JP2003106432A - Hydraulic control circuit for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compatibly improve a hydraulic control precision in an advance speed gear stage and secure engagement torque capacity necessary for retreating without adding any additional device in frictional engagement elements engaged with the both of the advance and retreat speed gear stages. SOLUTION: A line pressure is directly fed to a base pressure port m of a pressure control valve 38 controlling a hydraulic pressure to a 35R clutch 35R/C to be engaged with both of the advance and retreat speed gear stages and a drain port n is connected to a R port of a manual valve. In the advance speed gear stage, the line pressure of the base pressure port is set to a base pressure, a necessary hydraulic pressure is set to the maximum output pressure to be a low control gain, and in retreating, the REV pressure of a drain port is fed to the clutch so as to secure a necessary torque amount. In shifting from the retreat stage to the neutral stage, the line pressure is controlled so as to secure a release shelf pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control circuit for controlling an operating hydraulic pressure to a friction engagement element in an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle, a plurality of shift speeds are obtained by a combination of engagement and release of predetermined frictional engagement elements. In recent years, in order to obtain fine running performance, it has been proposed to realize a large number of shift speeds such as the first speed to the sixth speed in the forward D (drive) range. Are controlled by pressure control valves each consisting of a solenoid and a pressure regulating valve. In such a transmission, there are some transmissions that are engaged in both forward gears and reverse gears with respect to a specific frictional engagement element. For example, they are engaged in forward third speed and fifth gear as well as in reverse. The friction engagement element is referred to as 35R clutch 35R / C.

[0003]

In this case, the hydraulic pressure to the 35R clutch 35R / C is determined by the magnitude of the engaging torque capacity required for the clutch in the D range, in the third speed, the fifth speed and in the reverse. The REV (reverse) pressure required at the time of retreat is the maximum output,
At the fifth speed and the fifth speed, the solenoid pressure as the control signal pressure is adjusted to output the intermediate level required pressure. However, since the hydraulic pressure to the 35R clutch 35R / C is changed from zero to the maximum REV pressure only with the pressure regulating valve,
The control gain becomes large and unstable with respect to variations, and it becomes difficult to perform fine hydraulic control in the third speed and the fifth speed.

Therefore, as shown in FIG. 7, the pressure regulating valve 40 may be configured to switch between the D range pressure (D pressure) for the third forward speed and the fifth forward speed and the REV pressure for reverse. Conceivable. The pressure regulating valve 40 controls the D range pressure at the third speed and the fifth speed in the D range to control the 35R clutch 35R.
/ C, and when retreating, it operates so as to supply a large REV pressure as it is. According to this, the control gain for the D range pressure can be set low without being restricted by the REV pressure, so that fine hydraulic control at the third speed and the fifth speed can be obtained.

However, the shift lever has a REV pressure of 3
In order to secure the shelving pressure of the REV pressure when the reverse (R) position supplied to the 5R clutch 35R / C is operated to the neutral (N) position, as shown in FIG.
It is necessary to provide a pull-out diaphragm 42 in the V voltage circuit. That is, when the REV pressure is supplied to the pressure regulating valve 40, the hydraulic pressure is passed through the one-way valve 44 provided in parallel with the release throttle 42 without resistance and passes through the release throttle 42 in the release direction.

However, in this case, at the forward third speed and the fifth speed, while the pressure regulating valve 40 regulates the D range pressure, R
Since the EV pressure circuit serves as a drain circuit, if the REV pressure circuit has the above-mentioned pull-out diaphragm 42, the drain capacity will be insufficient and the pressure adjustment will be affected.

As a countermeasure against this, as shown in FIG. 8, the pressure regulating valve 40 is exclusively used for regulating the D range pressure, and the pressure regulating valves 40 and 35 are provided.
It is conceivable to provide a switching valve 46 between the R clutch 35R / C. In this case, at the time of shifting from the reverse (R) position to the neutral (N) position, the RE having the escape stop 42 is provided.
The V pressure circuit is connected to the 35R clutch 35R / C, and the pressure regulating valve 40 is connected to the 35R clutch 35R at the third speed and the fifth speed.
Connect to R / C. Thus, when shifting from the reverse (R) position to the neutral (N) position, RE
It is possible to secure the shelf pressure of the V pressure and to properly regulate the D range pressure without any obstacle in the drain in the third speed and the fifth speed. However, this measure requires the switching valve 46 as an additional device, and therefore has a problem that the structure is complicated and the cost is increased.

Therefore, in view of the above problems, the present invention does not require a special additional device when controlling the hydraulic pressure to the frictional engagement elements that are engaged at both the forward shift stage and the reverse shift stage. Improvement of hydraulic control accuracy of
An object of the present invention is to provide a hydraulic control circuit for an automatic transmission that achieves both a required engagement torque capacity when reversing.

[0009]

Therefore, the present invention according to claim 1 is an automatic transmission that obtains a plurality of shift stages by a combination of fastening and releasing of a plurality of friction fastening elements, in both forward and reverse stages. The pressure control valve that controls the hydraulic pressure to the friction engagement element to be engaged is composed of a pressure regulating valve and a solenoid that gives a control pressure to the pressure regulating valve.The pressure regulating valve is directly supplied with line pressure to the base pressure port, and the drain port is It is assumed that the valve is connected to the R range pressure oil passage that is drained at a position other than the retracted position by a manual valve that is switched by a select operation. At the forward stage, the line pressure supplied to the base pressure port is regulated by the pressure regulating valve to obtain the required hydraulic pressure, while at the time of reverse, the REV pressure from the R range pressure oil passage is supplied to the friction engagement element.

According to the second aspect of the present invention, particularly when the select operation is performed from the retracted position to a position other than the retracted position, the solenoid is controlled to adjust the line pressure supplied to the base pressure port by the pressure regulating valve to advance the forward stage. The release pressure control from the friction engagement element that is engaged in both reverse and reverse is performed.

Further, according to the invention of claim 3, in the parking position and the neutral position, the solenoid is controlled so that the pressure regulating valve regulates the line pressure supplied to the base pressure port so that the forward stage and the backward stage are both controlled. The frictional fastening elements to be fastened are kept fastened.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, FIG. 1 is a skeleton diagram showing a speed change mechanism to which the embodiment is applied. The speed change mechanism 1 is provided with two first and second planetary gears 4 and 5 on an input shaft 3. The first ring gear 4R of the first planetary gear 4 is coupled to the input shaft 3, and the first sun gear 4S thereof is fixed to the case 2. The first pinion carrier 4PC is connected to the case 2 via the 35R clutch 35R / C and the 26 brake 26 / B.

The second planetary gear 5 is a Ravigneaux type,
The second pinion carrier 5PC is connected to the case 2 via the low and reverse brake L & R / B on the one hand, and the input shaft 3 via the high clutch H / C on the other hand.
Are linked to. Low and reverse brake L
A one-way clutch OWC is provided in parallel with & R / B.

The second sun gear 5Sa includes 26 brakes 26 /
It is connected to the case 2 via B. The third sun gear 5Sb is connected to the 35R clutch 3 via the low clutch L / C.
It is connected to 5R / C. And the second ring gear 5R
Is coupled to the first output gear 6. The first output gear 6 meshes with an input gear 8 supported by an intermediate shaft 7 parallel to the input shaft 3, and a second output gear 9 of the intermediate shaft 7 meshes with a final gear 10 having a differential gear 11.

The combination of the engagement and disengagement of each of the above-mentioned clutches and brakes makes it possible to obtain six forward gears (first to sixth speeds) and one reverse gear as shown in FIG. In the figure, ○ indicates fastening and × indicates release.

FIG. 3 shows a hydraulic control system for actuating the above-mentioned respective fastening elements. The manual valve 22 is a valve that can be switched by a select operation. In the D range, the line pressure is output to the D range pressure oil passage 23, and the R range pressure oil passage 2 is output.
Drain 4 In the R range, the line pressure is output to the R range pressure oil passage 24 and the D range pressure oil passage 23 is drained. The pilot valve 25 reduces the line pressure to a constant pilot pressure and outputs it to each pressure control valve described later via the pilot pressure oil passage 26.

A first pressure control valve 27 is provided in the oil passage 32 to the low clutch L / C, and the first pressure control valve 27 is A
It is controlled by a command from the T control unit 20. The first pressure control valve 27 is provided with a solenoid valve corresponding to the above command and operates based on the solenoid pressure, but the solenoid valve is not shown. The pilot pressure supplied through the pilot pressure oil passage 26 becomes the base pressure of the solenoid valve. The same applies to other pressure control valves described later.

26 brake 26 / B, 35R clutch 3
5R / C, high clutch H / C, and low and reverse brake L & R / B oil passages 33, 34, 35,
36 is also provided with a second pressure control valve 28, a third pressure control valve 29, a fourth pressure control valve 30, and a fifth pressure control valve 31, respectively, and each pressure control valve is an AT control unit 20.
It is controlled by the command from.

First, second and fourth pressure control valves 27,
28 and 30 are supplied with the D range pressure from the manual valve 22 through the D range pressure oil passage 23, and the third pressure control valve 29 is supplied through the R range pressure oil passage 24 with the R range pressure (R
The EV pressure) is supplied, and the line pressure is also directly supplied. The line pressure is directly supplied to the fifth pressure control valve 31.

The AT control unit 20 includes a vehicle speed sensor 40, a throttle sensor 41, an engine rotation sensor 42, a turbine rotation sensor 43, an inhibitor switch 44, an oil temperature sensor 45, a vehicle speed, an engine speed, a turbine speed, and a select lever. The selected position and the hydraulic oil temperature signal are input to determine the gear stage according to the operating state, and the low clutch L / C, the 26 brake 26 / B, the 35R clutch 35R / C, and the high clutch, which are the fastening elements, are determined. H
/ C and low-and-reverse brake L & R / B, a command is sent to each pressure control valve so as to obtain a combination of engagement and release corresponding to the gear.

FIG. 4 shows the configuration of the third pressure control valve 29 for the 35R clutch 35R / C. Third pressure control valve 2
The reference numeral 9 includes a pressure regulating valve 38 and a solenoid 39. Pressure regulator 3
8, the line pressure is directly supplied to the base pressure port m, the drain port n is connected to the R range pressure oil passage 24, and the output port p is connected to the 35R clutch 35R / C. The solenoid pressure generated by the solenoid 39 using the biasing force of the spring S and the pilot pressure as a base pressure is applied to one control end of the pressure regulating valve, and the output pressure of the output port p is fed back to the other control end. , R range pressure is applied. The R range pressure oil passage 24 and the manual valve 22 that are sequentially connected to the drain port n are RE
It forms a V voltage circuit.

Next, the operation of the third pressure control valve 29 will be described. First, the middle and high speed stages of the forward movement (here, the third
5A), the pressure regulating valve 38 regulates the line pressure supplied to the base pressure port m as indicated by the thick line in FIG. 5A, and the output pressure thereof is adjusted to the 35R clutch 35R. /
Supply to C. Since the output pressure (clutch pressure) is fed back to the control end, the output pressure is the solenoid pressure (SO
The pressure adjustment value corresponds to the L pressure. Here, the required hydraulic pressure in the middle and high speed stages is set as the maximum pressure, and the pressure is adjusted with a low control gain as shown by the solid line in FIG.

When the select lever selects the reverse (R) stage after passing through the neutral (N) position, first, at the N position,
As indicated by the thick line in FIG. 5B, the solenoid pressure is eliminated and the output pressure of the pressure regulating valve is regulated to a low pressure corresponding to the load of the spring S. At this time, since the pressure is regulated but the pressure is low, the 35R clutch 35R / C is in the non-engaged state.

After this, when the select lever is in the R position and the manual valve 22 is switched, the R range pressure is supplied to the drain port n of the pressure regulating valve 38 and the R range pressure is changed, as shown by the thick line in (c). Is applied to the control end, the pressure regulating valve 38 connects the drain port n to the output port p.
Switch to the position to communicate with and keep that state.
As a result, the pressure cannot be adjusted, and the 35R clutch 35
The line pressure is directly supplied to the R / C as the R range pressure.

When the select lever is returned from the reverse position to the neutral position (R → N), the R range pressure supplied to the drain port n is drained from the manual valve 22. At this time, as indicated by a thick line in (d) of FIG. 5, the pressure regulating valve 38 is actuated by the solenoid pressure of the solenoid 39, and the line pressure supplied to the base pressure port m is regulated by the pressure regulating valve 38, thereby the 35R clutch. Controls the shelving pressure of 35 R / C.

The present embodiment is constructed as described above, and the 35R clutch 35R / is engaged between the forward and middle high speed stages and the reverse.
In the third pressure control valve 29 for controlling the hydraulic pressure to C, the line pressure is directly supplied to the base pressure port m of the pressure regulating valve 38, and the drain port n is manually operated via the REV pressure circuit, that is, the R range pressure oil passage 24. It was connected to the R port of the valve.
Thus, in the forward middle and high speed stages, the line pressure supplied to the base pressure port m is used as the base pressure, the required hydraulic pressure is set to the maximum output pressure, and the zero to maximum reverse (R
Compared to changing to the EV) pressure, the control gain with a low control gain is adjusted as indicated by the solid line, while the REV pressure (= line pressure) from the manual valve supplied to the drain port n is used as the output pressure when retreating. The required torque capacity can be secured. For this reason, a separate switching valve or the like is not required.

Since the line pressure is directly supplied to the base pressure port m of the pressure regulating valve 38, the line pressure is regulated at the time of switching from the reverse position to the neutral position.
35R clutch 35R / C without providing a throttle
It is possible to secure the shelving pressure of the hydraulic pressure from the. The REV connected to the drain port n of the pressure regulating valve 38
Since the pressure circuit has no throttling, the pressure is drained from the manual valve immediately when adjusting the pressure in the middle and high speed stages of forward movement, so there is no adverse effect on the pressure adjusting function due to insufficient drain capacity.

Furthermore, since the base pressure of the pressure regulating valve 38 is a direct line pressure, the 35R clutch 35R / C can be engaged regardless of the selection range of the select lever. For example, the parking (P) position or By engaging the clutch at the neutral (N) position, it is possible to simplify the control during selection from neutral to reverse.

In the embodiment, the engagement forward shift speed of the friction engagement element that is engaged both forward and backward is the third.
Although the example of the fifth speed and the fifth speed has been described, the present invention is not limited to this, and the present invention can be applied to control of an arbitrary friction engagement element having different required torque capacities when moving forward and when moving backward.

[0030]

As described above, according to the present invention, the line pressure is directly supplied to the base pressure port of the pressure regulating valve for controlling the hydraulic pressure to the friction engagement element that is engaged in both the forward stage and the reverse stage, and the drain port is Since it is assumed that the valve is connected to the R range pressure oil passage that is drained at a position other than the reverse position by the manual valve, the REV pressure from the R range pressure oil passage is supplied to the friction engagement element at the time of reverse, while at the forward stage the base pressure is supplied. By adjusting the line pressure supplied to the port with a pressure regulating valve, it is possible to achieve a low control gain with the required hydraulic pressure in the forward stage as the maximum pressure, without any additional device such as a switching valve, and to perform friction engagement with high accuracy. The hydraulic pressure to the element can be controlled.

Particularly, when the select operation is performed from the retracted position to the neutral position, the drain pressure is controlled by adjusting the line pressure supplied to the base pressure port by the pressure adjusting valve to control the release pressure from the friction engagement element. There is no need to set a draw-throttle in the circuit, and the configuration of the hydraulic circuit is simplified while preventing the drain capacity shortage at the forward stage.

Further, at the parking position and the neutral position, the line pressure supplied to the base pressure port is regulated by the pressure regulating valve to fasten the friction engagement element, so that the neutral position and the retracted position can be maintained. The control during the select operation is simplified.

[Brief description of drawings]

FIG. 1 is a skeleton diagram showing a speed change mechanism of an automatic transmission to which the present invention is applied.

FIG. 2 is a diagram showing a combination of fastening and releasing a friction fastening element.

FIG. 3 is a diagram showing a hydraulic control system in the embodiment.

FIG. 4 is a diagram showing a configuration of a pressure control valve of a friction engagement element that is engaged in both forward and reverse directions.

FIG. 5 is an explanatory view showing the operation of the pressure control valve.

FIG. 6 is an explanatory diagram showing the operation of the pressure control valve.

FIG. 7 is a graph showing a pressure regulating state of a pressure control valve.

FIG. 8 is a diagram showing an example of a pressure regulating valve that switches a base pressure.

FIG. 9 is a diagram showing an example in which a switching valve is added to the pressure regulating valve.

[Explanation of symbols]

1 speed change mechanism 2 cases 3 input axes 4 First planetary gear 5 Second planetary gear 6 First output gear 7 Middle axis 8 input gears 9 Second output gear 10 final gear 20 AT control unit 22 Manual valve 23 D range pressure oil passage 24 R range pressure oil passage 25 pilot valve 26 Pilot pressure oil passage 27 First pressure control valve 28 Second pressure control valve 29 Third pressure control valve 30 4th pressure control valve 31 5th pressure control valve 32, 33, 34, 35, 36 Oil passage 38 Regulator 39 solenoid 35R / C 35R clutch 26 / B 26 brake L & R / B Low and reverse brake H / C high clutch OWC One Way Clutch L / C low clutch m Base pressure port n Drain port p output port S spring

Claims (3)

[Claims] 1. An automatic transmission that obtains a plurality of shift speeds by a combination of engagement and release of a plurality of friction engagement elements,
The pressure control valve that controls the hydraulic pressure to the friction engagement element that is engaged in both the forward stage and the reverse stage is composed of a pressure control valve and a solenoid that applies control pressure to the pressure control valve, and the pressure control valve has a line pressure at the base pressure port. A hydraulic control circuit for an automatic transmission, which is directly supplied, and a drain port is connected to an R range pressure oil passage which is drained at a position other than the reverse position by a manual valve which is switched by a selection operation. 2. When a select operation is performed from the retracted position to a position other than the retracted position, the solenoid is controlled to regulate the line pressure supplied to the base pressure port by the pressure regulating valve to control the forward speed and the reverse position. The hydraulic pressure control circuit for an automatic transmission according to claim 1, wherein the hydraulic pressure control is performed from a friction engagement element that is engaged by both. 3. A friction engagement element that is controlled in the parking position and the neutral position to control the solenoid to control the line pressure supplied to the base pressure port by the pressure control valve and to be fastened in both the forward stage and the reverse stage. The hydraulic control circuit for the automatic transmission according to claim 1 or 2, wherein