GB2102747A - Hydraulic transmission for bicycle - Google Patents

Abstract

Comprising a pedal driven variable displacement oil hydraulic axial piston pump, which is integrated into the frame, driving a variable displacement axial piston hydraulic motor which is integrated into the driving wheel, the ratio between these two being infinitely variable and controlled by the pressure in the system, i.e., force on the pedals, a neutral free-wheel condition existing when no pedal pressure is applied. There is a secondary pump, operated by the springing of the rear wheel, providing boost pressure to the inlet side of an open circuit system which also incorporates a reservoir and a pneumatic pressure accumulator. <IMAGE>

Description

SPECIFICATION Hydraulic transmission for bicycle Note: in some cases where the same items are used in both pump and motor they are referred to thus:- item (no.) m - motor- sheet 3 or item (no.) p pump-sheet 2.

The axial piston pump Sheet 1, and the axial piston motor Sheet 2 are integrated into the swinging member items 11 and 23. The drive pistons item 1 5p in the pump motor are rotated axially via the pedals and shaft item 45, and caused to reciprocate within the rotor item 14p by bearing on the converter item 22p, inducing the fluid medium through the inlet porting in the porting plate item 16p and expelling it under pressure through the outlet porting in the porting plate. This is conveyed through the springing member item 11 to the motor in the hub of the rear wheel item 47 sheet 3 and induced through its porting plate item 16m pressurising the pistons on one side of the rotor item 1 4m and causing it to revolve, through their reaction against the motor converter item 22m. This will revolve the drive wheel through the medium of the shaft item 46.

If excess resistance is met at the drive wheel more turning force is required at the pedals, the subsequent increase in pressure in the system will react on the pressure sensing pistons items 17m and p, causing them to alto the angles of the converters items 17 m and p thus reducing the displacement of the fluid medium thereby increasing the number of turns of pedals to turns of back wheel.

When the excess resistance is no longer felt, pressure in the system reduces, having the opposite effect on the angle of the converters items 22 m and p, which are returned by means of the spring item 19 m and p loaded change rate control pistons item 18 m and p, increasing the displacement of the fluid media, thus reducing the turns of pedals to turns of back wheel ratio. If this is taken to its limit i.e., if the pressure falls to atmospheric (when no force is applied to the pedals), then the converter item 22m will adopt a neutral angle and a natural freewheel condition will exist.

The calibration of the convertor angles to the pedal/drive wheel ratio may be finally adjusted by means of the set screw item 20m and p and nuts item 21 m and p.

Assistance for the pedalling operation is available through the action of the suspension piston item 7 sheet 1,which extract the fluid media from the reservoir sheet 1 and compresses it via the nonreturn valves item 6 sheet 1, into the intake area and feed pipe item 5 sheet 1. This has the effect of turning the pump and pedals. If any excess flow or pressure is obtained from the suspension piston it may be stored in the accumulator item 3 sheet 1.

If there is a period of inactivity from the suspension piston, resulting in a falling of accumulator pressure then the flow through the inlet section will continue through the non-return valves under gravity feed.

The pneumatic pressure in the accumulator item 3 sheet 1 acting through the fluid media in the inlet section on the suspension piston item 7 sheet 1 which is linked by the thrust rod item 9 to the back wheel, will provide a hydro-pneumatic springing for the back wheel. The balance spring item 8 sheet 1 may be changed to suit the weight of individual operators.

Hydraulic transmission for bicycle.

Parts List. DRG. No 550 Item No no Description off 1 Filler/Breather for reservoir 1 2 Frame -with integrated reservoir and accumulator housing 1 3 Accumulatorlining-(special) 1 4 Plug-as required to blank off drillings as req.

5 Feed pipe-c/wfittings 1 6 Non-return valve-nylon-fix into frame 2 7 Suspension piston 1 8 Balance spring 1 9 Thrust rod-c/w pins 2 10 Return pipe-c/wfittings 1 11 Swinging member, with pressure connection and motor convertor cup. 1 12 Statorring 2 13 Needle race as req.

14 Rotor 2 15 Drive piston 18 16 Porting plate 2 17 Pressure sensing piston 2 18 Change rate control piston 2 19 Change rate control piston spring 2 20 Change rate control piston bolt 2 21 Change rate control piston nut 2 22 Converter 2 23 Swinging member with tie and pump converter cup 1 24 Pump and motor clamping bolts (not shown) 12 25 Ball race 15mm Bore 2 26 Ball race 12.5mm Bore 1 27 Ball race 10mm bore 1 28 Ball race 95mm bore 1 29 Oil seal 15mm bore 1 30 Oil seal 12.5mmbore 31 Oil seal 10mm bore 1 32 Circliptype1400M15 1 33 Circlip type 1300 M25 1 34 Circlip type 1400 M10 1 35 Circliptype 1400M12.5 1 36 Back wheel bolts 4 37 Pump sealing 'O' ring (not shown) 2 38 Motor sealing '0' ring (not shown) 2 39 Suspensionpiston'O'ring 40 41 Accumulator plug 42 Suspension pivot bolt 1 43 Pedal L.H.

44 Pedal RH. 1 45 Pump shaft 1 46 Motor shaft 1 47 Back wheel 1 48 49 50

Claims (4)

1. A pedal driven variable displacement axial pis ton hydraulic pump, driving a variable displacement axial piston hydraulic motor, integrated into the frame and driving wheel of a bicycle.

2. A secondary pump operated by the springing ofthe rear wheel, providing boosting pressure assisting the system as in Claim 1.

3. An infinitely variable, pedal R.P.M. to drive wheel R.P.M. ratio determined by the pressure in the system.

4. If the pressure in the system reaches atmospheric or less, i.e. no pedal movement, then a freewheel condition will exist.