JP2545796B2 - Differential - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a differential device, and more particularly to a differential device suitable as a differential gear of a drive system of a vehicle.

(Prior Art) When one wheel of a plurality of wheels coupled to a drive system having a differential gear rides on a road surface having a low friction coefficient such as snow and spins, due to the inherent characteristics of the differential gear, A phenomenon occurs in which the driving force to the other wheels connected to the driving system is reduced or the driving force is not transmitted to the other wheels at all. In order to suppress the occurrence of such a phenomenon and to actively control the turning radius of the turning, a differential case that rotatably supports the pinion and two side gears that are rotatably arranged in the differential case are provided. In a differential gear including a planetary gear train consisting of two rotating parts, a ring gear for transmitting power is attached to the differential case, and auxiliary power is transmitted to one of two shafts respectively connected to the two side gears. A differential device has been proposed in which the actuator is attached and the actuator is controlled by a control device (Japanese Patent Laid-Open No. 61-102333).

(Problems to be Solved by the Invention) In the differential device according to the above proposal, since the actuator such as the motor is directly fixed to the outer periphery of the differential case, it is necessary to avoid the interference between the drive pinion meshing with the ring gear and the actuator. Therefore, it is necessary to increase the outer diameter of the ring gear, which increases the overall size of the differential device. Further, since the actuator and the control device are directly attached to the rotating body such as the differential case, it is difficult to secure the reliability against the centrifugal force and to balance the rotating body.

An object of the present invention is to provide a differential device that can be downsized, can easily secure reliability against centrifugal force, and can be easily balanced.

Another object of the present invention is to provide a differential device which can prevent the driving force transmitted to the other wheels from being reduced when one of the plurality of driving wheels tries to idle.

(Means for Solving Problems) A differential device according to the present invention includes a rotatable pinion (34).
And a planetary gear train having three rotating parts including a pair of side gears (36) and concentric shafts (44, 48) connected to the side gears (36), and the planetary gear train. Means (50, 62) for rotating one of the rotating parts of the gear train, worm and worm wheel driving means (54) for driving another of the rotating parts, steering angle sensor (108) and vehicle speed Sensor (11
0), and a control device (106) for controlling the rotation speed of the drive means (54) for the worm and the worm wheel. This differential (3
0) has a single planetary gear train and is arranged between the left and right drive shafts (118, 124, 142, 148). One of the shafts (44, 48) has a gear train (116, 120, 14).
The left and right drive shafts (118, 1)
24, 142, 148), and the other of the shafts (44, 48) has drive couplings (122, 126, 128, 146, 150, 152) for transmitting driving force in the same rotational direction. Through the left and right drive shafts (118, 124, 142, 14
It is connected to the other side of 8).

(Operation and Effect) When the differential device is used as the front differential gear of the drive vehicle or as the rear differential gear of the rear wheel drive vehicle, the two shafts are individually connected to the drive wheels.

The control device calculates based on the signals from the steering angle sensor and the vehicle speed sensor, and controls the rotation speed of the worm and the drive means of the worm wheel.

Since the worm and the worm wheel are used, it is not necessary to fix an actuator such as a motor directly to the outer circumference of the rotating body. Therefore, the differential device can be formed in a small size, reliability against centrifugal force can be ensured, and vibration due to imbalance can be prevented.

According to the aspect in which the control device of the differential device controls the driving means for the worm and the worm wheel so as to maintain the rotational speed difference between the two shafts within a predetermined range, when the vehicle goes straight, either As a result of the drive wheels of the vehicle riding on snow or the like, if the drive wheels try to rotate at a rotational speed that exceeds the rotational speed that corresponds to the vehicle speed, the control device sets the rotational speed of the drive wheel to the rotational speed that corresponds to the vehicle speed. And keep the difference in rotational speed between the two drive wheels within a predetermined range. As a result, even when one of the plurality of drive wheels tries to idle, the power can be reliably transmitted to the other drive wheels. Further, when the vehicle turns, the control device maintains the difference between the rotational speeds of the drive wheels located outside the turning and the rotational speeds of the drive wheels located inside the turning within a predetermined range. You can turn without.

(Embodiment) The differential device 30 shown in FIGS.
And the pinion 34 arranged in the case 32 and the side gear
And 36.

The case 32 is a so-called differential case, which is arranged in the differential carrier 38 and is rotatably supported by a pair of rolling bearings 40 mounted on the differential carrier 38.

The pinion shaft 42 is attached to the case 32. In the embodiment shown in FIG. 2, two pinion shafts 42 are arranged orthogonal to each other. These pinion shafts
42 is an array in which each axis is orthogonal to the rotation axis of the case 32. A pair of pinions 34 are mounted on each pinion shaft 42 at intervals in the axial direction, and these pinions 34 are rotatably supported by the pinion shaft 42. If there is one pinion shaft 42, then two pinions
34 is rotatably supported by the pinion shaft 42. The case 32 and the pinion shaft 42 form a carrier assembly of the pinion 34.

Two side gears 36 are arranged in the case 32 at intervals, and each side gear 36 meshes with four pinions 34. The pinion carrier assembly and the two side gears 36 form a planetary gear train.

The first shaft 44 is serration-coupled to the one side gear 36, extends in one direction from the case 32, and protrudes from the differential carrier 38. The shaft 44 is supported on the shoulder of the case 32 via the boss 37 of the side gear 36 and on the bearing 46 via a rotating means 50 described later, and is rotatable about the axis of the case 32.

A second shaft 48 is serration-coupled to the other side gear 36, extends from the case 32 in a direction opposite to the first shaft 44, and projects from the differential carrier 38. The shaft 48 is supported by the shoulder of the case 32 via the boss 37 of the side gear 36 and by a bearing (not shown).
It can rotate around 32 axes.

The rotating means 50 includes a case 32, a first shaft 44 and a second shaft.
Incorporated into one of the shafts 48 of the. In the embodiment shown in FIG. 1, the rotating means 50 is a spur gear 50, and the first shaft
Serrated to 44. A pair of rolling bearings are mounted between the boss 51 projecting on both sides of the spur gear 50 and the differential carrier 38, and the spur gear 50 is rotatable about the same axis as the first shaft 44.

The rotating means 50 is engaged with another rotating means, which will be described later, so that the first shaft 44 and the second shaft 48 are combined with each other.
Transmits the driving force to.

A worm wheel 52 is incorporated into the case 32, one of the first shaft 44 and the second shaft 48 without the rotating means 50. In the embodiment shown in FIGS. 1 and 2, the worm wheel 52 is attached to the case 32.

The means 54 for driving the worm wheel 52 includes a worm 55. The worm 55 is rotatably supported by the differential carrier 38, the electric motor 56 is further attached to the differential carrier 38, and the shaft of the worm 55 is serration-coupled to the output shaft 57 of the electric motor 56.

As will be described later, signals from the steering angle sensor and the vehicle speed sensor are input to the control device. This control device controls the rotational speed of the driving means 54 to keep the rotational speed difference between the first shaft 44 and the second shaft 48 within a predetermined range. Further, the electric motor 56 is rotated at a rotational speed slightly higher than the theoretical value obtained by the calculation described later.

The differential device 60 shown in FIG. 3 is the same as the differential device 30 shown in FIGS. 1 and 2 in terms of the basic configuration. That is, the differential device 60 includes a case 32 rotatably supported by the differential carrier 38 and a pinion rotatably supported by a pinion shaft 42 arranged in the case 32.
34 and a pair of side gears 36 which are arranged in the case 32 so as to be engaged with the pinion 34. The differential 60 also includes a first shaft 44 extending from one side gear 36 and a second shaft 48 extending from the other side gear 36 in a direction opposite to the first shaft 44.

In the differential device 60, the spur gear 62, which is the rotating means, is the case 32.
It is attached by bolt 64 to. The spur gear 62 is rotated by another gear, the first shaft 44 and the second
The driving force is transmitted to the shaft 48 of. On the other hand, the worm wheel 66 is serration-coupled to the first shaft 44. The worm wheel 66 is rotated by the worm 68 to keep the rotational speed difference between the first shaft 44 and the second shaft 48 within a predetermined range.

 The aforementioned differential device is used in various ways.

Fourth Embodiment schematically showing an embodiment in which the differential device 30 is used as a front differential gear in a front-wheel drive vehicle
In the figure, the differential device 30 is interposed between the front wheels 90, 90.

A spur gear 116 is attached to the first shaft 44 of the differential device 30 and a spur gear 120 is attached to the left drive shaft 118, which meshes with the spur gear 116. The spur gears have the same number of teeth, whereby the rotation of the first shaft 44 is reversed, and the first shaft 44 is taken out to the left drive shaft 118.

A sprocket or pulley 122 is mounted on the second shaft 48 of the differential 30 while the right drive shaft 1
A sprocket or pulley 126 is attached to 24, and a chain or belt 128 is stretched between the second shaft 48 and the right drive shaft 124. This forms a drive coupling that transmits the driving force in the same rotational direction.

A spur gear 98 is connected to the transmission 100 and meshes with the spur gear 50. As a result, the transmission
Power from 100 is transmitted to the left front wheel 90 via the pair of spur gears 116, 120 and the left drive shaft 118 on the one hand, and to the right front wheel 90 via the differential 30, chain or belt 128 and the right drive shaft 124 on the other hand. To be

The control device 106 includes a steering angle sensor 108 and a vehicle speed sensor 110.
The signal from is input. The control device 106 calculates the rotational speed of the case by halving the differential rotational speed Δn ₁ of the front wheels, which will be described later, and multiplies the rotational speed of the case by the final reduction ratio i of the differential device 30 to output the electric motor 56. The theoretical rotation speed M is calculated. Then, the theoretical rotation speed M is multiplied by a constant A to obtain a control voltage, and the case is rotated. The actual rotation speed M ₀ of the electric motor 56 obtained by rotating the case is detected, and the left (MA−M ₀ A) is fed back to rotate the case. In this way,
Controls the rotation speed of the electric motor 56.

In FIG. 5, which schematically shows an embodiment in which two differential devices 30 are used as a front differential gear and a rear differential gear in a four-wheel drive vehicle, and a normal differential device is used as the center differential gear 130, in FIG. The differential carrier of the differential device 30 is arranged between the front wheels 90, 90, and the differential carrier of the rear differential device 30 is arranged between the rear wheels 132, 132, respectively, and are fixed to the vehicle body.

Spur gears on the first shaft 44 of the front side differential 30
116 is mounted, and further to the left drive shaft 118 is mounted a spur gear 120, which meshes with the spur gear 116. The spur gears have the same number of teeth, which reverses the rotation of the first shaft 44 and causes the left drive shaft 118 to rotate.
Taken out.

The sprocket or pulley 122 is attached to the second shaft 48 of the front side differential device 30, while the sprocket or pulley 126 is attached to the right drive shaft 124, and the second shaft 48 and the right drive shaft 124 are attached.
A chain or belt 128 is stretched between and.

A bevel gear 134 is connected to the shaft 136 of the differential gear 130 and is connected to the transmission 100 via the differential gear 130. Further, a bevel gear 50 which is a rotating means meshes with a bevel gear 134. As a result, the power from the transmission 100 is transmitted to the differential device 130, the bevel gears 134, 50.
To the first shaft 44 and then to the left front wheel 90 via the pair of spur gears 116, 120 and the left drive shaft 118 on the one hand and the differential 30, the chain or belt 128 and the right drive shaft 124 on the other hand. After that, it is transmitted to the right front wheel 90.

The spur gear 140 is attached to the first shaft 44 of the differential device 30 on the rear side.
And a spur gear 144 is attached to the right drive shaft 142, which meshes with the spur gear 140. The spur gears have the same number of teeth, whereby the rotation of the first shaft 44 is reversed, and the first shaft 44 is taken out to the right drive shaft 142.

A sprocket or pool 146 is attached to the second shaft 48 of the rear side differential device 30, while a sprocket or pulley 150 is attached to the left drive shaft 148, between the second shaft 48 and the left drive shaft 148. A chain or belt 152 is stretched over.

A bevel gear 154 is coupled to the shaft 156 of the differential 130 and is coupled to the transmission 100 via the differential 130. Further, a bevel gear 50, which is a rotating means, meshes with a bevel gear 154. As a result, the power from the transmission 100 reaches the first shaft 44 via the differential 130, the bevel gears 154, 50, and then, on the one hand, via the pair of spur gears 140, 144 and the right drive shaft 142. It is transmitted to the wheel 132, on the other hand, via the differential 30, the chain or belt 152 and the left drive shaft 148 to the left rear wheel 132.

The control device 106 includes a steering angle sensor 108 and a vehicle speed sensor 11
Calculates the signal from 0, while the front differential 3
0 to control the electric motor 56 of the left and right front drive shafts 118 and 124 to keep the left side of the rotational speed within a predetermined range, while controlling the electric motor 56 of the rear side differential device 30 to control the left and right rear drive shafts 148, The rotational speed difference of 142 is kept within a predetermined range.

The calculation in the control device is performed by appropriately using the following equations.

As shown in FIG. 6, the rotation speed of the front propeller shaft is N ₁ , the vehicle wheel base is 1, the tread is m, the tire turning angle is δ, and the final reduction ratio of the front differential gear is i ₁ . Rotation speed N ₁
And the tire cutting angle δ are detected by a vehicle speed sensor and a steering angle sensor, respectively.

Then, the front wheel average turning radius R ₁ (OB), the rear wheel average turning radius R ₂ (OA), the front inner wheel turning radius R ₁₁ (OC), the front outer wheel turning radius R ₁₂ (OD), and the rear inner wheel turning radius R ₂₁ ( OE) and the rear outer wheel turning radius R ₂₂ (OF) are as shown in Fig. 6.

Rear propeller shaft rotation speed N ₂ , front / rear propeller shaft rotation speed difference ΔN, front wheel average rotation speed
n ₁ and the rear wheel average rotation speed n ₂ are as follows.

N ₂ = cosδ ・ N ₁ ΔN = N ₁ −N ₂ = (1-cosδ) N ₁ Then, the rear inner wheel rotation speed n ₂₁ is From the relationship, Similarly, the rear outer wheel rotation speed n ₂₂ is From the relationship, Therefore, the rear wheel differential rotation speed Δn ₂ is On the other hand, the front inner ring rotation speed n ₁₁ is From the relationship, Similarly, the front outer wheel rotation speed n ₁₂ is From the relationship, Therefore, the front wheel differential rotation speed Δn ₁ is obtained from Δn ₁ = (n ₁₂ −n ₁₁ ).

[Brief description of drawings]

1 is a cross-sectional view of the differential gear cut along the rotation axis of the case, FIG. 2 is a cross-sectional view cut along the line 2-2 of FIG. 1, and FIG. 4 is a sectional view of the embodiment of the present invention taken along the axis of rotation of the case, FIG. 4 and FIG. 5 are diagrams schematically showing a specific application using a differential device, and FIG. It is a figure which shows the cutting angle and other specifications. 30、60 …… Differential unit 32 …… Case 34 …… Pinion 36 …… Side gear 38 …… Differential gear 44 …… 48 …… Shaft 50,62 …… Rotation means (spur gear) 52,66 …… Worm wheel 55 , 68 …… Warm

Claims (4)

(57) [Claims] 1. A concentric shaft (44) having three rotating parts including a rotatable pinion (34) carrier assembly and a pair of side gears (36) and connected to the side gears (36). , 48), means for rotating one of the rotating parts of the planetary gear train (50, 62), and means for driving a worm and a worm wheel for driving another of the rotating parts (50, 62). 54), and a control device (106) for performing calculation based on signals from the steering angle sensor (108) and the vehicle speed sensor (110) and controlling the rotational speed of the drive means (54) for the worm and the worm wheel. A differential gear (30) comprising a single planetary gear train, and
It is arranged between the left and right drive shafts (118, 124, 142, 148), and one of the shafts (44, 48) is the left and right drive shafts via a gear train (116, 120, 140, 144). (118, 124, 142, 148) and the other of the shafts (44, 48) is connected to one of the drive couplings (122, 126, 128, 14) for transmitting the driving force in the same rotational direction.
6, 150, 152) through the left and right drive shaft (1
18, 124, 142, 148) connected to the other of the differentials. 2. A driving means (54) for the worm and worm wheel drives a carrier assembly of the pinion, and a rotating means (50) for the shaft (44, 4).
8) The differential device according to claim 1, which drives one side. 3. The control device (106) includes the shaft (4).
4. The differential device according to claim 2, wherein the driving means (54) for the worm and the worm wheel are controlled so as to maintain the rotational speed difference (4, 48) within a predetermined range. 4. The worm and worm wheel drive means (66, 68) drive one of the shafts (44, 48) and the rotating means (62) drives the pinion carrier assembly. The differential gear according to the range (1).