US3567330A - Speed control means - Google Patents

Speed control means Download PDF

Info

Publication number
US3567330A
US3567330A US850867A US3567330DA US3567330A US 3567330 A US3567330 A US 3567330A US 850867 A US850867 A US 850867A US 3567330D A US3567330D A US 3567330DA US 3567330 A US3567330 A US 3567330A
Authority
US
United States
Prior art keywords
machine
rotational speed
valve
pressure
motor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US850867A
Other languages
English (en)
Inventor
Ulf Martin Christian Apelskog
Lennart Erik Idoft Gidlund
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atlas Copco AB
Original Assignee
Atlas Copco AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atlas Copco AB filed Critical Atlas Copco AB
Application granted granted Critical
Publication of US3567330A publication Critical patent/US3567330A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
    • A61C1/02—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design characterised by the drive of the dental tools
    • A61C1/05—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design characterised by the drive of the dental tools with turbine drive
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C1/00—Dental machines for boring or cutting ; General features of dental machines or apparatus, e.g. hand-piece design
    • A61C1/0007—Control devices or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
    • F01D15/06—Adaptations for driving, or combinations with, hand-held tools or the like control thereof
    • F01D15/062—Controlling means specially adapted therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S415/00—Rotary kinetic fluid motors or pumps
    • Y10S415/904—Tool drive turbine, e.g. dental drill

Definitions

  • This invention relates to speed control means and more particularly to rotational speed control means for hand sustained machines having a pressure fluid driven rotary motor and intended for such operations as grinding and drilling preferably in connection with dental work.
  • a reduction valve by which the pressure level of the pressure fluid entering the motor may be adjusted whereby the rotational maximum idling speed of the motor and its torque under working load are influenced.
  • Such machines are to be used with tools which because of the Working process or by reason of strength considerations must be driven with low carefully limited rotational speed, such being the case for example in special dental tools for root filling operations and in grinding disks.
  • Another measure applicable particularly in connection with grinding machines is to provide the machine with a centrifugal regulator controlling the pressure of the working fluid.
  • This solution is inappropriate in machines with very high rotational speed because of the usually restricted working range of centrifugal regulators and the regulator furthermore causes an undesirable increase in weight which is inconvenient particularly in dental machines.
  • a pressure fluid driven rotary motor for grinding, drilling and the like, a pressure fluid driven rotary motor, a supply conduit connected to said motor for supplying pressure fluid thereto, a pressure reduction valve in said supply conduit for adjusting the pressure level therein, and a rotational speed control means for said machine, said rotational speed control means com- 3,567,330 Patented Mar.
  • an automatic pressure control valve in said supply conduit between said reduction valve and said motor actuatable for controlling the pressure before said motor, a servo element in said control valve for the actuation thereof, and a control circuit
  • said control circuit including a servo circuit connected to said servo element for actuating said control valve, a gauging circuit for sensing the actual value of the rotational speed of said motor, an adjusting circuit for adjusting the rotational speed of said motor to a selective reference value lower than the rotational idling speed of said motor as defined by the adjustment of said pressure reduction valve, and means in said control circuit for controlling through the medium of said servo element and said control valve the pressure before said motor such as to keep said actual value substantially equal to said reference value from the instant the motor rotates idle up to the motor being under full Working load at the pressure level defined by said reduction valve.
  • FIG. 1 shows a longitudinal section through the rear portion of a hand sustained machine embodying the invention.
  • FIG. 2 shows a diagrammatic longitudinal section through an automatic control valve embodying the invention.
  • FIG. 3 illustrates a reduction valve for the machine shown in FIG. 1.
  • FIG. 4 shows an end view on the line 4-4 in FIG. 1.
  • FIG. 5 is a partial cross section and top view of the motor in FIG. 4.
  • FIG. 6 shows diagrammatically an electrical control circuit associated with the automatic control valve depicted in FIG. 2.
  • FIG. 7 shows a longitudinal section through a modified embodiment of the control valve.
  • FIG. 8 is a section on the line 88 in FIG. 7.
  • a composite housing 10 in the shape of a hand piece is provided with a rotatably journalled drive spindle 11 which via drive axle parts 12, not shown in more detail, in known manner drives a dental tool such as a drill, a grinding disk, or the like, received in the machine .10.
  • the housing 10 is provided with a throttle valve 13 inserted between a supply conduit or hose 14 and an inner chamber 15 in the machine housing 10. From the chamber 15 pressure fluid supplied through hose 14 is led via guide openings 16 against the blades 17 in a motor in the shape of a pressure fluid driven turbine 18. After the turbine 18 the pressure fluid is expelled to the surrounding atmosphere via openings 19, 20.
  • the turbine 18 is drivingly connected to the drive spindle 11.
  • the throttle valve 13 is actuated manually by means of a lifter 21 which latter through the medium of a spring-loaded cam sleeve 22 can be displaced rearwardly in the housing 10 by a spring loop 23, not shown in more detail, graspable at the forward portion of the housing 10, the spring loop 23 being afilxed to the cam sleeve 22.
  • Pressure fluid for driving the motor 18 of the machine 10 is supplied from a suitable source via a hose 24, FIG. 3, to a reduction valve 25 constructed in conventional way.
  • a ball valve 27 to be opened by means of a lifter 28 against the pressure of the fluid delivered by the hose 24.
  • the lifter 28 is loaded by a spring 30 abutting thereagainst through the intermediary of a diaphragm 31, the spring 30 being adjustable as to its spring load by a knob 29.
  • the diaphragm 31 is disposed in a chamber 32 connected by a conduit 33 with an outlet conduit 34 disposed downstream with respect to the ball valve 27. By turning of the knob 29 the load of the spring 30 is set so that there will be maintained in the outlet conduit 34 a pressure level reduced to the desired degree relative to the pressure level in the hose 24.
  • the pressure control valve 36 is connected by a hose 37 with the outlet conduit 34 of the reduction valve 25 and includes a throttling means or aperture 38, a central passage 39 having a widening diifusor portion 40, and a diverting portion 42 terminated by a valve seat 41.
  • the hose r14 of the machine 10 is connected to the diffusor portion of the central passage 39.
  • the control valve 36 is provided with a solenoid 43 which actuates magnetically a servo eiement 44 pivotally journalled in the control valve 36.
  • the servo element 44 has a plate-shaped portion 45 cooperating with the valve seat 41 and rapidly adjusting itselr" relative thereto to automatically regulated adjusting positions defined by the largeness of the DC. voltage energizing the solenoid 43.
  • a piston 46 is supplied with pressure fluid from the hose 37 via a passage 47 immediately after the throttling aperture 38. As a result the piston 46 will strive to load the plate-shaped portion 45 of the servo element 44 towards the seat 41 against incoming fluid flow action in the diverting portion 42. With the valve seat 41 open the pressure fluid is expelled from the diverting portion 42 via a cavity 4 8 in the control valve 36 to the surrounding atmosphere.
  • FIGS. 2 and 6 By numeral 50 in FIGS. 2 and 6 is designated an electrical unit box which together with the automatic control valve 36 and the reduction valve 25- is mounted separately from the hand sustained machine 10.
  • the electrical unit box 50 includes the main components in an automatic control circuit associated with the control valve 36.
  • the electrical unit box 50 includes conventional transistorized components fed by a suitable voltage source, not shown.
  • a gauging circuit including a conductor 51 which is extended from an induction coil 52 fixed in the machine 10, in which coil 52 voltage pulses are induced by permanent magnets 53 carried by the turbine 18.
  • the conductor 51 is connected to an amplifier 54 in which the weak voltage pulses from the induction coil 52 are amplified for then being fed into a rectifying and integrating block 55, the output signal of which repre sents a DC voltage value proportional to the actual rotational speed of the motor 18.
  • This direct current voltage value represents the actual value in the control circuit of the pressure control valve 36.
  • an adjusting circuit 56 in which an adjustable potentiometer 57 fed by suitable DC. voltage forms the main part.
  • a DC. voltage value which in the control circuit represents the desired reference value for the rotational speed.
  • the actual value and the reference value are fed in the form of DC. voltage values into a controlling means consisting of a servo amplifier 58 working as an integrating operational amplifier in which the actuai value and the desired value are compared over resistances 59, 60 placed in series and an output signal defined as to its polarity and largeness is produced which is fed into a power amplifier 61. From the power amplifier 61 the output signal in the form of a DC. voltage is led over a conductor 62 to the solenoid 43 of the control valve 36 for actuation of the servo element 44.
  • the pressure reduction valve 25 is set to a pressure level resulting in a certain maximai idling rotational speed and the desired torque under full working load, respectiveiy.
  • the reference value is set to maximum at the potentiometer 57 which results in the servo element 44 keeping the valve seat 41 closed and the pressure level in the hose 14 to the machine 10 becoming substantially equal to the level adjusted at the pressure reduction valve 25.
  • the servo circuit is actuated by setting by means of the potentiometer 57 and the adjusting circuit 56 as a reference value a calibrated voltage value which puts an upper limit on the idling rotational speed.
  • the pressure reduction valve 25 is maintained on the pressure level which is necessary for giving sufficient torque under working load.
  • the increase in voltage coming in from the gauging circuit 51, 52 and and corresponding to a beginning increase of the actual value of the rotational speed of the motor 18, is received in the servo amplifier 58, the latter delivering an. output signal via the conductor 62 which as to its polarity and largeness is adapted to adjust the servo element 44 by means of the solenoid 43.
  • Such adjustment causes a diversion of pressure fluid from the central passage 39 in the pressure control valve 36 so that the pressure before the machine 10 is regulated during idling and thus the rotational speed is controlled towards taking the adjusted rotational speed reference value.
  • FIGS. 7, 8 a modification of the pressure control valve.
  • the control valve 36 in question is provided with a solenoid 65 which is fixed to a throttling valve body 66.
  • the throttling valve body 66 projects into a chamber 67 set in between the hoses 37, 14 for throttling therein the flow area when on the basis of voltage received in the solenoid 65 the pressure is to be influenced in the hose 14.
  • a pressure fluid driven rotary motor a supply conduit connected to said motor for supplying pressure fluid thereto, a pressure reduction valve in said supply conduit for adjusting the pressure level therein, and a rotational speed control means for said machine
  • said control circuit including a servo circuit connected to said servo element for actuating said control vaive, a gauging circuit for sensing the actual value of the rotational speed of said motor, and adjusting circuit for adjusting the rotational speed of said motor to a selective reference value lower than the rotational idling speed of said motor as defined by the adjustment of said pressure reduction valve, and means in said control circuit for controlling through the medium of said servo element and said control valve the pressure before said motor such as to
  • control circuit is electrical and said gauging and adjusting circuits thereof are connected to feed said controlling means with electrical DC. voltage values corresponding respectively to said actual value and to said reference value, said controlling means including an integrating operational amplifier for delivering a DC. output signal to actuate said servo element of said control valve.
  • said gauging circuit includes inductive voltage pulse gauge means consisting of permanent magnets arranged on said motor and cooperating with induction coil means in said machine, said coil means forming part of said gauging circuit.
  • a machine in which said supply conduit of said motor is a supply hose connected to said machine, said gauging circuit includes an amplifier separate from said machine, and said induction coil means is connected to said amplifier through the medium of a conductor extended through said supply hose.
  • control valve includes a valve seat connected to said supply conduit and to passage means for diverting pressure fluid from said supply conduit, and in which said servo element includes a valve body cooperating with said valve seat for controlling fluid diversion through said passage means, and solenoid means for actuating said valve body.
  • said servo element includes a throttle valve body in said control valve actuatable for throttling fluid flow through said supply conduit, and solenoid means for actuating said throttle valve body.

Landscapes

  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Control Of Non-Electrical Variables (AREA)
US850867A 1968-08-27 1969-08-18 Speed control means Expired - Lifetime US3567330A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE11529/68A SE319574B (de) 1968-08-27 1968-08-27

Publications (1)

Publication Number Publication Date
US3567330A true US3567330A (en) 1971-03-02

Family

ID=20294131

Family Applications (1)

Application Number Title Priority Date Filing Date
US850867A Expired - Lifetime US3567330A (en) 1968-08-27 1969-08-18 Speed control means

Country Status (8)

Country Link
US (1) US3567330A (de)
AT (1) AT301743B (de)
BE (1) BE737974A (de)
CH (1) CH494426A (de)
FR (1) FR2017040A1 (de)
GB (1) GB1234903A (de)
NL (1) NL6913005A (de)
SE (1) SE319574B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955283A (en) * 1974-10-31 1976-05-11 Timothy William Mehallick Flexible handpiece mounted control for dental drills
US3959883A (en) * 1973-07-23 1976-06-01 Walls Earl L Hand control system for power hand tools
US4256998A (en) * 1976-12-17 1981-03-17 Samuels Basil J Electrical control arrangement
US5782634A (en) * 1995-08-11 1998-07-21 Kaltenbach & Voigt Gmbh & Co. Medical, in particular dental turbine handpiece
US6146137A (en) * 1998-11-19 2000-11-14 Vogel; William Charles Contamination prevention device for ultra high speed dental type handpieces
US20030070301A1 (en) * 2001-10-16 2003-04-17 Bettcher Industries, Inc. Pneumatic hand tool with improved control valve

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959883A (en) * 1973-07-23 1976-06-01 Walls Earl L Hand control system for power hand tools
US3955283A (en) * 1974-10-31 1976-05-11 Timothy William Mehallick Flexible handpiece mounted control for dental drills
US4256998A (en) * 1976-12-17 1981-03-17 Samuels Basil J Electrical control arrangement
US5782634A (en) * 1995-08-11 1998-07-21 Kaltenbach & Voigt Gmbh & Co. Medical, in particular dental turbine handpiece
US6146137A (en) * 1998-11-19 2000-11-14 Vogel; William Charles Contamination prevention device for ultra high speed dental type handpieces
US20030070301A1 (en) * 2001-10-16 2003-04-17 Bettcher Industries, Inc. Pneumatic hand tool with improved control valve
US6655033B2 (en) * 2001-10-16 2003-12-02 Bettcher Indusrties, Inc. Pneumatic hand tool with improved control valve

Also Published As

Publication number Publication date
BE737974A (de) 1970-02-02
NL6913005A (de) 1970-03-03
GB1234903A (en) 1971-06-09
AT301743B (de) 1972-09-11
SE319574B (de) 1970-01-19
FR2017040A1 (de) 1970-05-15
CH494426A (de) 1970-07-31

Similar Documents

Publication Publication Date Title
US4485595A (en) Grinding and polishing apparatus
US3568367A (en) Glass drilling apparatus
US3567330A (en) Speed control means
US1990052A (en) Fluid actuated drill feed
US3180612A (en) Torque tools
US4454459A (en) Method of controlling the speed of a drill, hammer-drill, or rotary hammer and apparatus therefor
US5190421A (en) Coolant supply system for a machine tool
US4744752A (en) Dental handpiece control device
ES2200545T3 (es) Metodo y sistema de control adaptativo de operaciones de torneado.
GB934316A (en) Feed control device for a machine tool
GB1082848A (en) Portable rotary machining apparatus
EP0079319B1 (de) Pneumatisch angetriebenes Drehwerkzeug
EP0146633A4 (de) Numerisches steuersystem.
US3584522A (en) Machine tool with tool break detector
US11607788B2 (en) Compressed air-driven tool
US2130528A (en) Tool cutting machine equipped with resistance mechanism
US2441291A (en) Spindle positioning mechanism
US1996467A (en) Electromagnetic hydraulic feed control
JPS5455879A (en) Adaptive control circuit for deep hole drilling machine
JPS6051977B2 (ja) Ｎｃ工作機械の手動ハンドル制動方法および装置
JPS6122773Y2 (de)
GB966565A (en) Machine tools
GB962096A (en) Control system with quick response to reference changes
DE1941159A1 (de) Vorrichtung zur Drehzahlregelung von Hand gefuehrter,durch Druckmittelmotoren angetriebener Maschinen zum Schleifen,Bohren usw.
SU420404A1 (ru) Устройство для стабилизации силы резания на металлорежущих станках