JP2010053939A - Belt-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt-type continuously variable transmission which improves fuel efficiency by securing two power transmission paths without a complex structure. <P>SOLUTION: The belt-type continuously variable transmission includes a direct connection clutch which locks a direct connection gear constantly engaging with a power source to a rotation element on the driving wheel side of a fastening element by sliding a pulley of the belt-type continuously variable transmission to the high gear ratio side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt-type continuously variable transmission that changes a groove width of a pulley and changes a gear ratio steplessly.

Conventionally, it is known that a belt-type continuously variable transmission has a smaller belt winding diameter with respect to a secondary pulley on the high gear ratio side, and power loss associated with belt deformation increases. In order to cope with this problem, on the high gear ratio side, a technique for transmitting power by meshing gears without using a belt is known. In the technique described in Patent Document 1, in addition to the configuration of a normal belt-type continuously variable transmission, the CV clutch for transmitting power shifted by the belt-type continuously variable transmission and the gear meshed with each other are shifted. A gear clutch for transmitting power is provided, and two power transmission paths are secured.
JP-A-4-285354

  However, in the technique described in Patent Document 1, there are four fastening elements including a CV clutch, a gear clutch, and two fastening elements (forward clutch and reverse brake) provided in the forward / reverse switching mechanism, There has been a problem that a hydraulic circuit for fastening each fastening element is complicated. Moreover, since there are many fastening elements, there is a problem that the number of components increases, leading to an increase in cost and weight.

  The present invention has been made paying attention to the above problems, and an object thereof is to provide a belt-type continuously variable transmission that can improve fuel efficiency by securing two power transmission paths without complicating the configuration. To do.

  In order to achieve the above object, according to the present invention, the driving force of the direct-coupled gear that is always meshed with the power source is caused to slide closer to the driving wheel side than the fastening element and the belt by sliding the pulley of the belt type continuously variable transmission mechanism toward the high gear ratio side. A direct clutch is provided to transmit to the rotating element.

  By using the slide of the pulley as the fastening force of the direct coupling clutch, it is not necessary to add a device for generating the fastening force, and no additional hydraulic circuit is required. In addition, it is possible to switch the power transmission path by adding only a direct clutch as a fastening element and releasing the fastening element of the forward / reverse switching mechanism, avoiding complication of the hydraulic circuit, and increasing the cost due to the increase in component configuration It is possible to change to a fixed gear ratio while suppressing an increase in weight.

  Hereinafter, the best mode for realizing the belt type continuously variable transmission of the present invention will be described based on an embodiment shown in the drawings.

  FIG. 1 is a skeleton diagram showing the overall configuration of the first embodiment, FIG. 2 is a cross-sectional view showing the overall configuration of the first embodiment, and FIG. 3 is a schematic diagram showing the arrangement relationship of the rotating elements. The driving force output from the engine ENG (power source) is output via the engine crankshaft 12. A converter housing 5 of the torque converter 9 is connected to the engine crankshaft 12. The converter housing 5 includes a drive plate 11 that closes the engine ENG side of the converter housing 5 and a pump impeller 9 that closes the transmission side.

  The converter housing 5 includes a stator 14 fixed to the casing 8 housing the transmission via a one-way clutch, and a turbine runner 13. The turbine runner 13 is connected to the driven plate 18 via a damper 18a. The driven plate 18 is connected to the transmission input shaft IN.

  The driven plate 18 is provided with a lock-up piston 17 that is spline-fitted so as to be slidable in the axial direction. A friction lining 15 is provided between the lock-up piston 17 and the drive plate 11 to constitute a lock-up clutch 16 that is fastened to the drive plate 11 by an axial stroke of the lock-up piston 17.

  The rotation output from the transmission input shaft IN is input to the forward / reverse switching mechanism 26. The forward / reverse switching mechanism 26 includes a planetary gear 30, a forward clutch 1 (engagement element), and a reverse brake 2. The planetary gear 30 includes a sun gear 29 that is fixed to the main shaft 3, a ring gear 28 that is fixed to the transmission input shaft IN, and a pinion carrier 27 that supports the pinion that meshes with each of the sun gear 29 and the ring gear 28. Have.

  The forward clutch 1 selectively engages between the ring gear 28 and the sun gear 29. The reverse brake 2 selectively locks the pinion carrier 27 with respect to the casing 8. During forward travel, the reverse brake 2 is released and the forward clutch 1 is engaged to rotate the planetary gear 30 integrally and transmit the rotation from the engine ENG to the main shaft 3 as it is. At the time of reverse, the forward clutch 1 is released and the reverse brake 2 is engaged, so that the rotation of the sun gear 29 is opposite to the rotation of the ring gear 28 and the rotation from the engine ENG is reversed and transmitted to the main shaft 3.

  A high drive gear 33 is connected to the transmission input shaft IN. The high drive gear 33 is disposed between the torque converter 9 and the forward / reverse switching mechanism 26 and is rotatably supported on the outer circumference of the stator shaft 8a attached to the casing 8.

  A primary pulley 19 is provided on the main shaft 3. The primary pulley 19 includes a fixed sheave 20 that is integral with the main shaft 3, and a movable sheave 21 that slides in the axial direction at a position facing the fixed sheave 20. The movable sheave 21 is integrally formed with a drive pulley cylinder 21a and is in sliding contact with a drive pulley piston 31 fixed to the main shaft 3 to form a cylinder chamber 31a. Then, the groove width is changed by sliding the movable sheave 21 in the axial direction by the hydraulic pressure supplied to the cylinder chamber 31a.

  The countershaft 4 is provided with a secondary pulley 23. The secondary pulley 23 includes a fixed sheave 24 that is integral with the countershaft 4, and a movable sheave 25 that slides in the axial direction at a position facing the fixed sheave 24. A driven pulley cylinder 25a is formed integrally with the movable sheave 25, and forms a cylinder chamber 32a by sliding contact with a driven pulley piston 32 fixed to the countershaft 4. Then, the groove width is changed by sliding the movable sheave 25 in the axial direction by the hydraulic pressure supplied to the cylinder chamber 32a.

  FIG. 4 is an enlarged sectional view of the vicinity of the countershaft 4, and FIG. 5 is an enlarged sectional view of the direct coupling clutch 36. On the counter shaft 4, a high driven gear 35 (directly connected gear) that is always meshed with the high drive gear 33 and the high idler gear 34 is provided on the engine ENG side of the secondary pulley 23. By changing the rotation direction of the high drive gear 33 by the high idler gear 34, the rotation direction is made to coincide with the rotation direction transmitted through the pulley and the belt.

  Between the counter shaft 4 and the high driven gear 35, needle bearings 35 a are arranged in two rows in the axial direction, and the high driven gear 35 can rotate relative to the counter shaft 4. Lubricating oil is supplied to the needle bearing 35a from the shaft core oil passage. Thereby, lubricating oil can always be supplied to the location which rotates relatively, and durability and silence are ensured.

  A clutch hub 36a of the direct coupling clutch 36 is fixed to the side surface of the high driven gear 35 by welding. A spline 36a0 is formed on the clutch hub 36a, and a plurality of driven plates 36a1 are attached to the spline 36a0 so as to be movable in the axial direction. A contact surface 36a2 is formed at the end of the spline 36a0.

  A piston surface 25a1 is formed at the end of the driven pulley cylinder 25a of the movable sheave 25, and a direct clutch cylinder 36b is spline-fitted and fixed in the axial direction by a snap ring 36c. A spline 36b0 is formed on the inner periphery of the direct coupling clutch cylindrical portion 36b, and a plurality of drive plates 36b1 are attached to the spline 36b0 so as to be movable in the axial direction. The drive plate 36b1 and the driven plate 36a1 are arranged so as to alternately overlap in the axial direction. Also, a disc spring 36b2 is attached to the end of the direct coupling clutch cylindrical portion 36b, and axial movement is restricted by the snap ring 36b3.

  An output gear 37 is fixed on the counter shaft 4. Further, an idler gear 39 that always meshes with the output gear 37 is fixed to the idler shaft 50, and the rotation of the idler gear 39 rotationally drives the reduction gear 40 fixed to the idler shaft 50. A differential mechanism 41 is always engaged with the reduction gear 40, and rotation is transmitted to the left and right drive wheels.

  The relationship between the rotating elements described above is based on FIG. 3 which is a front view seen from the engine side, and only the configuration of the high idler gear 34 is added to the shaft arrangement relationship of the conventional belt type continuously variable transmission. Since the other configuration is basically arranged on the existing shaft, the configuration does not increase in the radial direction. Even in the axial direction, only the thickness of the high drive gear 33 is added.

  The direct coupling clutch 36 is disposed on the counter shaft 4 side, and is disposed so as to overlap the forward / reverse switching mechanism 26 provided on the main shaft 3 in the radial direction at the axial position. Since this space is an area where a space is originally provided as an operating range of the movable sheave 25 of the secondary pulley 23, it is not necessary to form a new space. Therefore, there is no increase in the axial direction.

  Further, the operation of the direct coupling clutch 36 is performed by the operation of the movable sheave 25. In other words, the direct coupling clutch 36 can be controlled by the hydraulic pressure supplied to the cylinder chamber 32a that controls the operation of the existing movable sheave 25, and there is no need to construct a new hydraulic circuit or the like, and a new electromagnetic valve or This is advantageous in that it is not necessary to provide an oil passage.

(Direct clutch engagement)
Next, the fastening operation of the direct coupling clutch 36 will be described. 5A is a partial cross-sectional view when the groove width of the secondary pulley 23 is narrow and the gear ratio is low, and FIG. 5B is a partial cross-sectional view when the groove width of the secondary pulley 23 is wide and the gear ratio is high.

  At the low gear ratio, the position of the secondary pulley 23 is in the left direction as shown in FIG. At this time, the piston surface 25a1 and the contact surface 36a2 are greatly separated and the direct coupling clutch 36 is in a released state, so that relative rotation between the clutch hub 36a and the secondary pulley 23 is allowed. That is, the high driven gear 35 rotates at a fixed gear ratio with respect to the rotational speed of the transmission input shaft IN, whereas the secondary pulley 23 corresponds to the pulley ratio with respect to the rotational speed of the transmission input shaft IN. This is because the rotational speeds of the two are different.

  On the other hand, at the high gear ratio, the position of the secondary pulley 23 is in the right direction as shown in FIG. At this time, the piston surface 25a1 and the contact surface 36a2 approach each other, and the disc spring 36b2 is completely crushed to engage the direct coupling clutch 36. A fastening capacity corresponding to the elastic force of the disc spring 36b2 is generated until the disc spring 36b2 is crushed.

  Here, in the belt-type continuously variable transmission of the first embodiment, the fixed gear ratio achieved by the high drive gear 33, the high idler gear 34, and the high driven gear 35 is achieved by the primary pulley 19 and the secondary pulley 23. The gear ratio is higher than the transmission gear ratio (hereinafter referred to as the maximum gear ratio). Thereby, ratio coverage can be taken largely. The ratio coverage (gear ratio width) is the minimum reduction ratio / maximum reduction ratio, and in other words, expressed as the maximum transmission ratio / minimum transmission ratio. Large ratio coverage means that the range in which the gear can be changed can be widened, and fuel consumption can be improved.

(About control configuration)
Next, a control configuration of the belt type continuously variable transmission using the above hardware configuration will be described. FIG. 6 is a system diagram showing a control configuration of the belt type continuously variable transmission mechanism according to the first embodiment.

  The CVT controller 200 includes an APO sensor 101 that detects the accelerator pedal opening, a vehicle speed sensor 102 that detects the vehicle speed, a shift sensor 103 that detects the position of the shift lever, and a primary sensor that detects the rotational speed of the main shaft 3. The sensor signal from 104 is input.

  The CVT controller 200 includes a target gear ratio calculation unit 201 that sets a target gear ratio based on the accelerator pedal opening and the vehicle speed, and an actual gear ratio calculation unit 202 that calculates an actual gear ratio based on the primary rotation speed and the vehicle speed. A traveling direction control unit 203 that outputs an engagement command to the forward clutch 1 and the reverse brake 2 based on the position of the shift lever, a switching control unit 204 that controls the engagement state of the forward clutch 1 based on the actual gear ratio, A shift control unit 205 that outputs a drive command to the step motor in order to change the relationship between the primary pulley groove width and the position of the shift control valve according to the target gear ratio. Further, the CVT controller 200 outputs a command for controlling the engaged state of the lockup clutch 16 according to the traveling state.

  In addition, since the point which sets a target gear ratio based on an accelerator pedal opening degree and a vehicle speed, and the point which controls a gear ratio by the control command to a step motor are well-known techniques, detailed description is abbreviate | omitted. Instead of a step motor, a type that independently controls the pressure in each pulley cylinder chamber or a double piston type may be used, and there is no particular limitation.

  FIG. 7 is a flowchart showing the control contents in the switching control unit 204 of the first embodiment. This control is executed when the position of the shift lever is the D range position and the forward clutch 1 is in the engaged state (hereinafter referred to as the on state). In the following description, a path for transmitting a driving force with a gear ratio achieved by the primary pulley 19 and the secondary pulley 23 is referred to as power transmission by a belt-type continuously variable transmission mechanism. Similarly, a path through which a driving force is transmitted by a fixed gear ratio achieved by the high drive gear 33, the high idler gear 34, and the high driven gear 35 is described as power transmission by the high gear.

  In step S1, it is determined whether or not the actual speed ratio is greater than or equal to a predetermined speed ratio. If the actual speed ratio is greater than or equal to the predetermined speed ratio, the process proceeds to step S2. Here, the predetermined gear ratio is a gear ratio slightly smaller than the maximum gear ratio achieved by the pulley of the belt type continuously variable transmission mechanism, and is a value corresponding to the groove width at which the disc spring 36b2 of the direct coupling clutch 36 starts to collapse. is there.

  In step S2, slip control for reducing the engagement capacity of the forward clutch 1 by a predetermined amount is started. The slip control is for avoiding an interlock due to the engagement of the direct clutch 36. Note that the current input torque to the forward clutch 1 may be estimated, and the engagement capacity may be several percent lower than the input torque.

  In step S3, it is determined whether or not the primary rotational speed change rate has changed from negative to positive. If it is determined that it has changed, the process proceeds to step S4. Otherwise, the process returns to step S2 to continue the slip control. .

  When the forward clutch 1 is slip-controlled, the torque transmitted to the main shaft 3 is reduced, so the rotational speed of the primary pulley 19 begins to decrease once, and this appears as a primary rotational speed change rate = negative. In this slip control state, when the groove width of the secondary pulley 23 increases and the fastening of the direct coupling clutch 36 is started, power transmission is started between the countershaft 4 and the high driven gear 35 (power transmission by the high gear). That is, the engine driving force starts to be transmitted to the countershaft 4 from the constant meshing mechanism of the high drive gear 33 → the high idler gear 34 → the high driven gear 35, not the belt type continuously variable transmission mechanism.

  The gear ratio by high gear (drive, idler, driven) is higher than the maximum gear ratio achieved by the belt type continuously variable transmission mechanism. Therefore, when the power transmission to the countershaft 4 is via the direct coupling clutch 36, the rotation of the countershaft 4 driven via the high gear is transmitted from the secondary pulley 23 via the belt to the primary pulley 19 to increase the primary rotational speed. Therefore, the primary rotational speed change rate changes from negative to positive. This timing is detected based on the primary rotational speed.

  In step S4, it is determined that the power transmission path via the direct clutch 36 has been secured, and the forward clutch is turned off (completely released). In the steps so far, switching from power transmission via the belt type continuously variable transmission mechanism to power transmission via the high gear is performed.

  In step S5, it is determined whether or not the target speed ratio is less than the maximum speed ratio. If the target speed ratio is less than the maximum speed ratio, it is determined that switching from the high gear to the belt type continuously variable transmission mechanism is performed, and the process proceeds to step S6. When the ratio is greater than or equal to the ratio, power transmission is continued with a fixed gear ratio by the high gear.

  In step S6, a predetermined engagement capacity is given to the fully released forward clutch 1, and slip control is started.

  In step S7, it is determined whether or not the actual gear ratio is less than the predetermined gear ratio. The slip control of the forward clutch 1 is maintained until the predetermined gear ratio is reached, and when the gear ratio is less than the predetermined gear ratio, the process proceeds to step S8. To turn on the forward clutch 1 (completely engaged). Here, the predetermined gear ratio corresponds to a gear ratio at which the disc spring 36b2 of the direct coupling clutch 36 shifts from a completely crushed state to a state in which an elastic force is exerted. This achieves a smooth shift while avoiding the interlock.

(Operation by switching control)
Next, the operation based on the flowchart will be described. FIG. 8 is a time chart showing the relationship between the rotating elements when switching from power transmission by the belt type continuously variable transmission mechanism to power transmission by the high gear. As a precondition, it is assumed that the forward clutch 1 is completely engaged and an upshift is gradually performed by the belt-type continuously variable transmission mechanism.

  At time t1, the gear ratio by the belt-type continuously variable transmission mechanism exceeds 1, and overdrive occurs. Thereafter, when the predetermined speed ratio is reached at time t2, the slip control of the forward clutch 1 is started. Then, the primary rotational speed starts to decrease once. At this time, since the engagement of the direct coupling clutch 36 is also gradually started, the secondary rotational speed that is the rotational speed of the secondary pulley 23 is transmitted by the high gear, and the rotational speed does not decrease so much.

  At time t3, when the engagement capacity of the direct coupling clutch 36 increases, the fixed gear ratio by the high gear is higher than the maximum gear ratio of the belt-type continuously variable transmission mechanism, so that the driving force input from the engine is high gear. To the primary pulley 19 via the secondary pulley 23 and the belt to increase the primary rotational speed.

  With the increase in the primary rotational speed as a trigger, the forward clutch 1 is completely released from the slip control, and the power transmission by the belt-type continuously variable transmission mechanism is switched to the power transmission by the fixed shift by the high gear.

As described above, the effects listed below can be obtained in the first embodiment.
(1) An engine ENG (power source), a belt-type continuously variable transmission mechanism having a pair of pulleys that slide in the axial direction to change the groove width, and a belt that is stretched over both pulleys, an engine ENG, and a drive wheel , A forward / reverse switching mechanism 26 that switches the rotational direction by engaging and releasing the forward clutch 1 and the reverse brake 2, a high driven gear 35 (directly connected gear) that is always meshed with the engine ENG, and a pulley toward the high gear ratio side. A direct coupling clutch 36 that is fastened by sliding and that transmits the driving force of the high driven gear 35 to the forward clutch 1 and the countershaft 4 that is a rotating element closer to the driving wheel than the belt is provided.

  By using the slide of the pulley as the fastening force of the direct coupling clutch 36, it is not necessary to add a device for generating the fastening force, and it is not necessary to add a hydraulic circuit. Further, only the direct coupling clutch 36 is added as a fastening element, and the power transmission path can be switched by releasing the forward clutch 1, thereby avoiding complication of the hydraulic circuit, increasing the cost and weight associated with the increase in the component configuration. It is possible to change to a fixed gear ratio while suppressing the above.

  (2) an actual speed ratio calculating unit 202 (speed ratio detecting means) for calculating an actual speed ratio, a primary sensor 104 (rotation speed detecting means) for detecting a primary speed that is the output side speed of the forward clutch 1; When a predetermined gear ratio set on the lower gear ratio side than the gear ratio when the direct coupling clutch 36 is completely engaged is detected, the engagement capacity of the forward clutch 1 is reduced to perform slip control, and the primary rotational speed is directly coupled. And a switching control unit 204 (switching control means) for completely releasing the forward clutch 1 when it varies due to engagement of the clutch 36.

  That is, since whether or not the direct coupling clutch 36 has a certain amount of engagement capacity is determined based on the primary rotational speed, it is possible to execute a smooth switching of power transmission while avoiding the interlock.

  (3) The transmission ratio by the direct connection gear 35 is higher than the maximum transmission ratio of the belt type continuously variable transmission mechanism. Accordingly, the trigger for the number of revolutions in the power transmission switching control can be determined by a clear signal that the rotation is increased, and the accuracy of the switching control can be improved. Further, since the ratio coverage is increased, the fuel consumption performance during high-speed driving can be improved.

  (4) The high driven gear 35 and the direct coupling clutch 36 are arranged coaxially with the secondary pulley 23 and are fastened by sliding the movable sheave 25 of the secondary pulley 23.

  Since this space is an area where a space is originally provided as an operating range of the movable sheave 25 of the secondary pulley 23, it is not necessary to form a new space. Therefore, there is no increase in the axial direction. Further, the operation of the direct coupling clutch 36 is performed by the operation of the movable sheave 25. In other words, the direct coupling clutch 36 can be controlled by the hydraulic pressure supplied to the cylinder chamber 32a that controls the operation of the existing movable sheave 25, and there is no need to construct a new hydraulic circuit or the like, and a new electromagnetic valve or This is advantageous in that it is not necessary to provide an oil passage.

  Although the first embodiment has been described above, the present invention is not limited to the above-described configuration, and the effects of the present invention may be achieved by other configurations. For example, although the direct coupling clutch 36 is provided coaxially with the counter shaft 4, it may be provided coaxially with the main shaft 3.

  Moreover, although the structure which fastens the direct coupling clutch 36 by the slide of the secondary pulley 23 was shown, you may fasten by the slide of the primary pulley 19. FIG.

  The direct coupling clutch 36 locks the high driven gear 35 and the counter shaft 4. However, the high drive gear 33 is allowed to rotate relative to the engine ENG, and the high drive gear 33 is engaged with the engine ENG. It is good also as a structure which switches a power transmission path | route by stopping.

1 is a skeleton diagram illustrating an overall configuration of Embodiment 1. FIG. 1 is a cross-sectional view illustrating an overall configuration of Example 1. FIG. FIG. 3 is a schematic diagram illustrating an arrangement relationship of rotating elements according to the first embodiment. FIG. 3 is an enlarged cross-sectional view in the vicinity of a countershaft according to the first embodiment. It is an expanded sectional view of the direct coupling clutch of Example 1. FIG. 3 is a system diagram illustrating a control configuration in the belt-type continuously variable transmission mechanism according to the first embodiment. 3 is a flowchart illustrating control contents in a switching control unit according to the first embodiment. 3 is a time chart showing the relationship of each rotary element when switching from power transmission by the belt type continuously variable transmission mechanism of Example 1 to power transmission by a high gear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forward clutch 2 Reverse brake 3 Main shaft 4 Counter shaft 19 Primary pulley 23 Secondary pulley 25 Movable sheave 26 Forward / reverse switching mechanism 33 High drive gear 34 High idler gear 35 High driven gear 36 Direct coupling clutch 39 Idler gear 40 Reduction gear
104 Primary sensor
ENG engine
IN Transmission input shaft

Claims (4)

Power source,
A belt-type continuously variable transmission mechanism having a pair of pulleys that slide in the axial direction to change the groove width and a belt that spans the pulleys;
A forward / reverse switching mechanism that is disposed between the power source and the driving wheel and switches a rotation direction by fastening / release of a fastening element;
A direct gear that always meshes with the power source,
A direct coupling clutch that is fastened by sliding the pulley toward the high gear ratio side, and that transmits the driving force of the direct coupling gear to the fastening element and the rotating element closer to the driving wheel than the belt;
A belt type continuously variable transmission. The belt-type continuously variable transmission according to claim 1,
Gear ratio detecting means for detecting the gear ratio;
A rotational speed detection means for detecting an output side rotational speed of the fastening element;
When a predetermined gear ratio set on the lower gear ratio side than the gear ratio when the direct coupling clutch is completely engaged is detected, slip control is performed by reducing the engagement capacity of the engagement element, and the output of the engagement element When the side rotation speed fluctuates due to the engagement of the direct coupling clutch, switching control means for completely releasing the engagement element;
A belt type continuously variable transmission. The belt type continuously variable transmission according to claim 1 or 2,
The belt type continuously variable transmission according to claim 1, wherein a gear ratio by the directly connected gear is higher than a maximum gear ratio of the belt type continuously variable transmission mechanism. The belt-type continuously variable transmission according to any one of claims 1 to 3,
The pair of pulleys are a primary pulley on the driving side and a secondary pulley on the driven side,
The direct-coupled gear and the direct-coupled clutch are arranged coaxially with the secondary pulley and are fastened by sliding of the secondary pulley.

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