JP3203471B2 - Control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a continuously variable transmission, and more particularly to a technology for controlling a shift pressure.

[0002]

2. Description of the Related Art Conventionally, as a continuously variable transmission, a driving pulley (primary pulley) and a driven pulley (secondary pulley) whose effective diameters can be continuously changed, and a winding between these two pulleys. A driving belt, wherein the effective diameter of the driven pulley is changed based on the line pressure, while the line pressure is used as an original pressure, and the original pressure is reduced based on a hydraulic pressure (primary pressure) adjusted by a shift control valve. 2. Description of the Related Art There is known a pulley-type continuously variable transmission having a configuration in which a gear ratio is steplessly changed by changing an effective diameter of a driving pulley.

In such a pulley type continuously variable transmission, as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-143744, the primary pressure is estimated when a sensor or the like for determining a shift operation fails and the estimated pressure is estimated. A fail-safe technique for performing a shift operation by pressure control based on the primary pressure has been proposed.

[0004]

In the conventional primary pressure estimation method, a change in hydraulic pressure is calculated based on a flow rate calculation (inflow and outflow flow rates) of the shift control valve, and the calculated change is used as an initial hydraulic pressure (speed ratio is low). , Ie, the hydraulic pressure at the time of the gear ratio i = imax) to estimate the primary pressure.

However, this estimation method has the following problems. (1) Initial hydraulic pressure may not be determined. That is, when the gear ratio is i = imax (initial hydraulic pressure state), there is a possibility that the movable sheave of the transmission control valve has moved to the mechanical movable range limit. In this case, the pulley on the primary pulley side Since the thrust is shared between the mechanical stopper and the primary pressure, it has been difficult to separate the primary pressure.

(2) Initial conditions are limited. That is, the hydraulic pressure could not be calculated unless the gear ratio was i = imax (initial hydraulic pressure state). Therefore, in the conventional estimation method,
Due to the above-described problems, the primary pressure cannot be estimated with high accuracy, and the shift control during the execution of the fail-safe has been insufficient.

Accordingly, the present invention has been made in view of the above-described conventional problems, and alleviates the precondition for estimating the primary pressure.
An object of the present invention is to provide a control device for a continuously variable transmission capable of estimating a primary pressure with high accuracy with a simple configuration.

[0008]

Therefore, according to the first aspect of the present invention, as shown in FIG. 1, a driving-side rotating member A receiving a rotational force of a power source, a driven-side rotating member B, Power transmission member C interposed between and transmitting power between them
And a drive-side contact rotation radius that is a distance from a rotation center of a contact position between the drive-side rotation member A and the power transmission member C; and the driven-side rotation member B and the power transmission member C. By changing the driven-side contact rotation radius, which is the distance from the rotation center of the contact position, steplessly relative to each other, the gear ratio between the drive-side rotation member A and the driven-side rotation member B is changed. A control device for a continuously variable transmission configured to be able to be set steplessly, a hydraulic supply means D for supplying a hydraulic pressure to the driving side rotating member A and the driven side rotating member B at a predetermined line pressure; D and the drive-side rotary member A, and controls the line pressure to a primary pressure that presses the drive-side rotary member A against the power transmission member C, thereby changing the speed of the continuously variable transmission. Transmission control means E for setting the ratio, Line pressure detecting means F for detecting a down pressure
A related value detecting means G for detecting a value related to an opening area ratio between an opening area of the hydraulic pressure and an opening area of the outflow side in the shift control means E, and the continuously variable transmission in a steady state.
Steady state determining means H for determining whether or not
The determination means H determines that the continuously variable transmission is in a steady state.
When it is a primer for estimating the primary pressure based on the value associated with the detected line pressure and opening area ratio
And a re-pressure estimating means I, and the shift control means E can execute a shift control based on the estimated primary pressure.

With this arrangement, the continuously variable transmission is in a steady state.
, The primary pressure is estimated with high accuracy based on the value related to the line pressure and the opening area ratio, and the shift control of the continuously variable transmission can be executed by the pressure control based on the estimated primary pressure. Invention, the steady-state according to claim 2, wherein
The state determination means determines that the speed ratio of the continuously variable transmission is within a predetermined range.
Is determined that the continuously variable transmission is in a steady state.
I did it .

With this configuration, the gear ratio of the continuously variable transmission can be increased.
When the continuously variable transmission is in the steady state when it is within the predetermined range,
Is determined. According to a third aspect of the present invention, the shift control means is a three-port spool valve, and the first port communicates with the second port by the operation of the spool.
Whether the communication between the second port and the third port is switched or not, and the spool and the port have an underlap relationship.

With this configuration, the shift control means can be constituted by one simple spool valve, so that the structure of the control device of the continuously variable transmission is simplified, and the reliability is improved. According to a fourth aspect of the present invention, the speed change control means is driven by a solenoid attached to the speed change control means or a pilot pressure adjusted by a solenoid valve, and the value related to the opening area ratio is set to The drive signal is a drive signal for a solenoid attached to the shift control means or a solenoid valve for adjusting pilot pressure.

With this configuration, the shift control means is driven by a simple hydraulic circuit or a solenoid, so that the configuration of the control device for the continuously variable transmission is simplified, as in the third aspect of the present invention. As a result, reliability is improved. According to a fifth aspect of the present invention, the driving-side rotating member is a pulley capable of changing an effective winding radius, the driven-side rotating member is a pulley capable of changing an effective winding radius, and the power transmission member is a pulley capable of changing the effective winding radius. The structure is a winding transmission medium that can be wound.

With this configuration, the continuously variable transmission is performed by continuously changing the effective diameters of the two pulleys, and the speed change control for changing the effective diameter can be performed by the pressure control based on the estimated primary pressure. Become.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 2 shows a system configuration of an embodiment of the continuously variable transmission according to the present invention. In FIG.
A continuously variable transmission 3 is provided on the output side of the internal combustion engine 1 via a long travel damper (spring-type damper for absorbing rotation fluctuation) 2. In a system in which a starting clutch 7 described later is interposed between the internal combustion engine 1 and the continuously variable transmission 3 or a system in which a torque converter is interposed, the long travel damper 2 can be omitted.

The continuously variable transmission 3 includes a primary pulley 4 (driving-side rotating member) on the internal combustion engine 1 side, a secondary pulley 5 (driven-side rotating member) on the driving shaft (diff) side, and a winding therebetween. subjected rubber or metal, or primary pressure P _P of the belt 6 consisting of a combination thereof and a (power transmitting member), the primary pulley actuator 4a which receiving area is larger (gear shift control hydraulic chamber) (speed change pressure), and the adjustment of the line pressure P _L to the secondary pulley actuator 5a (for tension control hydraulic chamber), the pulley ratio (the secondary pulley belt winding effective diameter / primary pulley belt winding effective diameter) The speed ratio can be changed steplessly by changing the speed ratio.

However, other known continuously variable transmissions such as a toroidal type can also be used. That is, the continuously variable transmission 3 includes a driving-side rotating member that receives the rotating force of the power source, a driven-side rotating member, and a power transmission member interposed therebetween. And a drive-side contact rotation radius that is a distance from a rotation center of a contact position between the power transmission member and
A driven-side contact rotation radius that is a distance from a rotation center of a contact position between the driven-side rotating member and the power transmission member,
May be a continuously variable transmission which is capable of setting the gear ratio between the driving-side rotating member and the driven-side rotating member in a stepless manner by changing steplessly.

The hydraulic circuit for controlling the shift of the continuously variable transmission 3 includes an oil pan 10 serving as a driving source of the continuously variable transmission 3 for storing oil, an oil pump 11 for supplying oil under pressure, and an oil pump 11. solenoid valve 12 pressure pressurized the supplied oil adjusted to a predetermined line pressure P _L from the spool valve 13 performs pressure adjustment of the primary pressure P _P is supplied to the primary pulley actuator 4a, the pilot pressure PP
The spool valve 13 is _operated by the solenoid pressure P _SOL in which I is reduced.
And a hydraulic pipe 15a to 15d communicating with various hydraulic devices. The oil pan 10, the oil pump 11, the solenoid valve 12, and the hydraulic pipes 15a to 15d constitute a hydraulic supply unit, and the spool valve 13 and the solenoid valve 14 constitute a shift control unit.

The spool valve 13 communicates with the first port 13a receiving the supply of the line pressure P _L and the primary pulley side actuator 4a to adjust the primary pressure P _P.
It has three ports, a port 13b and a third port 13c as a drain. The operation of the built-in spool 13d allows the first port 13a to communicate with the second port 13b, or the second port 13b and the third port 13c. Whether to communicate with the three ports 13c can be switched. The spool 13d, the first port 13a and the third
The port 13c has a so-called underlap relationship, and when the spool 13d is located at a position as shown in the figure, oil inflow and oil outflow are performed simultaneously. Further, a control port 13e for introducing a solenoid pressure P _SOL for controlling the drive of the spool 13d is formed.

The solenoid valves 12 and 14 are connected to the control unit 1 having a microcomputer.
The opening degree is controlled by the duty ratio of the drive pulse signal from the controller 6 to control the line pressure P _L and the solenoid pressure P _SOL to the spool valve 13, respectively. The control unit 16 has a function as a line pressure detecting unit , a related value detecting unit , a steady state determining unit, and a primary pressure estimating unit.

In order to perform such control, the input rotation speed Nin on the primary pulley 4 side and the secondary pulley 5
Various output signals from the rotation speed sensors 17 and 18 for detecting the output rotation speed Nout on the side are respectively input to the control unit 16. Further, a start clutch 7 is interposed between the output side (secondary pulley 5) of the continuously variable transmission 3 and the drive shaft side (for example, differential), and the start clutch 7 is provided via an actuator such as a hydraulic pressure. The intermittent control is performed by the control unit 16.

The control device for a continuously variable transmission having the above-described configuration controls the duty ratio of the drive pulse signal to the solenoid valve 14 based on the various output signals when the output signals from the various sensors are normal. Then, the shift control is performed such that the pulley ratio matches the traveling condition, that is, the gear ratio i. Here, for example, consider a case where a disconnection or the like occurs in a sensor for determining a shift operation. At this time, since the output signal from the sensor becomes 0, the shift control of the continuously variable transmission 3 cannot be performed as it is. Therefore, it is necessary to estimate the primary pressure and control the speed change of the continuously variable transmission 3 by pressure control based on the primary pressure. The principle of estimating the primary pressure will be described in detail below.

First, the following three assumptions are made during shift control. (1) Under normal conditions, the volume of the primary pulley-side actuator 4a (shift control hydraulic chamber) is constant. (2) Therefore, the flow rate Qin flowing into the spool valve 13 is equal to the flow rate Qout flowing out.

(3) The shift control valve (spool valve 13) is shown in FIG.
As described above, the openings on the supply side and the discharge side can be approximated by orifices, and leaks and the like can be ignored. Based on such an assumption, the primary pressure P _P at steady state
For example, when the spool valve 13 is an underlap valve, it can be obtained by the following procedure from the expression of the flow rate before and after the orifice.

The flow rate Qin flowing into the spool valve 13 is represented by a constant C and an opening area of the inflow portion of the spool valve 13 by A
in, if the density of oil is ρ,

[0025]

(Equation 1)

The flow rate Q flowing out of the spool valve 13
out is the opening area of the outflow portion in the spool valve 13
out

[0027]

(Equation 2)

[0028] Here, since the a Qin = Qout By assumption, the open area ratio Ar Ar = Ain / Aout, the line pressure P _L putting the P _L = Prssen, the primary pressure P _P is

[0029]

(Equation 3)

The following can be obtained. Incidentally, the opening area ratio Ar of the spool valve 13 is closely related to the displacement of the spool 13d, and the displacement of the spool 13d is determined by the solenoid pressure Psol. That is, the solenoid pressure Psol is set to the pilot pressure PPI by the solenoid valve 14.
When the solenoid pressure Psol is determined, the displacement x of the spool 13d is determined by the following equation.

[0031]

(Equation 4)

Here, A1 and A2 are the spool valves 13
Represents a pressure receiving area of each of the solenoid pressure Psol and the pilot pressure PPI. However, when the solenoid pressure Psol = 0, the displacement x = 0, and the direction in which the spool 13d is in the supply direction of the solenoid pressure Psol (rightward in the figure) is the positive direction. Therefore, the opening area ratio Ar is determined by the duty ratio of the drive pulse signal to the solenoid valve 14, and for example, when experimental data is shown, there is a relationship between the duty ratio and the opening area ratio as shown in FIG.

Next, the primary pressure estimation of the control device for the continuously variable transmission according to the present invention will be described with reference to the flowchart of FIG. In step 1 (abbreviated as S1 in the figure, the same applies hereinafter), it is determined whether the continuously variable transmission 3 is in a steady state, that is, whether or not the pulley ratio (speed ratio) i is within a predetermined range. This pulley ratio is, for example, the rotation speed sensor 1
I = Nout / Nin based on the input rotation speed Nin and the output rotation speed Nout detected by 7 and 18. Then, if it is determined that the vehicle is in the steady state, the process proceeds to step 2, and if it is determined that the vehicle is not in the steady state, the routine ends.

In step 2, a counter Co for determining whether or not the steady state of the continuously variable transmission 3 has continued for a predetermined time.
Increment unt_st. In the following step 3,
In order to calculate the average value of the duty ratio of the drive pulse signal to the solenoid valve 14 within a predetermined time, the duty ratio Duty is added to the variable Dt_sum for calculating the average duty ratio value. In step 4, the line pressure average value calculation variable PL is calculated in order to calculate the average value of the line pressure within a predetermined time.
The line pressure P _L obtained by referring to the map shown in FIG. 8 from the duty ratio of the drive pulse signal to the solenoid valve 12 is added to _sum. The process of calculating the line pressure P _L in step 4 corresponds to a line pressure detecting unit.

In step 5, it is determined whether or not the steady state of the continuously variable transmission 3 has continued for a predetermined time. That is, the counter
Count_st is compared with a predetermined value PPC, and if Count_st ≧ PPC (continues for a predetermined time), the process proceeds to step 6 and Count_st
If <PPC (predetermined time does not continue), this routine ends. In steps 1, 2 and 5, the continuously variable transmission
3 is a series of processes for determining whether or not
The process corresponds to a steady state determination unit. In step 6, the counter Count_st is reset in preparation for the next estimation.

In step 7, the duty ratio average value Dtyave is calculated by dividing the duty ratio average value calculation variable Dt_sum by a predetermined value PPC. In the following step 8, the line pressure average value PLave is calculated by dividing the line pressure average value calculation variable PL_sum by the predetermined value PPC. Step 9
In FIG. 7, based on the calculated duty ratio average value Dtyave,
By referring to a map as shown in FIG.
Then, the opening area ratio Ar of No. 3 is obtained. Note that the calculation processing of the opening area ratio Ar in step 9 corresponds to the related value detecting means.

In step 10, the primary pressure Pp is estimated from the opening area ratio Ar and the average line pressure PLave obtained by the above processing using the following equation.

[0038]

(Equation 5)

According to the above-described processing, the primary pressure can be estimated over a wide range with a simple configuration. For example, the sensor for determining the shift operation of the continuously variable transmission has failed due to disconnection or the like. Even when fail-safe operation is performed, the continuously variable transmission can be set to an appropriate speed ratio by the primary pressure control, so that the quality and reliability of the control device of the continuously variable transmission can be improved.

Next, FIG. 4 shows a system configuration of another embodiment of the control device for the continuously variable transmission according to the present invention. In this system configuration, the spool valve 13 of the control device for the continuously variable transmission shown in FIG. 2 is replaced with a spool valve 19 of a current control type, and a line pressure P is used as a sensor for determining a shift operation.
It is the same as that of FIG. 2 except that a hydraulic pressure sensor 20 (line pressure detecting means) for detecting _L is added. Therefore, only different points will be described here.

The spool valve 19 has a first port 19a and a second port 19 like the spool valve 13 in FIG.
b, a third port 19c, and a built-in spool 19d having a first port 19a and a third port 1
9c and a so-called underlap relationship. Also, a solenoid 19e is built in to drive the spool 19d, and a pin 19f provided at one end of the spool 19d is sucked according to the strength of the current from the control unit 16, and the opening area ratio Ar of the spool valve 19 is adjusted. Is controlled. The opening area ratio Ar of the spool valve 19 is
Primary pressure P _P to the primary pulley actuator 4a is changed, the speed ratio i of the continuously variable transmission 3 is set in accordance with.

When a fail-safe operation is performed when a sensor for determining the shift operation of the continuously variable transmission 3 fails, PLave of the primary pressure P _P estimating equation (5) in step 10 of the flowchart of FIG. 3 is executed. on behalf of the estimation accuracy is improved by using the average value of the line pressure P _L which is detected by the oil pressure sensor 20. Hereinafter, the improved primary pressure estimation will be described with reference to the flowchart of FIG. Note that the same processes as those in the flowchart of FIG. 3 are denoted by the same step numbers as those in FIG. 3, and the description thereof will be simplified.

In step 1, it is determined whether or not the continuously variable transmission 3 is in a steady state. If it is in a steady state, the process proceeds to step 2, and if not, this routine is terminated. In step 2, the counter Count_st is incremented.
In the following step 3 ′, the supply current Current is added to the supply current average value calculation variable Cur_sum in order to calculate the average value of the supply current to the solenoid 19b built in the spool valve 19 within a predetermined time. In step 4, the line pressure average value calculation variables PL_sum, oil pressure sensor
The line pressure P _L detected by step 20 is added.

In step 5, it is determined whether or not the steady state of the continuously variable transmission 3 has continued for a predetermined time. If the predetermined time has elapsed, the process proceeds to step 6. If the predetermined time has not elapsed, this routine ends. In step 6, prepare for the next estimation
Reset the counter Count_st. In step 7 ′, the supply current average value calculation variable Cur_sum is set to a predetermined value PPC.
By dividing by, the average value of the supply current Curave is calculated. In the following step 8, the line pressure average value calculation variable PL_sum
Is divided by a predetermined value PPC to calculate a line pressure average value PLave.

In step 9 ', the opening area ratio Ar of the spool valve 19 is obtained by referring to a map as shown in FIG. 7 based on the calculated average value of the supply current Curave. In step 10, the above-described estimating equation (5) is obtained from the opening area ratio Ar and the line pressure average value PLave obtained by the above processing.
Is used to estimate the primary pressure Pp. According to the processing described above, the current control type spool valve and the oil pressure sensor for detecting the line pressure are used, so that the line pressure estimating processing is performed in comparison with the control device of the continuously variable transmission in FIGS. In addition, it is possible to reduce a decrease in estimation accuracy due to a variation in the spool valve or the like, and to further improve the estimation accuracy of the primary pressure.

[0046]

As described above, according to the first aspect of the present invention, when the continuously variable transmission is in the steady state, the primary pressure is accurately determined based on the value related to the line pressure and the opening area ratio. Is estimated, and the shift control of the continuously variable transmission can be executed based on the pressure control based on the estimated primary pressure. For example, when a sensor for determining the shift operation of the continuously variable transmission fails due to disconnection or the like. When the fail-safe is performed, the continuously variable transmission can be set to an appropriate speed ratio, so that the quality and reliability of the control device of the continuously variable transmission can be improved.

According to the second aspect of the invention, a continuously variable transmission is provided.
When the transmission ratio is within the predetermined range, the continuously variable transmission
State can be determined. According to the third aspect of the present invention, the shift control means can be constituted by one simple spool valve, so that the structure of the control device of the continuously variable transmission is simplified, thereby improving reliability and reducing costs. be able to.

According to the fourth aspect of the present invention, the shift control means is driven by a simple hydraulic circuit or a solenoid. The structure is simplified, and the reliability can be improved and the cost can be reduced. According to the fifth aspect of the present invention, the continuously variable transmission is performed by continuously changing the effective diameters of the two pulleys, and the speed change control for changing the effective diameter is performed by the pressure control based on the estimated primary pressure. It is possible to do it.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a diagram showing an embodiment of a control device for a continuously variable transmission according to the present invention.

FIG. 3 is a flowchart of primary pressure estimating processing according to the first embodiment;

FIG. 4 is a diagram showing another embodiment of the control device for the continuously variable transmission according to the present invention.

FIG. 5 is a flowchart of a primary pressure estimation process according to the first embodiment;

FIG. 6 is a diagram showing experimental data of a relationship between a duty ratio and an opening area ratio Ar.

FIG. 7 is a diagram showing a relationship between a duty ratio and an opening area ratio Ar.

[8] graph showing the relationship between the duty ratio and the line pressure P _L

[Explanation of symbols]

 3 Continuously Variable Transmission 4 Primary Pulley 4a Primary Pulley Side Actuator 5 Secondary Pulley 5a Secondary Pulley Side Actuator 6 Belt 10 Oil Pan 11 Oil Pump 12 Solenoid Valve 13 Spool Valve 13a First Port 13b Second Port 13c Third Port 13d Spool 14 Solenoid valves 15a to 15d Hydraulic piping 16 Control unit 17 Rotation speed sensor 18 Rotation speed sensor 19 Spool valve 19a First port 19b Second port 19c Third port 19d Spool 19e Solenoid 20 Oil pressure sensor

Claims (5)

(57) [Claims] A driving-side rotating member for receiving a rotating force of a power source; a driven-side rotating member; and a power transmitting member interposed between the driven-side rotating member and transmitting power between the two. A drive-side contact rotation radius that is a distance from a rotation center of a contact position between a rotating member and the power transmission member, and a driven-side rotation radius that is a distance from a rotation center of a contact position between the driven rotation member and the power transmission member. Control of a continuously variable transmission in which a gear ratio between the driving-side rotating member and the driven-side rotating member can be set in a stepless manner by changing a driving-side contact rotating radius and a stepless relative change. In the apparatus, a hydraulic pressure supply means for supplying a hydraulic pressure to the driving side rotating member and the driven side rotating member at a predetermined line pressure, and the line pressure is interposed between the hydraulic pressure supplying means and the driving side rotating member. The drive side rotating member is connected to the power transmission unit. Speed control means for setting the speed ratio of the continuously variable transmission by controlling the primary pressure to be pressed against the material, a line pressure detection means for detecting the line pressure, and a hydraulic pressure inflow opening in the speed change control means and related value detecting means for detecting a value related to the aperture area ratio between the area and the outflow side opening area, the continuously variable transmission
A steady state determination means for determining whether or not the vehicle is in a steady state;
The continuously variable transmission is in a steady state by the steady state determining means.
Primary pressure estimating means for estimating the primary pressure based on the detected line pressure and a value related to the opening area ratio. A control device for a continuously variable transmission, which is capable of executing shift control based on pressure. 2. The continuously variable transmission according to claim 1 , wherein
When the gear ratio of the continuously variable transmission is within the predetermined range,
The control device for a continuously variable transmission according to claim 1, wherein it is determined that the vehicle is in a normal state . 3. The shift control means is a three-port spool valve, and the first port communicates with the second port or the second port communicates with the third port by operation of the spool. 3. The control device for a continuously variable transmission according to claim 1, wherein the switching is performed, and the spool and the port have an underlap relationship. 4. 4. The transmission control means is driven by a solenoid attached to the transmission control means or a pilot pressure regulated by a solenoid valve, and a value related to the opening area ratio is: 4. A drive signal for a solenoid attached to the shift control means or a solenoid valve for adjusting a pilot pressure.
The control device for a continuously variable transmission according to any one of the above. 5. The driving-side rotating member is a pulley whose effective winding radius can be changed, the driven-side rotating member is a pulley whose effective winding radius can be changed, and the power transmission member is wound around these. The control device for a continuously variable transmission according to any one of claims 1 to 4, wherein the control device is a winding transmission medium.