JP2011122694A - Shaft structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft structure which prevents its own deflection with its structure. <P>SOLUTION: In the shaft structure employed for a power transmission component, the shaft structure comprises a shaft member 10 formed into a hollow shape, and central portion members 11, 14 fitted into the hollow inside portion of the shaft member 10 and made up of a substance with a Young's modulus relatively larger than that of the shaft member 10. Otherwise, in the shaft structure employed for a power transmission component, the shaft structure comprises the shaft member 13 formed into a hollow shape, and the central portion member 14 filled in the hollow inside portion of the shaft member 13 with rigidity changing depending on a change in electromagnetic condition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to general details of a power transmission device, and more particularly to a shaft structure of a power transmission system.

  BACKGROUND ART A power transmission device for a vehicle is provided with power transmission elements such as gears and belts, and these power transmission elements are provided with a rotation shaft that rotates about a central portion as an axis. A rotating shaft provided with such a power transmission element is arranged coaxially or in parallel, that is, with another shaft provided away from one shaft by a certain inter-axis distance. Since the power transmission element receives a radial load from another power transmission element, the rotary shaft having such a power transmission element is subjected to a stress and undergoes bending deformation. Such bending of the power transmission element such as the rotating shaft and the gear affects the performance of the power transmission device. Further, mechanical elements having various functions are used in the power transmission device, and in general, these bending deformations also affect the performance of the power transmission device.

  In Patent Document 1, a gear is provided between a part of gears of a gear transmission and a second fixed wall, which are supported so as to be movable in the axial direction between first and second fixed walls facing each other. 1 A vibration isolating structure for a gear transmission is described, in which a wave washer is provided on the fixed wall side. The vibration isolating structure of the gear transmission is configured such that a cylindrical portion surrounding the wave washer protrudes from one end face of the gear and the second fixed wall, and the cylindrical portion comes into contact with the other end face to thereby provide the wave washer. It is comprised so that the increase beyond the fixed value of the amount of bending of may be controlled. Thereby, the wave washer can always exhibit a normal buffer function.

  Further, in the parallel shaft type conical gear device described in Patent Document 2, a conical small gear is attached to a first rotating shaft, and a second rotating shaft is arranged in parallel to the first rotating shaft. A conical large gear meshing with the conical small gear is attached to the second rotating shaft. The small gear and the large gear have substantially the same cone angle, and are supported by the support means so as to be movable in the axial direction of the first rotating shaft. Thrust is biased by the biasing means in the axial direction of the first rotating shaft. A load support that supports the thrust biased by the biasing means and allows a radial displacement of the first rotation shaft is provided at the shaft end of the first rotation shaft. This facilitates adjustment in the gear device and reduces backlash.

JP 2004-1000085 A1 JP 2006-118623 A

  As described above, the deflection of the power transmission element such as the rotating shaft and the gear affects the performance of the power transmission device. For example, the meshing loss of a helical gear is exacerbated by misalignment of the gear system, that is, a meshing failure. Such a meshing loss also occurs due to the deflection of the rotating shaft of the gear. Therefore, if the bending of the rotating shaft is suppressed, the gear meshing loss is suppressed or reduced.

  In the structure described in Patent Document 1, since it is configured by a support structure such as a washer or a bearing, it is possible to regulate the movement of the rotating shaft portion due to vibration or the like, but the rotating shaft itself due to the separation force between the gears. It is not possible to reduce the deflection of. Moreover, in the apparatus described in Patent Document 2, since the position where the load support is installed is adjusted with respect to the thrust generated in the axial direction of the conical gear, the load applied to the gear is dispersed to the tooth surface. The generated reaction force is suppressed to prevent gear loss. However, the apparatus becomes complicated such as providing a load support and processing the gear box to accommodate it. As described above, there is still room for improvement regarding the suppression of the bending of the shaft provided in the power transmission device in terms of simplifying the shaft structure and improving the energy efficiency.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a shaft structure that suppresses the deflection by the configuration of the shaft.

  In order to achieve the above object, the invention according to claim 1 is a shaft structure used for a power transmission element, wherein the shaft member is formed in a hollow shape, and is fitted into the hollow shape of the shaft member. It is characterized by comprising a central member made of a material having a relatively higher Young's modulus than the member.

  According to a second aspect of the present invention, in a shaft structure used for a power transmission element, a shaft member formed in a hollow shape and the hollow shape of the shaft member are filled, and the rigidity changes according to a change in electromagnetic atmosphere. It is characterized by comprising a central part member.

  A third aspect of the present invention is the shaft structure according to the first aspect, wherein a gear is fixed to the shaft member.

  According to the first aspect of the present invention, in the shaft structure used for the power transmission element, the shaft member is formed in a hollow shape, and is fitted into the hollow shape of the shaft member, and is relatively younger than the shaft member. Since it consists of the center part member comprised with the substance with a big rate, the bending of a shaft member can be suppressed.

  According to the invention of claim 2, in the shaft structure used for the power transmission element, the shaft member formed in a hollow shape, and the hollow shape of the shaft member is filled to respond to a change in the electromagnetic atmosphere. Therefore, the shaft member can be prevented from being bent and the shaft member can be prevented from being broken. Further, since the rigidity changes according to the change in the electromagnetic atmosphere, for example, the rigidity of the shaft member can be changed in accordance with the driving force of the driving force source.

  Further, according to the invention of claim 3, since the gear is fixed to the shaft member, for example, in a configuration in which two gears meshed with each other to be opposed to each other are fixed to the shaft member, When power is transmitted by the shaft, the shaft member can be prevented from being bent with respect to the radial load caused by the gears being meshed with each other, so that the meshing loss between the gears can be suppressed.

It is a schematic diagram showing an example of the shaft structure concerning this invention. It is a schematic diagram showing the other example of the shaft structure which concerns on this invention. It is a control flowchart in the other example of the shaft structure concerning this invention. It is a schematic diagram showing the gear system of the helical gear which can apply the shaft structure of this invention.

  Next, the present invention will be described more specifically. The present invention relates to a structure that suppresses bending of a shaft (shaft, rotating shaft) used as a general mechanical element. In general, in a power transmission path of a vehicle or the like, a rotating element such as a gear, a belt, or a chain is fixed to a shaft. The shaft rotates while being supported by bearings at both ends, and the rotational force causes bending. This bending is also generated by a force acting from a rotating element such as the aforementioned gear provided on the shaft. When a bending moment acts on the shaft due to the bending caused by such factors, even if the bending stress generated on the shaft is less than the allowable stress value of the shaft material, if the bending becomes larger than a certain level, a bearing per piece will occur. The gear meshing performance is deteriorated, and the machine performance is lowered. Also, since the shaft is a kind of spring against bending and torsion, if the natural frequency of such a shaft matches the bending moment acting on the shaft or the fluctuation cycle of the torque, the shaft will resonate, etc. There is also.

  Thus, the deflection affecting the shaft can be reduced by increasing the Young's modulus E and the moment of inertia of the cross section. The present invention relates to a shaft structure of the shaft in which such shaft bending is suppressed, and the shaft structure of the shaft will be described below with reference to the drawings. FIG. 4 shows a gear system 1 to which the shaft structure of the present invention can be applied. The gear system 1 includes a gear 4 and a gear 5 as elements that transmit rotational motion from the shaft 2 to a shaft 3 that is separated from the shaft 2 by a certain inter-axis distance. Both ends of the shaft 2 defined by the length L are rotatably supported by the bearings 6 and 7, respectively. Since the bearings 6 and 7 are helical gears of the gear 4 described below, angular contact ball bearings or tapered roller bearings that can receive a radial load and a thrust load are used. Further, the gear 4 is provided in an intermediate portion supported by the bearings 6 and 7, that is, in the vicinity of the central portion in the axial direction. Specifically, the gear 4 has a key groove on the boss hole surface that is cut away from the position where the shaft 2 is supported by the bearing 6 in the axial direction by a distance of length a, and a key (not shown). It is being fixed to the shaft 2 by.

  On the other hand, the shaft 3 is rotatably supported by bearings 8 and 9 at both ends defined by the length L. The bearings 8 and 9 are helical contact gears that can receive a radial load and a thrust load because the gear 5 described below is a helical gear. Further, the gear 5 is provided in an intermediate portion supported by the bearings 8 and 9, that is, in the vicinity of the central portion in the axial direction. Specifically, the gear 5 has a key groove (not shown) in which a key groove is cut in a boss hole surface at a position a distance a in the axial direction from the position where the shaft 2 is supported by the bearing 8. It is being fixed to the shaft 3 by. The gears 4 and 5 of the gear system 1 configured as described above are helical gears. The gears 4 and 5 of the gear system 1 according to the present invention may be other spur gears or helical gears. The gears 4 and 5 are engaged with each other with their gear surfaces facing each other.

  In the configuration of the gear system 1 described above, the present invention increases the rigidity by changing the structure of the shafts 2 and 3 in consideration of this point in order to suppress the bending of the shafts 2 and 3. Hereinafter, the shaft structure of the shafts 2 and 3 to which the gears 4 and 5 are respectively attached will be described. Since the shafts 2 and 3 may have the same structure, the shaft 2 will be described as an example. FIG. 1 shows an example (cross-sectional view) of the shaft structure of the shaft 2 of the present invention. The shaft 2 includes a hollow shaft-shaped shaft member 10 and a solid shaft-shaped central member (center member) 11. The shaft member 10 and the center member 11 are configured such that the center member 11 has a relatively higher Young's modulus than the shaft member 10. In other words, the central member 11 is configured by a member having a higher degree of resistance to deformation than the shaft member 10. Such a central member 11 is inserted into the shaft member 10 to form a double structure. The central member 11 is made of a material having a large Young's modulus (for example, metal) by a manufacturing method such as shrink fitting to increase the Young's modulus. The shaft member 10 and the center member 11 configured as described above are configured such that, for example, the shaft member 10 is SCr20 (Young's modulus E = 200 GPa) and the center member 11 is cemented carbide (E = 440 to 550 Pa). Also good. Further, the central member 11 may be a member that is hardened only by hardening a metal surface, such as a member subjected to induction hardening, and has high flexibility while maintaining the toughness inside.

  The operation of the gear system 1 configured as described above will be described. If the shaft 2 is an input side and the shaft 3 is an output side, both ends are rotated by bearings 6 and 7 when power is transmitted to the shaft 2. The freely supported shaft 2 rotates. When the shaft 2 rotates, the gear 4 fixed to the shaft 2 also rotates together. When the gear 4 rotates, power is transmitted to the gear 5 meshed with the gear surface facing the gear 4 via the tooth surfaces of both gears 4 and 5. When power is transmitted to the gear 5, the gear 5 rotates, and the shaft 3 that fixes the gear 5 is also supported by the bearings 8 and 9 and rotates together. In this way, power is transmitted from the shaft 2 to the shaft 3 via the gears 4 and 5.

Thus, when power transmission is performed by the gear system 1, since the gears 4 and 5 are helical gears and the tooth surfaces thereof are inclined, a separating force by an input torque, that is, a radial load is applied. The load in the axial direction (axial direction) is received by the bearings 6, 7, 8, and 9, and this separation force is also received by the bearings 6, 7, 8, and 9, but the gears 4, 5 that are engaged with each other are opposed to each other. They also act on each other and cause the shafts 2 and 3 to bend. In the shaft structure of the present invention, the shaft 2 is provided with the solid shaft-shaped center member 11 having a larger Young's modulus inside the hollow shaft-shaped shaft member 10 as described above. Can be suppressed. When the deflection amount is calculated by paying attention to the shaft 2, the deflection amount ymax is expressed by the following equation (1), where P is the separation force, E is the Young's modulus, and Iz is the second moment of section.

  As can be seen from the equation (1), in order to reduce the amount of deflection, the Young's modulus E and the secondary moment of inertia Iz need only be increased. Since the center member 11 is provided, this bending can be suppressed. Moreover, since bending can be suppressed, the meshing loss of the gears 4 and 5 due to misalignment of the gears 4 and 5 can be suppressed. In addition, since it is possible to suppress the bending of the shafts 2 and 3 with a simple structure, the productivity is improved and the cost can be reduced. Further, the shaft 2 is made of a lightweight member such as a lightweight alloy, and the shaft 2 is highly rigid by combining the center member 11 with a member having a higher specific gravity but a higher Young's modulus. Therefore, the fuel consumption can be improved and the vehicle behavior can be improved.

  Next, another configuration example of the shaft structure of the present invention will be described. Another example of the configuration of the shaft structure of the shaft is that only the shaft structure of the shaft is different from the gear system 1 described above, and therefore only the shaft structure of the shaft will be described. Further, the configuration is the same as that of the gear system 1 except for the shaft structure of the shaft, and description will be made using the same reference numerals. FIG. 2 shows a shaft 12 which is another configuration example of the shaft structure of the present invention. The shaft 12 is applied to the shaft 2 or 3 in the gear system 1 described above. The shaft 12 includes a shaft member 13 formed with a space inside, and the rigidity changes according to the change in the electromagnetic atmosphere inside the shaft 12, or a voltage is applied to the inside thereof. A liquid material (center member, center member) 14 having a variable rigidity is sealed (filled) in a liquid-tight manner. The central member 14 may not be liquid, but may be powder or solid. The shaft 12 has a double structure in which the liquid material 14 is inserted into the shaft member 13. The liquid material 14 has a Young's modulus depending on the change in the electromagnetic atmosphere inside the shaft member 13 or the degree of application of voltage. It is made up of a fluid that changes, in other words, a fluid that changes the degree of resistance to deformation.

  Specifically, the liquid material 14 may be a magnetic fluid or the like, and has a configuration in which the rigidity is changed by a change in the electromagnetic atmosphere inside the shaft member 13 according to a voltage application state. Therefore, one end of the conducting wires 15, 16 is inserted into the shaft member 13 through the wall portion 17 of the shaft member 13, and a coil or the like is connected to one end of the conducting wires 15, 16 so that the shaft member 13 is connected. It is configured to be able to change the electromagnetic atmosphere inside. The other ends of the conducting wires 15 and 16 are connected to a power supply device (not shown). In the power supply device, the degree of voltage application is controlled by an electronic control device (not shown). The degree of voltage application by the electronic control device is determined by the magnitude of torque input to the shaft 12, for example, a torque signal from an internal combustion engine such as an engine or a driving force source such as an electric motor is input to the electronic control device from a sensor (not shown). To be done.

  FIG. 3 is a flowchart showing an example of control for changing the rigidity of the liquid material 14 inside the shaft member 13 by changing the electromagnetic atmosphere inside the shaft member 10 by changing the degree of voltage application by the electronic control device. It is described in. First, in step S1, it is determined whether or not the engine torque Teng is larger than the torque determination reference value Tref. The torque determination reference value Tref is a value for determining whether or not to increase the Young's modulus E by applying a voltage, and is calculated by an electronic control device or provided by a map prepared in advance. . If a negative determination is made in step S1, it is not necessary to increase the rigidity of the liquid material 14, that is, to increase the Young's modulus E, so no voltage is applied, that is, the power is turned off (step S3). . If a positive determination is made in step S1, the control in step S2 is executed. That is, in step S2, since it is necessary to increase the rigidity of the liquid material 14, that is, to increase the Young's modulus E, a voltage is applied, that is, the power supply is turned on. The control routine according to the flowchart shown in FIG. 3 is performed at predetermined intervals, and the rigidity of the shaft 12, that is, the Young's modulus E is changed as appropriate. In this flowchart, two states, ie, a power ON state and an OFF state, are shown as voltage application states. When the power source is ON, a voltage is applied according to the engine torque Teng. The value can be changed.

  When power transmission is performed by the gear system 1 to which the above other configuration examples are applied, the gears 4 and 5 are constituted by helical gears as in the configuration having the solid shaft-shaped central member 11 described above. In addition, since the tooth surface is inclined, a separation force by an input torque, that is, a radial load is applied. The load in the axial direction (axial direction) is received by the bearings 6, 7, 8, 9, but this separating force acts on the gears 4, 5 that are meshed with each other so as to bend the shaft 12. Cause. In the shaft structure of the present invention, as described above, the shaft 12 includes the shaft member 13 formed with a space in the interior thereof, and the liquid body (the rigidity of which is variable by changing the electromagnetic atmosphere inside the shaft member 13 ( Since the central member 14 is sealed (filled) in a liquid-tight manner, the bending thereof can be suppressed. Further, as represented by the above-described formula (1), in order to reduce the amount of bending, the Young's modulus E and the secondary moment of inertia Iz need only be increased. In another configuration example of the present invention, As described above, since the liquid 14 that can increase the Young's modulus by applying a voltage is provided, this bending can be suppressed. Moreover, since it can suppress and reduce bending, the meshing loss of the gears 4 and 5 by the misalignment of the gears 4 and 5 can be suppressed. Furthermore, since the voltage application state can be changed by the torque applied to the shaft 12 according to the above-described flowchart by the electronic control device, for example, the necessary rigidity can be given by changing the degree of the voltage application state as appropriate. Further, the shaft 12 is configured by combining the shaft member 13 with a lightweight member such as a lightweight alloy, and the center member (liquid body) 14 with a member having a higher specific gravity but a higher Young's modulus. Since 12 can be configured to be highly rigid and lightweight, it is possible to improve fuel consumption and eventually improve vehicle behavior.

  In the two embodiments described above, the examples where the shafts 2 and 12 are applied to the gear system 1 have been described. However, the shaft according to the present invention has a hollow shaft shape or a shape having a space inside. It is configured by a member (shaft member), and any member having a Young's modulus larger than that of the shaft member may be accommodated (filled) in the hollow portion or in the internal space without a gap. The present invention can also be applied to a power transmission system such as a rotation transmission element such as a belt or a chain. The gears 5, 6, 7, and 8 applied to the gear system 1 are helical gears. However, the shaft structure of the present invention (specifically, a gear to which a load is applied in the radial direction) Specifically, the shafts 2 and 12) can be applied.

  10, 13 ... shaft member, 11, 14 ... central member (center member, liquid).

Claims (3)

  In a shaft structure used for a power transmission element, a shaft member formed in a hollow shape, and a center formed by a material having a higher Young's modulus than the shaft member and fitted in the hollow shape of the shaft member A shaft structure characterized by comprising a member.   In a shaft structure used for a power transmission element, a shaft member formed in a hollow shape and a central member that is filled in the hollow shape of the shaft member and changes in rigidity according to a change in electromagnetic atmosphere. A shaft structure characterized by that.   The shaft structure according to claim 1, wherein a gear is fixed to the shaft member.

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