Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
  • F15B11/12—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor providing distinct intermediate positions; with step-by-step action
  • F15B11/121—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor providing distinct intermediate positions; with step-by-step action providing distinct intermediate positions
  • F15B11/123—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor providing distinct intermediate positions; with step-by-step action providing distinct intermediate positions by means of actuators with fluid-operated stops
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
  • F15B11/12—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor providing distinct intermediate positions; with step-by-step action
  • F15B11/121—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor providing distinct intermediate positions; with step-by-step action providing distinct intermediate positions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/08—Characterised by the construction of the motor unit
  • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
  • F15B15/1423—Component parts; Constructional details
  • F15B15/1466—Hollow piston sliding over a stationary rod inside the cylinder
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
  • F16H61/26—Generation or transmission of movements for final actuating mechanisms
  • F16H61/28—Generation or transmission of movements for final actuating mechanisms with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted
  • F16H61/30—Hydraulic or pneumatic motors or related fluid control means therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
  • F16H61/26—Generation or transmission of movements for final actuating mechanisms
  • F16H61/28—Generation or transmission of movements for final actuating mechanisms with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted
  • F16H61/30—Hydraulic or pneumatic motors or related fluid control means therefor
  • F16H2061/307—Actuators with three or more defined positions, e.g. three position servos

Definitions

• Control cylinder for a gearbox a gearbox with such a control cylinder, and a vehicle with such a gearbox
• the present invention relates to an operating cylinder for a gearbox according to the preamble of claim 1.
• the invention relates also to a gearbox, which is provided with such an operating cylinder, according to the preamble of claim 10.
• the invention also relates to a vehicle, which is provided with such a gearbox, according to the preamble of claim 11.
• the gearbox is provided with one or more operating cylinders which have the function of changing the gear ratio across the gearbox.
• the operating cylinder controls the engagement and disengagement of gearwheels in the gearbox so that appropriate gear ratios are achieved.
• the cylinder is preferably of pneumatic type and operated by compressed air, although other fluids might be used to operate it, e.g. hydraulic oil.
• the gearbox in trucks often takes the form of an automatic gearbox comprising a large number of interacting components for effecting the automatic gearchanging.
• the operating cylinder therefore needs to be as small as possible so that there is room for all of the components which need to be accommodated in the gearbox.
• One or more electronic units of the vehicle receive information via sensors about its propulsion and deliver signals to, inter alia, valves which supply/remove compressed air or hydraulic oil to/from the operating cylinder, which thus controls the engagement and
• GB-A-759235 refers to an operating cylinder for a motor vehicle gearbox, which cylinder can be put into three different operative positions by means of a pressurised fluid, e.g. compressed air or hydraulic oil, which is supplied through apertures formed in a cylinder housing.
• a pressurised fluid e.g. compressed air or hydraulic oil
• a piston in the cylinder is journalled against the inside of the cylinder housing by annular shell parts which have recesses for seals. The seals thus in this version absorb substantial force.
• the cylinder housing needs to be of considerable length to allow it to have a long enough bearing surface for the annular shell parts.
• US-A-4593606 refers to an operating cylinder for a gearbox for a vehicle.
• the cylinder is provided with an extra piston, making it possible for a main piston to be put into an intermediate position.
• the main piston is provided with a plain bearing running round its outside and abutting against the inside of the cylinder housing. To allow the main piston to be journalled against the inside of the cylinder housing, the cylinder housing needs to be of sufficient length.
• the object of the present invention is to propose an operating cylinder with small dimensions for a gearbox.
• Another object of the invention is to propose a compact operating cylinder with low manufacturing cost for a gearbox.
• a further object of the invention is to propose a vehicle with a gearbox with an operating cylinder with small dimensions.
• a vehicle which is provided with a gearbox of the kind mentioned in the introduction and is characterised by the features indicated in claim 11.
• Such an operating cylinder is of smaller axial extent than existing operating cylinders, thereby reducing the space requirement for the operating cylinder in the gearbox so that there is room in the gearbox for all of the latter' s necessary components.
• Vehicle gearboxes usually have a plurality of gear steps, making it necessary to provide two or more operating cylinders in the gearbox. This further increases the need for the respective cylinders to be of small dimensions.
• the possibility of the cylinder being of smaller dimensions also reduces the material requirement, leading to reduced manufacturing costs for the cylinder.
• the gearbox may as a whole be compact in cases where the operating cylinder is of small dimensions, leading to reduced weight of the vehicle and hence also to less fuel consumption.
• FIG. 1 is a schematic side view of a vehicle with an operating cylinder and a gearbox according to the present invention
• Fig. 2 is a sectional view of the operating cylinder according to a first
• Fig. 3 is a sectional view of the operating cylinder according to the first
• Fig. 4 is a sectional view of the operating cylinder according to the first
• Fig. 5 is a sectional view of the operating cylinder according to a second
• Fig. 1 is a schematic side view of a vehicle 1, e.g. a truck.
• the vehicle is provided with a combustion engine 2 connected to a gearbox 4.
• the gearbox is connected to the vehicle's tractive wheels 6 via a propeller shaft 8.
• the gearbox is provided with an operating cylinder 10 which has the function of moving one or more gearwheels 12 in the gearbox with the object of changing the gear ratio across the gearbox.
• gearboxes for vehicles usually comprise a plurality of gear steps, two or more operating cylinders need to be provided in the gearbox.
• the cylinder 10 is preferably of pneumatic type and operated by compressed air, although other fluids might be used to operate it, e.g. hydraulic oil.
• the gearbox 4 in a truck often take the form of an automatic gearbox 4 comprising a large number of interacting components for effecting the automatic gearchanging.
• the operating cylinder 10 needs therefore to be as small as possible so that there is room for all of the components which need to be accommodated in the gearbox 4.
• Fig. 2 is a sectional view of the operating cylinder 10 according to a first embodiment of the present invention in a first extreme position. It has a cylinder housing 14 provided with respective first and second endwalls 16 and 18 to form a space 20 in which a piston 22 is arranged to be able to move axially to and fro.
• a piston rod 24 is connected to the piston via a fastening element 26.
• the piston rod is arranged to extend through an aperture 28 in the first endwall 16.
• the piston rod is provided with a fastening device 30 for connecting an arm which moves the gearwheels 12 in the gearbox for gear changes.
• the piston 22 divides the space 20 formed by the cylinder housing 14, the first endwall 16 and the second endwall 18 into respective first and second spaces 34 and 36.
• a first port 38 is in communication with the first space 34
• a second port 40 is in communication with the second space 36.
• a fluid for moving the piston relative to the cylinder housing 14 is supplied and removed through the first and second ports 38, 40.
• These ports are connected to a pressure source 42 for fluid via first and second valves 44, 46 which are preferably controlled by signals from a control unit 48.
• a sensor 50 Also connected to the control unit 48 is a sensor 50 which is fitted in the second endwall 18 and detects the position of the piston in the cylinder housing.
• a pin 52 which is connected to the piston and extends into an elongate cavity 54 in the sensor 50.
• the sensor 50 is preferably provided with an undepicted coil which registers by induction the position of the outer end of the pin relative to the coil. Using the sensor 50 to detect the pin's position in the elongate cavity makes it possible to determine the position of the piston 22 in the cylinder housing 14.
• a third port 56 provided in the cylinder housing 14 is in communication with surrounding atmospheric pressure. This third port is in contact with a third space 58 formed between the piston 22, the cylinder housing 14 and respective first and second radial seals 60, 62 situated between them. These radial seals are designed to slide on the piston and the cylinder housing during axial movements of the piston relative to the cylinder housing. They prevent pressurised fluid from flowing between the first, second and third spaces 34, 36, 58.
• the third port 56 has the function of equalising with atmospheric pressure any negative or positive pressures which occur in the third space 58.
• the first and second radial seals 60, 62 are provided with stiffening elements 64 intended to cooperate with a flange 68 which runs round the piston. These radial seals can therefore also serve as secondary pistons and transmit the force from the pressurised fluid to the piston's flange 68 in order thereby to exert axial force upon the piston.
• the piston 22 is provided with an axial cavity 70 arranged to abut by means of a plain bearing 72 against a protrusion 74 situated on the second endwall 18.
• the cavity 70 is preferably of substantially circular shape with a centreline 76 which substantially coincides with the piston centreline 78.
• the protrusion 74 is preferably of
• the first endwall 16 is provided at its aperture with a piston rod bearing 80 which in conjunction with a piston rod seal 79 journals and absorbs radial forces between the piston rod 24 and the first endwall 16.
• the combined effect of the plain bearing 72 between the piston 22 and the protrusion 74 on the second endwall 18 in conjunction with the piston rod bearing 80 is that the piston and the piston rod can with great stability move to and fro in the cylinder housing 14.
• the plain bearing 72 between the piston 22 and the protrusion 74 on the second endwall also make it possible to reduce the axial extent of the operating cylinder 10, thereby reducing the space requirement for the cylinder 10 in the gearbox 4 so that there is room in the gearbox 4 for all of the latter' s necessary components.
• the fact that the cylinder 10 can be of smaller dimensions also reduces the material requirement, leading to lower manufacturing costs for the cylinder 10.
• the gearbox 4 as a whole may be of compact construction in cases where the cylinder 10 is of small dimensions, leading to reduced weight of the vehicle 1 and hence also to less fuel consumption.
• the plain bearing 72 is situated in a recess 82 which runs round the inside of the cavity 70 in the piston 22. This means that the plain bearing 72 will accompany the piston's 22 reciprocating movements.
• the recess 82 is preferably situated in the vicinity of an end surface 84 of the piston 22 which faces away from the piston rod 24, resulting in greater stability along the whole travel of the piston 22.
• the operating cylinder 10 moves the gearwheels 12 situated in the gearbox 4 during gear changes.
• the piston 22 has to be directable to three positions in the cylinder housing 14, comprising respective first and second extreme positions and an intermediate position.
• pressurised fluid is supplied to both the first and second spaces 34, 36 in the cylinder housing 14 via both of the first and second ports 38, 40.
• the valves 44, 46 therefore open and pressurised fluid from the pressure source is supplied to the first and second spaces. The piston will thus be caused to move to the intermediate position depicted in Fig. 3.
• the radial seals 60, 62 abutting against the flange 68 which runs round the piston not only exert forces in opposite directions upon the piston but also act sealingly relative to the third space 58 formed between these two seals, so that the pressurised fluid is kept in the first and second spaces 34, 36 and cannot reach the third space 58 and therefore cannot leave the cylinder housing 14 through the third port 56.
• the inside of the cylinder housing is preferably provided with a notch 86 which runs round it and provides abutment surfaces 88 for the two radial seals 60, 62.
• the axial extent of this circular notch 86 preferably corresponds to that of the circular flange 68.
• the substantially central location of the circular notch 86 in the cylinder housing 14 rmeans that the
• pressurised fluid is supplied to the first space 34 through the first port 38, while at the same time the second space 36 is evacuated of fluid through the second port 40.
• the first valve 44 therefore opens and pressurised fluid from the pressure source 42 is supplied to the first space 34.
• the second valve 46 prevents fluid from being evacuated through the second port 40. The piston 22 will then move to the second extreme position depicted in Fig. 4.
• the first radial seal 60 will abut sealingly against the circular notch 86 in the cylinder housing 14 and prevent pressurised fluid from reaching the third space 58 formed between the radial seals 60, 62, with the result that the fluid is kept in the first space 34 and cannot reach the third space 58 and therefore cannot leave the cylinder housing through the third port 56.
• the operating cylinder 10 has moved the gearwheels 12 in the gearbox 4 to a second gear position.
• the piston's 22 movement from the intermediate position to the second extreme position has moved the pin 52 further into the cavity 54 in the sensor 50.
• the sensor therefore sends signals to the control unit 48 about the piston's position in the cylinder housing 14.
• the control unit 48, the valves 44, 46 and the pressure source 42 with associated connections and lines have been omitted in Fig. 4.
• fluid is supplied to the second space 36, whereupon the first and third spaces 34, 58 are evacuated of fluid.
• the second space 36 is thus in communication with the piston's axial cavity via the passage 90.
• the transverse duct 91 extends substantially radially, while the passage 90 extends substantially axially.
• Fig. 5 is a sectional view of the operating cylinder 10 in a second embodiment of the present invention in a first extreme position.
• the first embodiment differs from the second in that the plain bearing 72 is situated on the protrusion 74, which makes it easy for the bearing to be removed and replaced by the second endwall 18 being separated from the cylinder housing 14 and being refitted after a new plain bearing 72 has been fitted on the protrusion 74.
• Cited components and features indicated above may within the scope of the invention be combined with different cited embodiments.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Gear-Shifting Mechanisms (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

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ID=50435234

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (2)

Citations (13)

• 2012
  • 2012-10-03 SE SE1251112A patent/SE536688C2/sv unknown
• 2013
  • 2013-09-13 WO PCT/SE2013/051068 patent/WO2014055008A1/en active Application Filing
  • 2013-09-13 DE DE112013004343.2T patent/DE112013004343T5/de not_active Withdrawn

Patent Citations (13)

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