JP2010019301A - Balance shaft support structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide balance shaft support structure reducing a friction loss in a bearing, while sufficiently securing durability of the bearing. <P>SOLUTION: A balance shaft 4 has a plurality of journals 40 and 41 rotatably supported by a plurality of bearings 52 and 53 and an unbalance mass 44 eccentrically arranged to the axis. The journals 40 and 41 have support surface parts 42 and 43 oppositely supported to the bearings 52 and 53, and the support surface parts 42 and 43 are arranged in a larger diameter than both sides in the axial direction. The journals 40 and 41 and the bearings 52 and 53 are axially, relatively and movably constituted while sliding the support surface parts 42 and 43 of the journals 40 and 41 and the bearings 52 and 53, and are also constituted to be capable of increasing-decreasing the bearing contact area being the area of contacting the support surface parts 42 and 43 and the bearings 52 and 53 by relatively moving both in the axial direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a support structure for a balance shaft for suppressing vibration of an internal combustion engine.

Generally, when an internal combustion engine is operated, vibration is generated by reciprocal movement of a piston or the like. This is because an unbalanced inertial force or couple remains due to the cylinder arrangement. For example, in the case of an in-line four-cylinder internal combustion engine, the secondary component of the inertial force remains as a large unbalance and vibrations are generated.
Therefore, in order to reduce these vibrations, the internal combustion engine is provided with a balance shaft having an unbalanced mass on the crankshaft, and the balance shaft is driven and rotated by the crankshaft to cancel the vibration of the internal combustion engine. There is something like that.

Incidentally, in an internal combustion engine, improvement of fuel consumption is a very important problem. In the balance shaft, the fuel efficiency can be improved by reducing the friction loss in the bearing that rotatably supports the journal.
For example, Patent Document 1 discloses a balancer mechanism for an internal combustion engine that can suppress starting resistance in a state where the balance shaft is not warmed up by switching driving / non-driving of the balance shaft by temperature control. In Patent Document 2, the journal width on the anti-unbalance side of the balance shaft with a small oil film pressure (area contacting the bearing) is made smaller than that on the balance side, thereby reducing the weight of the balance shaft and driving loss of the internal combustion engine. The balance shaft which can reduce is disclosed.

JP 2002-349283 A Japanese Patent Laid-Open No. 2005-16644

However, with the balance shaft having the configurations of Patent Documents 1 and 2, it cannot be said that the friction loss in the bearing can be sufficiently reduced.
In particular, it is important to reduce the diameter and width of a bearing in order to reduce friction loss in a sliding bearing such as a bearing of a balance shaft. On the other hand, in order to ensure the life of the bearing, it is necessary to design the diameter and width of the bearing to be large so that the bearing is not seized even at the assumed maximum load. For this reason, in conventional balance shafts, it has been insufficient to achieve both reduction of friction loss in the bearing and durability of the bearing.

  The present invention has been made in view of such conventional problems, and intends to provide a support structure for a balance shaft that can reduce friction loss in the bearing while sufficiently ensuring the durability of the bearing. It is.

The present invention provides a support structure for supporting a balance shaft including a plurality of journals rotatably supported by a plurality of bearings and an unbalance mass provided eccentrically with respect to an axis.
The journal has a support surface portion that is supported to face the bearing, and the support surface portion is provided with a larger diameter than both sides in the axial direction.
Of the combination of the journal and the bearing as a pair, at least a pair of the journal and the bearing are configured to be relatively movable in the axial direction while sliding the support surface portion of the journal and the bearing. And a bearing contact area which is an area where the support surface portion and the bearing are in contact with each other by moving both relative to each other in the axial direction. It exists in the support structure of a shaft (Claim 1).

  In the balance shaft support structure of the present invention, the journal is rotatably supported by the bearing at the support surface portion. And the said support surface part is provided in larger diameter than the both sides adjacent to this support surface part in an axial direction. That is, the support surface portion is provided so as to protrude in the radial direction from both sides in the axial direction. Therefore, the region in which the support surface portion and the bearing are in contact with each other can be changed by relatively moving in the axial direction while sliding at least a pair of the journal and the bearing. Thereby, the bearing contact area which is a contact area of the said support surface part and the said bearing can be controlled easily.

  Here, when the balance shaft is applied to an internal combustion engine or the like, the load that the bearing receives (the inertial force of the unbalance mass) is proportional to the square of the rotational speed of the internal combustion engine. For this reason, the load received by the bearing differs greatly between low-speed rotation and high-speed rotation. In particular, in an internal combustion engine for automobiles, the time for operation near the maximum number of rotations is very limited. Usually, in the region of the number of rotations frequently operated by the user, the load received by the bearing is relatively small.

  Therefore, if the support structure for the balance shaft as in the present invention is adopted in, for example, an internal combustion engine, the bearing contact area is controlled according to the rotational speed of the internal combustion engine, and the bearing contact area suitable for the rotational speed is achieved. By doing so, the friction loss in the bearing can be efficiently reduced. In addition, the occurrence of seizure of the bearing can be suppressed, and the durability can be sufficiently ensured. As a result, fuel efficiency can be improved while maintaining the quality performance of the internal combustion engine.

  Thus, according to the present invention, it is possible to provide a support structure for a balance shaft that can reduce friction loss in the bearing while sufficiently ensuring the durability of the bearing.

  In the present invention, the balance shaft is applied, for example, to suppress vibration of an internal combustion engine. The balance shaft including the unbalance mass is attached to a crankshaft of the internal combustion engine, and is configured to be able to cancel vibrations of the internal combustion engine by being driven and rotated by the crankshaft.

The bearing contact area is the total area in which the support surface portion of the journal and the bearing are in contact with each other. Here, the contact area means the area of the portion of the support surface portion where the journal is rotatably supported by the bearing. Therefore, not all parts are in contact with each other.
The bearing contact area may be increased or decreased by increasing or decreasing the contact area between the bearing and the bearing of at least one pair of the journals in the combination of the journal and the bearing supporting the journal. If you can, you can do this.

In addition, the journal and the bearing increase or decrease the bearing contact area by moving the journal in the axial direction with respect to the bearing using a journal moving means for moving the journal in the axial direction. (Claim 2).
In this case, the bearing contact area can be easily controlled by changing the position of the journal in the axial direction using the journal moving means.

In the above configuration, the balance shaft is supported by the bearing fixed to the housing,
The journal moving means includes a balance shaft support portion for supporting the balance shaft in the axial direction, and the journal of the balance shaft is moved by moving the balance shaft support portion with respect to the housing by an actuator. Is preferably configured to be movable in the axial direction (claim 3).
In this case, the balance shaft support portion and the balance shaft (the journal) can be easily and accurately moved by the actuator. Therefore, the bearing contact area can be easily and accurately controlled.

The journal and the bearing may increase or decrease the bearing contact area by moving the bearing in the axial direction with respect to the journal by using a bearing moving means for moving the bearing in the axial direction. (Claim 4).
In this case, the bearing contact area can be easily controlled by changing the axial position of the bearing using the bearing moving means.

Further, in the above configuration, the bearing is fixed to the bearing support portion that is movably disposed with respect to the housing.
The bearing moving means is preferably configured to move the bearing in the axial direction by moving the bearing support portion with an actuator.
In this case, the bearing support portion and the bearing can be easily and accurately moved by the actuator. Therefore, the bearing contact area can be easily and accurately controlled.

  In the case of a configuration in which the bearing can be moved in the axial direction, a configuration in which at least one of the bearings supporting the journal can be moved to increase or decrease the bearing contact area. It only has to be.

Further, an oil supply passage for supplying lubricating oil between the journal and the bearing is provided inside the bearing,
It is preferable that the oil supply passage is open to the support surface portion of the journal regardless of the position within a range in which the journal and the bearing are relatively movable.
In this case, lubricating oil is always supplied between the support surface portion of the journal and the bearing, so that an oil film is formed. Therefore, good lubricity between the journal and the bearing can be maintained, and friction loss in the bearing can be suppressed.

The balance shaft is preferably applied to an internal combustion engine.
In this case, it is possible to further exert the effect of the present invention that the friction loss in the bearing can be reduced while sufficiently ensuring the durability of the bearing.
Various methods can be adopted as a specific control method when the balance shaft is applied to an internal combustion engine. For example, the bearing contact area can be continuously changed according to the rotational speed of the internal combustion engine or the like, or can be changed stepwise by high speed rotation or low speed rotation.

Example 1
A support structure for a balance shaft according to an embodiment of the present invention will be described.
In this example, as shown in FIGS. 1 and 2, an example in which the balance shaft 4 is applied to the in-line four-cylinder engine 1 is shown.
The balance shaft 4 is not necessarily limited to an in-line four-cylinder engine, and can be applied to the entire engine.

  As shown in FIG. 1, the engine 1 includes a cylinder block 11 and an oil pan 12 that stores lubricating oil 121 arranged below the cylinder block 11. A transmission means 3 and a balance shaft 4 are provided. The crankshaft 2 and the balance shaft 4 are connected by the rotation transmission means 3 and are arranged in parallel to each other.

  As shown in the figure, the crankshaft 2 includes a crank pulley 21 provided at one end and a flywheel 23 provided at the other end. Furthermore, the crankshaft 2 has a crankpin 22 and a crank journal 24. The crank journal 24 is rotatably supported by a crank bearing 25 in the cylinder block 11.

  As shown in the figure, the rotation transmission means 3 connects the crank gear 31 attached to the crankshaft 2, the idle gear 32, the balance shaft gear 33, and the balance shaft gear 33 and the balance shaft 4. And a connecting shaft 34. The crank gear 31 is fitted on the crankshaft 2. The crank gear 31 meshes with the idle gear 32, and the idle gear 32 meshes with the balance shaft gear 33. The balance shaft gear 33 is fitted on the connecting shaft 34.

  The rotation transmitting means 3 is configured to be able to rotate the balance shaft 4 by transmitting the rotation from the crankshaft 2 through the crank gear 31, the idle gear 32, the balance shaft gear 33, and the connecting shaft 34. ing. That is, the balance shaft 4 is driven and rotated by the crankshaft 2.

  As shown in the figure, the balance shaft 4 has a first balance shaft 4a and a second balance shaft 4b arranged in parallel. The first balance shaft 4a and the second balance shaft 4b have journals 40a and 41a and journals 40b and 41b, respectively. The first balance shaft 4a is extended from the connecting shaft 34. That is, the first balance shaft 4a and the connecting shaft 34 are integrally formed on the same axis.

  The first balance shaft 4a and the second balance shaft 4b are provided with semi-columnar unbalance masses 44a and 44b, respectively, so as to be eccentric with respect to the axis. Further, the journals 40a and 41a and the journals 40b and 41b are provided with support surface portions 42a and 43a and support surface portions 42b and 43b supported by bearings 52a and 53a (see FIGS. 3 and 4) described later. A gear 45a is fitted to one end of the first balance shaft 4a. A gear 45b is fitted to one end of the second balance shaft 4b. The gear 45a and the gear 45b mesh with each other.

  Then, the balance shaft 4 configured as described above is driven by the crankshaft 2 via the rotation transmission means 3, whereby the first balance shaft 4a rotates, and the unbalance mass 44a also rotates with this rotation. Then, the gear 45b is rotated by the gear 45a, whereby the second balance shaft 4b is rotated. At the same time, the unbalance mass 44b is rotated in the opposite direction to the unbalance mass 44a. Thereby, the vibration generated in the engine 1 can be reduced.

Next, a support structure for the balance shaft 4 will be described.
In this example, the support structure of the 1st balance shaft 4a and the 2nd balance shaft 4b has the same structure. Therefore, in this example, the support structure of the first balance shaft 4a will be described, and the description of the support structure of the second balance shaft 4b will be omitted.

  As shown in FIGS. 3 and 4, in the first balance shaft 4a, the journals 40a and 41a are provided with the support surface portions 42a and 43a as described above. The support surface portions 42a and 43a are provided with a larger diameter than both sides adjacent to the support surface portions 42a and 43a in the axial direction. That is, the support surface portions 42a and 43a are provided so as to protrude in the radial direction from both sides in the axial direction. The support surface portions 42 a and 43 a are provided to face cylindrical bearings 52 a and 53 a fixed to the housing 51. The journals 40a and 41a are rotatably supported by bearings 52a and 53a on the support surface portions 42a and 43a.

  The first balance shaft 4a is provided with a journal moving means 60a for moving the journals 40a and 41a in the axial direction. The journal moving means 60a includes a balance shaft support portion 61a for supporting the first balance shaft 4a in the axial direction, an actuator 62a for moving the balance shaft support portion 61a, and the balance shaft support portion 61a and the actuator 62a. And a connecting portion 63a to be connected.

The balance shaft support portion 61a is provided to engage with a recess 400a formed at one end of the first balance shaft 4a, and supports the first balance shaft 4a in the recess 400a so as to be rotatable. The actuator 62a is fixed to the housing 51. The connecting portion 63a is provided so as to be extendable and contractable by the actuator 62a.
The journal moving means 60a moves the balance shaft 4a in the axial direction by moving the balance shaft support 61a with respect to the housing 51 by the actuator 62a, and consequently moves the journals 40a and 41a in the axial direction. It is configured to be able to be made.

As described above, the first balance shaft 4a uses the journal moving unit 60a to move the journals 40a and 41a in the axial direction while sliding the journals 40a and 41a with respect to the bearings 52a and 53a. It is supported by the housing 51, journal moving means 60a and the like.
The first balance shaft 4a moves the journals 40a and 41a in the axial direction with respect to the bearings 52a and 53a, thereby bringing the support surface portions 42a and 43a of the journals 40a and 41a into contact with the bearings 52a and 53a. The bearing contact area, which is the area, can be increased or decreased. Here, the contact area means the area of the portion where the journals 40a, 41a are rotatably supported by the bearings 52a, 53a in the support surface portions 42a, 43a. Therefore, not all parts are in contact with each other.

Specifically, for example, by moving the first balance shaft 4a (journals 40a and 41a) from the state of FIG. 3 in the direction of arrow A, the support surface portions 42a and 43a of the journals 40a and 41a and the bearings 52a and 53a The contact area (bearing contact area) can be increased (state shown in FIG. 4).
Further, by moving the first balance shaft 4a (journals 40a and 41a) in the direction of arrow B from the state of FIG. (Contact area) can be reduced (state shown in FIG. 3).
In this way, the bearing contact area can be increased or decreased.

An oil supply passage 59 for supplying lubricating oil is provided between the journals 40a and 41a and the bearings 52a and 53a inside the bearings 52a and 53a. The oil supply passage 59 is provided so as to open to the support surface portions 42a and 43a of the journals 40a and 41a. The oil supply passage 59 is provided so as to communicate from the inside of the bearings 52 a and 53 a to the inside of the housing 51.
In this example, the oil supply passage 59 opens to the support surface portions 42a and 43a of the journals 40a and 41a regardless of the position within the range in which the journals 40a and 41a and the bearings 52a and 53a can move. It is configured to

  Although not shown, the tooth width of the balance shaft gear 33 is set wider than the idle gear 32. Thereby, for example, the engagement between the idle gear 32 and the balance shaft gear 33 is maintained even after the movement of the first balance shaft 4a in the arrow A direction. Note that the configuration for maintaining the meshing with the idle gear 32 before and after the movement of the balance shaft 4a is not limited to the above contents, and for example, a joint that can be expanded and contracted in the axial direction is arranged on the connecting shaft 34. Good.

Next, the effect in the support structure of the balance shaft 4 of this example is demonstrated.
In the support structure of the balance shaft 4 of this example, the journals 40 and 41 are rotatably supported by the bearings 52 and 53 on the support surface portions 42 and 43. And the support surface parts 42 and 43 are provided in larger diameter than the both sides adjacent to the support surface parts 42 and 43 in an axial direction. That is, the support surface portions 42 and 43 are provided to protrude in the radial direction from both sides in the axial direction. Therefore, by moving the journals 40 and 41 relative to the bearings 52 and 53 in the axial direction, the region where the support surface portions 42 and 43 are in contact with the bearings 52 and 53 can be changed. . Thereby, the bearing contact area which is a contact area of the support surface parts 42 and 43 and the bearings 52 and 53 can be easily controlled.

  Here, when the balance shaft 4 is applied to the engine 1, the load that the bearings 52 and 53 receive (the inertial force of the unbalance mass 44) is proportional to the square of the rotational speed of the engine 1. Therefore, the load received by the bearings 52 and 53 is greatly different between the low-speed rotation and the high-speed rotation. In particular, in the engine 1 for automobiles, the time for operation near the maximum number of rotations is very limited. Usually, in the region of the number of rotations frequently operated by the user, the load received by the bearings 52 and 53 is relatively small.

Therefore, if the support structure for the balance shaft 4 as in this example is adopted in the engine 1 for an automobile, the bearing contact area is controlled according to the rotational speed of the engine 1 to obtain a bearing contact area suitable for the rotational speed. As a result, the friction loss in the bearings 52 and 53 can be reduced. Further, this can suppress the occurrence of seizure or the like of the bearings 52 and 53, and can ensure sufficient durability. As a result, fuel efficiency can be improved while maintaining the quality performance of the engine 1.
At this time, the bearing contact area may be continuously changed according to, for example, the number of revolutions of the engine 1 or may be changed stepwise by high speed rotation or low speed rotation.

  Further, the balance shaft 4 is configured to increase or decrease the bearing contact area by moving the journals 40 and 41 in the axial direction with respect to the bearings 52 and 53 using the journal moving means 60. Therefore, the bearing contact area can be easily controlled by changing the positions of the journals 40 and 41 in the axial direction using the journal moving means 60.

  The journal moving means 60 is configured to move the journals 40 and 41 of the balance shaft 4 in the axial direction by moving the balance shaft support portion 61 with respect to the housing 51 by the actuator 62. Therefore, the balance shaft support 61 and the balance shaft 4 (journals 40 and 41) can be easily and accurately moved by the actuator 62. Thereby, the bearing contact area can be easily and accurately controlled.

  An oil supply passage 59 for supplying lubricating oil between the journals 40 and 41 and the bearings 52 and 53 is provided inside the bearings 52 and 53. Further, the oil supply passage 59 is open to the support surface portions 42 and 43 of the journals 40 and 41 regardless of the position within the range in which the journals 40 and 41 can move. Therefore, lubricating oil is always supplied between the support surface portions 42 and 43 of the journals 40 and 41 and the bearings 51 and 52, so that an oil film is formed. Thereby, the lubricity between the journals 40 and 41 and the bearings 52 and 53 can be maintained, and the friction loss in the bearings 52 and 53 can be suppressed.

  Thus, according to this example, it is possible to provide a support structure for the balance shaft 4 that can reduce the friction loss in the bearings 52 and 53 while sufficiently ensuring the durability of the bearings 52 and 53.

(Example 2)
In this example, the configuration of the support structure of the balance shaft 4 is changed.
Also in this example, the support structure of the 1st balance shaft 4a and the 2nd balance shaft 4b has the same structure. Therefore, in this example, the support structure of the first balance shaft 4a will be described, and the description of the support structure of the second balance shaft 4b will be omitted.

As shown in FIGS. 5 and 6, in the first balance shaft 4a, support surfaces 42a and 43a are provided on the journals 40a and 41a. The support surface portions 42a and 43a are provided with a larger diameter than both sides adjacent to the support surface portions 42a and 43a in the axial direction. That is, the support surface portions 42a and 43a are provided so as to protrude from both sides in the axial direction. The support surface portions 42 a and 43 a are provided to face cylindrical bearings 52 a and 53 a fixed to the housing 51. The journals 40a and 41a are rotatably supported by bearings 52a and 53a on the support surface portions 42a and 43a.
The housing 51 is provided with a balance shaft support portion 511a for supporting the first balance shaft 4a so as to engage with a recess 400a formed at one end of the first balance shaft 4a. 4a is rotatably supported in the recess 400a, and the movement of the first balance shaft 4a in the axial direction is prevented.

  The journals 40a and 41a are provided with bearing moving means 70a for moving the bearings 52a and 53a in the axial direction. The bearing moving means 70a connects between the bearing support portions 711a and 712a arranged to be movable with respect to the housing 51, the actuator 72a for moving the bearing support portions 711a and 712a, and the bearing support portions 711a and 712a. The bearing coupling portions 731a and 732a are provided so as to do so.

The bearing support portions 711a and 712a are fixed to the bearings 52a and 53a. The actuator 72a is fixed to the housing 51. The bearing connecting portions 731a and 732a connect the bearing support portions 711a and 712a. One bearing connecting portion 731a is attached to the actuator 72a and is configured to be movable in the axial direction by the actuator 72a.
And the bearing moving means 70a is comprised so that the bearings 52a and 53a can be moved to an axial direction by moving the bearing support parts 711a and 712a to the axial direction by the actuator 72a with the bearing connection parts 731a and 732a. Yes.

As described above, the first balance shaft 4a uses the bearing moving means 70a to move the bearings 52a and 53a in the axial direction while sliding the bearings 52a and 53a with respect to the journals 40a and 41a. It is supported by the housing 51, the balance shaft support portion 511a, the bearing moving means 70a and the like.
The first balance shaft 4a moves the bearings 52a and 53a in the axial direction with respect to the journals 40a and 41a, thereby bringing the support surface portions 42a and 43a of the journals 40a and 41a into contact with the bearings 52a and 53a. The bearing contact area, which is the area, can be increased or decreased.

Specifically, for example, by moving the bearings 52a and 53a in the direction of the arrow B from the state of FIG. 5, the contact area (bearing contact area) between the support surface portions 42a and 43a of the journals 40a and 41a and the bearings 52a and 53a. ) Can be increased (state shown in FIG. 6).
Further, by moving the bearings 52a and 53a in the direction of arrow A from the state of FIG. 6, the contact area (bearing contact area) between the support surface portions 42a and 43a of the journals 40a and 41a and the bearings 52a and 53a is reduced. (State shown in FIG. 5).
In this way, the bearing contact area can be increased or decreased.

  An oil supply passage 59 for supplying lubricating oil is provided between the journals 40a and 41a and the bearings 52a and 53a inside the bearings 52a and 53a. The oil supply passage 59 is provided so as to open to the support surface portions 42a and 43a of the journals 40a and 41a. The oil supply passage 59 is provided so as to communicate from the bearings 52a and 53a to the bearing support portions 711a and 712a, and further communicates from the bearing support portions 711a and 712a to the housing 51a. Is provided. The oil supply passage 59 inside the housing 51a is opened with a larger inner diameter on the bearing support portions 711a and 712a side.

In this example, the oil supply passage 59 is configured to open to the support surface portions 42a and 43a of the journals 40a and 41a regardless of the position where the bearings 52a and 53a can move. .
In addition, the oil supply passage 59 inside the bearing support portions 711a and 712a is located inside the housing 51a regardless of the position within the range in which the bearings 52a and 53a (bearing support portions 711a and 712a) can move. It is configured to communicate with the oil supply passage 59.
Other configurations are the same as those in the first embodiment.

  Also in this case, the contact area between the support surface portions 42 and 43 and the bearings 52 and 53 can be changed by sliding the bearings 52 and 53 relative to the journals 40 and 41 in the axial direction. . Therefore, the bearing contact area that is the contact area between the support surface portions 42 and 43 and the bearings 52 and 53 can be easily controlled. Thereby, the balance shaft 4 can reduce the friction loss in the bearings 52 and 53 while ensuring the durability of the bearings 52 and 53 sufficiently.

  In this example, the balance shaft 4 is configured to increase or decrease the bearing contact area by moving the bearings 52 and 53 in the axial direction with respect to the journals 40 and 41 using the bearing moving means 70. ing. Therefore, the bearing contact area can be easily controlled by changing the axial positions of the bearings 52 and 53 using the bearing moving means 70.

The bearing moving means 70 is configured to move the bearings 52 and 53 in the axial direction by moving the bearing support portions 711 and 712 by the actuator 72. Therefore, the bearing support portions 711 and 712 and the bearings 52 and 53 can be easily and accurately moved by the actuator 72. Thereby, the bearing contact area can be easily and accurately controlled.
The other functions and effects are the same as those of the first embodiment.

In Example 1, it is explanatory drawing which shows the structure of the internal combustion engine which provided the balance shaft. In Example 1, it is explanatory drawing which shows the connection state of a balance shaft and a crankshaft. In Example 1, it is explanatory drawing which shows the support structure of the balance shaft (1st balance shaft) of a state with a small bearing contact area. In Example 1, it is explanatory drawing which shows the support structure of the balance shaft (1st balance shaft) of a state with a large bearing contact area. In Example 2, it is explanatory drawing which shows the support structure of the balance shaft (1st balance shaft) of a state with a small bearing contact area. In Example 2, it is explanatory drawing which shows the support structure of the balance shaft (1st balance shaft) of a state with a large bearing contact area.

Explanation of symbols

4 Balance shaft 40, 41 Journal 42, 43 Support surface 44 Unbalance mass 52, 53 Bearing

Claims (7)

In a support structure for supporting a balance shaft including a plurality of journals rotatably supported by a plurality of bearings and an unbalance mass provided eccentrically with respect to an axis,
The journal has a support surface portion that is supported to face the bearing, and the support surface portion is provided with a larger diameter than both sides in the axial direction.
Of the combination of the journal and the bearing as a pair, at least a pair of the journal and the bearing are configured to be relatively movable in the axial direction while sliding the support surface portion of the journal and the bearing. And a bearing contact area which is an area where the support surface portion and the bearing are in contact with each other by moving both relative to each other in the axial direction. Shaft support structure.   2. The bearing contact area according to claim 1, wherein the journal and the bearing use a journal moving means for moving the journal in the axial direction to move the journal in the axial direction with respect to the bearing. A structure for supporting a balance shaft, characterized in that the structure can be increased or decreased. In Claim 2, the balance shaft is supported by the bearing fixed to a housing,
The journal moving means includes a balance shaft support portion for supporting the balance shaft in the axial direction, and the journal of the balance shaft is moved by moving the balance shaft support portion with respect to the housing by an actuator. A structure for supporting a balance shaft, characterized in that the shaft can be moved in the axial direction.   2. The bearing contact area according to claim 1, wherein the journal and the bearing use a bearing moving means for moving the bearing in the axial direction to move the bearing in the axial direction with respect to the journal. A structure for supporting a balance shaft, characterized in that the structure can be increased or decreased. The bearing according to claim 4, wherein the bearing is fixed to the bearing support portion arranged to be movable with respect to the housing.
The balance shaft, wherein the bearing moving means is configured to move the bearing in the axial direction by moving the bearing support portion with an actuator. In any one of Claims 1-5, the inside of the said bearing is provided with the oil supply path for supplying lubricating oil between the said journal and the said bearing,
The oil supply passage is open to the support surface portion of the journal at any position within a range in which the journal and the bearing can move relative to each other. .   7. The balance shaft support structure according to claim 1, wherein the balance shaft is applied to an internal combustion engine.

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