US3809034A

US3809034A - Speed regulator for an internal combustion engine

Info

Publication number: US3809034A
Application number: US00214231A
Authority: US
Inventors: H Durichen
Original assignee: Deutsche Vergaser GmbH and Co KG
Current assignee: Deutsche Vergaser GmbH and Co KG
Priority date: 1971-04-27
Filing date: 1971-12-30
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: GB1309505A; DE2120510A1; DE2120510B2; JPS517263B1; DE2120510C3

Abstract

A speed regulator for an internal combustion engine including a control device regulating the control valve for the fuel-air mixture to the engine. The control device is responsive to a voltage differential between a first voltage proportional to the engine speed and a second voltage based on a preset engine speed value, so as to provide for control of the valve. Another aspect lies in the provision of a thermal switch preventing operation of the control device during time when engine is below a minimum operating temperature, while concurrently maintaining the control valve in an engine idling attitude.

Description

United States Patent [191 Durichen [451 May 7,1974

[ SPEED REGULATOR FOR AN INTERNAL COMBUSTION ENGINE [73] Assignees Deutsche Vergaser Gesellschaft mbH & Co. K.G., Neuss, Germany [22] Filed: Dec. 30, 1971 [21] Appl. No.: 214,231

[30] Foreign Application Priority Data Apr. 27, 1971 Germany 2120510 [56] References Cited UNITED STATES PATENTS 3,667,020 5/1972 Senzaki 123/102 3,476,205 11/1969 Hato 123/102 3,661,131 5/1972 Croft 123/102 3,636,933 l/l972 Ohtani 123/102 Primary Exa minerLaurence M. Goodridge Assistant ExaminerRonald B. Cox Attorney, Agent, or Firm-Eric l-I. Waters 57] ABSTRACT A speed regulator for an internal combustion engine including a control device regulating the control valve for the fuel-air mixture to the engine. The control device is responsive to a voltage difierential between a first voltage proportional to the engine speed and a second voltage based on a preset engine speed value, so as to provide for control of the valve. Another aspect lies in the provision of a thermal switch preventing operation of the control device during time when engine is below a minimum operating temperature, while concurrently maintaining the control valve in an engine idling attitude.

8 Claims, 2 Drawing Figures SPEED REGULATOR FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a speed regulator for an internal combustion engine having a control valve for regulating the flow of fuel-air mixture to the engine and, more particularly, to an improved electrical control device connected to the control valve and which is adapted to continuously measure the speed of the engine, compared the measured speed with a preset speed value, and adjust the mixture flow rate through the control valve in response to any differential between the measured engine speed and preset values.

2. Description of Prior Art Speed regulators for controlling the idling speeds of internal combustion engines are widely known. For example, presently used regulators provide for comparisons between the electrical voltage of a tachometer generator with a second voltage which is set proportionate to a predetermined speed value or constant'for the engine, and which utilize the measured voltage differential between the two voltages to control an engine air supply or fuel-air mixture supply valve.

Prior art regulators are incapable of providing control for maintaining the engine at a speed which is continuously commensurate with the required preset speed value. In effecting speed control during the idling operation of the engine, a certain degree of fluctuation or extent of deviation from the preset speed value is permissible and generally harmless to the engine.

However, in order to maintain the speed of the internal combustion engine at constant value during the collective operating range of the engine and in view of varying loads, measures are required which are beyond the reach of the present state of technology.

Speed regulators as presently known are readily disrupted and rendered inoperative. Thus, for example, upon interruption of the power supplied to the regulator, the internal combustion engine may readily exceed its permissible speed and be thereby damaged. Furthermore, presently used regulators provide no protective measures to provide against the stalling of the internal combustion engines in view of premature high speeds under load upon cold starting.

SUMMARY OF THE INVENTION In accordance with the present invention, the problems and drawbacks encountered in prior art speed regulators are solved by providing, in the electrical circuitry of an internal combustion engine speed control device, a thermal switch which is sensitive and responsive to the operating temperature of the internal combustion engine, the electrical control device being restrained from acting upon a fuel-air supply control valve ofthe engine until the internal combustion engine reaches a predetermined minimum operating temperature. Furthermore, the control valve, which is positioned in the fuel-air conduit leading to the internal combustion engine, is provided with a device which automatically sets the control valve into a flow condition corresponding to the engine idling mode upon interruption of the current being supplied to the electrical control device. The thermal switch may, for example, be

responsive to the cooling system temperature of the internal combustion engine rather than the temperature of the engine itself, and may be located in the current supply circuit of an actuating motor for the control device, or in a separate electrical circuit.

In a modification of the present invention, the control valve cooperates with a variable-speed electric motor which is connected, across a low voltage relay, with an independent power source, whereas the relay is responsive to the power or current supply for the control device. Upon interruption of the current flow to the electric control device, the electric motor effects positioning of the control valve into the internal combustion engine idling operational mode.

In another aspect of the invention, the engine speed regulator assembly includes an electro-magnetic coupling which is located between the electrical control device and the control valve, and which provides for mechanical separation between these components upon interruption of the current supply tothe electrical control device is interrupted. The control valve further includes a tension spring which positions and retains the valve in its closed or engine idling mode in response to separation of the mechanical connection between the control valves and electrical control device. Preferably, the electro-magnetic coupling may be formed as a friction clutch.

The electrical control device is constituted of the following elements, considered, in the direction of its operating sequence towards the control valve, of a first voltage supply having a voltage proportioned in correspondence with the engine speed, and which may include a tachometer generator; a second voltage supply independent of the first voltage and which is set so as to be proportional with a desired preset engine speed value, an electronic comparator receiving the first and second voltages and having an output voltage formed by the differential between the first and second voltages, an electric amplifier connected to the comparator output, and a variable-speed electric motor connected to the amplifier output and including a number of selectively switched-in drives connected to the output shaft of the motor.

The first voltage, which is proportional to the engine speed, may also be generated with the assistance of a suitable impulse counter and energy conversion device, which is provided by the impulses of the engine ignition interruptors, or may be synchronous with an inductive member such as an induction coil extending about the engine crankshaft.

The electrical control device includes at least one integrally operating control or behavioral pattern. Further, during selective operating modes, the electrical control device may also include a proportionally or differentially operating control or behavioral pattern. The variable-speed electric motor preferably includes a practically instantaneously operating airbrake installation which, in a currentless condition, brakes the motor to a full stop. In lieu thereof, the variable speed motor may incorporate a stepping-switch arrangement. A suitable crankshaft drive, including a plate cam-and follower arrangement, is located between the electromagnetic coupling and the control valve.

It is accordingly an object of the present invention to provide an improved and novel speed regulator for an internal combustion engine so as to afford the engine increased applications for driving alternating current and three-phase current generators having a constant phase frequency.

Another object of the present invention is to provide a speed regulator or control device for an internal combustion engine adapted to maintain the engine at constant speeds under variable engine loads acting over extensive operating ranges.

Still another object of the present invention is to provide for a speed control device for an internal combustion engine which becomes operative only upon the engine attaining a predetermined minimum operating temperature.

A further object of the present invention is to provide for a speed regulator or control device for an internal combustion engine which incorporates an electrical switching system adapted, upon interruption of an electrical current being supplied to the'control device, to

position the control valve so as to convey a flow of fuelair mixture into the engine at a rate corresponding to the engine idling mode.

A BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be had to the drawings, describing a preferred embodiment of the invention, in which:

FIG. 1 illustrates a partially schematic view of a speed control device and control valve arrangement for an internal combustion engine in accordance with the present invention; and

FIG. 2 shows a view in the direction of arrow A in FIG. 1, illustrating the control valve, including the return spring, cam plate and follower arrangement of the camshaft drive of the internal combustion engine.

DETAILED DESCRIPTION Referring now in detail to the drawings, an engine speed regulator assembly includes a tachometer generator 11, the latter of which is connected to a I crankshaft assembly 23 of an internal combustion engine (not shown).

The tachometer generator 11 is connected to the input of a regulator 12, and generates a voltage which is proportionate to the rate of speed of the'internal combustion engine, the voltage being supplied to the input of the, regulator 12 in a controlled intensity X. A potentiometer 13 provides a variable voltage which is designated as the drive potential voltage intensity W, and is similarly connected into another input of the reg ulator 12. The regulator 12 contains a standard type of electronic comparator 40 which may be simply designated by an electrical bridge connection 41 and a transistor 42. Y

The differential between the two input voltages X and W fed into regulator 12 provides a voltage output intensity Y, which is conducted to and amplified in an amplifier 14, and then further conducted to a variablespeed electric motor 15. In accordance with the polarity of the output current, and output shaft 16 of the electric motor may be rotated clockwise or counterclockwise.

A brake 17 is adapted to be actuated so as to provide a braking effect on output shaft 16. The brake 17 is adapted to be actuated or raised away from contact with shaft 16 by means of air'operated magnets 18. The magnets 18 are actuated through an independent electrical power supply circuit 19, which may be closed by means of a voltage relay 20. As soon as a voltage is generated at theoutput end of the amplifier 14, the airoperated magnets 18 are released and the brake 17 is moved away from shaft 16 so as to permit the latter to rotate.

A drive 21 connects the electric motor 15 to a control valve 22 which may controllably set through a variation of The connection provided by the drive 21 also incorporates a crankshaft assembly or drive 23 which includes a cam plate 24 connected to a shaft 28. An eccentric 26, including a follower roller 27, is fastened to an end of a control valve shaft 25. The shaft 28 is connected to an output shaft 30 of drive 21 through a shaft coupling 29. The coupling 29 includes electrical circuit 31 actuating coupling magnets 32 which may be closed through the operation of a thermal switch 33. Upon the temperature of the internal combustion engine reaching a predetermined minimum operating value, the thermal switch 33, which may be located in the cooling system of the internal combustion engine, closes the electrical circuit 31 so as to provide electro-magnetic coupling of

shafts

30 and 28 whereby the two shafts are driven in unison. The thermal switch 33 will prevent the rotational speed of the internal combustion engine, upon cold starting under load conditions, approaching drive speed since at that time a sufficiently rich fuel-air mixture for satisfactory engine operation is not readily available.

The opposite end of control valve shaft 25 includes a stub shaft 34, having one end of the lever 35 fastened thereto. The other end of lever 35 is connected to a tensioned return spring36, as shown in FIG. 2 of the drawing, which imparts a tensile force to the control valve 22 tending to pull the latter into a fuel-air mixture flow rate attitude corresponding to the engine idling mode.

Upon cold starting of the internal combustion engine, a voltage is provided through an auxiliary contact, concurrent with the switching in of the engine ignition, in

electrical circuits

19 and 31, and in the electrical circuit 'of the amplifier 14. The coupling 29 between

shafts

28 and 30 remains open and the spring 36 restrains control valve 22 in the engine idling mode, as shown in FIG. 2 of the drawing. After engine starting,

the internal combustion engine runs at an idling speed,

which is below the loaded operating speed of the engine. Since the tachometer generator 11 provides a voltage which is proportional to the engine idling speed, regulator 12 provides output voltage intensity Y corresponding to the difference between the voltage intensity W provided by potentiometer 30 and the voltage intensity X generated by the tachometer generator. Amplifier 14 increases the value of voltage intensity Y to a height or intensity sufficient for the operation of variable-speed electric motor 15. Concurrently, voltage relay 20 is excited by a voltage generated across a conductor 37, thereby opening closed electrical circuit 19. This causes the air-operated magnets 18 to release brake 17, allowing rotation of shaft 16 and drive 21 so as to drive output shaft 30 in response thereto.

During this time internal, shaft coupling 29 is open, and remains in that position until thermal switch 33 senses that a predetermined minimum operating temperature for the internal combustion engine has been reached. At that instant, electrical circuit 31 is opened and coupling magnets 32 allows coupling 29 to interconnect

shafts

28 and 30. The coupling of the shafts is obtained in a generally smooth transitional sequence, since the coupling is preferably formed as a friction clutch.

Upon

shafts

28 and 30 being coupled, cam plate 24 is rotated in either direction, depending upon the polarity of the current, by electric motor 15, as shown in FIG. 2, and concurrently displaces eccentric 26 through follower roller 27 so as to pivot the control valve shaft 25 including control valve 22 in opposition to the tensile force of the spring 36 into an opening relationship until current ceases to flow through electric motor 15, in effect, until the measured engine speed coincides with the preset engine speed value on potentiometer 13. The increase in the engine speed is thereby facilitated, since an increased flow crosssection is provided through control valve 22 for an increased flow of combustion air, such as fuel-air mixture, into the internal combustion engine.

The variation in the cross-sectional flow aperture through the control valve 22 is not proportionate to the angle or degree of the valve opening extent. Accordingly, by an appropriate configuration of plate cam 24 it is possible that the flow-through cross-section of control valve 22 may be controlled so as to be approximately directly proportional to the rotational angle of shaft 28. In other embodiments the shape of the cam plate may be modified so as to provide further valve proportioning, and through experimentation based on the particular field of application adapted to the requirements of the associated internal combustion engine.

The selection of regulator 12 and of the variablespeed electric motor determines the control or behavioral pattern of the entire speed control device. An integrally controlled pattern or behavioral mode is presented when the motor receives a constant voltage from the regulator which forms the voltage output intensity, as long as a speed control deviation is in evidence. This will cause the control valve 22 to be varied as long as or until the deviation of the control voltage drops to zero. In actual operation, various fluctuations deviating from the preset engine speed value are experienced, which may be controlled within permissible parameters for lengthy periods of time through suitable control procedures.

A control or behavioral pattern of a greatly increased variable output is presented when electrical motor 15 consists of, for example,-a direct-current motor and receives at a predetermined intensity an output voltage from regulator 12, which is proportional to the voltage based on the degree of control deviation. This provides a control velocity which is increased in direct proportion to the increase of the instantaneous control deviation. The speed control thereby becomes quite rapid and is decreased to lesser and lesser amount as the control deviation becomes smaller. In accordance with a predetermined minimum valve of the control deviation, extending down to the value zero, the electric motor 15 receives a constant voltage. This, for example, occurs by providing a mono-stable switching arrangement in the form of a Schmitt trigger switch connected in parallel with a known preset speed value comparison switching arrangement in regulator 12.

At the commencement of engine speed control, the proportional behavioral mode dominates, whereas at the end of the speed control the integral pattern dominates. The remaining control deviation accordingly is then zero, in accordance with a purely integrally functioning control relationship. This type of control may be better measured with regard to engine drive conditions.

Finally, in the intermediate control range, a proportional control pattern may be directly provided, for example, by forming one of the bridge resistances in regulator 12 as a proportionate member. This facilitates the high speed operation of the internal combustion engine even more rapidly than by an exclusively intergrally controlled behavioral mode or pattern. However, in this instance, at the first pass through zero, larger deviations from preset speed values may be encountered than in the other embodiments.

In order to effect the control over the engine speed, it is important that the electric motor 15 be instantly braked as soon as the preset engine speed value is attained. In order to achieve this purpose, brake 17 may be provided with a step-switch system in lieu of airoperated magnet 18, for example, a Maltese drive may be provided. Furthermore, the electric motor 15 itself may consist of a step-motor. Similarly, the low-voltage relay 20 may be constituted as a time relay.

Upon interruption of the electrical power supply to the control device, or upon shutting-off of the ignition of the internal combustion engine, electrical current flow to coupling magnet 32 is discontinued. Accordingly, since shaft coupling 29 is thereby released so as to disengage the

shafts

28 and 30, return spring 36 pulls control valve 22 into an engine idling mode or attitude.

This operative sequence is incorporated for reasons of engine safety. The foregoing operative sequence prevents the internal combustion engine from exceeding its allowable speed upon interruption of the power supply to the control device, and concurrently provides for a controlled speed increase from the idling speed ofthe engine.

The advantages obtained by the present invention, in

essence, particularly provide for in that control over the engine speed is first initiated when the internal combustion engine reaches a predetermined iminimum operating temperature, and upon interruption or disturbance of the control device voltage, the control valve is automatically moved into an engine idling attitude. This also will prevent, through use of the foregoing, speed control disturbances, and if these do occur, the disturbances are rendered harmless to the engine.

A further advantage of the invention lies in the rapid and broadly effective constant and fluctuation-free engine speed control, which is achieved by the speed control behavioral modes or patterns in an inventive combination of integral and proportional, or proportional, or integral and differential control patterns.

While there has been shown what is considered to be the preferred embodiment of the invention, it will be obvious that modifications may be made which come within the scope of the disclosure and of the appended claims.

I claim:

1. In a speed regulator for an internal combustion engine having a control valve for regulating the flow of a fuel-air mixture to said engine; an electrical control device connected to said control valve, said control device including means for continuously measuring the speed of the engine, means for comparing the measured engine speed with a preset speed value, and means for adjusting the flow setting of said control valve in accordance with the measured differential between the engine speed and the preset speed value, the

tioned in the circuit of said electrical control device,

said switch means being adapted to interrupt connection between said control device and said control valve until saidengine attains a predetermined minimum operating temperature; means for setting said. control valve to provide a flow of said fuel-air mixture in an engine idling mode during the period of interrupted connection between the control device and the control valve; a variable-speed electric motor connected to said control valve; a low-voltage relay interposed in an electrical line energizing said motor, said electric motor including substantially instantaneously actuatable, electrically-controlled air brake means, said air brake means braking said motor in response to interruption to the flow of electrical current thereto and being adapted to receive an actuating brake-releasing current'coincident with resumption of current flow through said motor, said low-voltage relay being responsive to variations in the electrical current being applied to said electrical control device whereby, upon interruption of the electrical current to said control device, said motor adjusts the setting of said control valve into the engine idling mode.

2. An improvement as claimed in claim 1, the connection between the electrical control device and said with said control valve for movingthe latter into an engine idling mode upon said current interruption.

3. An improvement as claimed in claim 2, wherein said electromagnetic coupling comprises a friction clutch.

4. An improvement as claimed in claim 1, wherein the connection between said electrical control device and said control valve comprises a first voltage source,

means for varying the intensity of said voltage in proportion to the speed of said engine; a second voltage source independent of said first voltage source, said second voltage being adjustable in proportion to the preset speed value of said engine, said comparing means comprising an electronic comparator having an output voltage corresponding to the difference between said first and second voltages; an electrical amplifier receiving said output voltage; and a variablespeed electric motor.

5. An improvement as claimed in claim 4, said intensity varying means for said first voltage comprising a tachometer-generator.

6. An improvement as claimed in claim 2, comprising crankshaft drive means disposed intermediate said electromagnetic coupling and said control valve.

7. An improvement as claimed in claim 6, said crankshaft drive means including a plate cam and cam follower arrangement.

8. An improvement as claimed in claim 1, said control valve comprising a pivotable disc valve disposed in a fuel-air mixture supply conduit of said engine.

Claims

1. In a speed regulator for an internal combustion engine having a control valve for regulating the flow of a fuel-air mixture to said engine; an electrical control device connected to said control valve, said control device including means for continuously measuring the speed of the engine, means for comparing the measured engine speed with a preset speed value, and means for adjusting the flow setting of said control valve in accordance with the measured differential between the engine speed and the preset speed value, the improvement comprising; thermal switch means responsive to the temperature of the engine being positioned in the circuit of said electrical control device, said switch means being adapted to interrupt connection between said control device and said control valve until said engine attains a predetermined minimum operating temperature; means for setting said control valve to provide a flow of said fuel-air mixture in an engine idling mode during the period of interrupted connection between the control device and the control valve; a variable-speed electric motor connected to said control valve; a low-voltage relay interposed in an electrical line energizing said motor, said electric motor including substantially instantaneously actuatable, electrically-controlled air brake means, said air brake means braking said motor in response to interruption to the flow of electrical current thereto and being adapted to receive an actuating brake-releasing current coincident with resumption of current flow through said motor, said low-voltage relay being responsive to variations in the electrical current being applied to said electrical control device whereby, upon interruption of the electrical current to said control device, said motor adjusts the setting of said control valve into the engine idling mode.

2. An improvement as claimed in claim 1, the connection between the electrical control device and said control valve comprising an electromagnetic coupling, said coupling being adapted to interrupt connection between said control device and said valve in response to an interruption of the electrical current supply to said control device; and tension spring means associated with said control valve for moving the latter into an engine idling mode upon said current interruption.

4. An improvement as claimed in claim 1, wherein the connection between said electrical control device and said control valve comprises a first voltage source, means for varying the intensity of said voltage in proportion to the speed of said engine; a second voltage source independent of said first voltage source, said second voltage being adjustable in proportion to the preset speed value of said engine, said comparing means comprising an electronic comparator having an output voltage corresponding to the difference between said first and second voltages; an electrical amplifier receiving said output voltage; and a variable-speed electric motor.