CN100368824C

CN100368824C - Apparatus for detecting the presence of electrically-conductive debris

Info

Publication number: CN100368824C
Application number: CNB2004800097853A
Authority: CN
Inventors: 迈克尔·弗兰克·汤普森; 布赖恩·波拉德
Original assignee: R E Thompson & Co Vacuum Ltd
Current assignee: R E Thompson & Co Vacuum Ltd
Priority date: 2003-03-11
Filing date: 2004-03-09
Publication date: 2008-02-13
Anticipated expiration: 2024-03-09
Also published as: CN1813203A; GB0305558D0; GB0314959D0

Abstract

Apparatus for detecting the presence of electrically-conductive debris in a flow passageway has a bridge circuit with four arms. One arm of the bridge has a coil arranged to monitor the flow passageway. Operating circuitry provides alternating current across one diagonal of the bridge, monitoring circuitry monitors imbalance in the bridge across the other diagonal of the bridge, and balancing circuitry responds to an output of the monitoring circuitry for adjusting the value of at least one component of the bridge circuit in such a way to reduce imbalance in the bridge.

Description

Be used to detect the device that electrically-conductive debris exists

The present invention relates to be used for the device that the electrically-conductive debris of test fluid path exists.

This device is widely used in such as the metallic particles in the machine oil of internal combustion engine and detects.

The device that a variety of conduction fragments that are used for the test fluid path exist has been known, but these devices have following one or more shortcomings:

1. need frequent manual adjustment to guarantee reliable detection;

More 2. adopt the device of a more than coil very sensitive for the relative position of coil, and therefore can be owing to vibration, temperature variation etc. have problems;

3. circuit is subjected to the influence of temperature variation and temperature value easily; Compensating circuit can produce delay in the device of working under required sensitivity being suitable for;

4. internal noise has limited for short grained sensitivity

Therefore the objective of the invention is to reduce at least in part above-mentioned shortcoming.

According to a first aspect of the invention, the invention provides the device of the electrically-conductive debris existence that is used for the test fluid path, this device comprises the bridge circuit with four arms, an arm of this electric bridge comprises the coil that is provided for the monitoring fluid path, be connected across diagonal line of bridge circuit and be used to provide the function circuit of alternating current, be connected across another diagonal line of bridge circuit and be used for monitoring the unbalanced supervisory circuit of bridge circuit, be used for adjusting the balancing circuitry of the value of at least one element of bridge circuit in response to the output of supervisory circuit in the unbalanced mode that reduces bridge circuit.

This device can only comprise single coil.

Other element in function circuit, supervisory circuit, balancing circuitry and the bridge circuit except that coil can be away from the fluid passage setting.

Balancing circuitry one of is set to control in the group of the capacitive reactance, induction reactance and the impedance that comprise described at least one element at least.

Supervisory circuit comprises and is used for measuring the homophase of other diagonal line voltages of described electric bridge and the lock detector of quadrature component (synchronous detector).

Function circuit comprises the circuit of cross-over connection on a described diagonal line, and this circuit is used to apply sinusoidal wave as alternating current.

A described arm comprises the series circuit of described coil and capacitor element, and remaining three arm is made of the element that impedance effect is mainly resistance.

Capacitor element is controlled.

This described arm comprises the transformer with elementary winding, secondary winding, and this elementary winding is set to connect with capacitor element, and secondary winding is connected on the described coil.

This balancing circuitry comprise with a described arm in the controlled capacitance that is connected in parallel of fixed capacity.

Controlled capacitance comprises fixed capacity and is used to control the circuit of the alternating current that imposes on capacitor, thus the effect of control fixed capacity.

This balancing circuitry comprise with one of them arm of bridge circuit on the controllable resistor that is connected in parallel of fixed resistance.

According to a second aspect of the invention, the invention provides and be used for the device that test fluid path electrically-conductive debris exists, this device comprises the coil that is provided for monitoring path, be used to provide driving circuit by the alternating current of coil, be used for monitoring the sensor circuit of coil electric current, this sensor circuit comprises the compensating circuit that is used to compensate aging and temperature effect, wherein this driving circuit comprises that forming bridge circuit with coil makes this coil be arranged at the element in the arm of bridge circuit, and compensating circuit is set comprises one of them the capacitive reactance of a plurality of described elements with control, in the group of induction reactance and resistance at least one of them.

This device can only comprise single coil.

Element in function circuit, supervisory circuit, balancing circuitry and the bridge circuit except coil can be set to away from fluid passage.

Sensor circuit comprises and is used for measuring the homophase of bridge circuit diagonal line voltage and the lock detector of quadrature component.

Bridge circuit comprises four arms, and a described arm comprises the series circuit of described coil and capacitor element, and remaining three arm is made of the element that impedance effect is mainly resistance.

Driving circuit can comprise a cornerwise sine-wave oscillation of the bridge circuit source that is connected to.

Capacitor element is controlled.A described arm can comprise the transformer with elementary winding, secondary winding, and this elementary winding is set to the capacitor element series connection and secondary winding is connected on the described coil.

Compensating circuit comprises the controlled capacitance that is parallel-connected to fixed capacity in the described arm.

Controlled capacitance comprises fixed capacity and is used to control the circuit of the alternating current that imposes on electric capacity, thereby can control the effect of fixed capacity.

Compensating circuit comprises the controllable resistor of the fixed resistance of described all the other arms in one of them that is parallel-connected to bridge circuit.

Controllable resistor comprises fixed resistance and is used to control the circuit of the alternating current that imposes on resistance, thereby can control the effect of fixed resistance.

A plurality of coils can be set, and one of them has the axle with the misalignment of fluid passage axle at least, make to determine any coating of particles or guarantees the detection of highly asymmetric particle, for example thin and wide particle.

Now by with reference to the accompanying drawings, in the mode of embodiment embodiments of the present invention are described, wherein

Figure 1 shows that the block diagram (high level diagram) that is used for the device of the broken genus existence of test fluid path conduction according to the present invention;

Figure 2 shows that the block scheme of the part of partial graph 1 shown device;

Figure 3 shows that the block scheme of modification of the part of partial graph 2 shown devices;

Figure 4 shows that the embodiment that is applicable to according to the variable impedance circuit of device of the present invention;

Figure 5 shows that particle is just moving and is about to by the part sectioned view according to the coil of device of the present invention in fluid passage;

Figure 6 shows that particle is just moving and is about to by the part sectioned view according to the coil of another device of the present invention in fluid passage.

In different figure, same drawing reference numeral is represented same parts.

At first with reference to figure 1, the device (70) that is used for the existence of test fluid path electrically-conductive debris comprises the first 1 of the signal that the expression electrically-conductive debris is provided and receives the second portion 2 of representing the signal of chip and responding this signal.

First 1 by the inductive coil 10 that drives by driving circuit 20 and the sensor circuit 30 that is used for monitoring the coil electric current constitute.This sensor circuit 30 has the output 56a and the 57a of part of imposing on 2.In this embodiment, part 2 comprises and is used for identification signal to detect the analysis circuit 100 by the generation of the detected disturbance of coil.Only use a coil and mean that the change of change that produces owing to vibration or the line size that limits fluid passage is littler than adopting other influence that produces under difference device or the situation by a more than coil to the influence of circuit output generation.

With reference to figure 2, coil 10 is schematically illustrated as the pure inductance 11 that is connected in series to resistive element 12.This coil 10 is set is used for monitoring fluid path (not shown).Usually, coil 10 is wound in or is positioned at the periphery of the pipeline that limits fluid passage.This driving circuit 20 is set to be used for providing by the alternating current of coil and the electric current of sensor circuit 30 monitoring coils 10.Sensor circuit 30 comprises the compensating circuit 31 of the aging and temperature effect of the remainder that is used for compensation system.Driving circuit 20 in the present embodiment has first to the 3rd fixed

resistance

21,22,23, and this first to the 3rd fixed

resistance

21,22,23 forms the bridge circuit with four arms with coil, makes coil be arranged in the arm of bridge circuit.An arm of bridge circuit is made of the series circuit of coil 10 and fixed capacity 24, and this fixed capacity 24 is in parallel with automatically controlled capacitor (electronically controlled capacitor) 124.

At monitored fluid or awfully hot or have the place of very wide temperature value, preferably only coil is provided with near fluid passage.And other conglomerates (integer) preferably away from fluid passage to avoid temperature effect.

Bridge circuit 25 has first node 40 and the synchronic Section Point 41 that is connected to the arm that comprises coil 10 and comprises the arm of resistance 23 that is connected to first and

second resistance

21,22 simultaneously, should be from first node 40 to Section Point 41 path constitute the first electric bridge diagonal line (a first bridge diagonal).This bridge circuit 25 also has the 3rd node 42 that is connected to third and

fourth resistance

22,23 simultaneously and is connected to first resistance 21 simultaneously and comprises coil 10 and the 4th node 43 of an arm of fixed capacity 24.In the embodiment shown, capacitor 20 is connected to electric capacity 24 yet coil 10 is connected to the 4th node 43---, from broadest, this is not of the present invention basic.

Therefore bridge circuit 25 has the first arm, second arm that comprises first resistance 21 that comprise coil 10 and fixed capacity 24, comprises the 3rd arm of second resistance 22 and comprises the 4th arm of the 3rd resistance 23.Second diagonal line in the bridge circuit 25 is formed between third and fourth node 42 and 43.The 4th arm further comprises the automatically controlled resistance 123 that is parallel to the 3rd resistance 23.

Driving circuit 20 further comprises the minimizing harmonic wave low-pass filter 45 of

crystal oscillator

44,44 outputs of receiving crystal oscillator and the power amplifier 46 of receiving filter 45 outputs.The output of amplifier is connected to the first node 40 of bridge circuit 25.The Section Point 41 of bridge circuit 25 constitutes the reference mode of the reference mode terminal that connects crystal oscillator 44, low-pass filter 45 and power amplifier 46.Reference mode 41 ground connection in this embodiment.Can use sine-wave oscillator, but in said embodiment, this oscillator has square wave output.The filter circuit that matches is known for those skilled in the art, allows sinewave output to drive this electric bridge basically.

Sensor circuit 30 has input difference amplifier 51, and two input is connected to third and

fourth node

42,43 of bridge circuit 25.This differential amplifier 51 has the single-ended output 52 that is connected to first lock detector 53 and second lock detector 54.First lock detector 53 receives voltage at first node 40 and exchanges benchmark (alternating reference) as it.Second lock detector 54 has the voltage that 90 ° of phase-shift circuits 55 being connected to its reference termination and this phase-shift circuit 55 receive first nodes 40 and imports as it.

First lock detector 53 has the output 53a that input is provided to first amplifier and the filtering circuit 56 with output 56a successively.Second lock detector 54 has the output 54a that offers second amplifier and have the filtering circuit 57 of output 57a.Compensating circuit 31 has two inputs of the output 56a that is connected respectively to first amplifier and filtering circuit and second amplifier and filtering circuit output 57a.Compensating circuit 31 has two outputs in the present embodiment, connects first output 32 and connects to control automatically controlled resistance 123 with second output 33 of controlling automatically controlled electric capacity 124 and compensating circuit.This compensating circuit 31 also is set to monitor bridge circuit to reduce the imbalance that exists in this bridge circuit 25.

About Fig. 3, the modification of device shown in Figure 2 is shown.Comparison diagram 2 and Fig. 3 find that bridge circuit shown in Figure 3 125 is not directly connected between the 4th node 43 and the fixed capacity 24 except coil 10 but are basic the same with the circuit of Fig. 2 beyond being connected on the secondary winding 27 of transformer (26,27).In this embodiment, the elementary winding 26 of transformer (26,27) is connected between node 43 and the fixed capacity 24.

Present working condition with key diagram 2 embodiments.

Crystal oscillator 44 comprises the frequency dividing circuit (dividercircuitry) that is used to provide about 100KHz output frequency.In described embodiment, use the 25MHz crystal oscillator and carry out 256 frequency divisions.Because the high-frequency crystal volume is less so use high-frequency crystal that low sensitivity to vibration can be provided.The output of crystal oscillator is offered low-pass filter 45, the output of this low-pass filter 45 has low harmonic content, thereby low harmonic content helps to make the residual enough

low wave detector

53,54 that makes of electric bridge output that is connected across

node

42,43 under the bridge balance condition can not transship.After circuit is connected, balance bridge circuit 25 is come by homophase output 56a and orthogonal signal 57a in the loop that comprises compensating circuit 31, homophase output 56a provides reverse control to the resistance of automatically controlled resistor 123 with 10 changes in resistance of coil in the balanced bridge, and orthogonal signal 57a is used for controlling the variation of the reactance of automatically controlled capacitor 124 with the induction reactance 11 of balanced bridge coil 10.In the steady state conditions that does not have chip by coil, compensating circuit 31 receive homophases and orthogonal signal and with the two in conjunction with to be provided for the controlled variable of automatically controlled capacitor 124 and automatically controlled resistor 123.This loop is used to minimize the value of in-phase signal and orthogonal signal.Should be appreciated that second arm to the, four arms only comprise that resistor means that the first arm that comprises coil 10 and capacitor 24 when bridge balance also is impedance, this condition can realize by the resonance or the series resonant circuit of capacitor 24,124 and coil 10.For this reason, the capacitance that changes this automatically controlled capacitor 124 with the time and fixed condenser 24 keep resonance down in the driving frequency (real account is decided to be 97.5KHz) of about 100KHz together.

With reference now to Fig. 4,, gain control amplifying circuit 120 has and is connected its input 121 and exports capacitor 130 between 122.This input 121 is via fixed condenser 131 ground connection 133.Gain control 134 is input to amplifier 120, and allow to change shunting input 121 effective value of 133 electric capacity over the ground.So can change the total capacitance that between input 121, is constituted by the gain control input by capacitor 131 fixed capacities and effective variable capacitance.Replace capacitor 130,131 that variable resistance circuit can be provided with resistor.Other variable resistor/condenser networks are known for the skilled personnel and can alternate application.

Select the integration time constant of compensating circuit or balancing circuitry, make the signal that produces by the path of particle by coil can not influence tuning too soon and widely.In the embodiment of selecting, tuning have sufficient scope so that aging and temperature effect are allowed some leeway, simultaneously tuning have be better than four millionth enough accuracies with tuning electric bridge.In 10 seconds of turn-on control circuit, reach balance.

Adopt device shown in Figure 2, at 20～150 ℃, can detect the particle M50 below 85 microns in the oily temperature scope that flows through fluid passage.This device can respond approximately, and 1/10000000th coil impedance changes.

When power is increased to 10 watt-hours, can take special-purpose means to shelter this driving circuit in drive circuit power to reduce radiated noise and low harmonic content is provided.The input of this power allows to detect little particle to 25 microns.

Modification shown in Figure 3 can be used in the place that frequency of utilization is lower than 100KHz.If coil is connected in series to capacitor, adopt more that low frequency makes syntonizing coil more difficult, but adopt transformer coupledly, this point can be improved.The application of transformer also allows the balance drive coil, can improve the device noise and restrain performance: therefore, also be feasible with this alternative applications to high-frequency device.

Analysis circuitry 100 can provide be illustrated in one or more particles exist in the fluid passage output simply have a detecting device (presence detector).In addition, can use the indicating value that detected particle or continuous coating of particles and size are provided in the output shape of

output line

56a and 57a.

Must be according to the shape of required application choice coil.Should be realized that selected concrete shape will compromise between susceptibility and the flow velocity by fluid passage.Clearly can improve the susceptibility of coil, thereby make that particle relatively is bigger comparatively speaking by the diameter that reduces coil.But the more little diameter with regard to the inevitable requirement fluid passage of diameter core is more little, and this may limit the flow velocity of oil.

Described device is because following several reasons is better than existing scheme:

1. only need a coil for each oil body pipeline.

2. this device is fully automatically and without any need for adjusting.

3. in 6 seconds of conducting, begin operation usually.

4. by the output of homophase and quadrature is provided, make the granulomere be divided into possibility.

5. can be to work between 20～150 ℃ in oily temperature.

6. by simulation output is provided, can determine the size and dimension of particle.

Only need 6 watts and can use cheap circuit for the device of manipulating in one embodiment.

In some embodiments, the flow of oil path is divided into a plurality of narrow road footpath that has coil separately, allows to obtain high sensitive like this and keep very high oily flow velocity simultaneously.

In some environment, adopt single or in groups the coil device that is used to detect electrically-conductive debris may not detect the particle of some type.With reference to Fig. 5, for example, have little length along an axle but be arranged essentially parallel to the device of channel axis 101 by an axle along another particle with big relatively length, just may this thing happens.Therefore, the center line of minimum dimension approximately becomes an angle of 90 degrees with channel axis.Because this aforementioned means only can " be seen " narrow dimension, this means that this aforesaid device may not can be subjected to the influence of particle.The particle of this common type may indicate catastrophic mechanical disorder on the horizon.

In order to overcome this point, can make any particle that exists to detect at an easy rate by in flow path, making the stream rotation to improve this device.By providing this particle of rotating flow to rotate in circulation in the pipeline and improves the possibility that detects particle, so some points in rotary course, the width dimensions of the coil of detection appears being suitable for use in probably.

The another way that overcomes this shortcoming is to use two or more coil 10a, 10b.In embodiment shown in Figure 6, exist two to have the coil of axle 103,104 separately, be arranged so that their axle 103,104 is not parallel to the axle 101 of fluid passage, and become different angles with axis of flow.In an illustrated embodiment, 101 one-tenth 60 degree of axle 103 and channel axis angle, and 101 one-tenth 120 degree of axle 104 and axle angle.In having another embodiment of two coils, one has the axle that is parallel to the flow direction, and one has and flow to the axle that has certain angle.In other embodiments, two coils become incoherent angle substantially with respect to axle.

These or similar embodiment in one or two coil, produce signal and with the orientation independent of particle.Also can determine the coating of particles feature by this structure, because be not spherical just different from the signal of each coil constantly at particle only, that is, the sphere of standard will produce the same signal in two coils.

Because whether these multi-thread coil structures are not remained unchanged by the coil position antipode for its operation influence, so they can be to vibration sensing as the multi-thread coil apparatus that it is conventionally believed that.

Can use independent signal processing circuit for each coil.Selectable the series connection of a plurality of coils can be set.The angle of coil and quantity are distinguished to some extent according to application.

Although adopted positive controllable resistor and condenser network that this device is described, words if necessary also can use the negative impedance simulator to replace certainly.

Although with reference to description of drawings illustrative embodiments of the present invention, scope of the present invention is not limited to the technical characterictic of embodiment but extends to the scope of claims.

Claims

1. the device that is used for the electrically-conductive debris existence of test fluid path, this device comprises the bridge circuit with four arms, an arm of this electric bridge comprises that setting is to be used for the coil of monitoring fluid path, be connected across diagonal line of described bridge circuit and be used to provide the function circuit of alternating current, be connected across another diagonal line of described bridge circuit and be used for monitoring the unbalanced supervisory circuit of described bridge circuit, and the balancing circuitry that is used for adjusting the value of at least one element of described bridge circuit in response to the output of described supervisory circuit in the unbalanced mode that reduces bridge circuit, a wherein said arm comprises the series circuit of described coil and capacitor element, and its excess-three arm is formed by the element that impedance effect is essentially resistance.

2. device according to claim 1 is characterized in that described device only comprises single coil.

3. device according to claim 1 and 2 is characterized in that, with the combining of described fluid passage in, other element in described function circuit, supervisory circuit, balancing circuitry and the bridge circuit except that coil can be away from the fluid passage setting.

4. according to claim 1,2 described devices, it is characterized in that described balancing circuitry one of is set to control in the group of the capacitive reactance, induction reactance and the impedance that comprise described at least one element at least.

5. device according to claim 1 is characterized in that, described supervisory circuit comprises and is used for measuring the homophase of another diagonal line voltage of described electric bridge and the lock detector of quadrature component.

6. device according to claim 1 is characterized in that, described function circuit comprises that cross-over connection is used to apply sinusoidal wave circuit as described alternating current on a described diagonal line.

7. device according to claim 1 is characterized in that, described capacitor element is controlled.

8. device according to claim 1 is characterized in that, a described arm comprises the transformer with elementary winding, secondary winding, described elementary windings in series is set is connected on the described coil to capacitor element and described secondary winding.

9. device according to claim 1 is characterized in that, described balancing circuitry comprise with a described arm in the controlled capacitance that is connected in parallel of fixed capacity.

10. device according to claim 9 is characterized in that, described controlled capacitance comprises described fixed capacity and is used to control the circuit of the alternating current that imposes on electric capacity, thereby can control the effect of described fixed capacity.

11. device according to claim 1 is characterized in that, described balancing circuitry comprises the controllable resistor that is parallel-connected to fixed resistance described in one of them arm of described bridge circuit.