JP2010181017A - Belt-type continuously variable transmission - Google Patents

Abstract

A belt type continuously variable transmission including a pulley capable of suppressing the falling of a movable sheave.
A belt 5 is sandwiched between a fixed sheave 3 and a movable sheave 4 arranged to move back and forth with respect to the fixed sheave 3, and the belt with respect to a pulley 1 composed of the fixed sheave 3 and the movable sheave 4 is provided. In the belt type continuously variable transmission that changes speed by changing the winding radius of 5, a pressing mechanism 20 that presses the movable sheave 4 toward the fixed sheave 3 is provided on the back side of the movable sheave 4. An overhanging portion 12 for transmitting the pressing force of the pressing mechanism 20 to the movable sheave 4 is projected in the axial direction at a portion on the outer peripheral side of the back surface of the movable sheave 4. This is because a non-pressing region 13 that does not receive a pressing force toward the fixed sheave 3 is provided in a portion on the inner peripheral side from the overhanging portion 12.
[Selection] Figure 1

Description

  The present invention relates to a belt-type continuously variable transmission that transmits power via a belt wound around a pulley.

  This belt-type continuously variable transmission includes an input shaft that is connected in parallel to the power side and connected to the power side, an output shaft that is connected to the drive wheel side so that transmission is possible, and an input shaft and an output shaft. And provided pulleys. A belt composed of a large number of elements and a plurality of rings is wound around the pulley, and power is transmitted by the frictional force of the contact surface. The pulley is provided with a fixed sheave and a movable sheave, and the distance between the V-shaped pulley grooves formed in the pulley is changed by the back-and-forth movement of the piston mechanism provided on the back side of the movable sheave. For this reason, the wrapping radius of the belt wound between the pulley grooves changes, and the ratio between the input rotation speed and the output rotation speed, that is, the gear ratio can be changed. In order to change the gear ratio, the piston mechanism that moves the movable sheave in the axial direction is controlled by supplying and discharging pressure oil to a hydraulic chamber provided on the back side of the movable pulley. A hydraulic chamber is also provided on the back side of the movable sheave in the other pulley, and the hydraulic pressure corresponding to the torque input to the continuously variable transmission is supplied to the hydraulic chamber, so The pressure, that is, the transmission torque capacity is set.

  An example of such a belt type continuously variable transmission is described in Patent Document 1. The belt type continuously variable transmission described in Patent Document 1 is a movable sheave that may be generated when a pinching pressure is applied to a pulley in order to change the belt winding radius in addition to the above-described configuration and effects. It has a configuration in which a urging means is provided by a fixed sheave constituted by one of a hydraulic actuator and an elastic member for suppressing the collapse and a movable sheave constituted by the other. Further, a misalignment preventing means is provided by the urging means constituted by one of the hydraulic actuator and the elastic member.

  In the belt-type continuously variable transmission described in Patent Document 1, the hydraulic actuator includes a first hydraulic chamber and a second hydraulic chamber, and controls the hydraulic pressures of the two hydraulic chambers. By the action of the elastic member, the sheave is moved in the axial direction to change the gear ratio, and the sheave is prevented from falling or misaligned. Depending on the amount of misalignment caused by the change in the groove width due to the movement of the sheave in the axial direction, the amount of misalignment is corrected by driving the hydraulic actuator, and the tilt due to the clamping pressure of the belt of the movable sheave is suppressed or It is to reduce.

JP 2007-170504 A

  However, in the hydraulic actuator of the belt-type continuously variable transmission described in Patent Document 1, the outer peripheral portion of the movable pulley back surface is also urged, so that the fall can be reduced rather than urging only with the entire back surface of the movable pulley. Since the entire back surface including the inner peripheral portion of the back surface of the movable pulley is also urged, a great effect cannot be expected. In addition, two hydraulic chambers must be provided on the movable sheave side, which increases the number of parts, lowers productivity, and may increase costs.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a belt type continuously variable transmission including a pulley capable of suppressing the falling of the movable sheave.

  In order to achieve the above object, the invention of claim 1 is characterized in that a belt is sandwiched between a fixed sheave and a movable sheave arranged to move back and forth with respect to the fixed sheave. In a belt-type continuously variable transmission that changes speed by changing a winding radius of the belt with respect to the pulley, a pressing mechanism that presses the movable sheave toward the fixed sheave is provided on the back side of the movable sheave. An overhanging portion for transmitting the pressing force of the pressing mechanism to the movable sheave is projected in the axial direction at a portion on the outer peripheral side of the back surface of the movable sheave, and an inner periphery of the back surface of the movable sheave from the overhanging portion. A non-pressing region that is not subjected to a pressing force toward the fixed sheave is provided on the side portion.

  According to the first aspect of the present invention, the pressing force transmitted by the pressing mechanism is performed via the projecting portion protruding from the movable sheave, and the portion not located on the inner peripheral side of the projecting portion is not subjected to the pressing force. By providing the pressing area, a pressing force is relatively applied to the outer peripheral portion of the back surface of the movable sheave. Therefore, the deformation of the lower part of the sheave with the position of contact with the elements constituting the belt as a fulcrum and the so-called falling of the movable sheave associated therewith do not occur. Accordingly, phenomena such as so-called bottom hit contact, which are caused by element sinking or element inclination, can be avoided or suppressed to prevent a decrease in torque capacity and fuel consumption. Further, according to the invention of claim 1, sheave collapse can be suppressed without increasing the size and rigidity of the pulley, and therefore torque capacity and fuel consumption can be improved without increasing cost and weight.

It is a longitudinal cross-sectional view which shows the 1st structural example of the pulley of this invention. It is the schematic showing the sheave fall of the pulley of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an input-side pulley (primary pulley) 1 in a continuously variable transmission according to the present invention. The pulley 1 shown here is a fixed sheave 3 integrated with a rotating shaft (pulley shaft) 2. The movable sheave 4 is fitted to the pulley shaft 2 so as to face this. The facing surfaces of the sheaves 3 and 4 are formed in a tapered shape, and a winding groove 6 around which the belt 5 is wound (sandwiched) is formed by these tapered surfaces. The belt 5 has the same configuration as the conventional one, and is configured by winding a ring (hoop) around a number of elements arranged in an annular shape with the same posture.

  A cylinder member 8 opened to the movable sheave 4 side is disposed on the back side (left side in FIG. 1) of the movable sheave 4, and the boss portion of the movable sheave 4 fitted to the pulley shaft 2. 7 is inserted into the cylinder member 8. A piston member 9 is provided in contact with the outer peripheral surface of the boss portion 7 and the inner peripheral surface of the cylinder member 8 so as to be movable back and forth. A seal ring 10 is disposed on the inner and outer peripheral portions of the piston member 9, and thus a hydraulic chamber 11 is formed inside the cylinder member 8.

  A projecting portion 12 projecting in the axial direction toward the piston member 9 is formed on the outer peripheral portion of the back surface of the movable sheave 4, and the tip of the projecting portion 12 abuts on the piston member 9. It has been made. Therefore, the thrust by the piston member 9 is configured to act on the outer peripheral side portion of the back surface of the movable sheave 4 via the overhanging portion 12. Further, on the back side of the movable sheave 4, a portion between the projecting portion 12 and the boss portion 7 is a release space, and a portion corresponding to the release space on the back surface of the movable sheave 4 is from the piston member 9. The non-pressing area 13 is not subjected to thrust.

  An oil passage 14 is formed along the central axis of the pulley shaft 2, and branch oil passages 15 and 16 branched from the oil passage 14 in the radial direction are formed. One branch oil passage 15 opens in a portion of the outer peripheral surface of the pulley shaft 2 where the boss portion 7 is fitted, and the boss portion 7 is formed with a through hole 17 penetrating in the radial direction. Therefore, the hydraulic oil is supplied to the hydraulic chamber 11 through the branch oil passage 15 and the through hole 17. Further, the outer diameter of the pulley shaft 2 is large at the portion where the movable sheave 4 is fitted, and is relatively small at the portion where the boss portion 7 is fitted. A step portion 18 is formed at a portion where the outer diameter changes. The inner diameters of the movable sheave 4 and its boss 7 also change in size according to the outer diameter of the pulley shaft 2, and as a result, a sealed space 19 is formed in the stepped portion 18. The other branch oil passage 16 is opened in the sealed space 19.

  As described above, the oil passage 14 provided in the pulley shaft 2, the branch oil passages 15 and 16, the sealed space 19 formed in the stepped portion 18, the hydraulic chamber 11 formed in the cylinder member 8, the seal ring 10, A hydraulic actuator 20 is constituted by the piston member 9 and the like. Reference numeral 21 in the figure denotes a ball spline, and the ball spline 21 is configured to smoothly move the movable sheave 4 back and forth in the axial direction. Reference numerals 22 and 23 denote bearings, and the pulley shaft 2 is rotatably supported by these bearings 22 and 23. Although the pulley 1 is a primary pulley, it can also be applied to a secondary pulley by adjusting the shape of the pulley 1 and the like.

  Next, the operation of the pulley 1 will be described with reference to FIG. The pulley 1 is formed with the hydraulic actuator 20 described above, and hydraulic pressure is controlled and supplied by a hydraulic pump and a hydraulic control device (not shown). The supplied hydraulic pressure flows from an oil passage 14 provided in the pulley shaft 2 through a branch oil passage 15 to a hydraulic chamber 11 formed inside the cylinder member 8 from a through hole 17 penetrating in the radial direction of the boss portion 7. Oil is supplied. The pressure generated by the pump of the supplied oil and the pressure generated by the centrifugal force of the oil due to the rotational movement of the hydraulic chamber 11 abut against the protruding portion 12 on the back surface of the movable sheave 4 and are separated from the boss portion 7. Is applied to the pressure receiving surface of the piston member 9.

  The pressure applied to the pressure receiving surface of the piston member 9 is transmitted through the surface where the projecting portion 12 and the piston member 9 are in contact. The movable sheave 4 is moved back and forth by hydraulic pressure in a state where the piston member 9 and the overhanging portion 12 come into contact with each other and are integrated with the movable sheave 4. Oil pressure is also supplied to the branch oil passage 16 provided in the pulley shaft 2, and the oil is supplied to the sealed space 19 of the step portion 18 where the pulley shaft 2 and the movable sheave 4 are fitted via the branch oil passage 16. Supplied. The oil supplied to the sealed space 19 lubricates the portion where the outer diameter of the shaft 2 and the movable sheave 4 are fitted.

  When the movable sheave 4 is moved back and forth, the width of the tapered winding groove 6 formed between the fixed sheave 3 and the movable sheave 4 changes. When the width of the winding groove 6 changes, the winding radius of the sandwiched belt 5 is changed by the narrow pulley pressure and the belt tension. At this time, since the winding radius of the belt 5 can be changed while the pulley 1 is frictionally transmitted, the gear ratio is continuously changed. Then, the movable sheave 4 is moved back and forth by hydraulic pressure, and when a narrow pressure is applied to the belt 5, forces act on the contact surfaces of the movable sheave 4, the elements of the belt 5, and the fixed sheave 3. When a force acts on the contact surface between the movable sheave 4 and the elements of the belt 5 and the fixed sheave 3, so-called sheave collapse may occur.

  FIG. 2 shows a schematic view of the sheaves 3 and 4 falling down. A solid line represents a state in which the sheave is normal, for example, when the pulley is stopped. A dotted line represents a virtual line when a sheave collapse occurs due to a torque increase or the like. When the stress due to hydraulic pressure acts on the fixed sheave 3 and the movable sheave 4, the fixed sheave 3 and the movable sheave 4 are deformed. Due to the deformation of the sheaves 3 and 4, the phenomenon that the element of the belt 5 sinks in the direction of the arrow A (the element sinks) on the inner peripheral side of the winding groove 6, or the element is as indicated by the arrow B in FIG. 2. There is a possibility that a phenomenon of tilting by a moment acting in any direction may occur. Furthermore, a phenomenon that the element of the belt 5 comes into contact with the fixed sheave 3 and the movable sheave 4 on the inner peripheral side of the winding groove 6 (bottom contact) may occur due to the occurrence of the falling phenomenon. There is.

  In general, a configuration in which a force pushing the sheave by hydraulic pressure is also applied to the inner peripheral side of the back surface of the movable sheave 4 is common. In such a configuration, on the outer peripheral side of the winding groove 6 of the belt 5, the forces acting on the fixed sheave 3, the movable sheave 4, and the elements of the belt 5 are the reaction forces of each other and the outer periphery of the winding groove 6 of the belt 5. It is easy to maintain a balance with the pressure acting on the side. However, when pressure is applied to the inner peripheral side of the movable sheave 4, the moment with the contact position of the movable sheave 4 and the element of the belt 5 as a fulcrum acts in a direction that increases the deformation of the movable sheave 4, and the sheave collapses. It becomes easy to cause.

  In the present invention, it is avoided or suppressed that the sheave collapse due to the deformation of the sheaves 3 and 4 is likely to occur due to the thrust acting on the inner peripheral side of the movable sheave 4. Therefore, on the back side of the movable sheave 4, a non-pressing region 13 that does not receive thrust from the piston member 9 is provided in a portion between the protruding portion 12 and the boss portion 7. Therefore, when the projecting portion 12 receives thrust from the piston member 9, the movable sheave 4 does not receive thrust at a position below the contact position with the element of the belt 5, that is, the inner peripheral side of the movable sheave 4, and suppresses sheave collapse. Or it can be avoided. Further, in order to suppress the sheave collapse, there is no increase in the weight and cost of the pulley for reinforcing the sheave structure, and the sheave collapse can be suppressed. Furthermore, since sheave collapse can be suppressed, torque can be transmitted without loss, and fuel consumption can be improved.

  DESCRIPTION OF SYMBOLS 3 ... Fixed sheave, 4 ... Movable sheave, 5 ... Belt, 12 ... Overhang | projection part, 13 ... Non-pressing area | region, 20 ... Hydraulic actuator (pressing mechanism).

Claims (1)

A belt is sandwiched between a fixed sheave and a movable sheave arranged so as to move back and forth with respect to the fixed sheave, and a speed change is achieved by changing a winding radius of the belt with respect to a pulley composed of the fixed sheave and the movable sheave. In the belt type continuously variable transmission to perform,
A pressing mechanism for pressing the movable sheave toward the fixed sheave is provided on the back side of the movable sheave,
An overhanging portion for transmitting the pressing force of the pressing mechanism to the movable sheave is protruded in the axial direction on the outer peripheral side portion of the back surface of the movable sheave,
A belt-type continuously variable transmission in which a non-pressing region that does not receive a pressing force toward the fixed sheave is provided in a portion of the back surface of the movable sheave on the inner peripheral side from the projecting portion.

Images