US3926093A - Oil-hydraulic servo-motor - Google Patents

Oil-hydraulic servo-motor Download PDF

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Publication number
US3926093A
US3926093A US477064A US47706474A US3926093A US 3926093 A US3926093 A US 3926093A US 477064 A US477064 A US 477064A US 47706474 A US47706474 A US 47706474A US 3926093 A US3926093 A US 3926093A
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United States
Prior art keywords
oil pressure
piston
servo
oil
pressure chamber
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Expired - Lifetime
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US477064A
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English (en)
Inventor
Tadao Nakagawa
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Hitachi Astemo Ltd
Original Assignee
Nissin Kogyo Co Ltd
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Publication date
Application filed by Nissin Kogyo Co Ltd filed Critical Nissin Kogyo Co Ltd
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Publication of US3926093A publication Critical patent/US3926093A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
    • B60T13/142—Systems with master cylinder
    • B60T13/143—Master cylinder mechanically coupled with booster
    • B60T13/144—Pilot valve provided inside booster piston

Definitions

  • the present invention is intended to overcome such difficulties previously met with servo-motors of the type described and has for its principal object the pro vision of a new and improved oil-hydraulic servo-motor which not only normally gives an output adjustable with limited movement of the input member while enabling the operator to feel the intensity of such. output exactly through the input member and avoid any excessive input operation but is operable in any failure of the oil pressure system to actuate the associated device such as an automotive brake directly under the operators input effort and highly valuable from the standpoint of safety.
  • Another object of the present invention is to provide a servo-motor of the character described which is de signed so as to allow flow of pressure oil into the reaction oil pressure chamber only at such a limited rate as not causing any upleasant feeling to the operator even under sudden input operation.
  • Still another object of the present invention is to pro vide a servo-motor of the character described which is kept free from formation of any hollows in the power cylinder or the reaction oil pressure chamber even if the system is left inoperative for an extended period of time and thus can respond to the input as given by the operator at all times without delay.
  • FIG. 1 represents a partly schematic, axial cross section of the embodiment
  • FIG. 2 is a transverse cross-sectional view taken along the line IIII in FIG. 1;
  • FIG. 3 is a view similar to FIG. 2, taken along the line IIIIII in FIG. 1.
  • reference character M indicates a well-known form of brake master cylinder, in which an operating piston 1 is accommodated to serve the purpose of supplying pressure oil to the oilhydraulic components of the brake system.
  • an operating piston 1 is accommodated to serve the purpose of supplying pressure oil to the oilhydraulic components of the brake system.
  • a power cylinder P Connected to 'the master cylinder M at its rear end is a power cylinder P to the rear of which a control casing C is .connected.
  • An output piston 2 is slidably fitted in the power cylinder P and operably connected to the rear end of operating piston 1 with a restoring spring 3 arranged under compression between the master cylinder M and output piston 2 to bias the latter rearwards.
  • the control casing C has an interior space in the form of a shouldered cylindrical bore 4, which is in align ment with the power cylinder P and has a rear portion slightly reduced in diameter and connected with the forward, major bore portion through the medium of a tapered annular shoulder surface 5.
  • a servo piston 6 is slidably fitted in the reduced-diameter portion of the cylindrical bore 4 and defines therein a high oil pressure chamber A and a low oil pressure chamber B respectively on the front and rear sides thereof.
  • Extending axially forwardly from the servo piston 6 is an integral piston rod 6a which is slidably fitted in the rear portion of the power cylinder P- to serve as a stop for limiting the retracting movement of the output piston 2.
  • the piston 6 is formed at its forward end with an integral annular flange 7, which is slidably fitted in the major or larger-diameter portion of the cylindrical bore 4 and is formed with a number of radial notches 7a at circumferentially equal intervals, as shown in FIG. 3.
  • a high pressure line L Connected to the high oil pressure chamber A is a high pressure line L which is connected at the other end with an oil pressure pump 8 and includes an oil accumulator
  • a low pressure line L is connected to the low oil pressure chamber B and opening at the other end into an oil reservoir 10.
  • a relief valve 11 is arranged midway of the low pressure line L and adapted to open when the oil pressure in the low oil pressure chamber A reaches a predetermined level.
  • Reference numeral 12 indicates a pressure-regulating spring arranged on the valve 11 and serving to restore it to its normal closed position.
  • the servo piston 6 is formed with a cylindrical axial bore 13 opening rearwardly to receive a stopper element 14, which defines a valve chamber 15 in the forward portion of the axial bore 13.
  • the valve chamber 15 is in fluid communication with the high oil pressure chamber A through an oil inlet port 18 formed in the front wall of the valve chamber and further through an axial enlarged diameter bore 19 and transverse or diametral bores 20 all formed in the pistonrod 6a, as shown in FIG. 2.
  • the valve chamber 15 is also incomted therein for limited axial displacement and a valvespring 17 normally biasing the valve element 16 rearwards.
  • a ball-shaped second valve element 22 is accommodated in the axial bore 19 to close the oil inlet port 18 under the bias of a valve-closing spring 23 also accommodated in the axial bore 19.
  • a valve-opening rod 24 is extended forwardly from the first valve element 16 so that the second valve element or ball 22 is pushed forward by the rod 24 to open the oil inlet port 18 when the first valve element 16 is advanced.
  • the stopper element 14 is formed therein with a cylindrical bore 26, which communicates with the valve chamber 15 by way of through apertures 25 formed in the first valve element 16 and an annular flange 27 ex-.
  • An input piston 28 is slidably fitted, in the cylindrical bore 26 and defines therein a re-.
  • action oil pressure chamber R in co-operation with the annular flange 27.
  • .Formed on the front face of the operating piston 28 is an axial tubular projection 29 which extends into the annular flange 27 and defines together therewith an annular opening or orifice 30.
  • An annular stop 31 is secured to the periphery of input piston 28 to limit rearward movement thereof by abutting engagement with the adjacent wall of the control casing C.
  • a biasing spring 62 is arranged between the stop 31 and, stopper element 14 to normally hold the input piston 28 in its fully retracted position keeping a limited axial space between the first valve element 16 and tubular projection 29.
  • the input piston 28 is an axially extending oil outlet port 34 which openes forwardly through thetubular projection 29 and communicates at the rear end with the low oil pressure chamber B through a diametral bore or bores 33 formed in the input piston in intersecting-relation with the oil outlet port 34. It is to be understood that in this arrangement the oil outlet port 34 is closed against the back face of the first valve element 16 when the input piston 28 is driven forward.
  • An operating rod 36 is connected with the rear end of the input piston 28 by way of a cushioning member formed of rubber or the like material and, as will readily be understood, is operably connected with a brake pedal, not shown.
  • Reference numeral 37 cindicates annular seals fitted to the outer periphery of the servo piston 6 and other piston members of the servomotor.
  • the servo-motor is shown in it s inop erative position in which, as long as the oil pressure pump 8 and accumulator 9 are in normal operating condition, the high oil pressure chamber A is kept filled with pressure oil from the pressuresupply source so that the piston 6 is firmly held in its normal fully re tracted position, as shown, under the oil pressure.
  • valve element 16 is closed and subsequently the valve element 16 is driven forward to push forward the second valve ele ment 22 by means of the valve-opening rod 24 thereby to open the oil inlet port 18.
  • valve chamber 15 and oil passages 21 and the output piston 2 is driven forward together with the piston l in the master cylinder M thereby to energize the associated brake system.
  • part of the pressure oil flowing in the valve chamber 15 is directed through the annular orifice 30 into the reaction oil pressure chamber R and the oil pressure thus built therein acts upon the input piston 28 as a reaction against the input force applied by the operator.
  • the force of reaction is in proportion to the oil pressure in the power cylinder P and the operator can tell the intensity of the output of piston 2 exactly by feeling the magnitude of such reaction.
  • the rise in oil pressure in the chamber R is comparatively slow even where the pressure rise in thepower cylinder P is sudden and fast. This means that thereaction acting upon the input piston 28 is at all times never impulsive, giving no unpleasant feeling to th'e'operator.
  • the relief valve 1 1 is reclosed under the bias of spring 12 at the instant when the oil pressure in the low oil pressure chamber B is reduced to a predetermined level to maintain such level of oil pressure in the low oil pressure chamber B and in the power cylinder P, valve chamber 15, reaction oil pressure chamber R- and other interior spaces communicating with the low oil pressure chamber B.
  • the input piston 28 started as usual hefoperator' s' input effort and immediately d f f place'gljin 'iabutting engagement with the annular flange 27 on stopper element 14 acts to drive forward the servo piston 6 and piston rod 6a through the medium of stopper element 14 because of the lack of oil pressure serving to hold the servo piston 6 in its retracted position. In this manner, the piston l in the brake master cylinder M is actuated under the input in an effective manner despite of the failure in the oil supply system.
  • the high and low oil pressure chambers A and B are placed in fluid communication with each other through notches 7a, formed in the annular flange 7 of servo piston 6 and through the smaller diameter bore portion.
  • the oil held in the high oil pressure chamber A is thus allowed to flow into the low oil pressure chamber B as the servo piston 6 continues to advance and does not restrain its advancing movement to any extent.
  • piston 6 is kept in axial alignment with the cylindrical bore 4 for smooth sliding movement without jolting even after it has left the smaller diameter portion of cylindrical bore 4 as the annular flange 7 formed on the piston 6 at its forward end is still held in sliding engagement with the peripheral wall of the larger diameter portion of cylindrical bore 4.
  • the servo piston 6 Upon removal of the input, the servo piston 6 is retracted together with the output piston 2 under the bias of restoring spring 3 to again fit into the smaller diameter portion of cylindrical bore 4 without any danger of being injured as the annular seal 37 slightly bulging radially around the periphery of the piston 6 is guided into the smaller diameter bore portion smoothly over the tapered annular shoulder surface 5 formed on the bore wall.
  • An oil-hydraulic servo-motor comprising: a power cylinder having a bore and an output piston slidably fitted in said bore, a control casing secured to said power cylinder at the rear end thereof and defining a cylindrical bore in axial alignment with said power cylinder, a servo piston slidably fitted in said cylindrical bore and defining, when fully retracted, a high and a low oil pressure chamber in said cylindrical bore, respectively, in the front and rear portions thereof, a piston rod extending axially and forwardly from said servo piston and held in sliding engagement with the rear end portion of said power cylinder in end-to-end relation with said output piston, an oil pressure supply source connected to said high oil pressure chamber, an oil reservoir communicatin g with said low oil pressure chamber, a reaction oil pressure chamber defined in said servo piston and communicating with the bore in said power cylinder, an input piston slidably supported in said control casing in axial alignment with said servo piston and having the piston face thereof extending forwardly into said reaction oil
  • reaction oil pressure chamber is in fluid communication with said power cylinder through an orifice restricting the rate of pressure oil flow into said reaction oil pressure chamber.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Braking Systems And Boosters (AREA)
US477064A 1974-04-24 1974-06-06 Oil-hydraulic servo-motor Expired - Lifetime US3926093A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4617774A JPS5339953B2 (enrdf_load_stackoverflow) 1974-04-24 1974-04-24

Publications (1)

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US3926093A true US3926093A (en) 1975-12-16

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US477064A Expired - Lifetime US3926093A (en) 1974-04-24 1974-06-06 Oil-hydraulic servo-motor

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US (1) US3926093A (enrdf_load_stackoverflow)
JP (1) JPS5339953B2 (enrdf_load_stackoverflow)
GB (1) GB1460384A (enrdf_load_stackoverflow)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014171A (en) * 1974-06-10 1977-03-29 Aisin Seiki Co., Ltd. Hydraulic brake booster
US4050251A (en) * 1975-03-04 1977-09-27 Societe Anonyme D.B.A. Hydraulic booster
US4075848A (en) * 1975-02-07 1978-02-28 Aisin Seiki Kabushiki Kaisha Hydraulic brake booster
US4117766A (en) * 1975-11-21 1978-10-03 Societe Anonyme D.B.A. Hydraulic booster
US4143514A (en) * 1975-07-12 1979-03-13 Robert Bosch Gmbh Master brake cylinder for two-circuit braking system
US4201057A (en) * 1977-08-31 1980-05-06 Ford Motor Company Air hydraulic brake actuator
US4290340A (en) * 1978-11-10 1981-09-22 Aisin Seiki Kabushiki Kaisha Hydraulic booster
US4656923A (en) * 1984-10-17 1987-04-14 Jidosha Kiki Co., Ltd. Loss stroke reducing apparatus for hydraulic servomechanism
US4665701A (en) * 1985-10-30 1987-05-19 Allied Corporation Hydraulic brake booster with quick take-up and reduced stroke
US4685297A (en) * 1985-10-30 1987-08-11 Allied Corporation Hydraulic brake booster with quick take-up and full stroke
US4881449A (en) * 1987-10-26 1989-11-21 Nissin Kogyo Kabushiki Kaisha Hydraulic booster device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105416261A (zh) * 2015-12-17 2016-03-23 芜湖盛力科技股份有限公司 一种装载机的气顶液空气加力泵

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1708173A (en) * 1927-08-18 1929-04-09 Ingersoll Rand Co Submarine drill
US3093119A (en) * 1961-10-30 1963-06-11 Kelsey Hayes Co Fluid pressure motor
US3106874A (en) * 1961-09-08 1963-10-15 Bendix Corp Control valve actuating structure
US3115067A (en) * 1961-09-11 1963-12-24 Kelsey Hayes Co Power brake for motor vehicles
US3126794A (en) * 1964-03-31 ayers
US3252382A (en) * 1964-03-05 1966-05-24 Gen Motors Corp Fluid pressure servomotor reaction control mechanism
US3526089A (en) * 1967-10-30 1970-09-01 Bendix Corp Reaction means for fluid pressure control valve

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4846760A (enrdf_load_stackoverflow) * 1971-10-16 1973-07-03

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126794A (en) * 1964-03-31 ayers
US1708173A (en) * 1927-08-18 1929-04-09 Ingersoll Rand Co Submarine drill
US3106874A (en) * 1961-09-08 1963-10-15 Bendix Corp Control valve actuating structure
US3115067A (en) * 1961-09-11 1963-12-24 Kelsey Hayes Co Power brake for motor vehicles
US3093119A (en) * 1961-10-30 1963-06-11 Kelsey Hayes Co Fluid pressure motor
US3252382A (en) * 1964-03-05 1966-05-24 Gen Motors Corp Fluid pressure servomotor reaction control mechanism
US3526089A (en) * 1967-10-30 1970-09-01 Bendix Corp Reaction means for fluid pressure control valve

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014171A (en) * 1974-06-10 1977-03-29 Aisin Seiki Co., Ltd. Hydraulic brake booster
US4075848A (en) * 1975-02-07 1978-02-28 Aisin Seiki Kabushiki Kaisha Hydraulic brake booster
US4050251A (en) * 1975-03-04 1977-09-27 Societe Anonyme D.B.A. Hydraulic booster
US4143514A (en) * 1975-07-12 1979-03-13 Robert Bosch Gmbh Master brake cylinder for two-circuit braking system
US4117766A (en) * 1975-11-21 1978-10-03 Societe Anonyme D.B.A. Hydraulic booster
US4201057A (en) * 1977-08-31 1980-05-06 Ford Motor Company Air hydraulic brake actuator
US4290340A (en) * 1978-11-10 1981-09-22 Aisin Seiki Kabushiki Kaisha Hydraulic booster
US4656923A (en) * 1984-10-17 1987-04-14 Jidosha Kiki Co., Ltd. Loss stroke reducing apparatus for hydraulic servomechanism
AU575435B2 (en) * 1984-10-17 1988-07-28 Jidosha Kiki Co. Ltd. Servomechanism for hydraulic servo brake
US4665701A (en) * 1985-10-30 1987-05-19 Allied Corporation Hydraulic brake booster with quick take-up and reduced stroke
US4685297A (en) * 1985-10-30 1987-08-11 Allied Corporation Hydraulic brake booster with quick take-up and full stroke
US4881449A (en) * 1987-10-26 1989-11-21 Nissin Kogyo Kabushiki Kaisha Hydraulic booster device

Also Published As

Publication number Publication date
JPS5339953B2 (enrdf_load_stackoverflow) 1978-10-24
GB1460384A (en) 1977-01-06
JPS50139276A (enrdf_load_stackoverflow) 1975-11-07

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