A currently proposed device according to the present invention will be described below with simultaneous reference to the appended drawings, in which;
FIG. 1 shows from above and in basic representation a hydrostatic arrangement on a two-wheeled vehicle, in which a rear wheel shall give rise to propulsion force on a front wheel by means of a hydrostatic system,
FIG. 2 shows in vertical section a structural illustrative embodiment of a unit forming part of the hydrostatic arrangement according to FIG. 1, having a temperature-detection function and a connection and disconnection function for a bridging line in the hydrostatic arrangement, and
FIG. 3 shows in vertical section a further illustrative embodiment having a regulating valve, which can provide variable regulation of the medium flow.
In FIG. 1, a motorcycle is indicated diagrammatically by 1. The motorcycle comprises a rear wheel 2 and a front wheel 3. The motorcycle also comprises an engine 4 (shown in basic representation), which can be of a type which is known per se. The rear wheel is provided with a chain drive and the chain is symbolized by 5 and is driven from the gear ring 6 of the rear wheel. The gearbox of the vehicle is symbolized by 7 and a gearwheel assigned to the chain 5 has the notation 8. A pump arrangement forming part of the hydrostatic system 9 is indicated by 10. The pump arrangement is arranged to drive a drive assembly 11 for the front wheel 3. The pump arrangement and the assembly are connected to each other by a hydrostatic line system comprising a high-pressure line or high-pressure hose and a low-pressure line or low-pressure hose 13. On the low-pressure side, in the illustrative embodiment shown, a cooler 14 and a pressure accumulator 15 are fitted. The cooler 14 can form part of the arrangement if the motorcycle is to be driven in a hot climate, for example a desert climate.
The said gearwheel 8 is connected by a shaft 16 to a drive device 17 for the said pump arrangement 10. The drive device can be constituted by a type which is known per se and can comprise a chain running in an oil bath. The drive device drives the pump 10a in a manner which is known per se. The pump arrangement also comprises a pressure relief valve, which enters into operation when there is maximum pressure over or in the line 12. The valve 10b can be of a type which is known per se and does not concern the present invention per se. In addition, the pump arrangement 10 comprises a non-return valve 10c, which enters into operation where the front wheel 3 rotates faster than the rear wheel 2, for example, in vehicle turning, various braking situations, etc. The drive assembly comprises a motor part 11a, which is driven by the pump 10a. The assembly additionally includes a reduction gearing 11b. The units 11a and 11b can be constituted by a type which is known per se and will not therefore be described in detail here. The transmission of the drive function of the assembly 11 to the front wheel 3 is indicated diagrammatically by 18 and is achieved with positively connected gear teeth, so-called splines, in a manner which is known per se. The constructions of the rear and front wheels are otherwise realized in a manner which is known per se, which shall also be spared detailed description here. When the hydrostatic system is used, the pressure in the high pressure line 12 can be of the order of magnitude of 350 bar. With reference to normal running of the motorcycle, the rear wheel 2 rotates slightly faster than the front wheel and thereby gives rise to a propulsion force, symbolized by F, on the front wheel. The said accumulator 15 ensures that the low-pressure line 13 admits a minimum pressure, for example about 3 bar, throughout the propulsion.
According to the inventive concept, the arrangement is equipped with a bridging duct 19, which, as outlined below, can assume an open and a closed position. The bridging duct contains a thermostat 20 (shown in basic representation), which opens and closes the bridging duct 19 in dependence on the temperature in the hydrostatic medium. The medium in the high-pressure line 12 is symbolized by the arrow 21 and the medium in the low-pressure duct 13 is symbolized by 22. The said medium can be constituted by hydraulic oil with associated conventional additives. The bridging direction in the duct 19 is denoted by 23. The said bridging function may have a different construction and can be assigned a different position within the system. In the present case, the bridging function is arranged in the drive assembly. The bridging function needs to operate only with a small medium flow differential (change in volume flow) from the high-pressure line 12 to the low-pressure line 13 in order to produce a large change in pressure. In FIG. 1, a ground surface is additionally symbolized by 24.
FIG. 2 shows a constructional illustrative embodiment of the structure of a unit 25 equipped with, on the one hand, a thermostat function and, on the other hand, a connection and disconnection function for a bridging line according to FIG. 1 (compare 19). The unit comprises a sleeve-shaped outer part 26 provided with an external thread 27, by means of which the unit is arranged in a screw-in manner in the drive assembly housing. The unit has an external seal 28, which seals against an inner wall 29 of a drive assembly housing 30 (indicated in basic representation). The unit is provided with an internal chamber 31, which can be closed off with a screw 32 sealed by a seal 33. The chamber 31 passes into a chamber 34 of smaller diameter or cross-sectional area than the chamber 31. In the chambers 31 and 34, a fluid medium 35 is applied. The medium can be constituted by hydraulic oil with any associated additives. Alternatively, the hydraulic oil can be replaced by wax(es) 36, which is/are known per se within the general context of thermostats. The hydraulic oil operates on the basis of a substantially even expansion and contraction function. The wax or waxes (the medium) has/have more distinct melting and solidification temperature ranges. The chamber 34 contains a cone 37, which is sealed against the chamber 34 by means of a sealing ring 38. At its end, the cone 37 has a needle-shaped or plug-shaped member 39, which extends down into a cutout 40 in a seat 41. In the position shown in FIG. 2, the plug 39 has assumed a position which seals the cutout 40. The cone is arranged such that it is longitudinally displaceable along the centre line 42 of the unit, downwards in FIG. 2. In its upper parts, the plug is equipped with a tapered part 39a. When the plug is displaced, by means of the cone, in the direction of the arrow 43, the tapered section 39a is placed opposite the cutout 40 in the seat, with the result that a passage is formed on the outside of the tapered part 39a of the plug and the seat hole 40. The bottom side 41a of the seat is connected to the high-pressure line 12 (see FIG. 1) and the top side 41b of the seat is connected to the low-pressure line 13 (see FIG. 1). In the position shown in FIG. 2, the passage between the lines 12 and 13 is closed. If the plug is displaced and the passage is present between the outside 39a of the plug and the seat hole 40, the high and low-pressure lines are connected to each other, i.e. the bridging function is in place. The oil 35 or the wax(es) (=a first body) has/have linear expansion coefficients which result in the plug 39 being displaceable relative to the housing, the frame and the seat 41 (together forming a second body), which therefore have substantially smaller second linear expansion coefficients than the oil 35 and the wax(es) 36. The displacement takes place in the direction of the arrow 43 in dependence on the prevailing temperature in the unit. The linear expansion acts counter to the effect of counter-pressure in the direction of the arrow 44, which counter-pressure is produced by the high pressure on the bottom face 39b of the plug and the low pressure on the face 37a of the plug fastening in the cone 37. If the heat rises, the plug is therefore pressed downwards in FIG. 2 and, at a degree of displacement L which can measure between 1 and 3 mm, preferably about 2 mm, the connection between the lines 12 and 13 is opened. The oil or wax bodies 35 and 36 therefore perform their linear expansion in dependence on indirect heat from the temperature in the medium in the high and low pressure lines. The unit 25 can be considered to operate on the basis of a bleeding or leakage function. In FIG. 2, a part of the bridging duct is constituted by the passage between the plug 39 and the seat 41. The connections and the disconnections of the bridging line must be made within distinct temperature ranges, which are preferably chosen to be small, for example temperature ranges between 80° C. and 85° C.; 100° C. and 105° C., etc. It will be appreciated that the arrangement involving wax/waxes can be realized with more distinct temperature ranges. The oil or wax body is actuated by means of thermal conduction in the second body 25, which can be made of aluminium, alloy, steel, etc. The housing or frame 25 is fitted in a suitable place on the motorcycle, for example the drive assembly housing 30, which, for its part, can also convey heat indirectly or directly to the oil or wax body and can assist in the connections and disconnections of the bridging.
In the illustrative embodiment shown, the bridging, bridging execution and temperature-detection functions have been integrated in the unit 25. These functions can, of course, be separated with respect to location. The bridging execution can alternatively be electrically controlled from the temperature detection and/or, in turn, electrically control the bridging. The parts 26, 37, 39 and 41 can be made of material having a substantially lower thermal expansion coefficient than the oil/wax(es) and can be constituted, for example, by the said material type. The wax or waxes can be replaced by means of an equivalent nature.
In FIG. 3, a hydraulic motor is denoted by 45. A medium-conducting supply line has been indicated by 45 and a discharge line has been indicated by 46. The line 45 is connected to the outlet on a pump and the line 46 to the inlet of the pump. Arranged parallel with the hydraulic motor is a bridging line 47 for the medium. The primary flow to and from the motor 45 is indicated by arrows and a bleed flow in the line 47 is indicated by 49. A control member or control valve is indicated in basic representation by 50. The member/valve can be constituted by an electrically controlled unit in the form of a proportional valve, which can be constituted by a type which is known per se and can comprise a coil 51 and a needle 52, which operate against a seat 53 for bleed flow determination. The electric conductors 54 and 55 of the coil can be connected to an operating member, which, in dependence on manual or automatically controlled actions, determines the position of the needle in relation to the seat and hence the size of the bleed flow. The operating member can be constituted by a position-influencing member 57, thermostat 58, etc. Alternatively, the control member can be constituted by a mechanical member which can be correspondingly controlled. With the bleed function, the primary flow can be varied. The variation of the primary flow needs to be relatively small, for example 2-15%. When the vehicle is driven slowly and there is high pressure at the hydraulic motor, changes are made in the primary flow amounting to the 10% reduction. In normal driving on a main road, the flow reduction is in the order of magnitude of about 3%, etc. The control member can operate as a flow-changing or pressure-changing member. With the arrangement shown, the size of the front wheel drive can easily be varied, so that the size of the front wheel drive is altered in dependence on the driving conditions. The actuating members 57, 58 can be controlled by means of sensors, for example on the front and rear wheels, the throttle and/or a separate actuating member. The front-wheel drive can therefore be arranged such that it can be wholly or partially shut off. Pressure generators and temperature sensors for and in the oil/medium can also be provided. Wheel bearing sensors for detecting the air pressure in the wheels can also form part of the arrangement, as can spin-detecting sensors, etc.
The invention is not confined to the embodiment shown by way of example above but can be subject to modifications within the scope of the following patent claims and the inventive concept. In an further embodiment the actuating members can be controlled by voice operating device(-s).
Patent Application
20080053083
