CN217007451U - Measuring interface access circuit - Google Patents
Measuring interface access circuit Download PDFInfo
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- CN217007451U CN217007451U CN202220305298.7U CN202220305298U CN217007451U CN 217007451 U CN217007451 U CN 217007451U CN 202220305298 U CN202220305298 U CN 202220305298U CN 217007451 U CN217007451 U CN 217007451U
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Abstract
The application relates to a measurement interface access circuit belongs to production automation technical field, and the circuit of this application includes: first to fifth switching devices; the normally open end of the fourth switching device is connected with the first test gear terminal of the measuring instrument, the measuring common terminal of the measuring instrument is connected with the common end of the fifth switching device, and the normally open end of the fifth switching device is connected with the normally closed end of the first switching device, the normally open end of the third switching device and the power supply positive end of the product to be measured; the common end of the fourth switching device is connected with the normally open end of the first switching device, the common end of the first switching device is connected with the common end of the second switching device, the normally open end of the second switching device is connected with the common end of the third switching device and the power supply positive end of the test power supply, and the power supply negative end of the test power supply is connected with the power supply negative end of the tested product; the control end of each switching element is connected with the trigger signal circuit. The technical scheme of the application helps to ensure the measurement accuracy in measurement.
Description
Technical Field
The application belongs to the technical field of production automation, and particularly relates to a measuring interface access circuit.
Background
In the production and manufacturing process of some products (such as automobile central control screens), the voltage, the current and the like of the products need to be measured accurately. Due to the implementation requirements of manufacturing automation, high-precision measuring instruments (such as program-controlled multimeters) are used, and the problem of how to connect the measuring instruments to the products to be measured is involved.
In the related technology of the automatic test industry, when a current test is performed on an electrified product (taking a program-controlled multimeter as an example here), a relay is generally directly used for switching the access of the program-controlled multimeter to the circuit, and in the implementation mode, an instant power failure (time for switching off and on of the relay) occurs to the product in the switching process. Under relevant scenes, if the requirement of a tested product on power supply is high, particularly when the sleep current of the product is tested by using a low-current gear of a program-controlled multimeter (for example, the sleep current of vehicle navigation is generally required to be below 1 mA), the situation of inaccurate test result is easy to occur; if a product to be tested has a large capacitance, when the relay is used for switching on power supply, the phenomenon of sparking on the contact of the relay can be generated, and the service life of the relay is influenced.
SUMMERY OF THE UTILITY MODEL
To overcome the problems in the related art at least to some extent, the present application provides a measurement interface access circuit to facilitate better access of a measurement instrument to a product under test.
In order to achieve the purpose, the following technical scheme is adopted in the application:
the application provides a measure interface and insert circuit, its setting is being surveyed between product, test power supply and measuring instrument, and this measure interface inserts the circuit and includes: a first switching device, a second switching device, a third switching device, a fourth switching device, and a fifth switching device;
the normally open end of the fourth switching device is connected with the first test gear terminal of the measuring instrument, the measuring common terminal of the measuring instrument is connected with the common end of the fifth switching device, and the normally open end of the fifth switching device is connected with the normally closed end of the first switching device, the normally open end of the third switching device and the power supply positive end of the product to be measured;
the common end of the fourth switching device is connected with the normally open end of the first switching device, the common end of the first switching device is connected with the common end of the second switching device, the normally open end of the second switching device is connected with the common end of the third switching device and the power supply positive end of the test power supply, and the power supply negative end of the test power supply is connected with the power supply negative end of the tested product;
the control end of each switch device is connected with an external trigger signal circuit, and each switch device acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit of the measuring instrument.
Optionally, the normally-closed end of the fourth switching device is connected with the second test gear terminal of the measuring instrument;
and each switching device acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit or the second current measuring circuit of the measuring instrument.
Optionally, a first NTC thermistor is further included;
the common terminal of the third switching device is connected with the normally-open terminal of the second switching device and the power supply positive terminal of the test power supply through the first NTC thermistor.
Optionally, a first fuse is also included;
the common terminal of the third switching device is connected with the normally open terminal of the second switching device and the power supply positive terminal of the test power supply in sequence after passing through the first NTC thermistor and the first fuse.
Optionally, the first fuse is a recoverable fuse.
Optionally, a second NTC thermistor is further included;
the normally-open end of the fourth switching device is connected with the first test gear terminal of the measuring instrument after passing through the second NTC thermistor.
Optionally, a sixth switching device is further included;
the common end of the sixth switching device is connected with the normally closed end of the fifth switching device, the normally closed end of the sixth switching device is connected with the power supply negative end of the tested product, the normally open end of the sixth switching device is connected with the output floating ground voltage negative end of the tested product, and the output floating ground voltage positive end of the tested product is connected with the voltage test terminal of the measuring instrument;
and the control end of the sixth switching element is connected with the trigger signal circuit, and each switching element acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit, the second current measuring circuit or the voltage measuring circuit of the measuring instrument.
Optionally, a third NTC thermistor is further included;
the common terminal of the sixth switching device is connected to the normally-closed terminal of the fifth switching device via a third NTC thermistor.
Optionally, each of the switching devices is a relay; the measuring instrument is a program-controlled universal meter.
This application adopts above technical scheme, possesses following beneficial effect at least:
according to the technical scheme, the plurality of controllable switching devices are adopted, the measuring interface access circuit arranged among the tested product, the testing power supply and the measuring instrument is formed based on specific connection, in practical application, each switching device in the circuit acts under the trigger of the trigger signal, the current measuring circuit of the measuring instrument can be seamlessly accessed, and the accuracy of current measurement in a scene is guaranteed.
Additional advantages, objects, and features of the utility model will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the utility model. The objectives and other advantages of the utility model will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the technology or prior art of the present application and are incorporated in and constitute a part of this specification. The drawings expressing the embodiments of the present application are used for explaining the technical solutions of the present application, and should not be construed as limiting the technical solutions of the present application.
FIG. 1 is a schematic circuit diagram of a measurement interface access circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present disclosure;
fig. 3 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present application;
fig. 4 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present application;
FIG. 5 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present disclosure;
FIG. 6 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present disclosure;
fig. 7 is a schematic circuit diagram of a measurement interface access circuit according to another embodiment of the present application.
In the figure, the position of the upper end of the main shaft,
10-the product to be tested; 20-a test power supply; 30-a measuring instrument; 40-a trigger signal circuit;
k101 — first switching device; k102 — second switching device; k103 — a third switching device; k104 — fourth switching device; k105 — a fifth switching device; k106 — sixth switching device;
RT1 — a first NTC thermistor; RT 2-second NTC thermistor; RT 3-third NTC thermistor; f1 — first fuse;
DM _ mA-first test gear terminal; DM _ A-a second test gear terminal; DM _ COM-measuring common terminal; DM _ V-voltage measurement terminal;
VIN + -a power supply positive terminal of the test power supply; VIN- -the negative supply terminal of the test power supply;
vout + -the positive supply terminal of the product under test; vout- -the negative supply terminal of the product under test; vtest + -outputs a floating ground voltage positive terminal; vtest-output floating ground voltage negative terminal.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail below. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without making any creative effort, shall fall within the protection scope of the present application.
As described in the background art, in the related art, when a current test is performed on a powered product (taking a program-controlled multimeter as an example here), a relay is generally directly used to switch the powered product into a circuit for accessing the program-controlled multimeter, and in this implementation manner, the product has an instantaneous power failure (time for turning off and on the relay) during the switching process. Under relevant scenes, if the requirement of a tested product on power supply is high, particularly when the sleep current of the product is tested by using a low-current gear of a program-controlled multimeter (for example, the sleep current of vehicle navigation is generally required to be below 1 mA), the situation of inaccurate test result is easy to occur; if a product to be tested has a large capacitance, when the relay is used for switching on power supply, the phenomenon of sparking on the contact of the relay can be generated, and the service life of the relay is influenced.
In view of the above, the present application provides a measurement interface access circuit, which facilitates better implementation of accessing a measurement instrument to a product under test.
Example one
As shown in fig. 1, in this embodiment, the measurement interface access circuit proposed by the present application is disposed between a product under test 10, a test power supply 20, and a measurement instrument 30, in this embodiment, the product under test is a vehicle-mounted central control screen, and the measurement instrument is a program-controlled multimeter;
as shown in fig. 1, the measurement interface access circuit includes: a first switching device K101, a second switching device K102, a third switching device K103, a fourth switching device K104, and a fifth switching device K105, for example, in this embodiment, each of the switching devices employs a relay (a relay having a coil voltage of 12V as shown in fig. 1);
the normally open end of the fourth switching device K104 is connected to a first test gear terminal DM _ mA of the measuring instrument (specifically, in this embodiment, a terminal of a low current gear of the program controlled multimeter), the measurement common terminal DM _ COM of the measuring instrument is connected to the common terminal of the fifth switching device K105, and the normally open end of the fifth switching device K105 is connected to the normally closed end of the first switching device K101, one end of the third switching device K103 (specifically, the end is the normally open end of K103), and the power supply positive terminal Vout + of the product to be measured;
the common end of the fourth switching device K104 is connected to the common end of the first switching device K101, the common end of the first switching device K101 is connected to the common end of the second switching device K102, the common end of the second switching device K102 is connected to the other end of the third switching device K103 (correspondingly, the common end of the second switching device K103 is the common end), and the power supply positive end VIN + of the test power supply, and the power supply negative end VIN-of the test power supply is connected to the power supply negative end Vout-of the tested product in common (it is easy to understand that, in the application scenario of the present application, the common end is connected to the ground GND in common);
the control end of each switch device is connected with an external trigger signal circuit 40, and each switch device acts under the trigger signal generated by the trigger signal circuit 40 to realize the access of the first current measuring circuit (i.e. the measuring circuit corresponding to the low current level of the program-controlled multimeter) of the measuring instrument 30.
In this embodiment, each switching device is a relay, and for this purpose, the trigger signal is a high-low level signal for operating the relay, and under the action of the high-low level signal, a contact of the relay is closed or opened, so as to realize the connection of the measurement interface.
Specifically, fig. 1 shows an initial state of the circuit, and in practical application, under the action of a corresponding trigger signal, each switching device in the circuit changes to an initial state > K103 pull-in ═ K102 pull-in ═ K105 pull-in ═ K101 pull-in ═ K104 pull-in ═ K103 open;
in the process, the K103 is attracted, the power supply positive terminal VIN + of the test power supply is communicated with the power supply positive terminal Vout + of the tested product, and the VIN-and the Vout-are connected to the GND in common, so that the power supply of the tested product is realized; then, K102 actuation, K105 actuation, K101 actuation, K104 actuation, and K103 disconnection are performed, so that a first current measurement circuit of the measurement instrument is serially connected to the power supply loop (the whole circuit node is VIN + - > K102 ═ K101 ═ K104 ═ DM _ mA ═ DM _ COM ═ K105 ═ Vout +), and in this connected state, the current can be further measured. By adopting the mode, the power supply of the product does not have the process of instantaneous power failure in the measurement process, and the accuracy of a test result is favorably ensured.
According to the technical scheme, the plurality of controllable switch devices are adopted, the measurement interface access circuit arranged among the tested product, the test power supply and the measurement instrument is formed based on specific connection, in practical application, each switch device in the circuit acts under the trigger of the trigger signal, the current measurement circuit of the measurement instrument can be seamlessly accessed, and the accuracy of current measurement in a scene is guaranteed.
Example two
As shown in fig. 2, on the basis of the first embodiment, in the measurement interface access circuit in this embodiment, the normally-closed terminal of the fourth switching device K104 is connected to the second test gear terminal DM _ a (in this embodiment, specifically, the terminal of the high-current gear of the program-controlled multimeter) of the measurement instrument;
each switch device acts under the trigger signal generated by the trigger signal circuit, and the access of a first current measuring circuit (namely a measuring circuit corresponding to a small current gear of the program-controlled multimeter) or a second current measuring circuit (namely a measuring circuit corresponding to a large current gear of the program-controlled multimeter) of the measuring instrument is realized.
Similar to the embodiment, in the implementation process of accessing the large current gear, under the action of the corresponding trigger signal, each switching device in the circuit is changed into: the initial state is greater than K103 pull-in, greater than K102 pull-in, greater than K105 pull-in, greater than K101 pull-in, greater than K103 off.
In addition, it is easy to understand that, based on the specific needs of a scene, there may be a case where a low-current gear is switched to a high-current gear, and at this time, on the basis of the low-current gear access implemented in the first embodiment, each switching device in the subsequent circuit is changed to: k103 pull-in > K104 off > K103 off.
EXAMPLE III
As shown in fig. 3, on the basis of the second embodiment, the measurement interface in this embodiment is connected to a circuit, which further includes a first NTC thermistor RT 1;
the common terminal of the third switching device K103 is connected to the normally-open terminal of the second switching device K102 and the positive power supply terminal VIN + of the test power supply through the first NTC thermistor RT 1.
The first NTC thermistor RT1 is a negative temperature coefficient thermistor, when K103 is attracted, in the process of supplying power to a tested product, the RT1 in the power supply loop has a resistance of dozens of ohms when being started, and the contact of K103 can not be ignited.
Example four
As shown in fig. 4, on the basis of the third embodiment, the measurement interface in this embodiment is connected to a circuit, and further includes a first fuse F1;
the common terminal of the third switching device K103 is connected to the normally-open terminal of the second switching device K102 and the positive power supply terminal VIN + of the test power supply in sequence through the first NTC thermistor RT1 and the first fuse F1.
The first fuse F1 is arranged, so that the current caused by direct short circuit (such as the defect of the tested product) of Vout + and Vout-can be prevented from being overlarge, and the situations of burning out the relay K103 or power supply equipment (such as a test power supply) and wires and the like are avoided.
As a specific embodiment, the first fuse F1 may be a recoverable fuse.
EXAMPLE five
As shown in fig. 5, on the basis of the fourth embodiment, the measurement interface in this embodiment is connected to a circuit, and further includes a second NTC thermistor RT 2;
the normally open end of the fourth switching device K104 is connected to the first test notch terminal DM _ mA of the measuring instrument via the second NTC thermistor RT 2.
The RT2 is set to prevent the situation that the small current gear of the program-controlled multimeter is burnt out due to excessive current (such as overranging) in an actual loop when the small current gear of the program-controlled multimeter is switched.
Example six
As shown in fig. 6, on the basis of the fifth embodiment, the measurement interface in this embodiment is connected to a circuit, and further includes a sixth switching device K106;
the common end of the sixth switching device K106 is connected with the normally-closed end of the fifth switching device K105, the normally-closed end of the sixth switching device K106 is connected with the power supply negative electrode terminal Vout-of the tested product in common (connected to the ground GND in common), the normally-open end of the sixth switching device K106 is connected with the output floating ground voltage negative electrode terminal Vtest-of the tested product, and the output floating ground voltage positive electrode terminal Vtest + of the tested product is connected with the voltage test terminal DM _ V of the measuring instrument;
the control end of the sixth switching device K106 is connected to the trigger signal circuit 40, and each switching device operates under the trigger signal generated by the trigger signal circuit to realize the connection of the first current measuring circuit, the second current measuring circuit, or the voltage measuring circuit of the measuring instrument.
In an application scenario of the application, the measurement requirements for the common-ground voltage and the negative-ground voltage of a product to be measured exist, when the common-ground voltage is measured, the circuit in the embodiment is adopted, and under the condition that K103 is closed (namely when the product is powered on), the program-controlled multimeter can measure the common-ground voltage output by the product end; when the floating ground voltage is measured, the circuit in the embodiment is adopted, under the condition of K103 pull-in, K106 pull-in is carried out, and the program-controlled universal meter can measure the floating ground voltage output by a product end.
The access of the first current measuring circuit and the second current measuring circuit has already been described in the first and second embodiments, and is not described here again.
EXAMPLE seven
As shown in fig. 7, on the basis of the sixth embodiment, the measurement interface in this embodiment is connected to a circuit, and further includes a third NTC thermistor RT 3;
the common terminal of the sixth switching device K106 is connected to the normally-closed terminal of the fifth switching device K105 via a third NTC thermistor RT 3.
In this embodiment, the RT3 is provided to prevent the occurrence of burning out a large current gear of the program control multimeter due to the failure of K105 to pull in during the current test.
Finally, briefly describing the trigger signal circuit in the technical solution of the present application, as shown in fig. 7, the coils of the switching devices are connected in parallel with freewheeling diodes (for releasing reverse potential voltage), the positive terminals of the coils are connected to 12V (12V _ B in the figure), and the negative terminals of the coils are used for inputting trigger levels (such as contK101, contK102, contK103 … … in fig. 7), which is easy to understand that the trigger levels may be generated by manual switches or by associated controllers (such as a single chip microcomputer). When the trigger level is low level (for example, the negative end of the coil is connected to the ground), the coil is electrified, and the corresponding normally open contact of the relay is attracted and the normally closed contact is disconnected; when the trigger level is high level (for example, the negative end of the coil is disconnected with the ground), the coil loses power, and the corresponding normally open contact of the relay is disconnected and the normally closed contact is attracted.
By adopting the technical scheme, the switching process during current measurement ensures that the tested product is not powered off, which is beneficial to ensuring the accuracy of measurement; and when a large capacitor is arranged on a tested product, the relay contact for supplying power to the product cannot be ignited, so that the service life of the relay is ensured, and the service life of the relay is the mechanical life.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. The utility model provides a measurement interface access circuit, sets up between by survey product, test power supply and measuring instrument, its characterized in that includes: a first switching device, a second switching device, a third switching device, a fourth switching device, and a fifth switching device;
the normally-open end of the fourth switching element is connected with a first test gear terminal of a measuring instrument, a measuring common terminal of the measuring instrument is connected with a common terminal of the fifth switching element, and the normally-open end of the fifth switching element is connected with the normally-closed end of the first switching element, the normally-open end of the third switching element and the power supply positive terminal of a measured product;
the common end of the fourth switch device is connected with the normally open end of the first switch device, the common end of the first switch device is connected with the common end of the second switch device, the normally open end of the second switch device is connected with the common end of the third switch device and the power supply positive end of the test power supply in a common mode, and the power supply negative end of the test power supply is connected with the power supply negative end of the tested product in a common mode;
the control end of each switch device is connected with an external trigger signal circuit, and each switch device acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit of the measuring instrument.
2. The measurement interface access circuit according to claim 1, wherein the normally-closed terminal of the fourth switching device is connected to the second test position terminal of the measurement instrument;
and each switching device acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit or the second current measuring circuit of the measuring instrument.
3. The measurement interface access circuit of claim 2, further comprising a first NTC thermistor;
the common terminal of the third switching device is connected with the normally-open terminal of the second switching device and the power supply positive terminal of the test power supply through the first NTC thermistor.
4. The measurement interface access circuit of claim 3, further comprising a first fuse;
the common terminal of the third switching device is connected with the normally open terminal of the second switching device and the power supply positive terminal of the test power supply after passing through the first NTC thermistor and the first fuse in sequence.
5. The measurement interface access circuit of claim 4, wherein the first fuse is a recoverable fuse.
6. The measurement interface access circuit of claim 4, further comprising a second NTC thermistor;
the normally-open end of the fourth switching device is connected with the first test gear terminal of the measuring instrument after passing through the second NTC thermistor.
7. The measurement interface access circuit of any of claims 1-6, further comprising a sixth switching device;
the common end of the sixth switching device is connected with the negative end of the output floating ground voltage of the tested product, and the positive end of the output floating ground voltage of the tested product is connected with the voltage test terminal of the measuring instrument;
and the control end of the sixth switching element is connected with the trigger signal circuit, and each switching element acts under the trigger signal generated by the trigger signal circuit to realize the access of the first current measuring circuit, the second current measuring circuit or the voltage measuring circuit of the measuring instrument.
8. The measurement interface access circuit of claim 7, further comprising a third NTC thermistor;
the common terminal of the sixth switching device is connected to the normally-closed terminal of the fifth switching device via a third NTC thermistor.
9. The measurement interface access circuit of claim 7, wherein each of the switching devices is a relay; the measuring instrument is a program-controlled multimeter.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202220305298.7U CN217007451U (en) | 2022-02-15 | 2022-02-15 | Measuring interface access circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202220305298.7U CN217007451U (en) | 2022-02-15 | 2022-02-15 | Measuring interface access circuit |
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| CN217007451U true CN217007451U (en) | 2022-07-19 |
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