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Compact Homokinetic System - CHS

Compact Homokinetic System for steering the driven wheel of motorbikes and two-wheelers

 

General description

The compact homokinetic system enables the driven wheel of a motorbike, and by extension any two-wheeler, to be steered by means of a compact steering system.

The development of the advanced steering system has its origin in the search for a solution for steering the driven rear wheel of motorbikes. To date, there is no motorbike, and by extension two-wheeler, whose driven wheel is also used for steering the vehicle.  The wheel axle of the chain- or shaft-driven rear wheel of motorbikes is clamped on one or both sides respectively depending on whether a single- or double-sided swingarm is used. Consequently, the rear rotating around the wheel axle cannot be steered.

Steering the chain- or shaft-driven rear wheel on a motorbike, and by extension on a two-wheeler, requires solving two problems. Firstly, making a physical connection between the handlebars located at the front and above the front fork with the rear wheel located under the rider's seat, is not only difficult but also complicated. Secondly, steering driven wheels is possible only if a homokinetic coupling is used.  Torque or tractive force is transmitted to the input drive shaft via the chain or cardan. This input shaft in turn transmits the torque or tractive force to an output shaft connected to the wheel. If the driven wheel is used for steering, the output shaft can make a variable angle with the input drive shaft. The homokinetic coupling ensures that the angular velocities of input and output shaft are equal at all times. Homokinetic couplings have existed in shapes and sizes for decades. Their application in motorbikes and/or two-wheelers requires a specific design that takes into account the limited space in the wheel hub and the way the driven wheel is steered.

 

The advanced steering system described below solves the above problems. The first problem, steering without physical connection between handlebars and wheels, is solved by using the compact steering system. The compact steering system differs from traditional steering systems by its extremely compact construction and the absence of any mechanical connection between wheel(s) to be steered and handlebars.  Steering is simple, safe, independent, non-mechanical, precise and reliable by means of hydraulic or electric actuators inside the wheel hub. The second problem arising from the combination of steering and drive, in particular ensuring that the angular velocities of input and output shaft are equal at all times, is solved by providing the steered and driven wheel with a specifically designed compact homokinetic system inside the wheel hub. 

 

This advanced steering system can also be used at the front of the motorbike or two-wheeler. In this way, the manufacturer can use the front wheel for both steering and propulsion and as such realise front-wheel drive. Of course, the manufacturer can also apply this system both at the front and rear of the motorbike or two-wheeler and as such realise two-wheel drive.

 

As the steering in this advanced steering system is done by hydraulic or electric actuators in the wheel hub of one or both driven and non-driven wheels, the steering process can be easily automated. The advanced steering system for steering driven wheels enables self-steering and self-driving motorbikes and two-wheelers.

 

Summarised description

The Compact Homokinetic System for the steering of the driven wheel of motorbikes and two-wheelers, combines steering by means of a Compact Steering System with monitor and compensation system with a modified specific compact homokinetic actuator in the wheel hub.

Steering of the driven wheel is done in a simple, safe, independent, non-mechanical, precise and reliable way by means of an actuator in the wheel hub. As the driven wheel is used for steering, the output shaft can make a variable angle with the input drive shaft. The Compact Homokinetic System ensures that the angular velocities of the input shaft connected to the chain sprocket or cardan and the output shaft connected to the wheel are equal at all times.

The Compact Homokinetic System gives the constructor great freedom in the design and development of the vehicle, allows the combination of steering with driving front and/or rear wheel(s) and is the ideal basis for self-steering and self-driving motorbikes and two-wheelers.

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Detailed description of operation

The advanced steering system for steering driven wheels consists of two main components:

- the compact steering system;

- the compact homokinetic system.

 

The Compact Steering System

The compact steering system with monitor and compensation system is located inside the wheel spindle (4) and the steering house (2). Steering is done in a simple, safe, independent, non-mechanical, precise and reliable way by means of hydraulic or electric actuators inside  the wheel spindle (4) and the steering housing (2). The steering house (2) forms one unit with the wheel spindle (4). The wheel axle (4) is clamped on both sides (Figures 1, 2, 3 and 4) to the swingarm. The wheel spindle (4) might also be connected to the frame by a one-sided suspension bridge (Figures 3, 4, 5 and 6). In this case, the wheel hub (1) is completely closed at one side. The wheel hub (1) can rotate around the steering house (2). The hydraulic or electric actuators inside the wheel axle (4) and the steering house (2) makes the wheel hub (1) rotate around the steering house (2). No mechanical connection is needed between the steering wheel and the wheel hub (1). The wheel and disc brake are connected to and positioned on the wheel carrier (31) which is supported on the wheel hub (1). For a detailed description, click here.

 

The Compact Homokinetic System

Torque from the engine, combustion or electric, is transmitted via a chain to the chain sprocket (32), which is fixed to the chain sprocket carrier (30).  The wheel and disc brake are connected to and positioned on the wheel carrier (31), which in turn is supported on the wheel hub (1). The wheel hub (1) can rotate around the steering house (2). This creates a variable angle between chain sprocket carrier (30) and wheel carrier (31). The Compact Homokinetic System ensures that the angular velocity of the chain sprocket (32) connected to the chain sprocket carrier (30) and the angular velocity of the wheel carrier (31) connected to the wheel are equal at all times.

Instead of using a chain with chain sprocket (32) connected to the chain sprocket carrier (30), one can also realise the drive by means of a cardan. This in fact does not change the concept.

 

Hereafter, the three possible versions of the Compact Homokinetic System are described:

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Figure 8 and 9 - Version 1

The chain sprocket carrier (30) is connected to the outer ring of the constant velocity joint (33). The wheel carrier (31) is connected to the outer ring of the constant velocity joint (34). The inner ring of the constant velocity joint (33) and the inner ring of the constant velocity joint (34) are connected to each other by means of a connecting shaft (36). The constant velocity joint (33) and (34) are, just like the chain sprocket carrier (30), mounted on the wheel spindle (4). The wheel spindle (4) is clamped at both ends in swingarm. A double-sided swingarm is required in this version. The wheel hub (1) can rotate around the steering house (2). This creates a variable angle between the chain sprocket carrier (30) and the wheel carrier (31) as indicated in Figure 9. The compact homokinetic system described here ensures that the angular speed of the chain sprocket (32) connected to the chain sprocket carrier (30) and the wheel carrier (31) connected to the wheel, are equal at any time.

Figure 10 and 11 - Version 2

The chain sprocket carrier (30) is connected by means of the connecting shaft (36) to the inner ring of the constant velocity joint (35). The wheel carrier (31) is connected to the outer ring of the constant velocity joint (35). The chain sprocket carrier (30) is mounted on the wheel spindle (4). The constant velocity joint (35) is mounted on the wheel hub (1) together with the wheel carrier (31). The wheel spindle (4) can be clamped in the swingarm at both ends or only on the side of the chain sprocket. In this version, both a single-sided and double-sided swingarm can be used. The wheel hub (1) can rotate around the steering house (2). This creates a variable angle between the chain sprocket carrier (30) and the wheel carrier (31) as shown in Figure 11. The compact homokinetic system described here ensures that the angular speed of the chain sprocket (32) connected to the chain sprocket carrier (30) and the wheel carrier (31) connected to the wheel, are equal at any time.

Figure 12 and 13 – Version 3

The chain sprocket carrier (30) is connected by means of the input shaft (38) to the outer ring of the constant velocity joint (40). The wheel carrier (31) is connected by means of the output shaft (39) to the inner ring of the constant velocity joint (40). The chain sprocket carrier (30) and the input shaft are mounted inside the wheel spindle (4). The output shaft (39) of the constant velocity joint (40), connected with the wheel carrier (31), is mounted on the wheel hub (1). The wheel spindle (4) is clamped inside the swingarm at the side of the chain sprocket. This version is limited to motorbikes or two wheelers with a single-sided swingarm. The wheel hub (1) can rotate around the steering house (2). This creates a variable angle between the chain sprocket carrier (30) and the wheel carrier (31) as shown in Figure 13. The compact homokinetic system described here ensures that the angular speed of the chain sprocket (32) connected to the chain sprocket carrier (30) and the wheel carrier (31) connected to the wheel, are equal at any time.

 

The above described embodiment is non-limiting: additions, deviations and modifications can be made without departing from the spirit and scope of this concept. For example, there are multiple possibilities of using the various compact homokinetic systems combined with the various possible hydraulic or electric actuators inside the wheel hub to steer the driven wheel.

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