WO2017198097A1

WO2017198097A1 - Variable torque limited slip differential and method for designing same

Info

Publication number: WO2017198097A1
Application number: PCT/CN2017/083757
Authority: WO
Inventors: 吴春来
Original assignee: 泗阳县勇士机械制造有限公司
Priority date: 2016-05-20
Filing date: 2017-05-10
Publication date: 2017-11-23
Also published as: CN105782389A; CN105782389B

Abstract

Provided is a variable torque limited slip differential. A body of a planet gear (1) of the differential extends around the exterior of a gear tooth carrier (3) as a friction ring (9), and an annular friction boss (10) is disposed at the position on the gear tooth carrier where the gear tooth carrier corresponds to the friction ring. The friction ring and the friction boss are abutted against each other and the force transferring point of the planet gear shifts when the planet gear is pushed and pressed due to a radial force. The differential can not only have the function of limiting slip, but can also change a locking coefficient in a wide range by changing the radius of the friction ring, the pressure angle of the planet gear and the radius of the planet gear.

Description

Variable torque limited slip differential and design method thereof

Technical field

The invention relates to a differential, in particular to a torque-type limited-slip differential, which is specially designed for multi-wheel drive vehicles with front and rear axles or between front and rear wheels with limited slip, and belongs to the technical field of mechanical transmission.

Background technique

In a timely four-wheel drive or multi-wheel drive vehicle, in order to ensure that the vehicle is in the normal driving and off-hook state switching requirements, the differential with limited slip or lock function is often used to achieve the limited slip differential on the market. Mostly mechanical friction plate type, viscous coupling type, and mechanical friction plate type, viscous coupling type limited slip differential will generate a lot of friction heat during the working process, the friction piece itself wears, and the working temperature of the viscous liquid , the failure temperature, etc., will have a great impact on the reliability of the differential, increasing maintenance costs.

Summary of the invention

In order to achieve the above technical purpose, the present invention will adopt the following technical solutions:

A variable torque limited slip differential comprising a pair of half shaft bevel gears, a pair of planet gears, a driven gear and a carrier, each planet gear simultaneously meshing two half shaft bevel gears, the driven The gear is movably sleeved on a half shaft of a half shaft bevel gear, the teeth of the driven gear mesh with the power input shaft, the carrier is fixedly coupled to the wheel of the driven gear, and a pair of planetary gears are coaxially symmetrically distributed On the carrier, the wheel body of the planetary gear extends a ring of friction rings to the outside of the gear carrier, and the gear carrier is provided with a ring of friction bosses corresponding to the friction ring. When the planetary gear is pressed by the radial force, the friction ring and the friction boss interfere with each other, and the planetary gear and the housing boss contact point are offset, causing a change in the moment, thereby achieving a limited slip function.

Further, the right side gear, the left side gear, the planetary gear, the driven gear and the carrier, the planetary gear meshes with the right side gear and the left side gear at the same time, and the driven gear is sleeved to the left half shaft through the end cover. On the half shaft of the gear, the gear teeth of the driven gear mesh with the power input shaft, and the carrier is fixedly connected to the wheel body of the driven gear. A pair of planetary gears are coaxially distributed on the carrier, and the wheel gear of the planetary gear is gear teeth. A friction ring extends from the outside of the frame, and the gear carrier is provided with a frictional protrusion at a position corresponding to the friction ring. When the planetary gear is pressed by the radial force, the friction ring and the friction boss interfere with each other.

A design method using the variable torque differential design according to claim 1, wherein The relationship between the locking factor k and the radius R of the friction ring, the radius r of the planet wheel, and the pressure angle α of the planet gear are:

k=R*sinβ/r,tanβ=(Ft’-Ft”)*tanα/(Ft’+Ft”),

Among them, Ft' and Ft" are the symmetric radial forces on both sides of the planetary gear, and β is the transmission force point offset angle of the friction ring and the frictional projection.

Further, the torque transmission between the planetary gear and the gear carrier is transmitted through the friction ring and the friction boss. During the transmission of the torque, the positive pressure can be decomposed into a circumferential shear force Ft and a radial force Fr, and the relationship between Fr and Ft is:

Fr=Ft*tanα, α is the gear pressure angle,

It can be seen from this formula that the radial force Fr increases as the pressure angle increases.

Further, the difference in symmetric radial force on both sides of the planetary gear is as follows:

f'=Fr'-Fr"=(Ft'-Ft")*tanα,

It can be seen from this formula that f' directly affects the offset of the transmission force point at which the friction ring and the friction boss transmit, and the relationship between the offset angle β and the gear pressure angle α is: tanβ=(Ft'-Ft") *tanα/F, from which the contact point offset angle β and the pressure angle α are proportional to each other.

Further, the left and right forces of the planetary gears are in equilibrium, and the balance of the force moments can be known without considering the frictional force:

F=Ft'+Ft", Ft'*(r-Rsinβ)=Ft"*(r+R*sinβ),

It can be seen that the locking factor is: k=R*sinβ/r. From this formula, the locking coefficient k is proportional to the radius R of the friction ring and inversely proportional to the radius r of the planetary gear. The locking factor k and pressure of this patent are used. The angle α is proportional, so the locking factor can be changed over a wide range with the three parameters of R, r, and α being changed.

The invention adopts the above technical solution, and has the following advantages: during the working process, the torque of the two side gears is changed by changing the displacement of the force point between the planetary gear and the casing, so that the half shaft with better adhesion is obtained. The wheel produces more torque and gets out of trouble. The invention is not realized by high friction in the process of limiting slip, so that high friction heat is not generated, and it is an effective method for solving problems in the technical background.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention;

2 is a schematic view showing the assembly of a planetary gear and a carrier;

Figure 3 is a mechanical analysis diagram of the planetary gears under stress;

Figure 4 is a schematic view of the mechanics of the planetary gear receiving the balance;

Figure 5 is a schematic view of the mechanics of the planetary gear receiving the balance;

Figure 6 is a schematic diagram of the force of the planetary wheel pressure angle α

1. Planetary gear, 2. Right half shaft gear, 3. Gear frame, 4. Limit pin, 5. Limit ring, 6. Left side shaft gear, 7. End cover, 8. Limit shaft, 9. Friction Ring, 10. friction boss, 11. driven gear.

detailed description

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate, without limitation, the structural drawings of the preferred embodiments of the invention.

A torque-type limited slip differential, as shown in FIG. 1, includes a right side gear 2, a left side gear 6, a planetary gear 1, a driven gear 11 and a carrier 3, and the planetary gear 1 simultaneously meshes with the right half The shaft gear 2, the left side gear 6, the driven gear 11 is movably sleeved on the half shaft of the left side gear 6 through the end cover 7, the teeth of the driven gear 11 mesh with the power input shaft, and the carrier 3 is fixedly connected On the wheel body of the moving gear 11, a pair of planetary gears 1 are coaxially symmetrically distributed on the carrier 3, and the wheel body of the planetary gear 1 extends a ring of friction rings 9 to the outside of the gear carrier 3, and the gear carrier 3 is in the same The friction ring 9 is provided with a ring of friction bosses 10 corresponding thereto. When the planetary gear 1 is pressed by the radial force, the friction ring 9 and the friction boss 10 are in contact with each other, and the planetary gear 1 and the housing boss 10 are in contact with each other. Move, causing the torque to change, thus playing a limited slip.

The design method of the differential will be described in detail below with reference to the accompanying drawings. The torque transmission between the friction ring 9 and the friction boss 10 is transmitted through the A surface on the planetary wheel and the B surface on the carrier as shown in FIG. 2, as shown in the figure. As shown in Fig. 6, the positive pressure can be decomposed into the circumferential shear force Ft and the radial force Fr during the transmission of the involute gear. The relationship between Fr and Ft is:

Fr = Ft * tan α, formula (1), α: gear pressure angle.

From equation (1), Fig. 4 shows that the radial force Fr increases with the increase of the pressure angle, and the difference between the symmetric radial forces on both sides of the planetary gear is as follows:

f' = Fr' - Fr" = (Ft' - Ft") * tan α, formula (2).

It can be known from equation (2) that f' directly affects the point of transmission between the A face on the planet gear and the B face on the casing. The offset, as shown in Fig. 4, is the reaction force of f' (Ft', Ft" force difference), and the relationship between the offset angle β and the gear pressure angle α is:

Tanβ=f/F=(Ft'-Ft")*tanα/F, formula (3).

It can be seen from equation (3) that the contact point offset angle is proportional to the magnitude of the pressure angle.

The torque transmission between the friction ring 9 and the friction boss 10 is transmitted through the A face on the planetary gear as shown in FIG. 2 and the B face on the carrier. When the pressure angle is constant, when the left side gear is slipped, the force point change can be simplified from FIG. 3 to FIG. 4, and the planetary gear does not shift left and right at this time, so it can be regarded as the left and right of the planetary gear. The force is in equilibrium. When the friction is not considered, the force is calculated by point A as shown in Fig. 5. The balance of the moments is known:

F = Ft' + Ft", formula (4).

Ft'*(r-Rsinβ)=Ft"*(r+Rsinβ), formula (5).

It can be seen from equation (4) (5) that the locking factor is:

k = R * sin β / r, formula (6).

It can be known from formula (6) that the locking factor k of this patent is proportional to the radius R of the contact surface A, and inversely proportional to the radius r of the planetary wheel. Combined with the formula (3), the formula (6) shows that the locking factor k of the patent and The pressure angle α is proportional. This patent can change the locking factor of this patent to a large extent in the case of changing the three parameters of R, r, and α.

When the left and right side gears produce a difference in speed or one side slips, it can be seen that the resistance difference of the left and right side gears changes. Since the straight bevel gears generate radial thrust during the transmission process, the planetary gears are in the left and right radial direction. Under the action of the force difference, it will be displaced to the side with the small radial force, so that the working point of the planetary gear and the working face of the outer casing will shift from the midpoint in the equilibrium state to the side with the larger adhesion, so that the left and right axles During the transmission process, the arm changes, so a relatively large thrust is obtained in the half of the arm. Thereby it can play a role of limited slip.

The value of the specific locking factor k is as follows:

Ft'=30N, Ft"=10N, α=30°, R=28, r=17.5 (calculated without considering friction)

f'=(Ft’-Ft”)*tanα=(30-10)*tan30=20*0.577

F=Ft’+Ft”=30+10=40

Tanβ=f/F=20*0.577/40=0.2887

β=16.1°

k=R*sinβ/r=28*sin16.1/17.5=0.4437

By changing the radius of the working surface, the pressure angle of the bevel gear, and the radius of the planetary gear, the locking coefficient of the differential is changed within a wide range to achieve the limit slip requirement of different vehicles. When the locking coefficient is 1, it can be used as a free Wheel differential is used.

The patent is installed between the front and rear axle wheels or between the front and rear wheels. It can be expressed as: when one side of the slip occurs, the other side can obtain a larger torque output than the pulley, thus solving the problem that the ordinary differential slips on the side of the occurrence. At the same time, the output torque of the other side becomes smaller at the same time.

The limited sliding effect of the patent is mainly realized by the torque change, and is not realized by the friction, so the friction heat of the existing limited slip differential and the easy loss effect of the friction member are solved, and the maintenance cost is greatly reduced.

Claims

A variable torque limited slip differential comprising a pair of half shaft bevel gears, a pair of planet gears, a driven gear and a carrier, each planet gear simultaneously meshing two half shaft bevel gears, the driven The gear is movably sleeved on a half shaft of a half shaft bevel gear, the teeth of the driven gear mesh with the power input shaft, the carrier is fixedly coupled to the wheel of the driven gear, and a pair of planetary gears are coaxially symmetrically distributed On the carrier, the wheel body of the planetary gear extends a ring of friction rings to the outside of the gear carrier, and the gear carrier is provided with a ring of friction bosses corresponding to the friction ring. When the planetary gear is pressed by the radial force, the friction ring and the friction boss interfere with each other, and the planetary gear and the housing boss contact point are offset, causing a change in the moment, thereby achieving a limited slip function.
The variable torque limited slip differential according to claim 1, comprising: a right side gear, a left side gear, a planetary gear, a driven gear and a carrier, wherein the planetary gear meshes with the right side gear, The left side gear, the driven gear is movably sleeved on the half shaft of the left side gear through the end cover, the gear teeth of the driven gear mesh with the power input shaft, and the carrier is fixedly connected to the wheel body of the driven gear, a pair of planetary gears Coaxially symmetrically distributed on the carrier, the wheel body of the planetary gear extends a ring of friction rings to the outside of the gear carrier, and the gear carrier has a ring of friction protrusions corresponding to the friction ring when the planetary gear receives the diameter When the force is pushed, the friction ring and the friction boss interfere with each other.
A design method using the torque limited slip differential design according to claim 1, wherein the relationship between the locking coefficient k and the radius R of the friction ring, the radius r of the planetary wheel, and the pressure angle α of the planetary gear is :

k=R*sinβ/r,tanβ=(Ft’-Ft”)*tanα/(Ft’+Ft”),

Among them, Ft' and Ft" are the symmetric radial forces on both sides of the planetary gear, and β is the transmission force point offset angle of the friction ring and the frictional projection.
The method for designing a torque limited slip differential according to claim 3, wherein the torque transmission between the planetary gear and the gear carrier is transmitted through the friction ring and the friction boss, and the tooth surface is subjected to the torque transmission process. The positive pressure can be decomposed into a circumferential shear force Ft and a radial force Fr. The relationship between Fr and Ft is:

Fr=Ft*tanα, α is the gear pressure angle,

It can be seen from this formula that the radial force Fr increases as the pressure angle increases.
The torque differential design method according to claim 3, wherein the difference in symmetric radial force between the two sides of the planetary gear is as follows:

f'=Fr'-Fr"=(Ft'-Ft")*tanα,

It can be seen from this equation that f' directly affects the offset of the transmission force point at which the friction ring and the friction boss transmit, and the relationship between the offset angle β and the gear pressure angle α is:

Tanβ=(Ft'-Ft")*tanα/F, from which the contact point offset angle β and the pressure angle α are proportional to each other.
The variable torque differential design method according to claim 3, wherein the left and right forces of the planetary gear are in an equilibrium state, and the balance of the force moments is known without considering the frictional force:

F=Ft'+Ft", Ft'*(r-Rsinβ)=Ft"*(r+Rsinβ),

It can be seen that the locking factor is: k=R*sinβ/r-(6). From this formula, the locking coefficient k is proportional to the radius R of the friction ring and inversely proportional to the radius r of the planetary gear. The coefficient k is proportional to the pressure angle α, so that the locking factor can be changed over a wide range with the three parameters of R, r, and α being changed.