Description

Adjustable-height shock absorber provided with automatic or semiautomatic electrohvdraulic actuator.

The present patent application relates to an adjustable-height shock absorber provided with an automatic or semiautomatic electrohydraulic actuator. The said shock absorber has been designed for preferential use in the motorcycle sector, to which the following description refers. It must be noted that the height of the shock absorber is the distance between the two "eyes", one fixed to the frame and the other fixed either directly or through a system of levers to the fork on which the back wheel of the motorcycle is mounted. The possibility to adjust the said distance is a very important technical characteristic of the motorcycle, since the height of the shock absorber considerably affects the attitude of the motorcycle, modifying the weight distribution between the two wheels, which determines the behaviour of the motorcycle, meaning the speed of direction changes, the agility in curves, and the performance when braking. The main characteristic of the shock absorber according to the invention consists in the fact that the adjustment or self-adjustment can take place during motion, while all the adjustable shock absorbers for motorcycles that are currently known are provided with mechanical adjustment systems, which require the use of wrenches or screwdrivers, that can be actuated only when the motorcycle is stopped.

It appears evident that the possibility to adjust the height of the shock absorber during motion allows to adjust and optimise the attitude of the motorcycle to all environmental or driving conditions. The shock absorber according to the invention is made of two components that are physically integrated, but operate independently: a first component with shock-absorbing function and a second component with height- adjustment function.

This type of structure, formed of two components that are physically integrated and operate independently, considerably simplifies the design and construction of each component, and makes the shock absorber of the invention extremely flexible and modular, allowing to integrate it, from the mechanical, hydraulic and electronic viewpoint, on different models of motorcycles with simple adjustment and turning actions. The first component with the typical shock-absorbing function has the typical structural configuration of a standard shock absorber, being formed of a spring and a first hydraulic cylinder provided on the bottom with the first eye of the shock absorber of the invention.

The second component with height-adjustment function is formed of a second hydraulic cylinder provided on the bottom with the second eye of the shock absorber of the invention. The two chambers of the second hydraulic cylinder are inserted inside an external oil-pressure power circuit and work in antiphase, meaning that while one chamber is filled, the other chamber is emptied, being understood that the total oil volume contained in the two chambers remains constant. From this brief description of the shock absorber of the invention it can be understood that the shock absorber height can be modified by introducing pressurised oil in one of the two chambers in antiphase.

To this end, it must be noted that the shock absorber of the invention is equipped with an external oil-pressure power circuit used to vary the oil volume contained in the two chambers in antiphase. The system is controlled by a control unit. The control unit receives the main inputs from the driver and from sensors installed on the vehicle.

By means of suitable buttons, the driver defines the desired operation mode (cross, race, comfort, etc.) and the sensors provide information on the vehicle status (on/off engine, motorcycle speed, suspension travel, motorcycle inclination, battery charge, height from ground, wheel revolution speed, etc.). Given the input data, the control unit defines the total height of the shock- absorbing system by means of previously tested algorithms and sends the

output commands to the electrical engine and the electro-valve system. The new shock absorber revolutionises the management of motorcycles and offers several new perspectives.

By raising and lowering the back suspension, the driver can distribute the weight on the two wheels, with consequent variations of the dynamic behaviour and grip of the motorcycle. The main benefits and opportunities offered to final users are as follows:

- While driving, the driver can change the motorcycle height and inclination to obtain the most comfortable position; - While driving, the driver can change the motorcycle height and inclination to obtain the best driving feeling and optimise performance;

- In case of wet or slippery surfaces, the driver can change the motorcycle height and inclination, distributing the loads on the front and the back to modify the motorcycle grip; - The driver can choose from several automatic programmes for the intelligent management of the motorcycle position, according to the environmental conditions and desired performance.

- The shock absorber can be integrated with other control devices for the integrated management of the motorcycle dynamics. - The driver can set a function to automatically lower the motorcycle at low speed, restoring the normal height when the speed starts to increase again; the said device allows all drivers (including short ones) to comfortably get on and off the motorcycle also from higher motorcycles and put the feet on the ground when stopping in traffic; this opportunity can be especially beneficial for specific groups of new potential users (such as women and short people).

For purposes of clarity, the description of the tank of the invention continues with reference to the enclosed drawings, which are intended for purposes of illustration only and not in a limiting sense, whereby: - figures 1 , 2 and 3 are a view of the shock absorber of the invention sectioned with an axial plane in three different positions, which correspond to the maximum height, minimum height and intermediate height;

- fig. 4 is a view of the shock absorber of the invention sectioned with an axial plane together with the oil-pressure power circuit and the electronic management and control system.

With reference to figures 1 , 2 and 3, the adjustable-height shock absorber according to the invention comprises two components that are physically integrated but operate independently: a first component (1) with shock- absorbing function and a second component (2) with height-adjustment function. The first component (1) has the typical structural configuration of a standard shock absorber and is formed of a spring (10) externally inserted on the stem (11) of a first hydraulic cylinder (12) provided on the bottom (13) with the first eye (F1 ) of the shock absorber of the invention.

Small seeping holes, not shown in the figure, are traditionally obtained on the piston (14) of the first cylinder (12) that allow oil to leak from the lower chamber (Ci) to the upper chamber (Cs) of the first cylinder (12).

The oil transfer from the lower chamber (Ci) to the upper chamber (Cs) and vice versa occurs with energy dissipation, which favours the end of the oscillatory motion of the piston (14) in a few compression and extension cycles. The second component (2), which has a height-adjustment function, is formed of a second hydraulic cylinder (20), whose stem is the same as the stem (11) of the first hydraulic cylinder (12), so that the piston (21 ) of the second hydraulic cylinder (20) is joined by means of the stem (11) to the piston (14) of the first hydraulic cylinder (12). The bottom (22) of the second hydraulic cylinder (20) is externally provided with the second eye (F2) of the shock absorber of the invention. The two chambers (20a and 20b) of the second hydraulic cylinder (20) work in antiphase, meaning that while the first chamber (20a) meaning that while one chamber is filled, the other chamber (20b) is emptied, and vice versa, being understood that the total oil volume contained in the second cylinder (20) remains constant. Obviously, until one of the said chambers is not emptied in antiphase and the

other chamber is simultaneously filled, the piston (21 ) cannot slide inside the second cylinder (20), which is practically inert, without any prejudice for the regular operation of the first component (1).

The height (H) of the shock absorber can be modified by introducing pressurised oil in either one of the two chambers in antiphase, as shown in figures 2 and 3, where the chamber (20a) is completely full (maximum height = Hmax) or completely empty (minimum height = Hmin). To generate the pressurised oil flow, in short time and with high output, a pressurised oil accumulator (30) is filled at regular time intervals, taking the oil from one low pressure tank (40) by means of a pump (31 ) actuated by an electric motor (32).

The use of the accumulator (30) provides several advantages, first of all the fact that the pump (31) can have compact dimensions and the motor (32) can have a low power, because the accumulator (30) provides the power necessary to provide the correct amount of oil in one of the two chambers (24a and 24b) in a very short time.

The introduction and discharge of the oil in the chambers (24a and 24b) are controlled by means of two three-way electrovalves (33a and 33b). According to the opening way from the electrovalves (33a and 33b), the chambers (24a and 24b) communicate, selectively and alternatively, with the inlet branch (30a) from the accumulator (30) or with the outlet branch (40a) ending in the tank (40).

Evidently, if one of the two chambers communicates with the inlet branch (30a), a positive variation of the oil volume contained in the chamber is obtained, which corresponds to the simultaneous variation, with identical value and opposite sign, of the oil volume contained in the other chamber; and if one of the two chambers communicates with the outlet branch (40a) a negative variation of the oil volume contained in the chamber is obtained, which corresponds to the simultaneous variation, with identical value and opposite sign, of the oil volume contained in the other chamber.

Until both electrovalves (33a and 33b) are closed, no oil flow through the second component (2) is possible, since the second component (2) acts as a

stiff, inert part of the frame, without impairing the regular operation of the first component (1 ) in charge of the shock-absorbing action. As mentioned above, the operation of the second component (2) is managed and controlled by an electronic control unit (50) powered by the battery (60) that receives the data transmitted by the button panel (70) actuated by the driver, in case of semiautomatic operation mode, or by the sensors (80) installed on the motorcycle, in case of automatic operation mode. In semiautomatic operation mode, the driver controls the opening of the electrovalves (33a and 33b) with the control unit (50) and sets the height of the shock absorber at the desired value.

In automatic operation mode the control unit (50) detects the motorcycle conditions through the sensors (80) installed on the motorcycle and determines the best instantaneous height of the shock absorber. To better understand the actuation of the different components during the operation of the system, this description continues with reference to a simple actuation procedure in which the driver brakes the motorcycle. In this case the control algorithm provides for lowering the shock absorber to optimise the weight distribution and improve braking. The sensor (80) on the braking circuit detects the increase in pressure and the acquisition and control unit (50) saves this datum.

The variation of this parameter directs the selection between the different management programme to the "BRAKING" programme. The control unit (50) starts acquiring the data from the longitudinal accelerometer installed on the motorcycle with a higher frequency. The intensity of the acceleration (or deceleration) determines the amount of height variation of the back shock absorber.

The control unit (50) sends the control signal for the modification of the fuse position to the electrovalves (33a and 33b), so that the electrovalve (33b) associated with the chamber (24b) creates a communication between the said chamber and the oil inlet branch (30a), while the electrovalve (33a) associated with the chamber (24a) creates a communication between the said chamber (24a) with the oil outlet branch (40a), with consequent

reduction of the height of the shock absorber proportional to the motorcycle deceleration.

The control unit (50) leaves the electrovalves (33a and 33b) open until the desired height is reached (instantaneously detected by the linear potentiometer installed on the shock absorber) or until the braking phase is completed (the signals from the pressure sensor (80) of the braking system and accelerometer indicate the motion of the motorcycle second by second and immediately indicate the end of the braking action). When one of these two conditions is achieved (end of braking phase or achievement of desired height) the control unit (50) sends to the electrovalves (33a and 33b) a signal to invert the position of the fuse, so that the electrovalve (33b) associated with the chamber 24b creates a communication between the said chamber with the oil outlet branch (40a), while the electrovalve (33a) associated with the chamber (24a) creates a communication between the said chamber (24a) and the oil inlet branch (30a), with consequent increase of the shock absorber length. The control unit (50) instantaneously measure the height of the shock absorber. When the height of the shock absorber is equal to the height defined as "initial", the control unit (50) sends the electrovalves (33a and 33b) the command to switch to the closing position of the conduits. Once the adjustment of the height of the shock absorber has been completed, the motor (32) actuates the pump (31 ) that starts charging the accumulator (30). The charging phase ends when the pressure inside the accumulator, which is measured by a suitable sensor, reaches the predefined value. Once the correct charge pressure has been reached, the system restores the stand-by configuration until the sensors (80) installed on the motorcycle send a new signal that activates a programme to change the height of the shock absorber.