US3024770A - Ram damping device - Google Patents

Ram damping device Download PDF

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Publication number
US3024770A
US3024770A US56055A US5605560A US3024770A US 3024770 A US3024770 A US 3024770A US 56055 A US56055 A US 56055A US 5605560 A US5605560 A US 5605560A US 3024770 A US3024770 A US 3024770A
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United States
Prior art keywords
ram
cylinder
piston
damper
port
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Expired - Lifetime
Application number
US56055A
Inventor
Alibright Dennis Howard
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Dunlop Rubber Co Ltd
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Dunlop Rubber Co Ltd
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Publication date
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Publication of US3024770A publication Critical patent/US3024770A/en
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    • 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
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/046—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed depending on the position of the working member
    • F15B11/048—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed depending on the position of the working member with deceleration control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/755—Control of acceleration or deceleration of the output member

Definitions

  • the invention accordingly provides a fluid-pressure operated ram comprising a ram cylinder containing a ram piston, a damper cylinder, a damper piston in the damper cylinder which is normally ineiective but is movable into a position in which it restricts the ilow of l'luid from the exhaust end of the ram cylinder and means for moving the damper piston from its inoperative to its restricting position when the ⁇ ram piston has performed a predetermined portion of its stroke.
  • the ram cylinder has a port which is unmasked by the ram piston, towards the end of its stroke, to admit fluid under pressure from the ram cylinder to the damping cylinder and thereby cause the damping piston to move into its restricting position.
  • the ram includes a conventional ram cylinder 1 containing a ram piston 2, connected to a piston rod 3.
  • the cylinder 1 is provided with an inlet port 4 at one end and an exhaust port 5 at the other end. While these ports are herein termed inlet and exhaust ports, it will be understood that their functions can be reversed, in known manner, to return the ram piston 2 after its oper ative stroke.
  • the damper cylinder 6 Secured alongside the exhaust end of the ram cylinder 1 is a damper cylinder 6 the axis of which is parallel to the axis of the ram cylinder.
  • the damper cylinder 6 is provided at one end with a port 7 communicating with the exhaust port 5 of the ram cylinder ⁇ and also with an outlet 8. It has at the other end another and smaller port 9 which communicates with a port 10 ⁇ in the ram cylinder 1 situated at about one third of its length from the exhaust end.
  • the ports 9, 10 communicate with a space 11 between the end of the damper cylinder and a piston assembly slidable therein.
  • the piston assembly comprises a piston 12 having the usual sealing rings 13 and a plunger 14 of smaller diameter secured to the piston 12.
  • Said end of the plunger is formed with 'a chamfer 18 and the set screw 17 is so adjusted that when the plunger 14 abuts it in an annular gap of predetermined width is provided between the chamfer 18 and a step 19 formed in the cylinder 6, so restricting the ilow of fluid from the port 5 and retarding the movement of the ram piston 2 to an extent determined by the adjustment of the set screw 17.
  • the location along the stroke of the ram piston 2 at which damping becomes effective is determined by the position of the port il@ leading to the damper cylinder.
  • the extent of the damping obtained is varied by adjustment of the set screw 17.
  • damper cylinder 6 has been illustrated as lying alongside the ram cylinder it is of course obvious that it can be located in any convenient position and connected to the ram cylinder 1 by suitable conduits.
  • a iluid pressure operated assembly comprising a ram cylinder and a damper cylinder, said ram cylinder being provided intermediate its ends with a rst aperture connected to one end of the damper cylinder and being provided at one end with a second aperture connected to the other end of said damper cylinder, a. ram slidable in said ram cylinder under pressure from a source, a damper piston slidable in the damper cylinder when said iirst aperture is uncovered by said ram to connect said damper cylinder with said pressure source, an adjustable stop for said damper piston and restrictor means formed on said damper piston to restrict the iiow of pressure fluid from said second aperture through an exhaust port in said damper cylinder.
  • a ram as claimed in claim 2 comprising a spring disposed in said damping cylinder and urging the damping piston to its inoperative position.

Description

March 13, 1962 D. H. ALLBRIGHT 3,024,770
RAM DAMPING DEVICE Filed Sept. 14, 1960 tent iice 3,024,171) .latented Mar. 13, 1952 3,624,770 RAM DAMPING DEJMIE Dennis Howard Ailbright, Coventry, England, assigner to Dunlop Rubber Company Limited, London, Engiand,
a British company Filed Sept. 14, 1960, Ser. No. 56,055 Claims priority, application Great Britain Sept. 29, 1959 3 Claims. ('Cl. 121-33) It is frequently required to slow down or damp the movement of a iluid-pressure operated ram as it ap proaches the end of its stroke and the object of the present invention is to provide a device whereby this may be done.
The invention accordingly provides a fluid-pressure operated ram comprising a ram cylinder containing a ram piston, a damper cylinder, a damper piston in the damper cylinder which is normally ineiective but is movable into a position in which it restricts the ilow of l'luid from the exhaust end of the ram cylinder and means for moving the damper piston from its inoperative to its restricting position when the `ram piston has performed a predetermined portion of its stroke.
Preferably the ram cylinder has a port which is unmasked by the ram piston, towards the end of its stroke, to admit fluid under pressure from the ram cylinder to the damping cylinder and thereby cause the damping piston to move into its restricting position.
One embodiment of the invention will now be described in detail, by Way of example, with reference to the accompanying drawing which is a longitudinal section through the ram and damper cylinders.
The ram includes a conventional ram cylinder 1 containing a ram piston 2, connected to a piston rod 3. The cylinder 1 is provided with an inlet port 4 at one end and an exhaust port 5 at the other end. While these ports are herein termed inlet and exhaust ports, it will be understood that their functions can be reversed, in known manner, to return the ram piston 2 after its oper ative stroke.
Secured alongside the exhaust end of the ram cylinder 1 is a damper cylinder 6 the axis of which is parallel to the axis of the ram cylinder. The damper cylinder 6 is provided at one end with a port 7 communicating with the exhaust port 5 of the ram cylinder `and also with an outlet 8. It has at the other end another and smaller port 9 which communicates with a port 10` in the ram cylinder 1 situated at about one third of its length from the exhaust end. The ports 9, 10 communicate with a space 11 between the end of the damper cylinder and a piston assembly slidable therein. The piston assembly comprises a piston 12 having the usual sealing rings 13 and a plunger 14 of smaller diameter secured to the piston 12. A helical spring 15 encircling the plunger 14 and having one end seating on a step 16 formed in the wall of the damper cylinder, normally forces the piston assembly into the position illustrated and in this position of the assembly the port 7 is unobstructed by the plunger 14.
When iluid under pressure is admitted to the inlet 4, the ram piston 2 is forced to the left. As it nears the end of its stroke, the piston 2 unmasks the port 10, so admitting fluid under pressure to the space 11 and causing the piston 12 to move to the left until it is arrested by a set screw 17, adjustable from outside the damper cylinder 6, which forms an adjustable stop for the adjacent end of the plunger 14. Said end of the plunger is formed with 'a chamfer 18 and the set screw 17 is so adjusted that when the plunger 14 abuts it in an annular gap of predetermined width is provided between the chamfer 18 and a step 19 formed in the cylinder 6, so restricting the ilow of fluid from the port 5 and retarding the movement of the ram piston 2 to an extent determined by the adjustment of the set screw 17.
On the reverse stroke of the ram piston, where no damping is required, the damper piston assembly moves back under the action of its spring 15 to remove the fiow restriction. If damping on the return stroke also is required a similar device may be fitted to the other end of the ram cylinder.
The location along the stroke of the ram piston 2 at which damping becomes effective is determined by the position of the port il@ leading to the damper cylinder. The extent of the damping obtained is varied by adjustment of the set screw 17.
Although the damper cylinder 6 has been illustrated as lying alongside the ram cylinder it is of course obvious that it can be located in any convenient position and connected to the ram cylinder 1 by suitable conduits.
Having now described my invention, what I claim is:
1. A iluid pressure operated assembly comprising a ram cylinder and a damper cylinder, said ram cylinder being provided intermediate its ends with a rst aperture connected to one end of the damper cylinder and being provided at one end with a second aperture connected to the other end of said damper cylinder, a. ram slidable in said ram cylinder under pressure from a source, a damper piston slidable in the damper cylinder when said iirst aperture is uncovered by said ram to connect said damper cylinder with said pressure source, an adjustable stop for said damper piston and restrictor means formed on said damper piston to restrict the iiow of pressure fluid from said second aperture through an exhaust port in said damper cylinder.
2. A fluid-pressure operated ram as claimed in claim l wherein said restrictor means comprises a chamfer on a cylindrical forward extending plunger of the damper piston which abuts said adjustable stop in a position close to an annular step to leave an annular restricting passage therebetween.
3. A ram as claimed in claim 2 comprising a spring disposed in said damping cylinder and urging the damping piston to its inoperative position.
References Cited in the tile of this patent UNITED STATES PATENTS 1,490,633 Peters Apr. 15, 1924 2,674,138 Mize Apr. 6, 1954 2,735,404 Komph Feb. 2l, 1956 FOREIGN PATENTS 393,054 Great Britain June l, 1933
US56055A 1959-09-29 1960-09-14 Ram damping device Expired - Lifetime US3024770A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3442178A (en) * 1967-08-21 1969-05-06 Herbert H Peters Hydraulically actuated stop for a hydraulic ram unit
US20060076154A1 (en) * 2003-04-01 2006-04-13 Makita Corporation Power tool
US20080190634A1 (en) * 2003-03-21 2008-08-14 Black & Decker Inc. Vehicle control system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1490633A (en) * 1921-09-02 1924-04-15 Deutsche Maschf Ag Pilgering mill
GB393054A (en) * 1931-04-15 1933-06-01 Aubert J Compressed gas servo-motor
US2674138A (en) * 1952-04-30 1954-04-06 Paul D Mize Drilling, boring, or other machine
US2735404A (en) * 1956-02-21 L- komph

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735404A (en) * 1956-02-21 L- komph
US1490633A (en) * 1921-09-02 1924-04-15 Deutsche Maschf Ag Pilgering mill
GB393054A (en) * 1931-04-15 1933-06-01 Aubert J Compressed gas servo-motor
US2674138A (en) * 1952-04-30 1954-04-06 Paul D Mize Drilling, boring, or other machine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3442178A (en) * 1967-08-21 1969-05-06 Herbert H Peters Hydraulically actuated stop for a hydraulic ram unit
US20080190634A1 (en) * 2003-03-21 2008-08-14 Black & Decker Inc. Vehicle control system
US7562721B2 (en) * 2003-03-21 2009-07-21 Black & Decker Inc. Vibration reduction apparatus for power tool and power tool incorporating such apparatus
US20060076154A1 (en) * 2003-04-01 2006-04-13 Makita Corporation Power tool
US7252157B2 (en) * 2003-04-01 2007-08-07 Makita Corporation Power tool

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