JPH01115728A - Four-wheel-drive device - Google Patents

Abstract

PURPOSE:To eliminate the need for a design anticipating excessive torque by arranging a torque limiter onto a driving shaft arranged between plural numbers of axles in such a way as to be in series with a viscous coupling so as to control input torque to a differential gear device arranged onto a rear wheel axle. CONSTITUTION:Torque outputted from a front engine 1 is inputted into a prime moving shaft 5 acting as No.1 axle via a speed change gear 2, besides, the prime moving shaft 5 drives a right and a left front wheel 5 and 6 acting as No.1 wheel via a differential gear 4 respectively. And then, the driving shaft 5 is connected with one end of a driving shaft 8 via a gear train 7, and moreover, a viscous coupling 10 is arranged onto the driving shaft 8. In addition, the other end of the driving shaft 8 is connected with a differential gear 14 of a driven shaft 13 acting as No.2 axle driving a right and a left rear wheel 11 and 12 acting as No.2 wheel. In the constitution as described above, a torque limiter 9 is arranged onto the driving shaft 8 in series with the viscous coupling 10. This constitution controls torque inputted into the differential gear 14 to be less than a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides a first wheel driven by a first axle to which the output torque of an engine is input, and a first wheel driven by a first axle to which the output torque of the engine is input via a viscous coupling. The present invention relates to a four-wheel drive device including a second wheel driven by a second axle.

[Prior Art and its Problems] Conventionally, the above-mentioned type of four-wheel drive device has been known, and as shown in FIG. It is simply called differential.)3
3, the first axle 34 inputs the first
The second wheel drives the wheel 35 while the second wheel drives the second wheel 36.
A viscous coupling (viscous clutch) 40 is interposed in the middle of the drive shaft 39 that transmits the output torque of the engine to the differential 38 of the axle 37, so that when the first wheel 35 loses traction and starts to slip or skid. , by operating the viscous coupling 40 and also driving the second wheel 36, the system shifts to four-wheel drive (Japanese Patent Application Laid-open No. 1983-1999).
(See Publication No. 172764).

By the way, in this type of four-wheel drive device, structurally,
Since the frequency at which driving force is input to the differential 38 of the second axle 37 is extremely low, it is possible to make the differential 38 smaller, but excessive torque is applied due to the bump phenomenon of the screw coupling 40, etc. Therefore, in order to ensure reliability, it is necessary to use a large differential 38 which is advantageous in terms of strength, resulting in a problem of deterioration of fuel efficiency.

[Object of the invention] The present invention has been made in view of the above problems, and includes:
In the above-mentioned type of four-wheel drive system, the basic purpose is to make the differential of the second axle more compact, improve fuel efficiency, and reduce the load on the differential in this case.

[Structure of the Invention] Therefore, in the present invention, we focused on the fact that the frequency of use of the second axle differential is extremely low, and therefore there is no need for the differential to have greater durability than necessary, and A torque limiter is provided in series with the viscous coupling on the drive shaft that connects the second axle to limit the input torque to the differential of the second axle to a predetermined setting value or less.

[Effects of the Invention] According to the present invention, since the input torque to the differential of the second axle is limited by the torque limiter, the strength and durability of the differential side need only be set in anticipation of the upper limit of human torque. As a result of no longer having to ensure strength and durability in anticipation of excessive torque, the differential can be made more compact, which in turn improves fuel efficiency.

[Embodiments] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

As shown in FIG. 1, which schematically shows the configuration of a four-wheel drive system according to the present invention, the output torque of the front engine l is directly inputted to a driving shaft 3 as a first axle via a transmission 2. The driving shaft 3 drives left and right front wheels 5 and 6 as first wheels via a differential 4. This driving shaft 3
is connected to one end of a drive shaft 8 via a gear train 7, and a torque limiter 9 and a viscous coupling IO are interposed in series in the middle of the drive shaft 8. The other end of this drive shaft 8 is connected to an input shaft of a differential 14 of a driven shaft 13 as a second axle that drives left and right rear wheels 11, 12 as second wheels. This torque limiter 9 regulates the torque input to the differential 14 of the driven shaft 13 to be below a preset upper limit when the viscous coupling IO is connected.
The load on the differential gear 14 is reduced by preventing input from occurring.

FIG. 2 schematically shows a structure in which the torque limiter 9 and the viscous coupling 10 are integrated. In this case, the torque limiter 9 is a viscous coupling l.
The rotational torque of the input drive shaft 81 is first transmitted to the multi-disc clutch type torque limiter 9, and then a viscous coupling! 0 is connected, the output is output from the output side drive shaft 8o via the viscous coupling 10.

When the rotational torque of the input drive shaft 81 increases beyond a preset upper limit, the clutch plate 15, which is slidably built into the multi-disc clutch type torque limiter 9, responds to the spring force of the spring 16 due to the increase in internal pressure. As a result, the internal pressure is relaxed, the degree of coupling is lowered, and the transmitted torque is regulated to an upper limit value.

FIG. 3 shows an example of the mechanical torque limiter 9. In this example, the cone clutch 1 is integrally formed with the tapered surface of the clutch plate 17 which is serrated connected to the tip of the input drive shaft 81 and the end of the output drive shaft 80.
The clutch plate 17 is brought into frictional contact with the tapered surface of the clutch plate 17 to transmit torque, and when the transmitted torque rises above the upper limit value, the clutch plate 17 By moving the cone clutch 18 backward relative to the cone clutch 18, the transmitted torque is regulated to an upper limit value.

The differential 14 of the driven shaft 13 as the second axle is as follows:
As shown in FIG. 4, a small-diameter hypoid gear 20 is attached to the shaft end of the input shaft 19 of the differential 14 connected to the output drive shaft 80.
It is possible to use a device in which the hypoid gear 20 is fitted with a ring gear 21 made of a large-diameter hypoid gear. However, as shown in Fig. 5, if a differential structure is adopted in which bevel gear pairs 22 and 23 with zero offset a are used as a manual gear and a ring gear, respectively, a more compact structure can be achieved since there is no need for an offset. can.

As is clear from the above explanation, the differential 14 of the driven shaft I3
Since the torque applied manually is limited, the strength and durability of the differential 14 side can be set in anticipation of the upper limit of input torque, and there is no need to ensure strength and durability in anticipation of excessive torque.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic configuration diagram of the four-wheel drive device of the present invention;
3 are cross-sectional views showing each side of the torque limiter according to the present invention, FIGS. 4 and 5 are cross-sectional explanatory views showing the gear structure of the differential on the driven shaft side, and FIG. 6 is a conventional 1 is an overall configuration diagram showing an example of a four-wheel drive device. l...engine, 2...transmission, 3...first
Driving shaft as axle, 4... Differential, 8... Drive shaft, 9... Torque limiter, IO... Viscous coupling, I3... Driven shaft as second axle, 14... Def.

Claims (1)

[Claims] (1) The first wheel driven by the first axle to which the engine's output torque is directly input, and the engine's output torque is input via the viscous coupling interposed on the drive shaft connected to the first axle. A four-wheel drive device comprising a second wheel driven by a second axle, wherein a torque limiter is interposed on the drive shaft in series with the viscous coupling, and a differential drive provided on the second axle is provided. A four-wheel drive device characterized in that input torque to a gear device is limited to a set value or less.