CA1276679C - Control of the energization of an electromagnet - Google Patents
Control of the energization of an electromagnetInfo
- Publication number
- CA1276679C CA1276679C CA000524701A CA524701A CA1276679C CA 1276679 C CA1276679 C CA 1276679C CA 000524701 A CA000524701 A CA 000524701A CA 524701 A CA524701 A CA 524701A CA 1276679 C CA1276679 C CA 1276679C
- Authority
- CA
- Canada
- Prior art keywords
- frequency
- electromagnet
- current
- decaying
- armature
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/08—Electromagnets; Actuators including electromagnets with armatures
- H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
- H01F7/1805—Circuit arrangements for holding the operation of electromagnets or for holding the armature in attracted position with reduced energising current
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
- H01H47/22—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for supplying energising current for relay coil
- H01H47/32—Energising current supplied by semiconductor device
- H01H47/325—Energising current supplied by semiconductor device by switching regulator
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Magnetically Actuated Valves (AREA)
- Valve Device For Special Equipments (AREA)
- Load-Engaging Elements For Cranes (AREA)
- Relay Circuits (AREA)
- Electromagnets (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method of and a circuit for measuring the fre-quency of the holding current of an electromagnet to deter-mine whether or not the armature of the electromagnet is in engagement with the stator.
A method of and a circuit for measuring the fre-quency of the holding current of an electromagnet to deter-mine whether or not the armature of the electromagnet is in engagement with the stator.
Description
~;~7~679 The invention relates to the control of electromagnets.
More particularly, it relates to a method and apparatus for controlling the energization of electromagnets useful for driving fuel intake and exhaust valve, hereinafter referred to as gas exchange valves of internal combustion engines between their terminal, i.e. open and closed, positions.
It is well known to maintain an electromagnet in a holding phase by current pulses, and a freewheeling circuit may be provided for the flow of such current within the coil of the L~ electromagnet wherever the current supply ls switched off. Such an arrangement has been disclosed for instance in west German Patent specification DE-OS 24 25 585.
A problem encountered with such devices is, however 1~ that the holding phase cannot commence until after the armature of the electromagnet has been securely attracted of pulled by the stator; for while the holding current may be sufflcient for maintaining the armature ln its engagement with the stator it is by no means sufficient to attract the armature.
2u Thus, circuits are known for measuring or monitoring the rise in current during the energizatlon phase of electromagnetic colls and for detectlng a flrst negatlve value or break in the rising current slope to derive therefrom an lndication of the engagement of the armature with the stator.
However, such circuits have been found not to function with the desired degree of reliability, for they are strongly dependent upon the supply voltage, and they are particularly prone to malfunction at an increase in the supply voltage.
West German Patent specification DE-OS 33 26 605 teaches a circuit for monitoring the stroke posltion of a solenold armature. It functions with a supply voltage for an electromagnet comprising a direct current with a superimposed 3~
~ ~ ~ 7 9 A.C. component. The circuit aims at detecting the engagement of the armature with the stator by measuring the level of the A.C.
component which when the armature is attracted is different from when it is not, because of the difference in inductivness of the solenoid.
This circuit is relatively complicated and depends for its effectiveness or reliability upon sophisticated current measuring methods.
Therefore, the present ~nvention provides for a simple lU and effective method of and apparatus for detecting the position of an armature in a solenoid during its operation.
The invention also provides for a method and apparatus 1~ for detecting whether an armature is in its rest position or in its operating position during a given energization phase of a solenoid.
In particular the invention provides of a simplified 2U method of and apparatus for monitoring the position of an armature in an electromagnet useful for driving a gas exchange valve of an internal combustion engine.
Furthermore, the invention improves the performance of piston engines the gas exchange valve of which are driven by electromagnets energized in cycles related to piston movement.
The invention accordingly comprises a mechanism and system processing the construction, combination of elements and arrangements of parts which are exemplified in the detailed 3~ disclosure.
According to the present invention therefore there is provided an apparatus for controlling the energizati~n of an electromagnet at least to a holding phase when its armature is in 3~
~27~679 engagement with its stator, comprising: energizing means for causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase;
means for measuring the frequency of said pulsating current;
means for comparing said measured frequency with a substantially stable reference frequency; means responsive to said comparing means for generating a signal when measured frequency deviates from said reference frequency by a value exceeding a predetermined value; said energizing means comprising switch means cooperating with said signal generating means for selectively connecting said electromagnet to a source of current;
~u said switch means comprising a transistor switchable by said signal generating means between conductive and non-conductive states; and said signal generating means rendering said transistor conductive when said reference frequency exceeds said measured frequency.
J
The present invention also provides a method of energizing an electromagnet at least to a holding phase when its armature is in engagement with its stator, comprising the steps 2~ f causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase;
measuring said decaying frequency; comparing said decaying frequency with a substantially stable reference frequency;
generating a signal when said reference frequency differs from said decaying frequency by a predetermined value; and switching 2J off said pulsating current when its frequency exceeds the frequency of said reference frequency.
The invention provides a method and circuitry for providing current pulses to an electromagnet during it holding 3U phases, i.e. when the armature is securely attracted against the stator. In accordance with the invention the current supply is switched off each time current flowing in the coil exceeds a predetermined upper value, and it is switched on again upon the current flowing in the coil reaching a predetermined lower value.
More particularly, it relates to a method and apparatus for controlling the energization of electromagnets useful for driving fuel intake and exhaust valve, hereinafter referred to as gas exchange valves of internal combustion engines between their terminal, i.e. open and closed, positions.
It is well known to maintain an electromagnet in a holding phase by current pulses, and a freewheeling circuit may be provided for the flow of such current within the coil of the L~ electromagnet wherever the current supply ls switched off. Such an arrangement has been disclosed for instance in west German Patent specification DE-OS 24 25 585.
A problem encountered with such devices is, however 1~ that the holding phase cannot commence until after the armature of the electromagnet has been securely attracted of pulled by the stator; for while the holding current may be sufflcient for maintaining the armature ln its engagement with the stator it is by no means sufficient to attract the armature.
2u Thus, circuits are known for measuring or monitoring the rise in current during the energizatlon phase of electromagnetic colls and for detectlng a flrst negatlve value or break in the rising current slope to derive therefrom an lndication of the engagement of the armature with the stator.
However, such circuits have been found not to function with the desired degree of reliability, for they are strongly dependent upon the supply voltage, and they are particularly prone to malfunction at an increase in the supply voltage.
West German Patent specification DE-OS 33 26 605 teaches a circuit for monitoring the stroke posltion of a solenold armature. It functions with a supply voltage for an electromagnet comprising a direct current with a superimposed 3~
~ ~ ~ 7 9 A.C. component. The circuit aims at detecting the engagement of the armature with the stator by measuring the level of the A.C.
component which when the armature is attracted is different from when it is not, because of the difference in inductivness of the solenoid.
This circuit is relatively complicated and depends for its effectiveness or reliability upon sophisticated current measuring methods.
Therefore, the present ~nvention provides for a simple lU and effective method of and apparatus for detecting the position of an armature in a solenoid during its operation.
The invention also provides for a method and apparatus 1~ for detecting whether an armature is in its rest position or in its operating position during a given energization phase of a solenoid.
In particular the invention provides of a simplified 2U method of and apparatus for monitoring the position of an armature in an electromagnet useful for driving a gas exchange valve of an internal combustion engine.
Furthermore, the invention improves the performance of piston engines the gas exchange valve of which are driven by electromagnets energized in cycles related to piston movement.
The invention accordingly comprises a mechanism and system processing the construction, combination of elements and arrangements of parts which are exemplified in the detailed 3~ disclosure.
According to the present invention therefore there is provided an apparatus for controlling the energizati~n of an electromagnet at least to a holding phase when its armature is in 3~
~27~679 engagement with its stator, comprising: energizing means for causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase;
means for measuring the frequency of said pulsating current;
means for comparing said measured frequency with a substantially stable reference frequency; means responsive to said comparing means for generating a signal when measured frequency deviates from said reference frequency by a value exceeding a predetermined value; said energizing means comprising switch means cooperating with said signal generating means for selectively connecting said electromagnet to a source of current;
~u said switch means comprising a transistor switchable by said signal generating means between conductive and non-conductive states; and said signal generating means rendering said transistor conductive when said reference frequency exceeds said measured frequency.
J
The present invention also provides a method of energizing an electromagnet at least to a holding phase when its armature is in engagement with its stator, comprising the steps 2~ f causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase;
measuring said decaying frequency; comparing said decaying frequency with a substantially stable reference frequency;
generating a signal when said reference frequency differs from said decaying frequency by a predetermined value; and switching 2J off said pulsating current when its frequency exceeds the frequency of said reference frequency.
The invention provides a method and circuitry for providing current pulses to an electromagnet during it holding 3U phases, i.e. when the armature is securely attracted against the stator. In accordance with the invention the current supply is switched off each time current flowing in the coil exceeds a predetermined upper value, and it is switched on again upon the current flowing in the coil reaching a predetermined lower value.
3~
~766~3 Upon being switched on the current does not increase abruptly because of the inductance of the electromagnet, and for the same reason it does not decay abruptly when switched off. A
freewheeling circuit may be provided for maintaining current flow within the coil of the solenoid for a predetermined time after it has been switched off.
Since the control of the current supply is dependent upon upper and lower predetermined values the resulting pulse frequency is influenced by several factors. THe frequency may, for instance, depend upon the supply voltage, the temperature of the coil, or upon the inductance of the electromagnet.
Surprisingly, it has been found, however, that deviations in the pulse frequency as a result of deviations in the supply voltage or in the temperature of the coil are negligible, in contrast to frequency deviations resulting from changes in the inductance o the electromagnet. This is though to result from the fact that when the armature is an engagement with the stator the inductance of the electromagnet is noticeably 2U different from when the armature is in its rest position, i.e.
when it is released from the stator.
The instant invention may be useful for controlling the movement and the electromagnetic retention of gas exchange valves 2l of internal combustion engines ln their operative positions. One such operative position may, for instanc~, correspond to the valve being fully open. Another operative position may correspond to the valve being closed. As will be appreciated by those skilled in the art, failure - 3a -~2'76~i~9 of the valves to move flawlessly between these operative positions would result in faulty, if any, combustion.
It is thus of the utmost importance that faulty valve movement be instantly detected and corrected. Operational parameters such as temperatures deviating vastly during normal engine operation, or changes in the supply voltage traceable to changes in the speed of the engine or to the charge of the battery have been found to be negligible, so that the method end circuit of the invention may provide for reliable engine performance, changes ln the mentioned parameters notwithstanding.
n accordance with the invention deviations in the pulse cycle frequency resulting from differences in the inductance are monitored so that it is possible to determine whether the armature has in i~act been attracted or not.
More specifically, the pulse frequency is monitored during the holding phase of the electromagnet and is compared with a predetermined frequency, and a signal is generated when the difference detected exceeds a predetermined maxi~um.
Advantageously, the signal may be utilized to lnitiate another energization of the electromagnet.
The maximum deviation between the actual frequency and the predetermined frequency may be about ~0 %.
In an advantageous embodiment of the invention the circuit may comprlse means for measuring the frequency of the current pulses and for switching on the control circuit for intiating another energization cycle.
.
Advantageously, the means for monitoring the frequency may be connected to the output of the control circuit.
~2~76679 The invention, in respect of its organization as well as its method of operation, together with advantages thereof will be further understood from the following description of the illustrative embodiment when read in conjunction with the accompanying drawings in which:
FIG. 1 is a diagram of current pulses for explaining the present invention; and FIG. 2 iS a diagram of a circuit for practicing the method in accordance with the invention.
10 FIG. 2 depicts a circuit in which an electromagnet 10 is seen to be provided with a freewheeling circuit 12 connected in parallel thereto. The freewheeling circuit comprises a d~ode 12a for controlling the direction of current flow. As may be seen, the electromagnet 10 and its freewheeling circuit 12 are connected between the positive terminal 14 of a voltage source and ground 16.
Whenever a switch, preferably a transistor 18 as shown, is closed, current may flow through the electromagnet 10 between the voltage supply 14 and ground 16. When the transistor 18 is at times switched to its non-conductive state, current flow from the supply 14 is interrupted, but gradually decaying current continues to flow in the electromagnet 10 and its freewheeling circuit 12.
A measuring resistor 26 is provided in the freewheeling circuit 12, and signals detected in the resistor 26 and indicative of the level of current flowing in the freewheeling circuit arrangement may be fed to a control circuit 22 along lines 24a and 24b connected, respectively, between the junctions of the resistor 26 with the electromagnet 10 and with the voltage source 14 and two inputs of the control circuit 22. A further input 20 of the control circuit 22 is provided for receiving signals from an 127~i679 external source. This latter source hes not been shown as it forms no part of the ins~ant invention.
The control circuit 22 may be of a kind well known in the art.
It may comprise an operational amplifier for amplifying the current measured across the resistor 26 as well as a comparator for comparing the measured current with a current of predetermined magnitude. The control circuit 22 may function as a level detector.
- 5a -~276~79 ~ eference is now made to FIG. 1 for explaining the function of the circuit of FIG. 2. When the armature (not shown) of the electromagnet lo has been attracted into engagement with the stator (also not shown) of the electro-magnet 1~, it is necessary to provide a current flowing at a predetermined minimum level to maintain this engagement.
The level of this current may deviate between upper and lower limits I1 and I2, respectively. Therefore, whenever the transistor 18 is rendered conductive the current will increase until reaching level I1. To prevent the current from rising further, the control circuit or level detector 22 will at this point switch off the transistor 1~. Current thereafter flowing in the freewheeling circuit 12 will gradually decay, the rate of decay being dependent upon several factors. The factor relevant in the present context is the inductance of the electromagnet. Other factors affecting the rate of decay may for present purposes be considered sufficiently negligible to be ignored. For instance, while the supply voltage does indeed influence the rate of current increase in the coil of the electromagnet 10, its ef~ect i5 limited to portion A of a frequency period which is generally less than 25 % of the total duration of the period. However, the decaying portion B is substan-tially longer than the energizing portion A, and ~ is a function of the inductance of the electromagnet. When the current has decayed to the lower level I2 the control circuit 22 again renders the transistor 18 conductive by applying a signal to its base along a line 32 by way of a driver circuit 28, and the current may once again rise to level I1.
The rising portion of the current flow period is identified in FIG.1 by letter A; the decaying portion is identified by letter B. The sum Qf the intervals A + B
constitutes the frequency of a~6~urrent pulse.
This frequency may be present as a s~uare wave signal at the output of the level detector 22 and may be fed to a conventional frequency measuring circuit 30 by way of a line 34. The frequency measuring circuit 30 may be a ~7~i679 comparator for comparing the frequency A + B with a predetermined reference frequency and ~or sending a signal to the control circuit 22 along a line 36 whenever A + B differs from the reference frequency by more than a predetermined maximum value, for instance by 20 %.
FIG. l depicts the curves of the holding current frequencies of the electromagnet 10 in the two possible states of its armature, i.e. when it is engaged with, or released from, the stator. The curves are identified by Kl and K2, respectively. As may be seen, the ~requency of the curves differs noticeably, depending on whether or not the armature is in engagement with the stator.
The change in frequency may amount to as much as 50 %. This is significant value and may be a convenient indlcation for determining whether or not the armature has moved into engagement with the stator.
If the evaluation of the freguency by the measuring circuit 30 indicates that there is no such engagement, the transistor 18 is rendered conductive by a signal from the control circuit 22 applied to its base, thereby to initiate another energizing phase.
The energization current has an initial high amplitude; but the subsequent holding current may be reduced substantially, for lnstance, to about 20 % of the maximum energizing current.
It will be appreciated by those skilled in the art that the control circuit or level detector 22, the driver circuit or amplifier 28, as well as the frequency measuring circuit or comparator 30 are entirely conventional and are thus believed not to reguire any specific description in the present context.
~766~3 Upon being switched on the current does not increase abruptly because of the inductance of the electromagnet, and for the same reason it does not decay abruptly when switched off. A
freewheeling circuit may be provided for maintaining current flow within the coil of the solenoid for a predetermined time after it has been switched off.
Since the control of the current supply is dependent upon upper and lower predetermined values the resulting pulse frequency is influenced by several factors. THe frequency may, for instance, depend upon the supply voltage, the temperature of the coil, or upon the inductance of the electromagnet.
Surprisingly, it has been found, however, that deviations in the pulse frequency as a result of deviations in the supply voltage or in the temperature of the coil are negligible, in contrast to frequency deviations resulting from changes in the inductance o the electromagnet. This is though to result from the fact that when the armature is an engagement with the stator the inductance of the electromagnet is noticeably 2U different from when the armature is in its rest position, i.e.
when it is released from the stator.
The instant invention may be useful for controlling the movement and the electromagnetic retention of gas exchange valves 2l of internal combustion engines ln their operative positions. One such operative position may, for instanc~, correspond to the valve being fully open. Another operative position may correspond to the valve being closed. As will be appreciated by those skilled in the art, failure - 3a -~2'76~i~9 of the valves to move flawlessly between these operative positions would result in faulty, if any, combustion.
It is thus of the utmost importance that faulty valve movement be instantly detected and corrected. Operational parameters such as temperatures deviating vastly during normal engine operation, or changes in the supply voltage traceable to changes in the speed of the engine or to the charge of the battery have been found to be negligible, so that the method end circuit of the invention may provide for reliable engine performance, changes ln the mentioned parameters notwithstanding.
n accordance with the invention deviations in the pulse cycle frequency resulting from differences in the inductance are monitored so that it is possible to determine whether the armature has in i~act been attracted or not.
More specifically, the pulse frequency is monitored during the holding phase of the electromagnet and is compared with a predetermined frequency, and a signal is generated when the difference detected exceeds a predetermined maxi~um.
Advantageously, the signal may be utilized to lnitiate another energization of the electromagnet.
The maximum deviation between the actual frequency and the predetermined frequency may be about ~0 %.
In an advantageous embodiment of the invention the circuit may comprlse means for measuring the frequency of the current pulses and for switching on the control circuit for intiating another energization cycle.
.
Advantageously, the means for monitoring the frequency may be connected to the output of the control circuit.
~2~76679 The invention, in respect of its organization as well as its method of operation, together with advantages thereof will be further understood from the following description of the illustrative embodiment when read in conjunction with the accompanying drawings in which:
FIG. 1 is a diagram of current pulses for explaining the present invention; and FIG. 2 iS a diagram of a circuit for practicing the method in accordance with the invention.
10 FIG. 2 depicts a circuit in which an electromagnet 10 is seen to be provided with a freewheeling circuit 12 connected in parallel thereto. The freewheeling circuit comprises a d~ode 12a for controlling the direction of current flow. As may be seen, the electromagnet 10 and its freewheeling circuit 12 are connected between the positive terminal 14 of a voltage source and ground 16.
Whenever a switch, preferably a transistor 18 as shown, is closed, current may flow through the electromagnet 10 between the voltage supply 14 and ground 16. When the transistor 18 is at times switched to its non-conductive state, current flow from the supply 14 is interrupted, but gradually decaying current continues to flow in the electromagnet 10 and its freewheeling circuit 12.
A measuring resistor 26 is provided in the freewheeling circuit 12, and signals detected in the resistor 26 and indicative of the level of current flowing in the freewheeling circuit arrangement may be fed to a control circuit 22 along lines 24a and 24b connected, respectively, between the junctions of the resistor 26 with the electromagnet 10 and with the voltage source 14 and two inputs of the control circuit 22. A further input 20 of the control circuit 22 is provided for receiving signals from an 127~i679 external source. This latter source hes not been shown as it forms no part of the ins~ant invention.
The control circuit 22 may be of a kind well known in the art.
It may comprise an operational amplifier for amplifying the current measured across the resistor 26 as well as a comparator for comparing the measured current with a current of predetermined magnitude. The control circuit 22 may function as a level detector.
- 5a -~276~79 ~ eference is now made to FIG. 1 for explaining the function of the circuit of FIG. 2. When the armature (not shown) of the electromagnet lo has been attracted into engagement with the stator (also not shown) of the electro-magnet 1~, it is necessary to provide a current flowing at a predetermined minimum level to maintain this engagement.
The level of this current may deviate between upper and lower limits I1 and I2, respectively. Therefore, whenever the transistor 18 is rendered conductive the current will increase until reaching level I1. To prevent the current from rising further, the control circuit or level detector 22 will at this point switch off the transistor 1~. Current thereafter flowing in the freewheeling circuit 12 will gradually decay, the rate of decay being dependent upon several factors. The factor relevant in the present context is the inductance of the electromagnet. Other factors affecting the rate of decay may for present purposes be considered sufficiently negligible to be ignored. For instance, while the supply voltage does indeed influence the rate of current increase in the coil of the electromagnet 10, its ef~ect i5 limited to portion A of a frequency period which is generally less than 25 % of the total duration of the period. However, the decaying portion B is substan-tially longer than the energizing portion A, and ~ is a function of the inductance of the electromagnet. When the current has decayed to the lower level I2 the control circuit 22 again renders the transistor 18 conductive by applying a signal to its base along a line 32 by way of a driver circuit 28, and the current may once again rise to level I1.
The rising portion of the current flow period is identified in FIG.1 by letter A; the decaying portion is identified by letter B. The sum Qf the intervals A + B
constitutes the frequency of a~6~urrent pulse.
This frequency may be present as a s~uare wave signal at the output of the level detector 22 and may be fed to a conventional frequency measuring circuit 30 by way of a line 34. The frequency measuring circuit 30 may be a ~7~i679 comparator for comparing the frequency A + B with a predetermined reference frequency and ~or sending a signal to the control circuit 22 along a line 36 whenever A + B differs from the reference frequency by more than a predetermined maximum value, for instance by 20 %.
FIG. l depicts the curves of the holding current frequencies of the electromagnet 10 in the two possible states of its armature, i.e. when it is engaged with, or released from, the stator. The curves are identified by Kl and K2, respectively. As may be seen, the ~requency of the curves differs noticeably, depending on whether or not the armature is in engagement with the stator.
The change in frequency may amount to as much as 50 %. This is significant value and may be a convenient indlcation for determining whether or not the armature has moved into engagement with the stator.
If the evaluation of the freguency by the measuring circuit 30 indicates that there is no such engagement, the transistor 18 is rendered conductive by a signal from the control circuit 22 applied to its base, thereby to initiate another energizing phase.
The energization current has an initial high amplitude; but the subsequent holding current may be reduced substantially, for lnstance, to about 20 % of the maximum energizing current.
It will be appreciated by those skilled in the art that the control circuit or level detector 22, the driver circuit or amplifier 28, as well as the frequency measuring circuit or comparator 30 are entirely conventional and are thus believed not to reguire any specific description in the present context.
Claims (4)
1. An apparatus for controlling the energization of an electromagnet at least to a holding phase when its armature is in engagement with its stator, comprising: energizing means for causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase;
means for measuring the frequency of said pulsating current;
means for comparing said measured frequency with a substantially stable reference frequency; means responsive to said comparing means for generating a signal when measured frequency deviates from said reference frequency by a value exceeding a predetermined value; said energizing means comprising switch means cooperating with said signal generating means for selectively connecting said electromagnet to a source of current;
said switch means comprising a transistor switchable by said signal generating means between conductive and non-conductive states; and said signal generating means rendering said transistor conductive when said reference frequency exceeds said measured frequency.
means for measuring the frequency of said pulsating current;
means for comparing said measured frequency with a substantially stable reference frequency; means responsive to said comparing means for generating a signal when measured frequency deviates from said reference frequency by a value exceeding a predetermined value; said energizing means comprising switch means cooperating with said signal generating means for selectively connecting said electromagnet to a source of current;
said switch means comprising a transistor switchable by said signal generating means between conductive and non-conductive states; and said signal generating means rendering said transistor conductive when said reference frequency exceeds said measured frequency.
2. The apparatus of claim 1, wherein said signal generating means renders said transistor conductive when said reference frequency exceeds said measured frequency by about 20%.
3. A method of energizing an electromagnet at least to a holding phase when its armature is in engagement with its stator, comprising the steps of: causing a current pulsating at a frequency decaying with time to flow in said electromagnet at least during said holding phase; measuring said decaying frequency, comparing said decaying frequency with a substantially stable reference frequency; generating a signal when said reference frequency differs from said decaying frequency by a predetermined value; and switching off said pulsating current when its frequency exceeds the frequency of said reference frequency.
4. The method of claim 3, wherein said pulsating current is switched off when its frequency is higher than that of said reference frequency by about 20%.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3543055.9-33 | 1985-12-05 | ||
| DE3543055A DE3543055C1 (en) | 1985-12-05 | 1985-12-05 | Circuit arrangement for driving an electromagnet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1276679C true CA1276679C (en) | 1990-11-20 |
Family
ID=6287740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000524701A Expired - Lifetime CA1276679C (en) | 1985-12-05 | 1986-12-05 | Control of the energization of an electromagnet |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0225444B1 (en) |
| JP (1) | JPS62134911A (en) |
| CA (1) | CA1276679C (en) |
| DE (2) | DE3543055C1 (en) |
| ES (1) | ES2018147B3 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7738233B2 (en) | 2003-12-16 | 2010-06-15 | Robert Bosch Gmbh | Method and device for operating an inductive load with different electric voltages |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3701985A1 (en) * | 1987-01-23 | 1988-08-04 | Knorr Bremse Ag | Ballast electronics for an apparatus which can be energised by DC voltage |
| DE3703089A1 (en) * | 1987-02-03 | 1988-08-11 | Vdo Schindling | Method and arrangement for operating an electromechanical actuating element (servo element) |
| DE3741734C2 (en) * | 1987-12-09 | 1996-09-26 | Herion Werke Kg | Device for measuring the inductance of a coil, in particular for measuring the armature position of a coil / armature magnet system |
| US5038247A (en) * | 1989-04-17 | 1991-08-06 | Delco Electronics Corporation | Method and apparatus for inductive load control with current simulation |
| US5053911A (en) * | 1989-06-02 | 1991-10-01 | Motorola, Inc. | Solenoid closure detection |
| DE3923477A1 (en) * | 1989-07-15 | 1991-01-24 | Fev Motorentech Gmbh & Co Kg | METHOD FOR CONTROLLING THE ANCHOR MOTION OF SHIFTING MAGNETS |
| GB9006973D0 (en) * | 1990-03-28 | 1990-05-23 | Vickers Systems Ltd | Digital pulse-width-modulation generator for current control |
| US5243296A (en) * | 1990-11-06 | 1993-09-07 | Tokimec Inc. | Method and apparatus for checking operation of solenoid |
| DE4130040A1 (en) * | 1991-09-10 | 1993-03-11 | Heidelberger Druckmasch Ag | CIRCUIT ARRANGEMENT FOR MONITORING AN ELECTROMAGNETICALLY ACTUATED CLUTCH |
| GB2260030A (en) * | 1991-09-14 | 1993-03-31 | Kloeckner Humboldt Deutz Ag | Control systems for electromagnetic valves |
| IT1263110B (en) * | 1992-03-24 | 1996-07-30 | Magneti Marelli Spa | STARTING SYSTEM FOR AN INTERNAL COMBUSTION AND SOLENOID ENGINE USABLE IN SUCH STARTING SYSTEM |
| GB2306679B (en) * | 1995-11-03 | 2000-05-17 | Motorola Ltd | Method for detecting closure of a solenoid coil |
| DE19623436A1 (en) * | 1996-06-12 | 1997-12-18 | Rapp Franz Josef | Apparatus for displaying performance of electromagnetic (EM) relay or valve |
| US5784245A (en) * | 1996-11-27 | 1998-07-21 | Motorola Inc. | Solenoid driver and method for determining solenoid operational status |
| WO1999046783A1 (en) * | 1998-03-11 | 1999-09-16 | Btr Industries Limited | Control of electrically powered actuation device |
| DE19821804C1 (en) * | 1998-05-15 | 1999-08-12 | Daimler Chrysler Ag | Method of functional monitoring of an electromagnetically actuated gas changeover valve |
| IT1321161B1 (en) * | 2000-03-24 | 2003-12-30 | Magneti Marelli Spa | METHOD FOR THE ADJUSTMENT OF CURRENTS DURING STATIONING PHASES ELECTROMAGNETIC INACTORS FOR THE ACTIVATION OF VALVES OF |
| DE10302988B3 (en) * | 2003-01-25 | 2004-10-28 | Festo Ag & Co. | Circuit device for generating a coil current flowing through a magnet coil arrangement and regulated by clocking |
| US7527002B2 (en) * | 2004-07-07 | 2009-05-05 | Cwa Constructions S.A. | Cableway cabin |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2102595A1 (en) * | 1971-01-20 | 1972-08-03 | Siemens Ag | Circuit arrangement for an electromagnet that can be controlled via an amplifier |
| DE2208135C3 (en) * | 1972-02-22 | 1975-04-17 | Voith Getriebe Kg, 7920 Heidenheim | Operating circuit for an electromagnet |
| DE2251472C3 (en) * | 1972-10-20 | 1983-11-10 | Robert Bosch Gmbh, 7000 Stuttgart | Circuit arrangement for controlling the mechanical movement of a solenoid valve armature |
| DD106243A1 (en) * | 1973-07-19 | 1974-06-05 | ||
| DE2601799A1 (en) * | 1976-01-20 | 1977-07-21 | Licentia Gmbh | Switch for electromagnetic contact actuation - has sensor in contactor electromagnetic range whose signals affect electronic switching element |
| US4123729A (en) * | 1977-07-22 | 1978-10-31 | General Motors Corporation | Displacement transducer |
| DE3326605A1 (en) * | 1983-07-23 | 1985-02-07 | Binder Magnete GmbH, 7730 Villingen-Schwenningen | Method and circuit arrangement for monitoring the stroke position of the armature of a lifting electromagnet, in particular a valve magnet |
-
1985
- 1985-12-05 DE DE3543055A patent/DE3543055C1/en not_active Expired
-
1986
- 1986-10-02 EP EP86113598A patent/EP0225444B1/en not_active Expired - Lifetime
- 1986-10-02 DE DE8686113598T patent/DE3675167D1/en not_active Expired - Fee Related
- 1986-10-02 ES ES86113598T patent/ES2018147B3/en not_active Expired - Lifetime
- 1986-11-17 JP JP61273837A patent/JPS62134911A/en active Granted
- 1986-12-05 CA CA000524701A patent/CA1276679C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7738233B2 (en) | 2003-12-16 | 2010-06-15 | Robert Bosch Gmbh | Method and device for operating an inductive load with different electric voltages |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0368522B2 (en) | 1991-10-28 |
| DE3543055C1 (en) | 1986-12-11 |
| DE3675167D1 (en) | 1990-11-29 |
| JPS62134911A (en) | 1987-06-18 |
| EP0225444A1 (en) | 1987-06-16 |
| EP0225444B1 (en) | 1990-10-24 |
| ES2018147B3 (en) | 1991-04-01 |
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Legal Events
| Date | Code | Title | Description |
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| MKLA | Lapsed |