JP2009041620A - Bolt fastening structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolt fastening structure capable of restraining looseness of bolt fastening caused by vibration. <P>SOLUTION: A bolt 60 is inserted into an insertion hole 61 formed on an outer flange 52a of a second housing 52, and is screwed with the first housing 51, and thereby, the second housing 52 is fastened to the first housing 51. The bolt 60 is formed by a material having a coefficient of thermal expansion smaller than that of the material of the second housing 52. A storage chamber 62 capable of storing lubricating oil is partitioned by an outer housing B3, the outer flange 52a of the second housing 52, and the first housing 51. A part of the lubricating oil heated to a high temperature by absorbing friction heat of a clutch disk B2 and a pressure disk B4 of a brake B is supplied to the storage chamber 62. The bolt 60 and the outer flange 52a of the second housing 52 fastened to the first housing 51 thereby are heated by the lubricating oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bolt fastening structure in which a bolt is inserted into an insertion hole formed in a fastened member, and the fastened member is fastened to a base member by the bolt.

As a conventional bolt fastening structure, the following structure is generally adopted. That is, in this bolt fastening structure, the bolt is inserted into the insertion hole formed in the member to be fastened, and the bolt is screwed into the base member, thereby fastening the member to be fastened to the base member. In such a bolt fastening structure, the greater the axial force of the bolt, the greater the contact surface pressure at the threaded portion, so that the fastened member and the base member are fastened with a greater fastening force.
JP 2003-1884849 A JP-A-61-192916

  By the way, when such a bolt fastening structure is used in an environment with high vibration such as a vehicle, there are concerns about the following inconveniences. That is, in such an environment, the contact surface pressure at the screwed portion of the bolt fluctuates due to the vibration, which may cause a decrease in the fastening force of the bolt, that is, loosening of the bolt. However, even in such an environment, if the axial force of the bolt is large to some extent, the bolt does not loosen due to vibration, or even if it occurs, the decrease in fastening force can be almost ignored. However, if the above-described vibration is input when the axial force of the bolt temporarily decreases due to some factor such as a change in environmental temperature, the bolt loosening due to the vibration proceeds rapidly. As a result, it becomes impossible to fasten the fastened member and the base member stably, which causes further inconveniences such as the occurrence of rattling. Incidentally, in the prior art, as a method for suppressing the loosening of the bolt as described above, a locking agent is applied to the screwed portion of the bolt (Patent Document 1), and the bolt hole formed in the tip portion of the bolt and the base member is used. A spacer having a different coefficient of thermal expansion is interposed between the bottom and the bottom in accordance with the operating temperature environment, and the axial force is prevented from decreasing by pressing the tip of the bolt with the spacer (Patent Document 2) Etc. have been proposed.

  The present invention has been made in view of the above-described conventional situation, and an object thereof is to provide a bolt fastening structure capable of suppressing the occurrence of loose bolt fastening caused by vibration.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The invention according to claim 1 is a bolt fastening structure in which a bolt is inserted into an insertion hole formed in the fastened member and the fastened member is fastened to the base member by the bolt, wherein the bolt is a material of the fastened member. The gist of the present invention is that a supply passage for supplying a heating liquid for heating the portion to be fastened is formed around the fastening portion by the bolt of the fastened member.

  According to this configuration, the bolt and the fastening portion of the fastened member fastened to the base member by the bolt are heated by the heating liquid and the temperature rises. Here, since the bolt is formed of a material having a smaller thermal expansion coefficient than the material of the member to be fastened, the amount of expansion of the member to be fastened in the axial direction of the bolt is larger than the amount of expansion of the bolt when the temperature rises. As a result, the axial force of the bolt increases. As described above, the bolt axial force increases through the supply of the heating liquid, thereby suppressing the occurrence of loosening of the bolt due to vibration.

  Therefore, for example, as described in claim 2, even when the base member and the fastened member are provided as one component member of a vehicle that travels under various temperature environments, the bolts are not loosened. It becomes possible to suppress.

  According to a third aspect of the present invention, in the bolt fastening structure according to the second aspect, the member to be fastened is located in the vicinity of a wet friction engagement mechanism provided in a driving force transmission system of the vehicle, and the heating liquid Is a lubricating oil that is supplied to the wet friction engagement mechanism and led out from the wet friction engagement mechanism to the supply passage.

  Since the lubricating oil supplied to the wet frictional engagement mechanism is heated by the frictional heat generated in the wet frictional engagement mechanism, the temperature of the lubricating oil increases. Since the bolt and the fastening portion of the member to be fastened are heated by the heat of the lubricating oil, it is not necessary to separately provide a heating source for raising the temperature of the lubricating oil, or such a heating source is separately provided. Even in this case, it is possible to reduce the size.

  Furthermore, as described in claim 4, it is possible to adopt a configuration in which the supply passage is a passage formed between the housing of the wet friction engagement mechanism and the fastened member. Therefore, by completing the assembly of the members in the driving force transmission system such as the housing of the wet friction engagement mechanism and the fastened member, the supply passage for supplying the lubricating oil can be partitioned and formed between them. Can be simplified.

  According to a fifth aspect of the present invention, in the bolt fastening structure according to any one of the first to fourth aspects, the fastened member includes a plurality of members, and the plurality of members include the bolts. The gist is that a washer interposed between other members is included, and the bolt is formed of a material having a smaller thermal expansion coefficient than the material of the washer.

  According to this configuration, for example, even if the member other than the washer among the fastened members is restricted by its function or the like and a material having a smaller thermal expansion coefficient than the bolt has to be used, the washer is thermally expanded. By doing so, the axial force of the bolt can be increased, and the occurrence of loosening of the bolt can be suppressed.

Hereinafter, an embodiment in which the present invention is applied to a bolt fastening structure of a driving force transmission system of a vehicle will be described with reference to FIGS.
FIG. 1 is a skeleton diagram showing a driving force transmission system of a front and rear wheel drive type vehicle in which front wheels are always driven wheels. As shown in FIG. 1, in a driving force transmission system 100 mounted on a vehicle, the driving force of an internal combustion engine 10 that is a driving force source is transmitted through an automatic transmission 11 to a center differential (hereinafter referred to as “center differential”). 12 is transmitted. The center differential 12 is connected to a front differential (hereinafter referred to as “front differential”) 14 and is connected to a rear differential (hereinafter referred to as “rear differential”) 18 via a propeller shaft 17. The driving force transmitted from the internal combustion engine 10 to the automatic transmission 11 is distributed by the center differential 12 to the front differential 14 and the rear differential 18 at an appropriate ratio according to the traveling state of the vehicle.

  Here, the front differential 14 transmits the driving force transmitted from the center differential 12 to the front wheels 16L and 16R through the pair of front accelerator shafts 15L and 15R, respectively, while the rear differential 18 also receives the driving force transmitted from the center differential 12. Transmission is made to the rear wheels 20L and 20R via a pair of rear accelerator shafts 19L and 19R. Further, the driving force transmission system 100 supplies hydraulic oil to the hydraulic devices of the rear differential 18 and hydraulic oil to the friction mechanisms of the rear differential 18 respectively according to the running state of the vehicle. A lubricating oil supply device 90 is provided.

  FIG. 2 is a skeleton diagram showing the configuration of the rear differential 18. As shown in FIG. 2, the rear differential 18 is connected to the differential device 30 for transmitting the driving force transmitted by the propeller shaft 17 to the rear wheels 20 </ b> L and 20 </ b> R, and connected to the differential device 30 to generate the driving force. The transmission 40 is distributed to the rear wheels 20L and 20R at an appropriate ratio.

  The differential device 30 includes a sun gear S1 that is connected to the right rear wheel 20R via the rear accelerator shaft 19R and rotates integrally with the right rear wheel 20R. A ring gear R1 is provided on the outer periphery of the sun gear S1. ing. A bevel gear U is fixed to the outer periphery of the ring gear R 1, and the bevel gear U meshes with a bevel gear 17 a fixed to the end of the propeller shaft 17. A plurality of pairs of planetary gears P1 meshing with each other are provided between the sun gear S1 and the ring gear R1, and one of the pair of planetary gears P1 meshes with the sun gear S1, and the other meshes with the ring gear R1. Yes. The differential device 30 is provided with a carrier CA1 that supports the pair of planetary gears P1 so as to be capable of rotating and revolving. The carrier CA1 is connected to the left rear wheel 20L via a rear accelerator shaft 19L. And rotate integrally with the left rear wheel 20L.

  The transmission 40 supports the sun gear S2 connected to the ring gear R1 of the differential device 30, the ring gear R2 meshed with the sun gear S2 via the plurality of planetary gears P2, and the planetary gear P2 so as to be capable of rotating and revolving. A carrier CA2 is provided. The ring gear R2 is selectively slidably engaged with the rear accelerator shaft 19L corresponding to the carrier CA1 and the left rear wheel 20L of the differential device 30 via the clutch C1, and the differential gear 30 of the differential device 30 via the clutch C2. It is selectively slipped and engaged with the rear accelerator shaft 19R corresponding to the sun gear S1 and the right rear wheel 20R. Further, the carrier CA2 is selectively connected to the first housing 51 of the rear differential 18 via the brake B.

  Here, the clutches C1 and C2 and the brake B are multi-plate wet friction engagement mechanisms, and the hydraulic oil supply device 80 described above is transmitted by the propeller shaft 17 by switching the engagement / release state thereof. The driving force is distributed to the rear wheels 20L and 20R at an appropriate ratio.

  For example, while the vehicle is traveling straight, the clutches C1 and C2 and the brake B are all switched to the disengaged state, the transmission device 40 is idling, and the differential device 30 functions as a normal open differential. That is, the driving force transmitted by the propeller shaft 17 is evenly distributed to the rear wheels 20L and 20R via the rear accelerator shafts 19L and 19R, and the differential device 30 rotates integrally with the rear wheels 20L and 20R. Rotate at the same rotational speed.

  On the other hand, while the vehicle is turning left, the brake B is engaged, the clutch C1 is slipped, and the clutch C2 is released. When the brake B is thus engaged, the carrier CA2 of the transmission 40 is locked, and the ring gear R2 rotates in the opposite direction to the ring gear R1. As the clutch C1 is slidably engaged, a resistance force against the rotation of the carrier CA1 is generated, and the driving force transmitted to the left rear wheel 20L via the rear accelerator shaft 19L is reduced. As a result, the driving force transmitted to the right rear wheel 20R is greater than that of the left rear wheel 20L, and the rotational speed of the right rear wheel 20R is greater than the rotational speed of the left rear wheel 20L.

  On the other hand, while the vehicle is turning right, the brake B is engaged, the clutch C2 is slidably engaged, and the clutch C1 is further released. When the brake B is thus engaged, the carrier CA2 of the transmission 40 is locked, and the ring gear R2 rotates in the opposite direction to the ring gear R1. As the clutch C2 is slidably engaged, a resistance force against the rotation of the sun gear S1 is generated, and the driving force transmitted to the rear wheel 20R via the rear accelerator shaft 19R is reduced. As a result, the driving force transmitted to the left rear wheel 20L becomes larger than the driving force of the right rear wheel 20R, and the rotational speed of the left rear wheel 20L becomes larger than the rotational speed of the right rear wheel 20R.

Next, the brake B and the surrounding structure will be described with reference to FIG.
FIG. 3 is a local sectional view showing a sectional structure in the vicinity of the brake B. As shown in FIG. 3, the brake B includes an inner housing B <b> 1 formed integrally with the above-described carrier CA <b> 2 and an outer housing B <b> 3 fixed to the first housing 51. A plurality of clutch disks B2 are fitted to the inner housing B1 so as to be relatively displaceable in the axial direction with respect to the inner housing B1 and not to be relatively displaceable in the circumferential direction, and a plurality of clutch disks B2 are fitted to the outer housing B3. The pressure disk B4 is fitted into the outer housing B3 so as to be relatively displaceable in the axial direction and not to be relatively displaceable in the circumferential direction. The clutch disk B2 and the pressure disk B4 are engaged with each other so as to overlap each other with a predetermined gap.

  The cylinder B5 formed in the outer housing B3 is provided with a piston B6 that can slide in the axial direction of the pressure disk B4. The piston B6 is pressed by the elastic force of a spring B7 fixed to the cylinder B5. It is biased in a direction away from the disk B4. An oil chamber B8 is defined by the end face of the piston B6 and the inner wall of the cylinder B5, and hydraulic oil is selectively supplied from the hydraulic oil supply device 80 to the oil chamber B8. Further, a housing chamber B9 for housing a friction portion between the clutch disk B2 and the pressure disk B4 is defined between the inner housing B1 and the outer housing B3.

  The hydraulic oil supply device 80 switches the engagement / release state of the brake B by switching the start / stop of the hydraulic oil supply to the oil chamber B8. That is, when the hydraulic oil is started to be supplied to the oil chamber B8 by the hydraulic oil supply device 80, the piston B6 slides to the pressure disk B4 side, and the pressure disk B4 and the clutch disk B2 are fixed to the piston B6 and the outer housing B3. It is sandwiched between the stopper B10. As a result, the brake B is engaged by the frictional force between the pressure disc B4 and the clutch disc B2. On the other hand, when the supply of the hydraulic oil to the oil chamber B8 by the hydraulic oil supply device 80 stops, the piston B6 slides away from the pressure disk B4 by the elastic force of the spring B7. As a result, the frictional force between the pressure disc B4 and the clutch disc B2 disappears, and the brake B is released.

  The sun gear S2 and the ring gear R2 described above are provided on the outer periphery of the rear accelerator shaft 19R, and the ring gear R2 meshes with the sun gear S2 via the planetary gear P2. Further, a main passage 91 connected to the discharge port of the lubricating oil supply device 90 is formed inside the rear accelerator shaft 19R, and a branch passage 92 connected to the main passage 91 is formed. On the other hand, in the ring gear R2 and the inner housing B1, communication holes 93 and 94 are formed at positions corresponding to the branch passage 92, respectively. With this configuration, the lubricating oil supplied by the lubricating oil supply device 90 is supplied to the storage chamber B9 through the main passage 91, the branch passage 92, and the communication holes 93 and 94. The lubricating oil thus supplied to the storage chamber B9 absorbs frictional heat between the clutch disk B2 and the pressure disk B4, and its temperature becomes higher than normal temperature (for example, 70 ° C.).

  The sun gear S 2, the planetary gear P 2, and the ring gear R 2 are accommodated by the second housing 52 of the rear differential 18, and the second housing 52 is fastened to the first housing 51 by a bolt 60.

  Hereinafter, the fastening structure of the bolt 60 will be described in more detail. An outer flange 52a is formed in the second housing 52, and the outer flange 52a is located between the first housing 51 and the outer housing B3. A plurality of insertion holes 61 (one of which is shown in the figure) are formed in the outer flange 52a at a predetermined interval in the circumferential direction. A plurality of bolts 60 (one of which is shown in the drawing) are inserted into the insertion holes 61 and screwed into the first housing 51, whereby the second housing 52 is fastened to the first housing 51. Has been. In addition, the assembly | attachment operation | work of the 2nd housing 52 and the 1st housing 51 by the volt | bolt 60 is performed when environmental temperature is normal temperature (for example, 25 degreeC). In the present embodiment, the bolt 60 is formed of a material having a smaller thermal expansion coefficient than the material of the second housing 52.

  The outer housing B3, the outer flange 52a of the second housing 52, and the first housing 51 define a substantially annular storage chamber 62 extending in the circumferential direction of the rear accelerator shaft 19R. The storage chamber 62 functions as a supply passage for supplying high-temperature lubricating oil around the outer flange 52 a of the second housing 52, that is, around the fastening portion by the bolt 60. Further, the outer housing B3 is formed with a communication path 63 that allows the storage chamber 62 to communicate with the storage chamber B9, and a recovery path 64 that returns the lubricating oil in the storage chamber 62 to the lubricating oil supply device 90. .

  With such a configuration, a part of the lubricating oil that has been supplied to the storage chamber B9 and has absorbed the frictional heat between the clutch disc B2 and the pressure disc B4 of the brake B and has become high temperature is supplied to the storage chamber 62 through the communication path 63. The After the lubricating oil is supplied to the storage chamber 62 in this way, the lubricating oil is recovered from the storage chamber 62 to the lubricating oil supply device 90 through the recovery path 64.

According to the embodiment described above, the following effects can be obtained.
(1) The bolt 60 and the outer flange 52a of the second housing 52 fastened to the first housing 51 by the bolt 60 are heated by the lubricating oil heated to high temperature by the frictional heat of the brake B so that the temperature rises. become. Here, since the bolt 60 is formed of a material having a smaller thermal expansion coefficient than that of the material of the second housing 52, the expansion amount of the second housing 52 in the axial direction of the bolt 60 is increased when the temperature thereof increases. It becomes larger than the amount of expansion, and the axial force of the bolt 60 increases. As a result, the axial force of the bolt 60 can be increased, and the occurrence of bolt loosening due to vibration can be suppressed. In particular, the lubricating oil supplied to the periphery of the fastening portion of the bolt 60 in this way is higher than the environmental temperature at the time of fastening the bolt 60 (70 ° C.> 25 ° C.) as described above. The force can be made larger than the initial axial force at the time of fastening. As a result, the above-described loosening suppression effect of the bolt 60 can be made more remarkable. Occurrence of loose bolt fastening caused by vibration can be suppressed.

  (2) Further, in order to heat the bolt 60 and the outer flange 52a of the second housing 52 in this way, high-temperature lubricating oil that absorbs frictional heat between the clutch disk B2 and the pressure disk B4 of the brake B is used. I made it. Therefore, it is not necessary to separately provide a heating source for raising the temperature of the lubricating oil, and the configuration can be simplified.

  (3) The storage chamber 62 is configured to be partitioned by the outer housing B3 of the brake B, the second housing 52, and the first housing 51. Therefore, by completing the assembly of the members in the rear differential 18 such as the outer housing B3, the second housing 52, and the first housing 51 of the brake B, the storage chamber 62 for supplying the lubricating oil therebetween can be defined. Therefore, the formation can be simplified.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the substantially annular storage chamber 62 extending in the circumferential direction of the rear accelerator shaft 19R is defined as a supply passage for supplying high-temperature lubricating oil around the fastening portion by the plurality of bolts 60. However, for example, a structure in which a plurality of storage chambers are separately formed corresponding to the fastening portions by the respective bolts 60 may be employed.

  For example, as shown in FIG. 4, a washer 65 formed of a material having a thermal expansion coefficient larger than that of the bolt 60 is disposed between the outer flange 52 a of the second housing 52 and the head of the bolt 60. A configuration can also be adopted. By adopting such a configuration, for example, even when the second housing 52 is restricted by its function or the like and a material having a smaller thermal expansion coefficient than the bolt 60 must be used, the washer 65 is thermally expanded. As a result, the axial force of the bolt 60 can be increased, and the occurrence of loosening of the bolt 60 can be suppressed.

  As shown in FIG. 5, the bolt 60 is inserted into the insertion hole 61 formed in the second housing 52 and the insertion hole 51 a formed in the first housing 51 and screwed into the nut 60 a. Thus, the present invention can be applied to the bolt fastening structure in which the second housing 52 is fastened to the first housing 51 with basically the same mode.

  In the above-described embodiment, a part of the lubricating oil that has become a high temperature by absorbing the frictional heat between the clutch disk B2 and the pressure disk B4 of the brake B is supplied to the storage chamber 62. For example, when the clutch C1 or C2 is located in the vicinity of the storage chamber 62, a part of the lubricating oil that has become a high temperature by absorbing the frictional heat between the clutch disk and the pressure disk of the clutch C1 or C2. It is also possible to adopt a configuration for supplying the water to the storage chamber 62.

  In the above embodiment, the case where the present invention is applied to the bolt fastening structure of the bolt 60 provided in the rear differential 18 of the vehicle is illustrated. The present invention is basically applicable to other bolt fastening structures such as a bolt fastening structure used for an internal combustion engine of a vehicle. In addition, when applying this invention to the bolt fastening structure provided in an internal combustion engine, the cooling water of an internal combustion engine can be used as a heating liquid.

The skeleton figure which shows the structure of the drive force transmission system of the vehicle which provides it about one Embodiment of the bolt fastening structure concerning this invention. The skeleton figure which shows the structure of the rear differential of the said power transmission system. The local sectional view showing the section structure near the brake provided in the rear differential. Sectional drawing which shows the modification about the bolt fastening structure concerning the said embodiment. Sectional drawing which shows another modification about the bolt fastening structure concerning the said embodiment.

Explanation of symbols

  B ... Brake, U ... Bevel gear, B1 ... Inner housing, B2 ... Clutch disc, B3 ... Outer housing, B4 ... Pressure disc, B5 ... Cylinder, B6 ... Piston, B7 ... Spring, B8 ... Oil chamber, B9 ... Storage chamber, B10: Stopper, C1, C2 ... Clutch, P1, P2 ... Planetary gear, R1, R2 ... Ring gear, S1, S2 ... Sun gear, CA1, CA2 ... Carrier, 10 ... Internal combustion engine, 11 ... Automatic transmission, 12 ... Center Differential, 14 ... Front differential, 15L, 15R ... Front accelerator shaft, 16L, 16R ... Front wheel, 17 ... Propeller shaft, 17a ... Bevel gear, 18 ... Rear differential, 19L, 19R ... Rear accelerator shaft, 20L, 20R ... Rear wheel, 30 ... differential gear, 40 ... strange Device 51: First housing 51a: Insertion hole 52 ... Second housing 52a: Outer flange 60 ... Bolt 60a ... Nut 61: Insertion hole 62 ... Reservoir chamber 63 ... Communication path 64 ... Recovery Road, 65 ... Washer, 80 ... Hydraulic oil supply device, 90 ... Lubricating oil supply device, 91 ... Main passage, 92 ... Branch passage, 93, 94 ... Communication hole, 100 ... Driving force transmission system.

Claims (5)

In a bolt fastening structure in which a bolt is inserted into an insertion hole formed in the fastened member and the fastened member is fastened to the base member by the bolt.
The bolt is made of a material having a smaller coefficient of thermal expansion than the material of the fastened member,
A bolt fastening structure characterized in that a supply passage for supplying a heating liquid for heating the part to be fastened is formed around the fastening part by the bolt of the member to be fastened. The bolt fastening structure according to claim 1,
The base member and the fastened member are each a component of a vehicle. In the bolt fastening structure according to claim 2,
The fastened member is located in the vicinity of a wet friction engagement mechanism provided in the driving force transmission system of the vehicle,
The bolt fastening structure, wherein the heating liquid is lubricating oil that is supplied to the wet friction engagement mechanism and led out from the wet friction engagement mechanism to the supply passage. In the bolt fastening structure according to claim 3,
The bolt fastening structure, wherein the supply passage is a passage formed between the housing of the wet friction engagement mechanism and the fastened member. In the bolt fastening structure according to any one of claims 1 to 4,
The fastened member is composed of a plurality of members, and the plurality of members include a washer interposed between the bolt and another member,
The bolt fastening structure is characterized in that the bolt is formed of a material having a smaller thermal expansion coefficient than the material of the washer.

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