JP2819026B2 - Belt ratio control device for continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt ratio control device for a continuously variable transmission, and more particularly to a target engine rotational speed and a vehicle speed in a coast mode indicating coasting at a medium to low speed. The present invention relates to a belt ratio control device for a continuously variable transmission, which calculates a target gear ratio, and controls the speed so that the actual gear ratio matches the target gear ratio, thereby improving the drivability in the coast mode.

[Related Art] In a vehicle, a transmission is interposed between an internal combustion engine and a driving vehicle. This transmission changes the driving force of the drive wheels and the traveling speed in accordance with the traveling conditions of the vehicle that vary over a wide range, thereby sufficiently exhibiting the performance of the internal combustion engine. The transmission is formed between both pulley parts of a pulley having a fixed pulley part fixed to the rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part. 2. Description of the Related Art There is a continuously variable transmission that changes the radius of rotation of a belt wound around a pulley by increasing or decreasing the width of a groove to transmit power and change a gear ratio (belt ratio). As this continuously variable transmission, for example, JP-A-57-186656,
These are disclosed in JP-A-59-43249, JP-A-59-77159, and JP-A-61-233256, respectively.

[Problems to be Solved by the Invention] By the way, in the conventional belt ratio control device for a continuously variable transmission, the target engine rotation is determined according to the throttle opening input to the control unit, the shift position of the shift lever, and the vehicle speed. The engine speed is controlled by setting the speed and feedback-controlling the engine speed.

The clutch control during running when the throttle is returned at medium to low speeds is performed to keep the clutch slip constant, and even if the engine torque increases by depressing the throttle from this state, torque fluctuation due to clutch slippage will occur. And control to prevent shock to the vehicle body and occupants.

At this time, the belt ratio control is the same engine speed control as in the drive mode.

In coast mode that indicates coasting at low speeds,
The throttle opening is less than 5%, the engine torque at this time is also low, and the reverse torque for driving the engine from the wheels is acting rather.
The slip amount is controlled to about m.

For this reason, the control of the belt ratio is performed by the engine rotation control having a fast response speed. For example, when the shift lever is downshifted from the D range to the L range during the coast mode, the clutch slip amount is kept constant by the clutch control unit. As a result, the clutch control and the above-described engine rotation control interfere with each other, and there is a possibility that belt slippage or engine stall may occur, and there is a disadvantage that the running feeling is deteriorated.

Also, at the time of first idling, the target engine speed is increased according to the throttle opening,
There is an inconvenience that the vehicle starts to move more than the driver expects and feels strange.

[Object of the Invention] Accordingly, an object of the present invention is to eliminate the above-mentioned disadvantages by providing both pulley portions of a pulley having a fixed pulley portion and a movable pulley portion detachably attached to the fixed pulley portion. In a belt ratio control device for a continuously variable transmission, the speed of which is controlled to increase or decrease the radius of rotation of the belt wound around the two pulleys by changing the groove width between the two pulleys to change the speed ratio, the driven of the continuously variable transmission is controlled. A clutch and a clutch control unit for controlling a coupling state of the clutch are provided on the side of the vehicle, and in a state where the control vehicle shifts to a running state and the clutch control unit completely couples the clutch (drive mode), at least the vehicle speed and the throttle opening state are set. The target engine speed is set as a function (map) of the degree-equivalent signal, and shift control (E) is performed so that the actual engine speed matches the target engine speed. Engine rotation control mode), while the vehicle is coasting below a predetermined vehicle speed and the clutch control unit is controlling the clutch to a predetermined slip amount (coast mode), the target engine rotation determined by a function (map) In the coast mode, the control unit is determined by the target engine speed and the vehicle speed determined by a function (map) by providing a control unit that performs control (ratio control mode) so that the speed ratio matches the target speed ratio determined by the speed and the vehicle speed. Control (ratio control mode) can be performed to match the gear ratio to the target gear ratio, preventing an increase in the number of parts as much as possible, simplifying the configuration and smoothing the movement of vehicle speed when shifting to the coast mode. In addition, belt ratio control can be performed smoothly during downshift operations, and belt slips and engine stalls occur. In realizing the belt ratio controller for a continuously variable transmission which can indeed prevented.

Means for Solving the Problems In order to achieve this object, the present invention provides a pulley having a fixed pulley part and a movable pulley part detachably attached to the fixed pulley part. In the belt ratio control device for a continuously variable transmission, the speed of which is controlled so as to increase or decrease the groove radius between the pieces to increase or decrease the rotation radius of the belt wound around the two pulleys and to change the gear ratio, A clutch is provided on the driven side and a clutch control unit for controlling a coupling state of the clutch is provided. In a state in which the control vehicle shifts to a running state and the clutch control unit completely couples the clutch (drive mode), at least the vehicle speed is increased. And the target engine speed as a function (map) of the throttle opening equivalent signal, and shift the actual engine speed to match the target engine speed. Control (engine rotation control mode), while the vehicle is coasting below a predetermined vehicle speed and the clutch control unit is controlling the clutch to a predetermined slip amount (coast mode).
Is characterized in that a control unit is provided for performing control (ratio control mode) so that the gear ratio matches a target gear ratio determined by the target engine rotation speed and the vehicle speed determined by the function (map).

[Operation] According to the above-described invention, in a state where the control vehicle shifts to the traveling state and the clutch control unit completely engages the clutch (drive mode), at least a target as a function (map) of a signal corresponding to the vehicle speed and the throttle opening degree is obtained. The engine speed is set, and a shift control (engine speed control mode) is performed so that the actual engine speed matches the target engine speed. When the vehicle is in a coasting state at a predetermined vehicle speed or less, the clutch control unit applies a predetermined clutch. In the state in which the slip amount is controlled (coast mode), the control unit performs control (ratio control mode) so that the gear ratio matches the target gear ratio determined by the target engine rotation speed determined by the function (map) and the vehicle speed. In addition to minimizing the number of parts and simplifying the configuration, the vehicle speed changes when shifting to the coast mode. The belt ratio control is performed smoothly when the downshift operation is performed, and the control interference is avoided to surely prevent the occurrence of belt slip and engine stall.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 6 show an embodiment of the present invention. In FIG. 4, 2 is a belt-driven continuous variable transmission, 2A is a belt, 4 is a driving pulley, 6 is a driving pulley piece, 8 is a driving movable pulley piece, 10 is a driven pulley,
12 is a driven-side fixed pulley piece, and 14 is a driven-side movable pulley piece. As shown in FIG. 4, the drive-side pulley 4 includes a drive-side fixed pulley piece 6 fixed to a rotating shaft 16,
And a drive-side drive pulley piece 8 attached to the rotary shaft 16 so as to be movable and non-rotatable in the axial direction of the rotary shaft 16.
The driven pulley 10 also has a driven-side fixed pulley piece 12 and a driven-side movable pulley piece 14, similarly to the drive-side pulley 4.

First and second housings 18 and 20 are mounted on the driving-side movable pulley piece 8 and the driven-side movable pulley piece 14, respectively, to form first and second hydraulic chambers 22 and 24, respectively. . At this time, the second hydraulic chamber 24 on the driven side
There is provided a biasing means 26 comprising a spring or the like for biasing the second housing 20 in the direction of enlargement.

An oil pump 28 is provided on the rotating shaft 16. The oil pump 28 communicates with the first and second hydraulic chambers 22 and 24 via first and second oil passages 30 and 32, respectively. Is provided with a primary pressure control valve 34 as a shift control valve for controlling a primary pressure as an input shaft sheave pressure. Further, the line pressure by the third oil passage 36 to the first oil passage 30 of the oil pump 28 side of the primary pressure control valve 34 (typically 5~25kg / cm ²⁾ to a constant pressure (3-4 kg / cm ²⁾
A first pressure control first three-way solenoid valve 42 is connected to the primary pressure control valve 34 via a fourth oil passage 40 to the primary pressure control valve 34.

In the middle of the second oil passage 32, a line pressure control valve 44 having a relief valve function for controlling a line pressure as a pump pressure is provided.
Through a fifth oil passage 46, and the line pressure control valve
The second oil passage 48 communicates with a second three-way solenoid valve 50 for line pressure control through a sixth oil passage 48.

Further, a clutch pressure control valve 52 for controlling a clutch pressure is communicated with a seventh oil passage 54 in the middle of the second oil passage 32 on the second hydraulic chamber 24 side of the portion where the line pressure control valve 44 communicates. An eighth oil passage 56 communicates with the clutch pressure control valve 52 with a third three-way solenoid valve 58 for clutch pressure control.

The primary pressure control valve 34, the primary pressure control first solenoid valve 42, the constant pressure control valve 38, the sixth oil passage 4
8. The second solenoid valve 50 for line pressure control and the clutch pressure control valve 52 are connected to each other by a ninth oil passage 60.

The clutch pressure control valve 52 communicates with a hydraulic start clutch 62 provided on the driven side of the continuously variable transmission 2 through a tenth oil passage 64.
On the way, a pressure sensor 68 is connected through an eleventh oil passage 66. The pressure sensor 68 can directly detect the hydraulic pressure when controlling the clutch pressure in the hold and start modes and the like, and contributes when instructing the detected hydraulic pressure to be the target clutch pressure. In the drive mode, the clutch pressure becomes equal to the line pressure, which also contributes to line pressure control.

An input shaft rotation detection gear 70 is provided outside the first housing 18, and a first rotation detector 72 on the input shaft side is provided near an outer peripheral portion of the input shaft rotation detection gear 70. Further, an output shaft rotation detection gear 74 is provided outside the second housing 20, and a second rotation detector 76 on the output shaft side is provided near an outer peripheral portion of the output shaft rotation detection gear 74. Then, detection signals from the first rotation detector 72 and the second rotation detector 76 are output to a control unit 82, which will be described later, to grasp the engine rotation speed and the belt ratio.

The hydraulic starting clutch 62 is provided with an output transmission gear 78, and a third rotation detector 80 for detecting the rotation of the final output shaft is provided near the outer periphery of the gear 78. That is, the third rotation detector 80 detects the rotation of the reduction gear, the differential, the drive shaft, and the final output shaft directly connected to the tire, and can detect the vehicle speed. Further, the second rotation detector 76 and the third
The rotation detector 80 can also detect rotation around the hydraulic start clutch 62, which contributes to the detection of the clutch slip amount.

Further, control for inputting various conditions such as the throttle opening of a carburetor (not shown) of the vehicle and the engine rotation and the vehicle speed from the first to third rotation detectors 72, 76, 80, and changing the duty ratio to perform shift control. The control unit 82 controls the first three-way solenoid valve 42 for primary pressure control and the constant pressure control valve 38, the second three-way solenoid valve 50 for line pressure control, and the third three-way solenoid valve 58 for clutch pressure control. It is configured to control the pressure sensor 68 while controlling the opening / closing operation. Further, the function of the input signal as the various signals input to the control unit 82 will be described in detail. A shift lever position detection signal... P, R, N, D, L, etc. Required line pressure, ratio, clutch control, carburetor throttle opening detection signal …… Detects engine torque from memory previously input into the program, determines target ratio or target engine speed, carburetor idle position detection signal Accuracy in correction and control of the carburetor throttle opening sensor and accelerator pedal signal Accelerator pedal signal Detects the driver's will based on the depression of the accelerator pedal, and determines the control direction when driving or starting, and a brake signal. Detects whether or not the brake pedal is depressed, determines the control direction such as disengaging the clutch, Power mode option signal …… Sports performance (or economy)
There is an option to use it.

The control unit 82 controls the vehicle speed at least when the control vehicle (also simply referred to as “vehicle”) equipped with the continuously variable transmission 2 shifts to the running state and the clutch control unit completely engages the clutch (drive mode). Target engine speed NESP as a function (map) of the throttle opening degree equivalent signal
R is set, the shift control (engine rotation control mode) is performed so that the actual engine speed NE matches the target engine speed NESPR, and the clutch control unit operates the clutch when the vehicle is coasting below a predetermined vehicle speed. In a state where the slip amount is controlled to a predetermined value (coast mode), the target engine speed NESP determined by the function (map) is used.
Control to make the actual gear ratio (belt ratio) match the target gear ratio determined by R and vehicle speed (ratio control mode)
The configuration has

That is, when trying to reduce the differential rotation of the hydraulic start clutch 62 between IN and OUT to reduce the shock at the time of reconnection, the hydraulic start clutch 62 is connected to the drive side of the continuously variable transmission 2. In the system of the present invention in which the hydraulic start clutch 62 is arranged on the driven side of the continuously variable transmission 2, the clutch control (clutch control) can be performed without any trouble. Interference with engine rotation control.

This control interference occurs for the coast mode. That is, in the coast mode, the hydraulic start clutch 62 is not connected, and the vehicle is in the slip control state. At the time of the slip control, the engine rotation speed changes depending on the degree of engagement of the hydraulic start clutch 62. Controlling the engine rotation speed by shifting causes interference between clutch control and engine rotation control.

For this reason, when the vehicle is coasting below a predetermined vehicle speed and the clutch control unit is controlling the clutch to a predetermined slip amount (coast mode), the shift control target is set based on the engine speed and the gear ratio. (Belt ratio).

Here, for reference, the CTV shift control in the drive mode in which the hydraulic start clutch 62 (hereinafter referred to as “clutch” in the following reference text) is directly connected and in the coast mode in which the slip control is performed is described. I do.

In the drive mode in which the engine, CVT, clutch, speed reducer, and drive wheels are sequentially disposed, the power train configuration is such that the CVT engine speed ω2 and the speed reducer engine speed ω3 Ω1 = i · ω2 Equation 1 ω1: engine rotation speed of the engine, i: CVT gear ratio.

 The CVT speed ratio i is as follows: i = ω1 / ω2 (2)

If the CVT shift control is expressed as simple proportional control only to facilitate understanding, in the target engine speed ω1d control, di / dt = K1 (ω1d−ω1) Equation 3 K1: proportional gain (positive number) In the target gear ratio id control, di / dt = −K2 (id−i) Equation 4 K2: proportional gain (positive number)

In either case, when the gear ratio is increased or decreased by Equation 3 or Equation 4 in accordance with the deviation of the target value, the engine speed ω
1 changes to match each target value. For example, if it changes from ω1 to ω1 + Δω, the gear shifts to i → i−Δi and overdrive side by the control of Expression 3, so that
From the relationship of Expression 1, ω1 + Δω → ω1, and ω1 is maintained at the target value ω1d.

In the coast mode in which the clutch is in the slip state, the clutch slip ωs = | ω3-ω2 | is controlled to the target value ωsd by clutch control. At this time, assuming that the clutch torque transmitted by the clutch is Tc, basic clutch control can be expressed by the following equation.

dTc / dt = −K3 (ωsd−ωs) Equation 5 K3: Proportional Gain (Positive Number) On the other hand, the relational expression between ω1 and ω3 is expressed as follows instead of Expression 1.

J1 · dω1 / dt = TE−Tc / i Equation 6 J3 · dω3 / dt = Tc−TL Equation 7 TE: Engine output torque (positive when driving, negative value when engine braking) TL: Vehicle Therefore, the clutch torque Tc has a positive value when the engine is driving the vehicle body, and has a negative value when the vehicle body is driving the engine.

Then, in the case of performing CVT shift control with Expression 3, that is, at the target engine rotation speed, according to the polarity of the clutch torque Tc,
It is necessary to change the polarity of the proportional gain K1.

In other words, in order to achieve the target value, the control side must be as shown in the following table.

On the other hand, in the case of performing the CVT shift control by the equation 4, that is, the target speed ratio control, regardless of the polarity of the clutch torque Tc,
The proportional gain K2 is a positive number.

 The above can be summarized as follows.

(1) As in the drive mode, when the clutch is directly engaged, the CVT speed change control is basically the same on the control side regardless of whether the target value is the engine speed or the CVT speed ratio, and is equivalent. Control.

(2) However, when the clutch is not directly engaged as in the coast mode, the CVT shift control is performed by setting the target value to the engine speed or the CV for the target gear ratio control.
It is necessary to change the shift side depending on whether the gear ratio is T.

(3) In the coast mode, it is desirable that the state of the CVT shift control in both modes be the same in order to smoothly continue the CVT shift control when shifting from the drive mode to the coast mode.

(4) For this reason, the present application employs the engine rotation control as the target value of the drive mode in which the clutch is directly connected, so that the state of the CVT shift control in both the drive mode and the coast mode is the same. For this purpose, the target engine speed, that is, the same map is used.

Further, a configuration when the vehicle shifts to a state (coast mode) in which the vehicle is in a coasting state at a predetermined vehicle speed or less and the clutch control unit controls the clutch to a predetermined slip amount (coast mode) will be described below.

More specifically, the control unit 82 receives a carburetor throttle opening signal θ (not shown) and a vehicle speed signal V, and outputs the target engine rotational speed NE according to the shift position of the shift lever.
The control mode RN for feedback control of the engine speed is set by setting the SPR and the target ratio value RATSP, and using the target engine speed NESPR and the engine speed NE.
In addition to calculating the EMOD, the control mode RATMOD for feedback control of the belt ratio is calculated from the target ratio value RATSP and the belt ratio RATC, and the mode RDIMOD for outputting a fixed duty value is calculated and controlled.

The first to third three-way solenoid valves 42, 50, and 58 have the same structure, and the schematic structure of the first three-way solenoid valve 42 will be described in detail with reference to FIG. The first three-way solenoid valve 42 includes a case 84, two electromagnetic coils 86 in the case 84, a plunger 88 moving between the electromagnetic coils 86, a steel sphere 90 at the tip of the plunger 88, and the sphere 90. The surrounding sheet portion 92 and the sheet portion
I / O ports 94, 96 and atmosphere port 98 provided in 92
And a spring 100 for urging the plunger 88 in the direction for preventing air release. That is, when the electromagnetic coil 86 is not energized, the plunger 88 is moved downward by the urging force of the spring 100, and the input port is moved by the sphere 90.
The output port 96 is communicated with the atmosphere port 98 by closing the 94, and when energized, a magnetic field is generated in the electromagnetic coil 86 to move the plunger 88 upward against the urging force of the spring 100. It is configured so that the input / output ports 94 and 96 are communicated by closing the 98. Further, the sphere 90 at the time of energization is normally in a free state, but the input port
It is pressed by the hydraulic pressure from 94 to close the atmosphere port 98.

102 is a piston of the hydraulic start clutch 62, 104 is an annular spring, 106 is a first pressure plate, 108 is a friction plate, 110 is a second pressure plate, 112 is an oil pan, and 114 is an oil filter.

As shown in FIG. 6, the primary pressure control valve 34 is provided with a spool valve 118 which reciprocates in the body 116, and the relationship between the primary side diameter D of the spool valve 118 and the clutch side diameter d is represented by D> d. The body 116 is provided with an air opening 120, a first oil passage 30, a second oil passage 32, an air opening 122, and a ninth oil passage 60 from the left side in FIG. A passage 40 is provided. Further, the spool valve 118 is provided in the body 116.
The first and second springs 124 and 126 are provided so as to bias each from the left and right sides to a predetermined position, that is, a position where each passage is not communicated as shown in FIG.

 Next, the operation will be described.

As shown in FIG. 4, the belt-driven continuously variable transmission 2 includes an oil pump 28 located on the rotating shaft 16 and a rotating shaft 16.
The oil is absorbed through an oil filter 114 from an oil pan 112 at the bottom of the transmission.
The line pressure, which is the pump pressure, is controlled by the line pressure control valve 44.If the amount of leakage from the line pressure control valve 44, that is, the amount of relief of the line pressure control valve 44, is large, the line pressure becomes low. If it is less, the line pressure will be higher.

Further, the line pressure control valve 44 has a shift control characteristic of performing three-stage control for changing the line pressure in each of a full low state, a full overtop state, and a fixed ratio state.

The operation of the line pressure control valve 44 is a dedicated second three-way solenoid valve.
The second three-way solenoid valve 50
The line pressure control valve 44 makes a differential following the above operation, and the second three-way solenoid valve 50 is controlled at a constant frequency duty ratio. That is, when the duty ratio is 0%, the second three-way solenoid valve 50 does not operate at all, the output side is connected to the atmosphere side, and the output oil pressure becomes zero. Also, duty ratio 100
The percentage means that the second three-way solenoid valve 50 is operated, the output side is connected to the input side, the maximum output oil pressure is the same as the control pressure, and the output oil pressure is varied according to the duty ratio. Therefore, the characteristics of the second three-way solenoid valve 50 are substantially linear, and the line pressure control valve 44 can be operated in an analog manner, and the duty ratio of the second three-way solenoid valve 55 can be changed arbitrarily. Line pressure can be controlled. The operation of the second three-way solenoid valve 50 is controlled by the control unit 82.

The primary pressure for shifting control is the primary pressure control valve.
The operation of the primary pressure control valve 34 is controlled by a dedicated first three-way solenoid valve 42, similarly to the line pressure control valve 44. This first three-way solenoid valve 42
Is used to conduct the primary pressure to the line pressure or to conduct the primary pressure to the atmosphere side, and to conduct the line pressure to shift the belt ratio to the full overdrive side, or to conduct to the atmosphere side to the full low side. It is to shift to.

The clutch pressure control valve 52 for controlling the clutch pressure is connected to the line pressure side when the maximum clutch pressure is required, and is connected to the atmosphere side when the minimum clutch pressure is required. The clutch pressure control valve 52 is also connected to the line pressure control valve 44.
Like the primary pressure control valve 34 and the primary pressure control valve 34, the operation is controlled by a dedicated third three-way solenoid valve 58, and the description is omitted.
The clutch pressure varies within a range from a minimum atmospheric pressure (zero) to a maximum line pressure.

There are four basic patterns for controlling the clutch pressure, which will be described later. These basic patterns are as follows: (1) Neutral mode When the shift position is N or P and the clutch is completely disengaged, the clutch pressure becomes the minimum pressure (zero). (2) Hold mode: When the shift position is D or R and the throttle is released and there is no driving intention, or when it is desired to decelerate during running and cut off the engine torque, the clutch pressure is low enough to make the clutch contact ( 3), start mode: When the clutch is to be engaged again at the time of starting or after the clutch is disengaged, the clutch pressure is determined according to the engine generated torque (clutch input torque) that prevents the engine from rising and allows the vehicle to operate smoothly. Appropriate level (4), drive mode ..... If the fully coupled, There are four high-level clutch pressure having a margin to withstand sufficiently the engine torque. The basic pattern (1) is performed by a dedicated switching valve (not shown) interlocked with the shift operation, and the other (2), (3), and (4) are first to third three-way solenoid valves by the control unit 82. It is performed by the duty ratio control of 42, 50 and 58. In particular, in the state (4), the seventh oil passage 54 and the tenth oil passage 64 are communicated by the clutch pressure control valve 52 so that a maximum pressure is generated, and the clutch pressure becomes the same as the line pressure.

Further, the primary pressure control valve 34 and the line pressure control valve 4
4, and the clutch pressure control valve 52 is controlled by the output hydraulic pressure from the first to third three-way solenoid valves 42, 50, 58, respectively. The control oil pressure to be controlled is a constant oil pressure generated by the constant pressure control valve 38. This control oil pressure is always higher than the line pressure, but is a stable and constant pressure. The control oil pressure is also introduced into the control valves 34, 44, and 52 to stabilize the control valves 34, 44, and 52.

Next, the electronic control of the belt-driven continuously variable transmission 2 will be described.

The continuously variable transmission 2 is hydraulically controlled, and in accordance with a command from the control unit 82, an appropriate line pressure for belt holding and torque transmission, a primary pressure for gear ratio change, and a clutch are securely connected. The clutch pressures for the engagement are secured respectively.

A flowchart for controlling the belt ratio of the belt-driven continuously variable transmission 2 will be described with reference to FIG.

First, a belt ratio control program for the belt-driven continuously variable transmission 2 is started (100).

Next, it is determined whether the vehicle is in the neutral mode (102). If YES, the mode is set to a mode RDIMOD (104) for outputting a fixed duty value.
The gear ratio control is performed according to the above, and the program for belt ratio control is shifted to return (126).

If the determination (102) is NO, the process proceeds to a determination (106) as to whether or not the mode is the hold mode, and this determination (106) is performed.

If the determination (106) is YES, the mode is set to the mode RDIMOD (108) for outputting a fixed duty value as in the above-described neutral mode, and the belt ratio control program is shifted to the return (126). In this case, it is determined whether or not the normal start mode is set (110).

If the determination (110) of the normal start mode is YES, the mode RDIMOD for outputting a fixed duty value as in the neutral mode and the hold mode described above.
Then, the program for belt ratio control is shifted to return (126). In the case of NO, it is determined (114) whether or not the mode is the special start mode.

If the determination (114) is YES, the control mode is set to the control mode RNEMOD (116) in which the engine rotation speed is feedback-controlled with respect to the target engine rotation speed determined by the throttle opening and the vehicle speed, and the belt ratio control program is returned ( The process proceeds to 126), and in the case of NO, it is determined whether or not the mode is the coast mode (118).

If the determination (118) of the coast mode is YES, the control mode is set to the control mode RATMOD (120) in which the belt ratio is feedback-controlled with respect to the target ratio rotation speed determined by the throttle opening and the vehicle speed, and the belt ratio is set. The program for the belt ratio control is shifted to the return (126) by the feedback control. If the determination in the coast mode (118) is NO, a determination is made in the drive mode (122).

If the determination (122) is YES, the control mode is set to the control mode PNEMOD (124) in which the engine speed is feedback-controlled relative to the target engine speed determined by the throttle opening and the vehicle speed, and the belt ratio control program is returned. The process proceeds to (126), and if NO, the belt ratio control program is returned (126).

The belt ratio control of the belt-driven continuously variable transmission 2 will be described with reference to FIGS.

First, with obtaining the detection signal and the shift position N first table 200 first target engine rotational speed N ₁ from by the carburetor of the throttle opening (theta), the detection signal and the shift position from the third rotation detector 80 N second seek from the table 202 the second target engine rotational speed N ₂ by the. At this time, in the coast mode, the clutch slip amount is controlled to about 50 rpm by a clutch control unit that controls the engagement state of the clutch 62.

Next, the first target engine rotational speed N ₁ compares the second target engine rotational speed N _2, elected either proper engine rotational speed of the upper and lower, the optimum target engine rotational speed N ₃ of this (204).

At this time, the belt ratio uses the same map as when the clutch lock-up, (a clutch output shaft revolution, the same substantially clutch input shaft rotation) the optimum target engine rotational speed N ₃ and the vehicle speed to determine the specific by rotational speed between the , then the optimum target engine rotational speed N ₃ of the primary delay constant corresponding to the shift position effect (206) is brought into the in determining the target engine rotational speed NESPR. Further, the primary delay constant, the optimum target engine rotational speed N ₃ is intended monkey vary depending on the shift position the time to reach the target engine rotational speed NESPR, arrival time is slowest at the D range position It is set as follows.

The optimum target engine rotational speed N ₃ and the limit processing to the value calculated (208) from the vehicle speed V (210), determine the target ratio value RATSP.

Then, as shown in FIG. 3, an error between the target engine speed NESPR and the actual engine speed NE is obtained. At this time, when the error becomes large, the duty ratio becomes large as a result, the opening of the primary pressure control valve 34 becomes large, and the shift speed becomes high.

Further, the error is multiplied by a proportional gain KAE determined from a third table corresponding to the actual engine speed NE, and a feedback control of the engine speed to a target engine speed NESPR determined from the throttle opening and the vehicle speed is performed. The mode RNEMOD is obtained (212).

An error between the target ratio value RATSP and the belt ratio RATC is obtained, and the error is multiplied by a proportional gain KAR determined from a fourth table corresponding to the belt ratio RATC, to obtain a target ratio value RATSP determined from the throttle opening and the vehicle speed. A control mode RATMOD for feedback control of the Bertrescio RATC is determined (214).

And these control modes RNEMOD, RATMOD
Is multiplied by the gain KBR (216), and this error is multiplied by the integral gain D1IR by the belt ratio RATC (21).
8) Add the fixed ratio (Null value) according to the oil temperature to calculate the error (220). Here, the fixed ratio value represents a duty value in a state where the ratio does not change due to the balance between the primary pressure and the line pressure.

The error is converted into a duty ratio, and each solenoid valve is excited by the duty ratio of the conversion ratio.

Accordingly, in a state where the vehicle is coasting below a predetermined vehicle speed and the clutch control unit is controlling the clutch to a predetermined slip amount (coast mode), the target engine rotation speed and the vehicle speed determined by a function (map) are determined. The control (ratio control mode) can be performed to match the gear ratio to the target gear ratio determined by the control. There is no significant increase in programs and memory, and the increase in the number of parts can be prevented as much as possible. The cost can be kept low, which is economically advantageous.

Further, since the target ratio value RATSP is calculated to maintain the same vehicle speed as in the drive mode, smooth ratio control can be performed even when the control mode shifts from the drive mode to the coast mode, and the occurrence of belt slip can be reliably prevented. It can be prevented and is practically advantageous.

Furthermore, the control mode RATMOD for feedback controlling the belt ratio RATC with respect to the target ratio value RATSP is:
Control mode in which the engine speed is feedback controlled with respect to the target engine speed NESPR. The response is slowed by reducing the proportional gain compared to RNEMOD, so the shift lever is shifted from the D range to the L range during the coast mode. Downshift operation,
Control interference with the clutch control is small, engine stall can be reliably prevented, and a smooth shift feeling can be obtained.

Furthermore, in the control mode RNEMOD, in which the engine speed is feedback-controlled with respect to the target engine speed NESPR where the throttle is depressed after the clutch locks up, good control of the response is required according to the throttle opening and the vehicle speed. However, it is impossible to make a rapid change in the engine torque due to the small throttle opening and the reverse torque, but the belt ratio RAT to the target ratio RATSP is impossible.
Control mode RATMOD for feedback control of C
By doing so, smooth control becomes possible.

When the throttle is opened in the drive mode, the target engine rotational speed is controlled by a value determined by the vehicle speed rather than a value determined by the throttle, thereby shifting from the drive mode to the coast mode. In this case, control is performed to a ratio calculated backward from the vehicle speed, thereby suppressing fluctuations in the engine rotation speed, eliminating a sense of incongruity, and maintaining continuity. Further, even when the throttle is opened more than usual at the time of the first idling, the transition from the drive mode to the coast mode is performed smoothly.

[Effects of the Invention] As described in detail above, according to the present invention, a space between both pulley parts of a pulley having a fixed pulley part and a movable pulley part detachably attached to the fixed pulley part is provided. In a belt ratio control device for a continuously variable transmission, which controls a speed change so as to increase or decrease a groove width to increase or decrease a rotation radius of a belt wound around the two pulleys to change a speed ratio, a clutch is provided on a driven side of the continuously variable transmission. And a clutch control unit for controlling the engagement state of the clutch. In a state in which the control vehicle shifts to a running state and the clutch control unit completely engages the clutch (drive mode), at least a vehicle speed and a throttle opening equivalent signal Set the target engine speed as a function (map) of the speed change control (engine speed control) so that the actual engine speed matches the target engine speed. Control mode), while the vehicle is coasting below a predetermined vehicle speed and the clutch control unit is controlling the clutch to a predetermined slip amount (coast mode), the target engine speed determined by the function (map) and In the coast mode, a control unit (ratio control mode) is provided to control the gear ratio to match the target gear ratio determined by the vehicle speed. Control (ratio control mode) can be performed to match the gear ratios, there is no significant increase in programs and memory, and increase in the number of parts can be prevented as much as possible. The configuration can be simplified, and costs can be reduced. Can be maintained. Even if the control mode shifts from the drive mode to the coast mode, smooth shift control can be performed, and belt slip can be reliably prevented, which is practically advantageous. Furthermore, even if the shift lever is shifted during the coast mode, the target is switched from the target engine speed to the target gear ratio, so that the occurrence of engine stall can be reliably prevented, and a smooth shift feeling can be achieved. Obtainable. Furthermore,
When the throttle is opened in the drive mode, the target engine speed is controlled by the value determined by the vehicle speed rather than the value determined by the throttle, so that the engine speed during the transition from the drive mode to the coast mode is controlled. It is possible to suppress the fluctuation of the speed and eliminate the sense of incongruity and maintain the continuity.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention, and FIG. 1 is a flow chart for ratio control of a belt-driven continuously variable transmission.
2 is an explanatory diagram for calculating a target engine rotational speed and a target ratio value, FIG. 3 is a diagram for explaining belt ratio control of a belt-driven continuously variable transmission, and FIG. 4 is a belt-driven continuously variable transmission. 5 is an enlarged sectional view of each three-way solenoid valve, and FIG. 6 is an enlarged sectional view of each control valve. In the figure, 2 is a belt-driven continuously variable transmission, 2A is a belt, 4 is a driving pulley, 10 is a driven pulley, 30 is a first oil passage, 32 is a second oil passage, and 34 is a primary pressure control valve. , 36 is a third oil passage, 38 is a constant pressure control valve, 40 is a fourth oil passage, 42 is a first three-way solenoid valve, 44 is a line pressure control valve, 46 is a fifth oil passage, 48 is a sixth oil passage, 50 is a second three-way solenoid valve, 52 is a clutch pressure control valve, 54 is a seventh oil passage, 56 is an eighth oil passage, 58 is a third three-way solenoid valve, 60 is a ninth oil passage, 62 is a hydraulic starting clutch, 64 is a tenth oil passage, 66 is an eleventh oil passage, 68 is a pressure sensor, 72 is a first rotation detector, 76 is a second rotation detector, 80 is a third rotation detector, 82 is a control unit, 112 is An oil pan 114 is an oil filter.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16H 63:06 (72) Inventor Takumi Tatsumi 840 Chiyoda-cho, Himeji-shi, Hyogo Mitsubishi Electric Corporation Himeji Works (72) Inventor Hiroaki Yamamoto Hyogo 13 Himeji, Himeji-shi, Japan Mitsubishi Electric Control Software Corporation Himeji Works (56) References JP-A-60-44652 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) F16H 61/00

Claims (1)

(57) [Claims] 1. A pulley having a fixed pulley part and a movable pulley part detachably mounted on the fixed pulley part, the groove width between the two pulley parts being reduced and wound around the two pulleys. A belt ratio control device for a continuously variable transmission that controls the speed of the continuously variable transmission to increase or decrease the radius of rotation of the belt to change the gear ratio, and a clutch on a driven side of the continuously variable transmission and a clutch that controls a coupling state of the clutch. A control unit is provided, and the control vehicle shifts to a running state, and the clutch control unit completely engages the clutch (drive mode).
Then, at least a target engine speed as a function (map) of the vehicle speed and the signal corresponding to the throttle opening is set, and a shift control (engine rotation control mode) is performed so that the actual engine speed matches the target engine speed. In a state in which the vehicle is coasting below a predetermined vehicle speed and the clutch control unit controls the clutch to a predetermined slip amount (coast mode), the vehicle speed is determined by a target engine rotation speed and a vehicle speed determined by the function (map). A belt ratio control device for a continuously variable transmission, comprising: a control unit that performs control (ratio control mode) so that the gear ratio matches a target gear ratio.