JP2012163143A - Control device for belt type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a belt type continuously variable transmission, which can obtain thrust according to a gear ratio and improve shift speed and durability.SOLUTION: In the belt type continuously variable transmission including a drive pulley, a driven pulley and a transmission belt wound on the pulleys, each tapered surface of the driven pulley is formed so that a friction coefficient of an outer part and a friction coefficient of an inner part are different in the radial direction. The device includes: a position determination means (step S3) which determines if a position, where the tapered surface of the driven pulley and the transmission belt are in contact, is in the inner part side or in the outer part side from a boundary position of the inner part and the outer part; and a means (step S6) for calculating the thrust making an axial load of a rotary shaft in the driven pulley act on a movable sheave based on the friction coefficient at the position determined by the position determination means.

Description

  The present invention performs power transmission via a transmission belt wound between a driving pulley and a driven pulley, and continuously changes the wrapping radius of the transmission belt to change the transmission ratio steplessly. The present invention relates to a control device for a belt type continuously variable transmission.

  In this type of belt type continuously variable transmission, by changing the groove width of the pulley around which the transmission belt is wound, the winding radius of the transmission belt is changed to set the transmission ratio steplessly. Torque is transmitted by frictional force generated between the pulleys to be wound. The transmission belt is divided into a metal belt formed by bundling a large number of metal pieces called elements or blocks, for example, with a steel band, and a non-metallic belt mainly composed of rubber or resin, for example. It can be divided roughly. A non-metallic belt has a friction coefficient larger than that of a metal belt because rubber, resin, or the like is in contact with the pulley, and the contact portion with the pulley is not lubricated with oil. In the belt type continuously variable transmission using the non-metallic belt, the friction coefficient of the non-metallic belt is larger than that of the metallic belt, so that the number of rotations of the pulley is low or the rotation of the pulley is stopped. It is known that shifting is difficult or cannot be performed in this state.

  An example of a belt-type continuously variable transmission using such a non-metallic belt is described in Patent Document 1. A belt-type continuously variable transmission described in Patent Document 1 includes a drive pulley, a driven pulley, a non-metallic belt wound between them, a transmission motor for changing the groove width of each pulley, As a major component. The speed change motor is a direct current type electric motor (that is, a DC motor), and the rotation characteristics such as the rotation speed and efficiency differ depending on the rotation direction. The rotational speed of the speed change motor when the speed ratio of the belt type continuously variable transmission is increased is faster than the speed of the speed change motor when the speed ratio is reduced. Has been. In other words, the speed change speed in the deceleration direction can be improved. Therefore, for example, when the speed ratio of the belt-type continuously variable transmission is small, the vehicle is driven by a sudden braking operation from the running state of the vehicle. Until the vehicle suddenly stops, the speed ratio of the belt-type continuously variable transmission can be changed from a state where the vehicle is stopped to a speed ratio at which the vehicle can start. For this reason, it is said that the re-startability of the vehicle can be improved.

JP 2004-116536 A

  A belt-type continuously variable transmission using a non-metallic belt has a non-metallic belt compared to when using a metal belt because the friction coefficient of the non-metallic belt is larger than that of the metal belt. And the pulley hardly slip, and generally the pulley needs to rotate to change the gear ratio. That is, there is rotation speed dependency. Therefore, in the apparatus described in Patent Document 1, the speed reduction of the belt-type continuously variable transmission is reduced so that the vehicle can start during the period from when the vehicle is running until it stops. It is comprised so that the speed change speed of a direction may be improved. However, if the rotational speed of the speed change motor is increased, energy is consumed correspondingly, so that the fuel consumption of the vehicle deteriorates or the pulley groove width is changed as the speed of the speed change motor increases. There is a possibility that the thrust to do will be excessive.

  The present invention has been made paying attention to the technical problem described above, and can control a belt-type continuously variable transmission that can obtain thrust according to a gear ratio and suppress or prevent a decrease in fuel consumption. The object is to provide an apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, the rotation of the driving pulley and the driven pulley is performed so that each of the driving sheave and the driven pulley approaches and separates from the stationary sheave integrated with the rotating shaft. The movable sheave is movable in the axial direction of the shaft, and the facing surface of the sheave is a tapered surface that forms a belt winding groove around which the transmission belt is wound, and the movable sheave is connected to the rotating shaft. In a control device for a belt-type continuously variable transmission in which a gear ratio is continuously changed by changing a winding radius of the transmission belt by moving in the axial direction and changing the groove width, each taper of the driven pulley The surface is formed so that the friction coefficient of the outer part and the friction coefficient of the inner part are different in the radial direction, and the tapered surface of the driven pulley and the transmission belt are in contact with each other. Position determining means for determining whether the position of the inner portion side or the outer portion side from the boundary position between the inner portion and the outer portion, and the driven pulley based on the friction coefficient at the position determined by the position determining means And a means for calculating a thrust for causing the load in the axial direction of the rotating shaft to act on the movable sheave.

  According to a second aspect of the present invention, in the first aspect of the invention, when the transmission belt moves from a side with a large friction coefficient to a side with a small friction coefficient, the friction coefficient is larger on the side where the friction coefficient is larger than the boundary position. A control device for a belt-type continuously variable transmission, further comprising means for increasing the thrust based on a friction coefficient on a smaller side.

  According to the invention of claim 1, the tapered surface of the driven pulley is formed so that the friction coefficient of the outer portion and the friction coefficient of the inner portion are different. Then, a position determining means for determining whether the position where the tapered surface of the driven pulley is in contact with the transmission belt is the inner part side or the outer part side from the boundary part between the inner part and the outer part, and a position judging means Based on the coefficient of friction at the determined position, there is a means for calculating a thrust that causes the load in the axial direction of the rotating shaft of the driven pulley to act on the movable sheave, so that the contact position between the transmission belt and the tapered surface is provided. The thrust can be calculated using the corresponding friction coefficient. Therefore, when the friction coefficient on the taper surface is in contact with the transmission belt at a small position, a frictional force for transmitting power between the transmission belt and the taper surface can be obtained, and the transmission at a position where the friction coefficient is large. When the belt is in contact with the belt, excessive frictional force between the transmission belt and the tapered surface can be suppressed or prevented. Therefore, since a thrust according to the contact position between the transmission belt and the tapered surface can be obtained, it is possible to suppress or prevent a reduction in fuel consumption due to excessive thrust.

  According to the second aspect of the present invention, when the transmission belt moves from the side having the larger friction coefficient to the side having the smaller friction coefficient, the thrust is based on the friction coefficient on the side having the smaller friction coefficient than the boundary position. Is further provided, so even if the transmission belt moves from a position where the friction coefficient is large to a position where the friction coefficient is small, the thrust is reduced to a small friction coefficient before the transmission belt reaches the position where the friction coefficient is small. Based on this, the thrust can be increased. Therefore, when the transmission belt moves to a position where the friction coefficient is small, it is possible to suppress or prevent a shortage of thrust temporarily.

It is a flowchart for demonstrating the control example of the control apparatus of the belt-type continuously variable transmission which concerns on this invention. It is a schematic diagram for demonstrating the structural example of the belt-type continuously variable transmission which can be made into the object of this invention. It is a figure for demonstrating the friction coefficient of the taper surface of the pulley provided in the belt type continuously variable transmission.

  Next, the present invention will be described with an example of a specific configuration. FIG. 2 is a diagram schematically showing a belt-type continuously variable transmission 1 that can be an object of the present invention. First, the configuration of the belt type continuously variable transmission 1 will be briefly described. A belt-type continuously variable transmission 1 shown in the figure has the same configuration as a conventionally known belt-type continuously variable transmission 1, and includes a driving pulley 2 to which torque is transmitted from a power source (not shown), and the driving pulley 2 The driven pulley 3 that outputs power to a wheel or gear train (not shown) and the transmission belt 4 that is wound around the pulleys 2 and 3 and transmits the torque of the driving pulley 2 to the driven pulley 3. It is configured.

  Each pulley 2 and 3 has a fixed sheave 2a (3a) formed integrally with the rotating shaft 5 (6), and the rotating shaft 5 (6) so as to approach and separate from the fixed sheave 2a (3a). The movable sheave 2b (3b) is movably held in the axial direction. Further, the facing surfaces of the sheaves 2a and 2b (3a and 3b) are tapered surfaces 2c and 2d (3c and 3d) that form belt winding grooves around which the transmission belt 4 is wound.

  The transmission belt 4 is a non-metallic composite belt 4 as an example, and the non-metallic composite belt 4 abuts against these belt grooves when wound around the pulleys 2 and 3 and receives pressure from the groove surface of the belt groove. And a number of blocks made of resin for holding the large number of blocks in a ring shape.

  The block is formed by coating a resin or the like on a plate-shaped member made of metal such as steel or aluminum alloy. Alternatively, a high-strength synthetic resin or the like can be integrally formed on a resin band. The left and right side surfaces of the block in the belt width direction are formed along the tapered surfaces of the pulleys 2 and 3, and come into contact with the tapered surfaces 2c and 2d (3c and 3d) of the pulleys 2 and 3. ing.

  That is, the movable sheave 2d (3d) moves in the axial direction, so that the transmission belt 4 moves along the tapered surfaces 2c and 2d (3c and 3d) in the radial direction of the pulley 2 (3). . In order to move the movable sheave 2b (3b) in the axial direction, in the example shown in the figure, the hydraulic chambers 7 and 8 are provided on the back surface of the movable sheave 2b (3b), that is, the surface opposite to the surface facing the fixed sheave. Is provided.

  Therefore, since the load received by the movable sheave 2b (3b) in the axial direction can be changed by increasing or decreasing the hydraulic pressure of the hydraulic chamber 7 (8), the movement of the transmission belt 4 by moving the movable sheave 2b (3b). It is possible to change the gear ratio by changing the winding radius and change the clamping pressure for clamping the transmission belt 4. Therefore, a conventionally known hydraulic control device 9 is provided in order to control the hydraulic pressure supplied to the hydraulic chambers 7 and 8. As an example of the hydraulic control device 9, a supply valve that supplies hydraulic pressure from a hydraulic source to the hydraulic chambers 7 and 8 and a discharge valve that discharges hydraulic pressure of the hydraulic chambers 7 and 8 to an oil pan (not shown) or the like are provided in each hydraulic chamber 7. , 8 are connected. Each valve is configured to supply or discharge hydraulic pressure in accordance with the energized power. Therefore, in order to control the electric power supplied to the hydraulic control device 9, the electronic control device 10 is electrically connected in the example shown in the figure. The electronic control device 10 receives various signals such as the rotational speed of the wheel, the engine rotational speed, or the accelerator opening, and outputs electric power based on the signals to each device such as the hydraulic control device 9. It is configured.

  Furthermore, the belt-type continuously variable transmission 1 that can be the subject of the present invention is formed such that the friction coefficient between the inner peripheral side and the outer peripheral side of each tapered surface 3c, 3d of the driven pulley 3 is different. In the example shown in FIG. 3, the inner peripheral friction coefficient is smaller than the outer peripheral friction coefficient. Specifically, the inner peripheral side of the tapered surface 3c (3d) is formed of a synthetic resin or the like, and the outer peripheral side is formed of a metal material so that the friction coefficient between the inner peripheral side and the outer peripheral side is changed. It is configured. The belt type continuously variable transmission 1 targeted in the present invention is only required to have different friction coefficients on the inner peripheral side and the outer peripheral side on the tapered surface. It may be formed larger than the friction coefficient. Further, the friction coefficient may be changed by various methods other than the above examples, such as forming the taper surface 3c (3d) by changing the surface roughness in order to change the friction coefficient.

  In the configuration example described above, the friction coefficient on the inner peripheral side is formed smaller than the friction coefficient on the outer peripheral side, so that the transmission belt 4 easily moves from the inner peripheral side to the outer peripheral side. For this reason, even when the vehicle is traveling at a high speed and the transmission gear ratio is on the speed increasing side, that is, when the transmission belt 4 is sandwiched on the inner peripheral side of the driven pulley 3, the transmission belt 4 Can move to the outer peripheral side of the driven pulley 3.

  On the other hand, if the clamping pressure of the driven pulley 3 is set in accordance with the speed increasing gear ratio, the clamping pressure becomes excessive when the gear ratio is on the deceleration side, resulting in a decrease in fuel consumption or the transmission belt 4 and the pulleys 2 and 3. On the contrary, if the clamping pressure is set in accordance with the gear ratio on the deceleration side, the clamping pressure may be insufficient when the gear ratio is on the acceleration side. The present invention is configured to obtain a clamping pressure corresponding to a gear ratio by controlling a thrust applied to the movable sheave 3d of the driven pulley 3. An example of controlling the thrust will be described with reference to the flowchart shown in FIG.

  First, the vehicle speed is taken from the vehicle speed sensor that detects the rotation speed of the wheels and the output shaft, the engine rotation speed is taken from the engine speed sensor that detects the engine rotation speed, and the engine state based on the accelerator opening and the engine rotation speed is used. The calculated estimated engine torque is taken in (step S1). Next, the speed ratio γ is calculated based on the rotational speed N1 of the input shaft 5 calculated based on the engine rotational speed and the rotational speed N2 of the output shaft 6 calculated based on the vehicle speed (step S2). This step S2 is a value obtained by dividing the rotational speed N1 of the input shaft 5 by the rotational speed N2 of the output shaft 6.

  Then, it is determined whether or not the speed ratio γ calculated in step S2 is larger than the switching speed ratio γc (step S3). Note that the switching speed ratio γc represents a speed ratio at which the radius at which the transmission belt 4 is wound around the driven pulley 3 is the boundary position of the friction coefficient. Therefore, if the determination in step S3 is affirmative, since the transmission belt 4 is wound around the driven pulley 3 on the deceleration side from the boundary position of the friction coefficient, the friction of the taper surfaces 3c and 3d of the contact portion. The coefficient is a large friction coefficient. Therefore, the friction coefficient μcal for calculating the thrust is defined as μ1 (step S4). On the other hand, if a negative determination is made in step S3, since the transmission belt is wound around the pulley on the speed increasing side from the boundary position of the friction coefficient, the friction coefficient of the tapered surface of the contact portion is small. Coefficient of friction. Therefore, the friction coefficient μcal for calculating the thrust is defined as μ2 (step S5).

Based on the friction coefficient μcal defined in steps S4 and S5, the target thrust Wsec of the driven pulley 3 is calculated (step S6). The thrust can be calculated based on the following formula.
Wsec = (SF * Tin * cos θ) / (2 * μcal * Rin)
SF is a safety factor, Tin is an input torque, θ is an inclination angle of the pulley, and Rin is a belt winding radius on the driving pulley 2.

  As described above, the gear ratio at the time of traveling is calculated, the friction coefficient based on the gear ratio is defined, and the thrust is calculated, thereby suppressing the shortage of thrust when the gear ratio is on the acceleration side or On the contrary, when the gear ratio is on the deceleration side, it is possible to suppress or prevent excessive thrust, so that fuel consumption is reduced and durability of the transmission belt 4 and the pulleys 2 and 3 is reduced. It is possible to suppress or prevent the property from decreasing.

  Further, in the above control example, the case where the vehicle travels at a constant speed and the gear ratio does not change is taken as an example. However, particularly when the gear ratio changes from the deceleration side to the acceleration side, the acceleration side Therefore, the control device for the belt-type continuously variable transmission 1 according to the present invention has a switching gear ratio γc in the determination in step S3 in the above control example. Is replaced with a gear ratio γc ′ offset to the deceleration side in consideration of the thrust response delay.

  By offsetting the switching speed ratio γc to the deceleration side in this way, even if the target speed ratio is the speed increasing side, the friction for calculating the thrust before the transmission belt 4 moves to the speed increasing side. Since the coefficient μcal is defined as the friction coefficient μ2 on the acceleration side, it is possible to suppress or prevent a shortage of thrust when the transmission belt 4 moves to the acceleration side.

  In the configuration example described above, the friction coefficient on the inner peripheral side of the driven pulley 4 is configured to be lower than the friction coefficient on the outer peripheral side. However, the friction coefficient on the inner peripheral side is larger than the friction coefficient on the outer peripheral side. It may be configured as follows. In that case, the friction coefficient may be defined as μ2 in step S4 in the above-described control example, and the friction coefficient may be defined as μ1 in step S5. The belt-type continuously variable transmission 1 that can be the subject of the present invention is one in which the transmission belt 4 and the tapered surfaces 3c, 3d are in contact with each other to transmit power, and the inner surface of the tapered surfaces 3c, 3d The transmission belt 4 may be made of metal as long as the friction coefficient is different between the circumferential side and the outer circumferential side. Further, the thrust applied to the driven pulley 3 may be one utilizing a transmission motor, other than one utilizing hydraulic pressure, or one utilizing another mechanism or means.

  DESCRIPTION OF SYMBOLS 1 ... Belt type continuously variable transmission, 2 ... Drive pulley, 3 ... Driven pulley, 2a, 3a ... Fixed sheave, 2b, 3b ... Movable sheave, 2c, 2d, 3c, 3d ... Tapered surface, 4 ... Transmission belt, 5 , 6 ... Rotating shaft.

Claims (2)

Each of the driving pulley and the driven pulley is constituted by a fixed sheave integrated with the rotating shaft and a movable sheave movable in the axial direction of the rotating shaft so as to approach and separate from the fixed sheave. The facing surfaces of the sheaves are tapered surfaces that form a belt winding groove around which the transmission belt is wound, and the transmission sheave is changed by moving the movable sheave in the axial direction of the rotating shaft to change the groove width. In a control device for a belt-type continuously variable transmission that continuously changes a gear ratio by changing a belt winding radius,
Each tapered surface of the driven pulley is formed such that the coefficient of friction of the outer part and the coefficient of friction of the inner part are different in their radial direction,
Position determining means for determining whether a position where the tapered surface of the driven pulley is in contact with the transmission belt is an inner part side or an outer part side from a boundary position between the inner part and the outer part;
And a means for calculating a thrust for causing the load in the axial direction of the rotating shaft of the driven pulley to act on the movable sheave based on the friction coefficient at the position determined by the position determining means. Control device for belt type continuously variable transmission.   Means for increasing the thrust based on the friction coefficient on the side where the friction coefficient is larger and the friction coefficient is smaller than the boundary position when the transmission belt moves from the friction coefficient side to the smaller friction coefficient side The control device for a belt-type continuously variable transmission according to claim 1, further comprising:

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