JP7333266B2 - Cooling mechanism of differential - Google Patents

Description

The present invention relates to a cooling mechanism for a differential device mounted on a vehicle.

2. Description of the Related Art Conventionally, a vehicle is equipped with a differential device that performs a differential operation to adjust the rotational difference that occurs between the left and right wheels during cornering, thereby achieving smooth turning. This differential device cools the heat generated by friction between gears and the frictional heat generated in the bearings that hold high-speed rotating shaft members such as the drive pinion shaft, and lubricates the gears and shaft members. , a lubricant such as molybdenum disulfide is put inside.

For example, Patent Literature 1 describes a differential device that enables cooling around a bearing of an input shaft member. The drive pinion shaft of the differential device has a first oil hole that penetrates in the axial direction and a second oil hole that penetrates in the radial direction. Lubricant flows through these oil holes. Patent Document 1 discloses a technique of a differential device that cools a drive pinion shaft by flowing lubricant.

JP 2017-115912 A

By the way, if the amount of lubricant is increased in order to prevent problems such as a decrease in durability and abnormal noise due to frictional heat, the cooling efficiency will improve, but drive loss (spin loss, etc.) will occur. There is a problem that power transmission efficiency deteriorates.

Therefore, in view of the above circumstances, the present invention provides a cooling mechanism for a differential device that suppresses the occurrence of drive loss, improves cooling efficiency, and prevents problems such as deterioration in durability and abnormal noise due to high temperatures. for the purpose.

A cooling mechanism for a differential device according to one aspect of the present invention includes a drive pinion shaft having a cylindrical drive shaft with a drive pinion provided at one end thereof, and a first spiral groove formed on the inner peripheral surface of the drive shaft. a pipe line mounted in the drive pinion shaft and having a hole formed in the one end side and communicating with the inside of the drive shaft at the one end side; is connected to the other end of the drive shaft, a power transmission shaft is fastened, and communicates with the drive shaft and the pipe line at the other end side. It flows along the first spiral groove and the second spiral groove due to the joint sleeve having a space and the centrifugal force accompanying the rotation of the drive shaft, so that the fluid in the drive shaft, the conduit and the joint a cooling medium circulating within the space of the sleeve.

According to the present invention, it is possible to provide a cooling mechanism for a differential device that suppresses the occurrence of drive loss, increases the cooling efficiency, and prevents problems such as deterioration in durability and abnormal noise due to high temperatures.

Cross-sectional view showing the configuration of the differential device An exploded perspective view showing the configuration of the drive pinion shaft, inner pipe and nut Sectional view showing the configuration of the drive pinion shaft Sectional view showing the configuration of the inner pipe A cross-sectional view showing the drive pinion shaft, inner pipe, nut, joint sleeve and propeller shaft assembled to explain the circulation of the liquid coolant. Cross-sectional view along the VI-VI line in FIG. The figure which shows the joint sleeve which has a radiation fin of a modification.

An embodiment of one aspect of the present invention will be described in detail below with reference to the drawings. In the drawings used for the following explanation, the scale of each component is changed in order to make each component recognizable on the drawing. It is not limited only to the number of components, the shape of the components, the size ratios of the components, and the relative positions of the components as described.

The cooling mechanism of the differential device of this embodiment will be described below.
Here, the differential device, which is the differential device, will be described here by exemplifying a rear differential device (so-called rear differential) that transmits power to the wheels on the rear wheel side of the vehicle. It should be noted that the configuration described below is a technique that can be applied to a front differential device (so-called front differential) that transmits power to the front wheels of the vehicle, as well as other cases than the rear differential.

A differential device 1 shown in FIG. 1 includes a differential carrier 2 which is a housing as a case body as an exterior part. The differential carrier 2 is provided with a hypoid gear 20 formed by meshing a drive pinion 11 of a drive pinion shaft 10 and a ring gear 21 on the rear side.

Further, the hypoid gear 20 is provided in a hypoid gear chamber 4 which is a closed space formed by attaching a carrier cover 3 as a lid to the differential carrier 2 .

The drive pinion shaft 10 has a cylindrical drive shaft 12 extending forward from a drive pinion 11 which is a gear portion. The drive shaft 12 is supported by three bearings 22 such as a hall bearing on the front side and a thrust bearing on the center and rear sides.
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Lubricants (not shown) such as differential oil, molybdenum disulfide, and a mixture thereof are injected into the hypoid gear chamber 4 to reduce frictional heat and wear of the hypoid gear 20 and the rotating drive pinion shaft 10.

The lubricant is scooped up by the rotation of the ring gear 21, circulates in the space inside the differential carrier 2, and lubricates the parts to be driven.

The drive shaft 12 is connected to a joint sleeve 13 having internal teeth 16 formed by a spline having external teeth 15 formed at the front end portion. An oil seal 5 is provided at the front end of the differential carrier 2, and the oil seal 5 holds a rotating joint sleeve 13 in a liquid-tight manner.

The joint sleeve 13 is bolted to the joint portion 7 of the propeller shaft 6, which is a driving force transmission shaft member, via a gasket. A space 14 is formed inside the joint sleeve 13 connected to the joint portion 7 of the propeller shaft 6 .

In this way, in the differential device 1 , the power of the rotation of the propeller shaft 6 is transmitted to the drive pinion 11 through the drive pinion shaft 10 .

That is, the rotational power transmitted from the drive pinion shaft 10 rotates the drive pinion 11 in the axial direction substantially orthogonal to the axial direction of the rotation axis C, thereby transmitting the power to the wheels.

Here, the main configuration of the cooling mechanism of the differential device 1 of the present embodiment will be described.
As shown in FIG. 2, the drive pinion shaft 10 is closed by a rear-side live pinion 11, and the drive shaft 12 has a hollow pipe shape. An inner pipe 30, which is a conduit, is mounted inside the drive pinion shaft 10, and a nut 17 is screwed to the front end of the inner pipe 30. As shown in FIG.

The inner pipe 30 has an outward flange-shaped rear connection end portion 31 at the rear end portion, a pipe body 32 extending from the connection portion 31 to the front side, and a front end portion of the pipe body 32. and a front-side connection end portion 33 .

A male threaded portion 35 is formed on the outer periphery of the rear connection end portion 31 , and the male threaded portion 35 is screwed into a female threaded portion 39 formed on the inner peripheral surface of the drive pinion shaft 10 on the front side. is worn (see FIG. 5).

The pipe body 32 has an outer diameter smaller than the inner diameter of the drive pinion shaft 10 . This pipe body 32 has a plurality of holes 34, six holes 34 on one side in this case, which communicate with the inside at substantially equal intervals in a predetermined range on the rear side, and are arranged in parallel along the longitudinal direction. A total of 12 holes 34 are drilled at point-symmetrical positions around it (see FIG. 4).

The front-side connection end portion 33 is provided so that four connection pieces 36 protruding in the outer diameter direction of the pipe body 32 are arranged at equal intervals in the circumferential direction. Four notches 37 are formed. The four connecting pieces 36 have a female threaded portion 19 engraved on the inner surface of the front end of the drive pinion shaft 10 and a male threaded portion 38 to be screwed into the female threaded portion 18 of the nut 17. there is

The front-side connection end portion 33 is formed, for example, by cutting out four recesses at equal intervals in the circumferential direction from the cylindrical body to the outer peripheral surface of the pipe body 32 so that the four notches 37 and the four connection pieces 36 are formed in the pipe body 32. It is formed integrally with the front end.

As shown in FIG. 3, the drive pinion shaft 10 is tapped so as to form helical unevenness on the inner peripheral surface of the drive shaft 12, and a helical groove 41 for conveying coolant, which will be described later, is formed. ing.

The helical groove 41 is tapped in a winding direction opposite to the rotating direction of the drive pinion shaft 10 when the vehicle moves forward so that the cooling fluid is sent to the front side. Note that the direction of rotation of the drive pinion shaft 10 when the vehicle moves forward here is the clockwise direction viewed toward the rear side, and the spiral direction of the spiral groove 41 is the counterclockwise direction viewed toward the rear side. is tapped to

As shown in FIG. 4, the inner pipe 30 also has a spiral groove 42 formed on the inner peripheral surface of the pipe body 32 by tapping such that spiral unevenness is formed to feed the coolant. The spiral groove 42 has a spiral direction opposite to the spiral direction of the spiral groove 41 of the drive shaft 12 .

That is, the helical groove 42 is tapped in a helical direction that is the same as the direction of rotation of the drive pinion shaft 10 when the vehicle moves forward so that the cooling fluid is sent to the rear side. As described above, the rotational direction of the drive pinion shaft 10 when the vehicle moves forward is the clockwise direction when viewed toward the rear side, so the spiral direction of the spiral groove 42 is clockwise when viewed toward the rear side. Tapped all around.

First, the inner pipe 30 is inserted into the drive pinion shaft 10 , and the rear connecting end portion 31 is screwed to the female screw portion 39 and the front connecting end portion 33 is screwed to the female screw portion 19 .

Next, the joint sleeve 13 is spline-coupled to the front end portion of the drive pinion shaft 10 , and the nut 17 is screwed to the front-side connecting end portion 33 of the inner pipe 30 .

Then, as shown in FIG. 5, a predetermined amount of liquid coolant R (indicated by broken lines in the drawing), which is a cooling medium such as coolant or oil, is injected into the drive pinion shaft 10 and the inner pipe 30. After that, the joint sleeve 13 and the joint portion 7 of the propeller shaft 6 are fastened.

A gap is formed between the inner peripheral surface of the drive pinion shaft 10 and the outer peripheral surface of the inner pipe 30 to form an outer flow path 43 through which the liquid coolant R flows in one direction. Further, the pipeline of the inner pipe 30 constitutes an inner flow path 44 through which the liquid coolant R flows in the other direction.

In the cooling mechanism of the differential device 1 configured as described above, the internal liquid coolant R flows through the flow paths 43 and 44 according to the rotation of the drive pinion shaft 10 to which the rotational driving force from the propeller shaft 6 is transmitted. It flows and circulates (circulates).

Specifically, the drive pinion shaft 10 to which the rotational driving force for moving the vehicle forward is transmitted rotates clockwise (in the RF direction in the figure) when viewed toward the rear side.

At this time, centrifugal force causes the liquid coolant R in the drive pinion shaft 10 to exert an inertial force on the inner peripheral surface side of the drive shaft 12 and the inner peripheral surface side of the pipe main body 32, thereby It flows along the spiral groove 42 of the pipe body 32 .

The rotation RF of the drive pinion shaft 10 causes the liquid coolant R in the outer flow path 43 to flow from the rear side to the front side along the spiral groove 41 of the drive shaft 12 . The liquid coolant R in the outer flow path 43 then flows into the space 14 of the joint sleeve 13 .

At this time, the liquid coolant R passes through four cutouts 37 (see FIG. 6) provided in the front-side connecting end portion 33 of the inner pipe 30 at the front-side end portion of the drive pinion shaft 10, and then the nut 17. It flows into the space 14 of the joint sleeve 13 through the opening 17 a and flows into the inner flow path 44 . That is, the four cutouts 37 and the space 14 form a front-side communication path that communicates the outer flow path 43 and the inner flow path 44 .

On the other hand, the liquid coolant R in the inner flow path 44 flows from the front side to the rear side along the spiral groove 42 of the pipe body 32 . The liquid coolant R in the inner flow path 44 flows out into the outer flow path 43 through a plurality of, here 12, holes 34 formed on the rear side of the pipe body 32 . That is, each hole 34 constitutes a rear-side communication passage that communicates the outer flow path 43 and the inner flow path 44 .

The liquid coolant R injected into the drive pinion shaft 10 in this way circulates through the outer flow path 43, the space 14 and the inner flow path 44 as the drive pinion shaft 10 rotates.

Therefore, the liquid coolant R circulating in the drive pinion shaft 10 absorbs heat generated by friction of the hypoid gear 20 and frictional heat generated when the drive pinion shaft 10 rotates mainly from the rear side. By flowing toward the front side and into the space 14, the heat is radiated from the joint sleeve 13 exposed to the outside air, and it is possible to suppress the temperature rise of the differential device 1. - 特許庁

As described above, the cooling mechanism of the differential device 1 according to the present embodiment prevents the temperature of the differential device 1 from rising by circulating the liquid coolant R in the drive pinion shaft 10 between the front and the rear so as to absorb and release heat. It is configured to suppress

Therefore, the cooling efficiency is improved without increasing the amount of lubricant in the differential device 1 . As a result, the differential apparatus 1 can maintain the specified amount of the lubricant, does not cause drive loss (spin loss, etc.), and prevents deterioration of the power transmission efficiency.

From the above explanation, it is possible to suppress the occurrence of driving loss of the differential device 1 by the cooling mechanism of the differential device 1, improve the cooling efficiency, and prevent the deterioration of durability due to high temperature and the occurrence of problems such as abnormal noise. can.

The injection amount of the liquid coolant R is determined by the outward flow path 43, which does not impair the fluidity of the liquid coolant R along the spiral grooves 41, 42 due to the centrifugal force accompanying the rotation of the drive pinion shaft 10. A predetermined amount less than the total capacity of the inner flow path 44 and the space 14 is set.
Moreover, the holes 34 formed in the pipe body 32 of the inner pipe 30 may be formed on the rear side, and the number and positions thereof can be changed as appropriate.

In the above description, the rotational driving direction of the drive pinion shaft 10 with respect to forward movement of the vehicle has been described.

Furthermore, the helical directions of the helical groove 41 of the drive shaft 12 and the helical groove 42 of the pipe body 32 are not limited to the directions described above, and may be opposite directions. Further, the groove depth and pitch of the spiral grooves 41 and 42 can be appropriately changed depending on the diameters of the drive pinion shaft 10 and the inner pipe, the assumed maximum number of revolutions, the rigidity, and the like.

(Modification)
As shown in FIG. 7, the joint sleeve 13 may have radiating fins 50 to improve cooling efficiency. Furthermore, since the heat of the joint sleeve 13 is transmitted to the joint portion 7 of the propeller shaft 6, the joint portion 7 may also be provided with heat radiation fins.

The invention described in the above embodiments is not limited to those forms, and various modifications can be made at the stage of implementation without departing from the scope of the invention. Furthermore, each of the above forms includes inventions at various stages, and various inventions can be extracted by appropriate combinations of the disclosed multiple constituent elements.
For example, even if some constituent elements are deleted from all the constituent elements shown in each form, if the stated problem can be solved and the stated effect can be obtained, this constituent element is deleted A configuration can be extracted as an invention.

DESCRIPTION OF SYMBOLS 1... Differential device 2... Differential carrier 3... Carrier cover 4... Hypoid gear chamber 5... Oil seal 6... Propeller shaft 7... Joint part 10... Drive pinion shaft 11... Drive pinion 12... Drive shaft 13... Joint sleeve 14... Space 15... External teeth 16 Internal teeth 17 Nut 17a Opening 18 Female screw 19 Female screw 20 Hypoid gear 21 Ring gear 30 Inner pipe 31 Rear connection end 32 Pipe body 33 Front connection end Part 34... Hole 35... Male screw part 36... Connection piece 37... Notch 38... Male screw part 39... Female screw parts 41, 42... Spiral groove 43... Outer flow path 44... Inner flow path 50... Radiation fin C … Rotating shaft R … Liquid coolant

Claims (4)

a drive pinion shaft having a cylindrical drive shaft with a drive pinion provided at one end;
a first spiral groove formed on the inner peripheral surface of the drive shaft;
a pipe line that is mounted inside the drive pinion shaft and has a hole that is formed at the one end side and communicates with the inside of the drive shaft at the one end side;
a second spiral groove formed on the inner peripheral surface of the pipeline and having a winding direction opposite to the first spiral groove;
a joint sleeve which is connected to the other end of the drive shaft and has a space inside which a power transmission shaft is fastened and which communicates with the drive shaft and the conduit on the other end side;
It flows along the first spiral groove and the second spiral groove due to the centrifugal force caused by the rotation of the drive shaft, and circulates in the drive shaft, the conduit, and the space of the joint sleeve. a cooling medium that
A cooling mechanism for a differential, comprising: An outer flow path formed by the inner peripheral surface of the drive shaft and the outer peripheral surface of the conduit communicates with the inner flow path of the conduit through the hole on the one end side and the space on the other end side. 2. A cooling mechanism for a differential device according to claim 1, characterized in that the cooling mechanism comprises: The winding direction of the first spiral groove is set so that the cooling medium in the outer flow path flows toward the other end when the drive shaft rotates in the direction in which the vehicle moves forward. 3. A cooling mechanism for a differential device according to claim 2, wherein the winding direction of said second spiral groove is set so that said cooling medium in the inner flow path flows in said one end direction. 4. A cooling mechanism for a differential device according to claim 1, wherein said joint sleeve has radiation fins.

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