the piston with
4d and 64e. The 3-speed servo release pressure accumulator 66 includes a stepped piston 66a elastically supported in the left half position in the figure by a spring 66b, and a chamber 66c defined between both ends of the stepped piston is connected to the line pressure circuit 78. The small-diameter end face and large-diameter end face of the stepped piston face the closed chambers 66d and 66e, respectively. The 4-speed servo apply pressure accumulator 68 is constructed by elastically supporting a stepped piston 68a at the left half position in the figure by a spring 68b, and defines a sealed chamber 68c between both ends of the elastic piston. The small diameter end face and the large diameter end face are sealed in sealed chambers 68d and 68, respectively.
Let's face e. Accumulator control valve 70 has spring 70
The spool 7 is supported in the left half position in the figure by a.
0b, and the spool 70b is remote from the spring 70a.
The control pressure of the circuit 81 is introduced into the chamber 70c facing the end face of the circuit 81. The spool 70b connects the output port 70d to the drain port 70e at the left half position in the figure, and connects the output port 70d to the drain port 70e.
When the control pressure increases and the spool 70b rises above the right half position in the figure, the port 70d is switched and connected to the line pressure circuit 78. and,
The output port 70d is connected to the accumulator chambers 64d and 68c by the circuit 111, and the spring 70
It is also connected to the chamber 70f that accommodates a. Thus, the accumulator control valve 70 raises the spool 70b above the right half position in the drawing by the control pressure applied to the chamber 70c except when the reverse movement is selected. As a result, the line pressure from the circuit 78 is output to the circuit 111, and when the pressure in the circuit 111 reaches a value corresponding to the control pressure, the spool 70b is elastically supported at the right half position in the figure. This is why circuit 11
The pressure of 1 is regulated to a value corresponding to the control pressure, but
Since the control pressure increases as the engine load (engine output torque) increases except when reverse is selected as described above, the accumulators 64 and 68 are removed from the circuit 111.
The pressure supplied to the chambers 64d and 68c as accumulator back pressure also increases as the engine output torque increases. In addition, since the control pressure is 0 when the reverse movement is selected, no pressure is output to the circuit 111. Next, to provide a supplementary explanation of the hydraulic circuit network, the circuit 106 extending from the port 36D of the manual valve 36 connects the port 38g of the first shift valve 38 and the second
While connecting to port 40g of shift valve 40,
It is also connected to port 56c of shuttle valve 56 and port 58g of overrun clutch control valve 58 via circuit 112 branched from circuit 106. The port 38f of the first shift valve 38 is connected to the circuit 11
3 to the port 50f of the 4-2 relay valve 50, and also to the accumulator chamber 64e and the 2-speed servo apply chamber 2S/A via the one-way orifice 114, and the port 50f is connected to the port 50f of the 4-2 relay valve 50 through the one-way orifice 114.
15, it is also connected to the chamber 32c of the shuttle valve 32. Furthermore, the port 38h of the first shift valve 38 is connected to the chamber 50e of the 4-2 relay valve 50 and the port 58h of the overrun clutch control valve 58 by a circuit 116, and the port 50c of the 4-2 relay valve 50 is connected to the chamber 50e of the 4-2 relay valve 50 by a circuit 117. Connected to port 40k of 2-shift valve 40. The ports 38k and 38l of the first shift valve 38 are connected to the port 4 of the second shift valve 40.
High clutch H/C by circuit 118 along with 0f
A pair of one-way orifices 119 and 120 arranged in opposite directions are inserted in the middle. A circuit 121 branched from the circuit 118 between these orifices and the high latch H/C is connected to the 3-speed servo release chamber 3S/R and the accumulator chamber 66e via the one-way orifice 122.
The ports 48c and 48d are connected to a circuit 123 that bypasses the one-way orifice 122, and the 3-2 timing valve 48 is connected to this circuit 123.
insert it inside. Circuit 1 between one-way orifice 122 and 3-speed servo relay chamber 3S/R
A circuit 124 branching from 21 is connected to the chamber 52e of the 4-2 sequence valve 52, and ports 52c and 52f of the 4-2 sequence valve 52 are connected to the port 38i of the first shift valve 38 and the port 40h of the second shift valve 40, respectively. Connecting. Port 38j of first shift valve 38 is connected to circuit 125
The port 38d is connected to the port 40d of the second shift valve 40 by the circuit 126, and the port 38d is connected to one inlet port of the shuttle ball 127 by the circuit 126. The other inlet port of shuttle ball 127 is connected to circuit 12.
8 is connected to the port 36R of the manual valve 36 together with the circuit 77 on the one hand, and to the reverse clutch R/C and the accumulator chamber 68d via the one-way orifice 129 on the other hand, and the outlet port of the shuttle ball 127 is connected to the port 36R of the manual valve 36 through the circuit 130. Connect to low reverse brake LR/B.
The port 40j of the second shift valve 40 is connected to the port 54c of the range pressure reducing valve 54 and the chamber 5 by the circuit 131.
4f, and the port 54 of the range pressure reducing valve 54.
d to manual valve 36 port 3 by circuit 132
Connect to 6. The port 56e of the shuttle valve 56 is connected to the chamber 48e of the 3-2 timing valve 48 through a circuit 133.
Port 56d is connected by circuit 134 to chamber 58c of overrun clutch control valve 58. Port 58d of overrun clutch control valve 58 is connected via circuit 135 to accumulator chamber 66d and via one-way orifice 136 to accumulator chambers 68e and 4.
Connect to speed servo apply chamber 4S/A. Port 58f of overrun clutch control valve 58 is connected to port 62d of overrun clutch pressure reducing valve 62 by circuit 137, port 62e of pressure reducing valve 62 is connected to overrun clutch 0R/C by circuit 137, ,1
A check valve 139 is provided between 38 and 38. Port 62c of overrun clutch pressure reducing valve 62 is connected by circuit 140 to port 36 of manual valve 36 and chamber 56g of shuttle valve 56. Incidentally, the duty solenoid 24 used in the hydraulic pressure control device is driven by a microcomputer 200 as a control means shown in FIG. This microcomputer 200 includes a central processing unit (CPU) 201, a memory 202,
It consists of an input/output interface circuit (I/O) 203. Then, the microcomputer 20
0 is the signal from the engine rotation speed sensor 204 that detects the engine rotation speed (Ne), the signal from the throttle opening sensor 205 that detects the engine throttle opening (TH), and the selected gear position of the automatic transmission (G ) and a signal from a voltage sensor 207 that detects the drive voltage (V) of the duty solenoid 24 that generates the duty control pressure are input.
In this embodiment, in addition to the above-mentioned signals, a signal from an oil temperature sensor 208 as a liquid temperature sensor that detects the oil temperature T of the control hydraulic fluid, that is, the hydraulic oil is input. The duty solenoid 24 is duty-controlled by the drive voltage output based on the calculation results of these signals. For this purpose, the microcomputer 200 executes the control program shown in FIG. 5, for example. That is, in this flowchart, the engine speed (Ne), engine throttle opening (TH), and gear position (G) are first read in the step, and then the target duty is calculated based on these three pieces of information Ne, TH, and G in the next step. Calculate control pressure. Then, in the next step, the reference duty (d) for the target duty control pressure is retrieved from the table data corresponding to FIG. After that,
In step and step, the solenoid drive voltage (V) and oil temperature T are read, and in step, these voltage (V), oil temperature T and constants β, γ are calculated.
In the next step, the duty correction coefficient α=β・V・T+γ is calculated from
d is determined, and this duty D is output to the duty solenoid 24 in the next step. In other words, the lower the oil temperature T, the smaller the duty D is corrected, and the ratio of the open period of the solenoid valve 24 decreases. Although not shown in the flowchart, when the oil temperature T is extremely low, for example -40°C or lower, the output duty D is fixed at 0%. Therefore, in the hydraulic pressure control device of this embodiment,
Orifice 80 due to increase in viscosity of hydraulic oil at low temperature
While the passage resistance increases at the orifice 8, the ON duty ratio of the duty solenoid 24, that is, the drain period ratio decreases based on the oil temperature T.
The control pressure obtained on the downstream side can be controlled to an appropriate target pressure regardless of the drop in oil temperature. The hydraulic pressure that has reached the appropriate target pressure is supplied as a control pressure to the upper end of the pressure modifier valve 22 in the figure, and is also supplied to the lower end of the accumulator control valve 70 in the figure. Therefore, the pressure modifier valve 22 operates properly, and the influence of oil temperature on the signal pressure output to the pressure regulator valve 20 via the circuit 76 can be eliminated. Therefore, the line pressure regulated by the pressure regulator valve 20 can be set to an appropriate pressure that is not affected by oil temperature. Problems such as large shift shocks caused by excessive line pressure at high temperatures can be prevented. In this embodiment, when the oil temperature T is extremely low, the duty ratio is 0% and the line pressure is applied as high as possible, so that each friction element is reliably engaged even at extremely low temperatures. Furthermore, the accumulator control valve 70
By supplying the duty control pressure from the duty solenoid 24 to the above, the accumulator back pressure supplied to the accumulators 64 and 68 can be maintained at an appropriate pressure regardless of the oil temperature T, and proper gear shifting can be achieved even at low temperatures. You can get the timing. In this embodiment, since the correction is made based on the drive voltage V in addition to the oil temperature T, it is possible to improve the responsiveness of the duty solenoid 24 to voltage fluctuations. FIG. 7 shows another embodiment of the control program executed by the microcomputer 200. In this embodiment, in step .
Processing similar to step . in the figure is performed. In the next step, the table data of FIG. 8 is searched based on the hot oil T read in the step. That is, this table data includes, for example, data corresponding to _T1 in the diagram when the oil temperature T is 120°C, data for _T2 when the oil temperature is 80°C, data for _T3 when the oil temperature is 60°C, and -30°C. When the temperature is ℃, T ₄ data is used. In addition, if the oil temperature T is extremely low, for example -40℃ or less,
As shown in the T ₅ data, a duty ratio of 0% is used as data.
Then, in the step, the output duty ratio D corresponding to the target duty control pressure is looked up from the retrieved table data, and
This duty ratio D is outputted to the duty solenoid 24 in steps. In this embodiment as well, the drive duty ratio of the duty solenoid 24 decreases as the oil temperature T decreases, so the increase in passage resistance of the orifice 80 due to the increase in viscosity can be offset, and an appropriate target duty control pressure can be generated. be able to. In each of the embodiments described above, the duty solenoid 24 performs duty control that takes oil temperature into consideration.
Although the explanation has been given using an example in which the lock-up control valve 30 is
It goes without saying that the present invention can also be applied to the duty solenoid 34 that supplies control pressure to the forward clutch control valve 46. Effects of the Invention As explained above, in the hydraulic pressure control device for an automatic transmission of the present invention, the open period ratio of the solenoid valve that opens and closes the drain passage is small at low temperatures when the viscosity of the control hydraulic fluid increases. Since the drive duty ratio is corrected in this way, the increase in the passage resistance of the orifice due to the increase in viscosity and the decrease in the drain period ratio are offset, and a decrease in the control pressure obtained on the downstream side of the orifice can be prevented. In other words, an appropriate control pressure can be ensured even at low temperatures, and control elements such as various valves and friction elements can be reliably controlled.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a hydraulic pressure control device for an automatic transmission according to the present invention, FIG. 2 is an overall circuit diagram showing an embodiment of the hydraulic pressure control device according to the present invention, and FIG. 3 is a conceptual diagram showing a hydraulic pressure control device for an automatic transmission according to the present invention. 4 is a schematic diagram showing a power transmission train of an automatic transmission; FIG. 4 is a system diagram showing an embodiment of the present invention; FIG.
The figure is a flowchart of the control program in the hydraulic pressure control device of the present invention, Figure 6 is a table data characteristic diagram of the standard duty used in the flowchart of Figure 5, and Figure 7 is a flowchart of the control program used in the present invention. FIG. 8 is a table data characteristic diagram of the output duty used in the flowchart of FIG. 7, and FIG. 9 is a characteristic diagram of changes in duty control pressure depending on oil temperature. 24, 34... Duty solenoid (solenoid valve), 79... Hydraulic pressure circuit, 200... Microcomputer (control means), 208... Oil temperature sensor (liquid temperature sensor), T... Oil temperature (liquid temperature sensor)... Warm).

Claims (1)

[Scope of Claims] 1. A control means for controlling the duty ratio of a control pulse signal based on the operating state; and a hydraulic circuit that supplies hydraulic pressure from a hydraulic pressure source to a control element via an orifice, downstream from the orifice. A hydraulic pressure control device for an automatic transmission, comprising: a drain passage connected to the drain passage; and a solenoid valve interposed in the drain passage and opening and closing the drain passage in response to the control pulse signal. a liquid temperature sensor that detects the temperature of the hydraulic fluid for use; a duty correction means that corrects the duty ratio of the control pulse signal so that the open period ratio of the solenoid valve becomes small at low temperatures based on the detected liquid amount; A hydraulic pressure control device for an automatic transmission, characterized by being provided with.