# Patent

## Title
Current clamp with jaw closure detection

## Abstract

A current clamp has a pair of jaws that are placed around an electrical conductor to measure a parameter (a measurable quantity or distinguishing or notable characteristic) corresponding to the electrical conductor.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 61/789,189, filed Mar. 15, 2013, the content of which is hereby incorporated by reference in its entirety.


BACKGROUND
The present invention relates to a current clamp. More specifically, the present invention relates to detecting closure of jaws on a current clamp.
A current clamp (also known as a current probe or amp clamp) is an electrical device that has a pair of jaws, which, when closed, form a closed curve (such as a circle or oval). When the jaws are closed around an electrical conductor, properties of the electric current flowing in the conductor can be measured, without requiring physical contact with the conductor or disconnection of the conductor for insertion through the probe. Current clamps can be used to read the magnitude of an alternating current. Also, in conjunction with more advanced instrumentation, the phase and wave form of the current can be detected as well.
One type of current clamp comprises a split ring of ferrite or soft iron. The split ring is split into two halves, each of which have a wire coil wound therearound. The wire coil forms one winding of a current transformer. When the current clamp is placed around a conductor, the conductor forms the other winding.
Another type of current clamp is referred to as an iron vane clamp. In this type of current clamp, the magnetic flux in the core directly affects a moving iron vane that allows both A/C and D/C current to be measured. It also gives a true RMS value for non-sinusoidal A/C wave forms.
Yet another type of clamp, with a meter, is referred to as a Hall Effect meter. This type of meter is more sensitive and is able to measure both D/C and A/C current. Normally, a current clamp only works when it is placed around one conductor of a circuit under test. The reason is that if it is placed around both conductors, the magnetic fields cancel.
When the current clamp is integrally combined with an electrical meter, the device is known as a clamp meter (and is also sometimes referred to as a clamp-on ammeter or tong tester). Clamp meters can also be used to measure electrical power and energy. The clamp is used to measure the current and other circuitry measures the voltage. The true power is the product of the instantaneous voltage and current integrated over a cycle.
The accuracy of each of these devices can be affected if the jaws do not fully close around the conductor. When this occurs, the magnetic loop is not continuous, and the meter reading associated with the current clamp is erroneous (and usually too low).
SUMMARY
A current clamp has a pair of jaws that are placed around an electrical conductor to measure a parameter (a measurable quantity or a distinguishing or notable characteristic) corresponding to the electrical conductor.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial block diagram, partial pictorial diagram of a current clamp.
FIG. 1A is a diagram of a current clamp with a meter.
FIG. 1B is a partial schematic diagram and partial block diagram showing a current clamp in a battery tester.
FIG. 2 shows the current clamp of FIG. 1 with the testing device and closure sensors shown in greater detail.
FIGS. 3A-3E show a portion of the current clamp of FIG. 1 with various embodiments of a closure sensor.
FIG. 4 shows another embodiment of tips of the jaws of the current clamp of FIG. 1.
FIG. 5 shows yet another embodiment of the current clamp and closure sensor.
FIG. 6 shows one embodiment of the current clamp with the closure sensor formed by an annular ring.



DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
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No. 10/958,812, filed Oct. 5, 2004, entitled SCAN TOOL FOR ELECTRONIC BATTERY TESTER; U.S. Ser. No. 60/587,232, filed Dec. 14, 2004, entitled CELLTRON ULTRA, U.S. Ser. No. 60/653,537, filed Feb. 16, 2005, entitled CUSTOMER MANAGED WARRANTY CODE; U.S. Ser. No. 60/665,070, filed Mar. 24, 2005, entitled OHMMETER PROTECTION CIRCUIT; U.S. Ser. No. 60/694,199, filed Jun. 27, 2005, entitled GEL BATTERY CONDUCTANCE COMPENSATION; U.S. Ser. No. 60/705,389, filed Aug. 4, 2005, entitled PORTABLE TOOL THEFT PREVENTION SYSTEM, U.S. Ser. No. 11/207,419, filed Aug. 19, 2005, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION FOR USE DURING BATTERY TESTER/CHARGING, U.S. Ser. No. 60/712,322, filed Aug. 29, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE, U.S. Ser. No. 60/713,168, filed Aug. 31, 2005, entitled LOAD TESTER SIMULATION WITH DISCHARGE COMPENSATION, U.S. Ser. No. 60/731,881, filed Oct. 31, 2005, entitled PLUG-IN FEATURES FOR BATTERY TESTERS; U.S. Ser. No. 60/731,887, filed Oct. 31, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER THAT CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER WITH CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/356,443, filed Feb. 16, 2006, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 11/519,481, filed Sep. 12, 2006, entitled BROAD-BAND LOW-CONDUCTANCE CABLES FOR MAKING KELVIN CONNECTIONS TO ELECTROCHEMICAL CELLS AND BATTERIES; U.S. Ser. No. 60/847,064, filed Sep. 25, 2006, entitled STATIONARY BATTERY MONITORING ALGORITHMS; U.S. Ser. No. 11/641,594, filed Dec. 19, 2006, entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRONIC SYSTEM; U.S. Ser. No. 60/950,182, filed Jul. 17, 2007, entitled BATTERY TESTER FOR HYBRID VEHICLE; U.S. Ser. No. 60/973,879, filed Sep. 20, 2007, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONARY BATTERIES; U.S. Ser. No. 60/992,798, filed Dec. 6, 2007, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 61/061,848, filed Jun. 16, 2008, entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/498,642, filed Jul. 7, 2009, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/697,485, filed Feb. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/712,456, filed Feb. 25, 2010, entitled METHOD AND APPARATUS FOR DETECTING CELL DETERIORATION IN AN ELECTROCHEMICAL CELL OR BATTERY; U.S. Ser. No. 61/311,485, filed Mar. 8, 2010, entitled BATTERY TESTER WITH DATABUS FOR COMMUNICATING WITH VEHICLE ELECTRICAL SYSTEM; U.S. Ser. No. 61/313,893, filed Mar. 15, 2010, entitled USE OF BATTERY MANUFACTURE/SELL DATE IN DIAGNOSIS AND RECOVERY OF DISCHARGED BATTERIES; U.S. Ser. No. 12/758,407, filed Apr. 12, 2010, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 12/769,911, filed Apr. 29, 2010, entitled STATIONARY BATTERY TESTER; U.S. Ser. No. 61/330,497, filed May 3, 2010, entitled MAGIC WAND WITH ADVANCED HARNESS DETECTION; U.S. Ser. No. 61/348,901, filed May 27, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 61/351,017, filed Jun. 3, 2010, entitled IMPROVED ELECTRIC VEHICLE AND HYBRID ELECTRIC VEHICLE BATTERY MODULE BALANCER; U.S. Ser. No. 12/818,290, filed Jun. 18, 2010, entitled BATTERY MAINTENANCE DEVICE WITH THERMAL BUFFER; U.S. Ser. No. 61/373,045, filed Aug. 12, 2010, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONERY STORAGE BATTERY; U.S. Ser. No. 12/888,689, filed Sep. 23, 2010, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 12/894,951, filed Sep. 30, 2010, entitled BATTERY PACK MAINTENANCE FOR ELECTRIC VEHICLES; U.S. Ser. No. 61/411,162, filed Nov. 8, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 13/037,641, filed Mar. 1, 2011, entitled MONITOR FOR FRONT TERMINAL BATTERIES; U.S. Ser. No. 13/037,641, filed Mar. 1, 2011, entitled: MONITOR FOR FRONT TERMINAL BATTERIES; U.S. Ser. No. 13/048,365, filed Mar. 15, 2011, entitled ELECTRONIC BATTERY TESTER WITH BATTERY AGE UNIT; U.S. Ser. No. 13/098,661, filed May 2, 2011, entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRICAL SYSTEM; U.S. Ser. No. 13/113,272, filed May 23, 2011, entitled ELECTRONIC STORAGE BATTERY DIAGNOSTIC SYSTEM; U.S. Ser. No. 13/152,711, filed Jun. 3, 2011, entitled BATTERY PACK MAINTENANCE FOR ELECTRIC VEHICLE; U.S. Ser. No. 13/205,949, filed Aug. 9, 2011, entitled ELECTRONIC BATTERY TESTER FOR TESTING STORAGE BATTERY; U.S. Ser. No. 13/205,904, filed Aug. 9, 2011, entitled IN-VEHICLE BATTERY MONITOR; U.S. Ser. No. 13/270,828, filed Oct. 11, 2011, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION; U.S. Ser. No. 13/276,639, filed Oct. 19, 2011, entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRICAL SYSTEM; U.S. Ser. No. 61/558,088, filed Nov. 10, 2011, entitled BATTERY PACK TESTER; U.S. Ser. No. 13/357,306, filed Jan. 24, 2012, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 61/665,555, filed Jun. 28, 2012, entitled HYBRID AND ELECTRIC VEHICLE BATTERY MAINTENANCE DEVICE; and U.S. Ser. No. 13/567,463, filed Aug. 6, 2012, entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No. 13/668,523, filed Nov. 5, 2012, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 13/672,186, filed Nov. 8, 2012, entitled BATTERY PACK TESTER; U.S. Ser. No. 13/687,673, filed Nov. 28, 2012, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION; U.S. Ser. No. 61/777,360, filed Mar. 12, 2013, entitled DETERMINATION OF STARTING CURRENT IN AN AUTOMOTIVE VEHICLE; U.S. Ser. No. 61/777,392, filed Mar. 12, 2013, entitled DETERMINATION OF CABLE DROP DURING A STARTING EVENT IN AN AUTOMOTIVE VEHICLE; U.S. Ser. No. 13/827,128, filed Mar. 14, 2013, entitled HYBRID AND ELECTRIC VEHICLE BATTERY MAINTENANCE DEVICE; U.S. Ser. No. 61/789,189, filed Mar. 15, 2013, entitled CURRENT CLAMP WITH JAW CLOSURE DETECTION; U.S. Ser. No. 61/824,056, filed May 16, 2013, entitled BATTERY TESTING SYSTEM AND METHOD; U.S. Ser. No. 61/859,991, filed Jul. 30, 2013, entitled METHOD AND APPARATUS FOR MONITORING A PLURALITY OF STORAGE BATTERIES IN A STATIONARY BACK-UP POWER SYSTEM; U.S. Ser. No. 14/039,746, filed Sep. 27, 2013, entitled BATTERY PACK MAINTENANCE FOR ELECTRIC VEHICLE; U.S. Ser. No. 61/915,157, filed Dec. 12, 2013, entitled BATTERY TESTER AND BATTERY REGISTRATION TOOL; U.S. Ser. No. 61/928,167, filed Jan. 16, 2014, entitled BATTERY CLAMP WITH ENDOSKELETON DESIGN; all of which are incorporated herein by reference in their entireties.
FIG. 1 is a block diagram of one illustrative embodiment of a current clamp 100. Current clamp 100 illustratively includes a pair of jaws 102 and 104 that can be opened and closed using jaw actuator 106. When jaws 102 and 104 close together, they illustratively contact one another at their distal tips 108 and 110, respectively. Current clamp 100 also illustratively includes a testing device 112 that is used to measure a parameter of conductor 114 (e.g., the current flowing through conductor 114). This may be spaced apart from the jaws 102, 104, or can be formed integrally as illustrated.
Testing device 112 can be a wide variety of different kinds of devices. For instance, FIG. 1 shows one example where testing device 112 is a battery or electrical system tester or analyzer (collectively referred to as a battery tester). It can be for transportation batteries (e.g., batteries used in vehicles) or for stationary batteries (e.g., those used in communication systems) or other systems. These are examples only. Other examples, such as where the testing device is a handheld current meter, can also be used, and some of them are discussed below.
In the embodiment shown in FIG. 1, current clamp 100 also includes a closure sensor component 116. As discussed in the background portion, when jaws 102 and 104 do not close, so that their distal tips 108 and 110 do not contact one another, testing device 112 can tend to produce an inaccurate measurement of the parameter (e.g., the current or another parameter) of conductor 114. Therefore, in the embodiment shown in FIG. 1, current clamp 100 includes closure sensing component 116. While closure sensing component 116 is shown disposed on testing device 112, it can illustratively be disposed at substantially any location. A number of different embodiments are discussed below with respect to FIGS. 2-6.
In operation, a user illustratively actuates jaw actuator 106 to separate jaws 102 and 104 from one another at their distal tips 108 and 110. The user then places conductor 114 between jaws 102 and 104 and either actuates jaw actuator 106 (or simply releases jaw actuator 106) to bring jaws 102 and 104 together so that their distal tips 108 and 110 are in contact with one another, as shown in FIG. 1.
Closure sensing component 116 illustratively provides a signal to testing device 112 indicating whether the jaws 102 and 104 are fully closed. If not, a user-observable indicator is provided to the user so that the user knows that the jaws are not closed, and can take remedial action. If the jaws are closed, then testing device 112 can illustratively measure the parameter and provide an output indicative of that parameter.
FIG. 1A is a pictorial illustration of one embodiment of current clamp 100 in more detail. Some of the items shown in FIG. 1A are similar to those shown in FIG. 1, and they are similarly numbered. In the embodiment shown in FIG. 1A, actuator 106 comprises a depressible lever or paddle. When the user grips testing device 112 and pushes actuator 106 in the direction generally indicated by arrow 118, this causes the distal tips 108 and 110 of jaws 102 and 104 to open in the directions indicated by arrows 120 and 122, respectively. Thus, the jaws open so that the user can place conductor 114 there between. When the user releases actuator 106 (by ceasing to press on it), jaws 102 and 104 are illustratively biased to the closed position shown in FIG. 1A, so that distal tips 108 and 110 again come into contact with one another.
In the embodiment shown in FIG. 1A, testing device 112 illustratively includes a user input mechanism, such as dial 124. This can provide the user with a number of different options. For instance, dial 124 can be used to change the particular parameter that testing device 112 is set to measure. Similarly, dial 124 can be used to change the sensitivity of current clamp 100 or to modify other operating characteristics of current clamp 100, as desired.
The current clamp 100 shown in FIG. 1A also illustratively includes a user interface display device 126. Display device 126 is illustratively a visual display (such as an LCD display, an LED display, or any other type of display) that provides a visual display of the measured parameter. It can also be used to provide a user display indicative of whether closure sensing component 116 senses that jaws 102 and 104 are completely closed, or whether they are still open. Of course, display device 126 can be used to generate a wide variety of other displays as well.
FIG. 1A also shows closure sensing component 116 in more detail. In the embodiment shown in FIG. 1A, closure sensing component 116 illustratively includes a closure sensor 130 and a closure detection component 132. Closure sensor 130 (as will be described in greater detail below) illustratively senses whether the distal ends 108 and 110 of jaws 102 and 104 are in contact with one another. Closure sensor 130 illustratively provides a signal indicative of this to closure detection component 132. Based on the signal from closure sensor 130, closure detection component 132 illustratively determines whether the jaws are open or closed. By way of one exemplary embodiment, closure sensor 130 may illustratively be a switch that detects that the ends 108 and 110 of jaws 102 and 104 are in contact with one another. Closure detection component 132 may illustratively be the electrical circuitry that receives the signal from the switch and determines whether the jaws are open or closed based on that signal. Of course, other embodiments can be used, and some of these are discussed below with respect to FIGS. 2-6.
FIG. 1B is a simplified block diagram in which testing device 112 comprises an electronic battery tester (or module) 16 that has current clamp 100 coupled to it, in accordance with one example embodiment. Module 16 is shown coupled to battery 10. Module 16 operates in accordance with one embodiment and determines the conductance (GBAT) of battery 10 and the voltage potential (VBAT) between terminals 12 and 14, as well as current flowing through conductor 114. Module 16 includes current source 50, differential amplifier 52, analog-to-digital converter 54, amplifier 55 and microprocessor 56.
Amplifier 55 is coupled to current clamp 100 and amplifies (or otherwise conditions) the signals generated therein and provides them to A/D converter 54. A/D converter 54 converts the signal to a digital value and provides it to processor 56. Processor 56 can use the signal in various calculations, or simply to output the current carried by conductor 114 or in other ways. Closure sensing component 116 also provides a signal to processor 56 indicative of whether jaws 102 and 104 are closed. Amplifier 52 is capacitively coupled to battery 10 through capacitors C1 and C2. Amplifier 52 has an output connected to an input of analog-to-digital converter 54. Microprocessor 56 is connected to system clock 58, memory 60, visual output 62 and analog-to-digital converter 54. Microprocessor 56 is also capable of receiving an input from input device 26. Further, an input/output (I/O) port 67 is provided.
In operation, current source 50 is controlled by microprocessor 56 and provides a current in the direction shown by the arrow in FIG. 1. In one embodiment, this is a square wave, sine wave, pulse or other signal with a time varying component or a pulse. Differential amplifier 52 is connected to terminals 22 and 24 of battery 10 through capacitors C1 and C2, respectively, and provides an output related to the voltage potential difference between terminals 12 and 14. In a preferred embodiment, amplifier 52 has a high input impedance. Circuitry 16 includes differential amplifier 70 having inverting and noninverting inputs connected to terminals 24 and 22, respectively. Amplifier 70 is connected to measure the open circuit potential voltage (VBAT) of battery 10 between terminals 12 and 14. The output of amplifier 70 is provided to analog-to-digital converter 54 such that the voltage across terminals 12 and 14 can be measured by microprocessor 56.
Module 16 is connected to battery 10 through a four-point connection technique known as a Kelvin connection. This Kelvin connection allows current I to be injected into battery 10 through a first pair of terminals while the voltage V across the terminals 12 and 14 is measured by a second pair of connections. Because very little current flows through amplifier 52, the voltage drop across the inputs to amplifier 52 is substantially identical to the voltage drop across terminals 12 and 14 of battery 12. The output of differential amplifier 52 is converted to a digital format and is provided to microprocessor 56. Microprocessor 56 operates at a frequency determined by system clock 58 and in accordance with programming instructions stored in memory 60. Microprocessor 56 determines the dynamic conductance of battery 10 by applying a current pulse I using current source 50. The microprocessor determines the change in battery voltage due to the current pulse I using amplifier 52 and analog-to-digital converter 54. The value of current I generated by current source 50 is known and is stored in memory 60. In one embodiment, current I is obtained by applying a load to battery 10. Microprocessor 56 calculates the dynamic conductance of battery 10 using the following equation:




  
    
      
        Conductance
        =
        
          
            G
            BAT
          
          =
          
            
              Δ
              ⁢
              
                
              
              ⁢
              I
            
            
              Δ
              ⁢
              
                
              
              ⁢
              V
            
          
        
      
    
    
      
        Equation
        ⁢
        
          
        
        ⁢
        1
      
    
  




where ΔI is the change in current flowing through battery 10 due to current source 50 and ΔV is the change in battery voltage due to applied current ΔI. A temperature sensor 62 can be thermally coupled to battery 10 and used to compensate battery measurements. Temperature readings can be stored in memory 60 for later retrieval.

In one embodiment module 16 includes a current sensor 63 which measures charge/discharge current of the battery 10. This can be measured by current clamp 100 instead, or in addition. The battery current measurements are utilized by microprocessor 56 to relatively accurately determine state of charge and state of health of battery 10. The current source 50 may comprise an active source or a passive source such as a resistor. In one configuration, source 50 can operate as a large load whereby a load test is applied to the battery 10. In such a load test, the voltage across the battery and/or the current through the battery is monitored (by current clamp 100 or other sensor 63) while a large resistive load is applied.
FIG. 2 is a partial block diagram, partial pictorial illustration, of testing device 112 in more detail. FIG. 2 shows that jaws 102 and 104 are not connected to testing device 112. However, in some embodiments, they are connected, as shown in FIGS. 1 and 1A above. They are shown separately and diagrammatically connected by arrow 140, for the sake of example only.
FIG. 2 also shows that, in one embodiment, testing device 112 not only includes closure detection component 132 and jaw actuator 106, but it includes measuring component 142, processor 144, user interface component 146, closure status indicator 148 and closure status memory 150.
Measuring component 142 illustratively includes the electrical circuitry used to measure the parameter of conductor 114. Processor 144 is illustratively a computer processor with associated memory and timing circuitry (not separately shown). Processor 144 is illustratively a functional part of testing device 112 and is activated by other items in testing device 112 to facilitate some of their functionality.
User interface component 146 illustratively receives the input from user input mechanisms 124 (such as the dial shown in FIG. 1A and other user input mechanisms) and provides appropriate signals to other portions of testing device 112. User interface component 146 also illustratively includes the circuitry necessary to generate the displays on display device 126.
Closure status indicator 148 is illustratively used to provide the closure status of jaws 102 and 104, as sensed by sensor 130 and detected by closure detection component 132. Closure detection component 132 illustratively provides a signal to closure status indicator 148 indicative of the closure status of jaws 102 and 104. In the embodiment shown in FIG. 2, closure status indicator illustratively provides some type of output that can be noticed by a user so the user can see whether the jaws 102 and 104 are properly closed.
FIG. 2 shows that the closure status indicator 148 can be one or more of a wide variety of different types of indicators. For instance, closure status indicator 148 can be an audio indicator 152 that provides an audio output for the user to indicate whether the jaws 102 and 104 are open or closed. The indicator can be a visual indicator 154, such as an output on display device 126, the illumination of a light on testing device 112, a textual message displayed on display device 126, or any other type of visual indicator. The closure status indicator can also be a tactile indicator 156. In one embodiment, this is a vibration of testing device 112. Of course, other tactile outputs can be provided as well.
In still other embodiments, closure status indicator 148 is a transmission to a separate device. For instance, it can be an instant message sent to an instant messaging device that is displayed to the user. This is indicated by block 158. It can be a cellular communication that is generated and transmitted to a cellular telephone or smart phone or other cellular device used by the user. This is indicated by block 160. It can also be any other type of wireless communication or even electronic mail (email) sent to a mobile device or other type of computing device used by the user. Wireless communication and email are indicated by blocks 162 and 164 shown in FIG. 2. Of course, the closure status indicator can take other forms as well, and this is indicated by block 166.
FIG. 2 also shows various embodiments of closure sensor 130. FIG. 2 shows that closure sensor 130 is illustratively disposed at a location proximate distal ends 108 and 110 of jaws 102 and 104, respectively. This is indicated diagrammatically by arrow 170. The precise location of closure sensor 130 relative to jaws 102 and 104, however, can vary based upon the particular type of closure sensor 130 that is used. FIG. 2 shows that among the embodiments for closure sensor 130, they can include micro switch 172, optical sensor 174, resistive sensor 176, reed switch 178, Hall Effect sensor 180, or other sensor 182.
Also, it will be appreciated that, while closure sensor 130 is shown in FIG. 2 positioned proximate the distal ends 108 and 110 of the jaws, it could be positioned at other places as well. For instance, if jaws 102 and 104 are positioned to pivot relative to one another about a pivot point 184, then closure sensor 130 can sense the pivoting motion, and position, of jaws 102 and 104 relative to one another proximate the pivot point 184 (that is near the proximal ends of jaws 102 and 104). By way of example only, a potentiometer placed at pivot point 184 can have its wiper connected to one of jaws 102 and 104 such that as the jaws are pivoted relative to one another, the wiper moves thus giving an indication of the position of jaws 102 and 104 relative to one another. However, for the sake of the present description, closure sensor 130 will be described closely proximate the distal ends 108 and 110 of jaws 102 and 104, respectively. This description is given by way of example only.
FIG. 3A is a partial pictorial and partial block diagram illustration of the distal ends 108 and 110 of jaws 102 and 104, respectively. In the embodiment shown in FIG. 3A, closure sensor 130 is a micro switch (also referred to as a miniature snap-action switch) that is actuated by very little physical force. The force can be directed to a micro switch actuator 190 which is a tipping-point mechanism (e.g., an over-center switch). That is, a relatively small movement of the actuator 190 produces a relatively large movement at a corresponding pair of electrical contacts. For instance, when the micro switch actuator is moved by the distal ends 108 and 110 of jaws 102 and 104 coming into contact with one another, this can operate to open or close a circuit at an associated set of electrical contacts. Closure detection component 132 can thus detect that the circuit has opened or closed, and thus provide an indication as to whether the distal tips 108 and 110 of jaws 102 and 104 are in contact with one another. Other arrangements of micro switch 172 can be used as well.
FIG. 3B shows an embodiment in which closure sensor 130 (shown in FIG. 2) is an optical sensor 174 (also shown in FIG. 2). The optical sensor illustratively includes an optical emitter 192 and an optical detector 194. Optical emitter 192 illustratively emits light rays that are sensed by optical detector 194. Optical detector 194 generates a signal indicative of detecting the light emitted by optical emitter 192 and provides it to closure detection component 132. Some optical sensors can measure changes from one or more light beams. The sensed change can be based on a change in the intensity of the light. When a phase change occurs, optical detector 194 can act as a photoelectric trigger, either increasing or decreasing the output signal provided to closure detection component 132. Therefore, when optical emitter 192 is in close enough proximity to optical detector 194, a signal indicative of this can be output to closure detection component 132 thus indicating that jaws 102 and 104 are closed. Other types of optical sensors can be used as well.
FIG. 3C shows one embodiment in which closure sensor 130 is a resistive sensor 176 (shown in FIG. 2). One type of resistive sensor is a transducer or electromechanical device that converts a mechanical change (such as displacement) into an electrical signal that can be monitored, after appropriate conditioning. One type of resistive sensor is a potentiometer that is an electromechanical device that includes a movable wiper arm. The wiper arm maintains electrical contact with a resistive surface. The wiper is coupled mechanically to a movable member or link (such as one of jaws 102 and 104). There are a wide variety of these types of resistive sensors, and some include carbon film, metal film, wire wound, conductive plastic film, ceramic-metal and slide wire devices. Regardless of which type of resistive sensor 176 is used, it is illustratively situated relative to jaws 102 and 104 to provide a signal indicative of whether the distal ends 108 and 110 of the jaws are in contact with one another. The signal indicative of a position of jaws 102 and 104 is provided to closure detection component 132, which detects whether the jaws are open or closed. Other arrangements of resistive sensors can be used as well.
FIG. 3D illustrates one embodiment in which closure sensor 130 is a reed switch or reed relay 178. A reed relay uses an electromagnet to control one or more reed switches. A reed switch has a pair of contacts that connect to either side of a coil. The voltage applied to those contacts (across the coil) applies a magnetic field to the coil and closes a switch that forms a circuit between a separate pair of contacts. Therefore, when the voltage is applied across the first pair of contacts, the circuit across the second pair of contacts closes, and when the voltage across the first pair of contacts is removed, the circuit between the second pair of contacts opens. In the embodiment shown in FIG. 3D, the reed switch is actually located on testing device 112 (such as in closure detection component 132). The voltage applied across the first set of contacts of the reed relay is applied along a conductor that runs from detection component 132 to a first contact 196 on one of jaws 102 and 104 (in this case jaw 104). Contact 196 is paired with a second contact 198 on the other jaw (in this case jaw 102). The conductor runs from contact 198 back to the coil of the reed switch 178. Contacts 196 and 198 are arranged on the distal ends 110 and 108 of jaws 104 and 102 (respectively) such that when the jaws are closed, contacts 196 and 198 are in contact with one another. Therefore, when the jaws are closed, the voltage is applied across the coil of reed switch 178. However, when the jaws 102 and 104 are not closed, then contacts 196 and 198 are not in contact with one another, and the voltage is not applied across the coil of the reed switch. Closure detection component 132 senses whether the reed switch is closed or open. Thus, closure detection component 132 can detect whether contacts 196 and 198 are in contact with one another (and hence whether jaws 102 and 104 are open or closed). Other arrangements of a reed switch can be used as well.
FIG. 3E shows one embodiment in which closure sensor 130 comprises Hall Effect sensor 180. Hall Effect sensor 180 includes magnet 200 and hall switch sensor 202. Hall switch sensor 202 is a transducer that varies its output voltage in response to the magnetic field by magnet 200. In one embodiment, sensor 202 operates as an analog transducer that directly returns a voltage based upon the applied magnetic field. With the known magnetic field generated by magnet 200, the distance between magnet 200 and Hall switch sensor 202 can be determined as well. In one illustrative embodiment, closure detection component 132 includes circuitry that allows Hall switch sensor 202 and magnet 200 to act in a digital on/off mode. Or, when the distal ends 108 and 110 of jaws 102 and 104 are close enough together, Hall switch sensor 202 provides an “on” signal to closure detection component 132. This indicates that jaws 102 and 104 are closed. However, when the distal ends 108 and 110 are separated from one another, hall switch sensor 202 illustratively provides an “off” signal to closure detection component 132, indicating that jaws 102 and 104 are open. Other arrangements of Hall sensors can also be used.
FIG. 4 shows another embodiment of jaws 102 and 104. In the embodiment shown in FIG. 4, the distal ends 108 and 110 of jaws 102 and 104 have an interlocking, or mating arrangement. While the embodiment shown in FIG. 4 is relatively simple, it will be noted that the distal ends of the jaws can have a more complex arrangement as well. For instance, multiple fingers on one jaw can interlock with multiple fingers on another jaw. Similarly, the jaws can mate coaxially or in other more simple or more complex ways as well. FIG. 4 is simply shown as an example that the closure sensor can be arranged relative to more complex surfaces than those shown in FIG. 3A-3E.
FIG. 5 shows yet another embodiment. In FIG. 5, the closure sensor is located on the external surface of jaws 102 and 104. FIG. 5 is shown because while FIGS. 3A-3E show that the closure sensor is located within jaws 102 and 104, or on a side surface thereof, it is also contemplated that it can be located on an external, distal surface as well. Similarly, of course, the closure sensor 130 can be located substantially anywhere that it can sense whether the distal ends 108 and 110 of jaws 102 and 104 are in contact with one another.
FIG. 6 shows yet another exemplary embodiment. FIG. 6 illustrates that closure sensor 130 can be disposed about the entire exterior surface of the distal ends of jaws 102 and 104 as well. In the embodiment shown in FIG. 6, closure sensor 130 is disposed as an annular flange on the distal end of one or both of jaws 102 and 104.
The embodiments discussed herein are exemplary only. There are a wide variety of other embodiments which include different types of closure sensors or closure detection circuitry and which include different physical arrangement of the sensors and circuitry relative to jaws 102 and 104. The closure indicator can take a wide variety of different forms as well. Those shown are shown for exemplary purposes only.
It should also be noted that various features of the different embodiments can be combined. That is, one or more features of one embodiment discussed above can be combined with one or more features of other embodiments discussed above. All of these arrangements are contemplated herein.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. The clamp of the present invention can be employed with any type of battery maintenance circuitry including battery testers and chargers, as well as vehicle electrical system testers, or other type of test equipment. In one configuration, the closure sensor senses a parameter other than the output of the amp clamp. This allows closure detection even when no current is present in the wire/component being measured.

## Claims

1. An electrical system testing device, comprising:
a clamp configured to open, receive a conductor, and close around the conductor;
an actuator that, when actuated, opens the clamp;
a testing device, operably coupled to the clamp, to measure a current flowing through the conductor for performing maintenance on a battery; and
a closure sensing component that senses a closure state of the clamp indicative of whether the clamp is closed and provides a closure signal indicative of the closure state of the clamp.

2. The electrical system testing device of claim 1 wherein the clamp comprises:
a first jaw; and
a second jaw, the first and second jaws being movable relative to one another to open and close the clamp.

3. The electrical system testing device of claim 2 wherein the first and second jaws each have a distal end, the distal ends of the jaws being in contact with one another when the clamp is closed and being separated from one another when the clamp is open.

4. The electrical system testing device of claim 3 wherein the closure sensing component is disposed to sense whether the distal ends of the jaws are in contact with one another.

5. The electrical system testing device of claim 4 wherein the closure sensing component includes a closure sensor disposed proximate the distal ends of the jaws.

6. The electrical system testing device of claim 3 wherein the jaws each have proximal ends and wherein the jaws are pivotable relative to one another at the proximal ends thereof.

7. The electrical system testing device of claim 6 wherein the closure sensor is disposed at the proximal ends of the jaws.

8. The electrical system testing device of claim 1 wherein the closure sensing component comprises an optical sensor.

9. The electrical system testing device of claim 1 wherein the closure sensing component comprises a resistive sensor.

10. The electrical system testing device of claim 1 wherein the closure sensing component comprises a micro switch.

11. The electrical system testing device of claim 1 wherein the closure sensing component comprises a reed switch.

12. The electrical system testing device of claim 1 wherein the closure sensing component comprises a Hall effect sensor.

13. The electrical system testing device of claim 1 wherein the closure sensing component provides a user-observable closure status indicator indicative of the clamp being open.

14. The electrical system testing device of claim 13 wherein the closure status indicator comprises an audio indicator.

15. The electrical system testing device of claim 13 wherein the status indicator comprises a visual indicator.

16. The electrical system testing device of claim 13 wherein the status indicator comprises a tactile indicator.

17. The clamp-on device of claim 1 wherein the testing device comprises a battery tester that measures current running through the conductor to test a battery.

18. A battery tester with a current clamp, comprising:
a clamp that defines a clamp opening and that has an opening end that opens to receive a conductor coupled to a battery terminal and closes so the conductor runs through the clamp opening;
a testing device that measures current running through the conductor; and
a closure sensing component that senses whether the clamp is open and that provides a user-observable closure status indicator indicative of the clamp being open.

19. The battery tester of claim 18 wherein the clamp has a pair of jaws that have ends that are separated from one another to open the clamp and in contact with one another to close the clamp and wherein the closure sensing component comprises a sensor configured to sense whether the ends of the jaws are in contact with one another.

20. A current clamp, comprising:
a clamp that defines a clamp opening and that has an opening end that opens to receive a conductor and closes so the conductor runs through the clamp opening, wherein the clamp has a pair of jaws that have ends that are separated from one another to open the clamp and in contact with one another to close the clamp;
a testing device that measures current running through the conductor; and
a closure sensing component that senses whether the clamp is open and that provides a user-observable closure status indicator indicative of the clamp being open, the closure sensing component comprising a sensor configured to sense whether the ends of the jaws are in contact with one another.