JP2013019712A - Specific heat measurement device and specific heat measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly and accurately measure the specific heat of a measurement sample without correcting the thermal capacity of a holding unit which holds the measurement sample in heat insulation type specific heat measurement.SOLUTION: There is provided a specific heat measurement method including: a first step of storing a first holding unit 1 which holds a measurement sample as an object of specific heat measurement and a second holding unit 2 which has the same thermal capacity therewith in a storage space enclosed with a heat insulation wall 3; a second step of changing the storage space into a heat insulation state; and a third step of inputting a predetermined quantity of heat to the measurement sample 8 while holding the storage space in the heat insulation state, and supplying the same quantity of heat to both the holding units so that no temperature difference is generated between the temperature in the first holding unit 1 and the temperature in the second holding unit 2 as a result of the input of the quantity of heat. In the third step, a change quantity of the temperature in the first holding unit generated when the predetermined quantity of heat is input to the measurement sample 8 is found, and the specific heat of the measurement sample 8 is calculated on the basis of the change quantity of the temperature.

Description

  The present invention relates to a specific heat measuring apparatus and a specific heat measuring method for measuring specific heat of a measurement sample.

  In recent years, development of hybrid vehicles and electric vehicles has become an urgent task in the automobile industry as a representative theme of green technology. An in-vehicle lithium ion battery, which is a main part of this type of automobile, has a high energy density and holds a large amount of energy inside the battery. One of the evaluation items for the thermal safety of a lithium ion battery for vehicle use is the specific heat of the battery.

  As the specific heat measuring device, an adiabatic specific heat measuring device and a dropping (falling) specific heat measuring device are known (see, for example, Patent Documents 1 and 2). The adiabatic specific heat measuring device measures a temperature change when a known amount of heat (Joule heat) is input to a measurement sample in an adiabatic state, and measures the specific heat of the measurement sample based on the measurement result.

  The drop-type specific heat measuring device includes an upper storage portion and a lower storage portion. The measurement sample is placed in the upper storage. The lower storage portion is filled with water at a specified temperature. In the actual specific heat measurement, the measurement sample placed in the upper storage part is poured (dropped) into the water in the lower storage part. At this time, the measurement sample is poured into water in a state where the temperature of the measurement sample is higher than the temperature of the water in the lower housing. Then, the heat of the measurement sample is received and the temperature of the water rises. Therefore, the specific heat of the measurement sample is measured from the temperature rise of the water at that time.

JP 2002-156345 A JP 2003-287510 A

By the way, in the adiabatic specific heat measuring device, the following two types of adiabatic control (1) and (2) are required.
(1) The temperature of the measurement sample and the holding unit (such as a container for storing the sample) that holds the sample is controlled to be the same as the temperature of the inner wall of the electric furnace.
(2) Adiabatic temperature control is performed so that there is no heat balance between the measured sample temperature and the holding unit temperature.
Regarding the heat insulation control of (2), when the temperature of the measurement sample itself rises due to an internal heater or a self-heating reaction, it is inevitable that the heat moves to the holding unit in direct contact with the measurement sample. That is, the heat cannot be kept from being dissipated from the measurement sample. Therefore, in the conventional adiabatic specific heat measurement method, assuming that the heat capacity of the holding unit is known on the assumption that heat is dissipated from the measurement sample to the holding unit, the measurement sample obtained after the measurement and the holding unit The specific heat of the holding unit is corrected from the total value of the Joule heat to obtain the specific heat of the unknown measurement sample. That is, for the specific heat value obtained by the specific heat measurement, it is necessary to always correct the heat capacity of the holding unit.

  The main object of the present invention is to provide a technique capable of directly and accurately measuring the specific heat of a measurement sample without correcting the heat capacity of a holding unit that holds the measurement sample in adiabatic specific heat measurement. It is in.

The first aspect of the present invention is:
A first holding unit for holding a measurement sample to be measured for specific heat;
A substantially empty second holding unit that has the same heat capacity as the first holding unit and does not hold the measurement sample;
A heat insulating wall forming an accommodation space for accommodating the first holding unit and the second holding unit;
A first temperature sensor for measuring a temperature in the first holding unit for holding the measurement sample;
A second temperature sensor that measures the temperature in the second holding unit that does not hold the measurement sample;
A third temperature sensor for measuring the temperature of the heat insulating wall;
A sample heater for heating the measurement sample held in the first holding unit;
A first heater for heating the first holding unit;
A second heater for heating the second holding unit;
A third heater for heating the heat insulation wall;
First temperature control means for controlling the driving of the third heater based on the measurement results of the first temperature sensor, the second temperature sensor, and the third temperature sensor;
Second temperature control means for controlling the driving of the first heater and the second heater based on the measurement results of the first temperature sensor and the second temperature sensor;
And calculating means for calculating specific heat of the measurement sample by calculation,
The first temperature control means includes a heat transfer between the first holding unit and the heat insulating wall and a heat transfer between the second holding unit and the heat insulating wall in the housing space formed by the heat insulating wall. Controlling the drive of the third heater so as to maintain a heat insulation state without
The second temperature control means is configured to input the prescribed amount of heat to the measurement sample by driving the sample heater in a state where the accommodation space is maintained in the heat insulating state. The same current is supplied to both the first heater and the second heater so that there is no temperature difference between the temperature measured by the sensor and the temperature measured by the second temperature sensor. ,
When the specified heat amount is input to the measurement sample in a state in which the accommodation space is maintained in the heat insulating state, the calculation means is configured to input the first temperature sensor based on a measurement result of the first temperature sensor. A specific heat measurement apparatus characterized in that a temperature change amount in a holding unit is obtained, and a specific heat of the measurement sample is calculated based on the temperature change amount.

The second aspect of the present invention is:
Connecting the first heater and the second heater in series;
The said 2nd temperature control means has a current circuit which supplies an electric current to the said 1st heater connected in series and the said 2nd heater, The said 1st aspect characterized by the above-mentioned. It is a specific heat measuring device.

The third aspect of the present invention is:
The measurement sample is a plate-like structure,
The first holding unit has a pair of holding members that hold the measurement sample in a sandwich shape,
The second heat retention unit according to the first or second aspect, wherein the second holding unit has a pair of holding members made of the same structure as the pair of holding members.

The fourth aspect of the present invention is:
The measurement sample is a lithium ion battery laminated with a film,
The second holding unit is a specific heat measuring apparatus according to the third aspect, wherein a film made of the same structure as the film is held as an empty sample.

According to a fifth aspect of the present invention,
A first holding unit that holds a measurement sample to be subjected to specific heat measurement, and a substantially empty second holding unit that has the same heat capacity as the first holding unit and does not hold the measurement sample. A first step of housing the in a housing space surrounded by a heat insulating wall;
After the first step, the housing space is changed to a heat insulating state in which there is no heat transfer between the first holding unit and the heat insulating wall and heat transfer between the second holding unit and the heat insulating wall. Two steps,
After the second step, a predetermined amount of heat is input to the measurement sample while maintaining the accommodation space in the heat insulating state, and the temperature in the first holding unit and the first amount are input by inputting the predetermined amount of heat. A third step of supplying the same amount of heat to both the first holding unit and the second holding unit so as not to cause a temperature difference with the temperature in the two holding units;
In the third step, obtaining a temperature change amount in the first holding unit that occurs when the prescribed heat amount is input to the measurement sample, and calculating a specific heat of the measurement sample based on the temperature change amount. This is a specific heat measurement method.

  According to the present invention, in the adiabatic specific heat measurement, it is possible to directly and accurately measure the specific heat of the measurement sample without correcting the heat capacity of the holding unit that holds the measurement sample.

It is the schematic which shows the structural example of the specific heat measuring apparatus which concerns on embodiment of this invention. It is a flowchart which shows an example of the procedure of the specific heat measuring method which concerns on embodiment of this invention. It is a figure which shows the temperature change in a 1st holding unit, and the temperature change in a 2nd holding unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the embodiment of the present invention, description will be given in the following order.
1. 1. Configuration of specific heat measuring device 2. Specific heat measurement method Effects of the embodiment 4. Modifications etc.

<1. Configuration of specific heat measuring device>
FIG. 1 is a schematic diagram showing a configuration example of a specific heat measuring apparatus according to an embodiment of the present invention. First, in the embodiment of the present invention, a lithium ion battery is assumed as an example of a measurement sample to be subjected to specific heat measurement. Further, among lithium ion batteries for various uses, a laminate type lithium ion battery mounted on a hybrid vehicle, an electric vehicle, or the like is used as a measurement sample. This measurement sample has a flat plate-like structure having a rectangular shape in plan view. To illustrate the size of the measurement sample, the planar dimension is about A4 size (297 mm × 210 mm) and the thickness dimension (plate thickness) is about 10 mm.

  The illustrated specific heat measuring apparatus 100 includes a first holding unit 1, a second holding unit 2, a heat insulating wall 3, a heater driving unit 4, and a first temperature in order to realize the specific heat measurement of the measurement sample described above. A control unit 5, a second temperature control unit 6, and a signal processing unit 7 are provided.

(First holding unit)
The 1st holding | maintenance unit 1 hold | maintains the measurement sample 8 which has the above-mentioned structure. The first holding unit 1 has a pair of holding members 11a and 11b. The pair of holding members 11a and 11b hold the measurement sample 8 in a sandwich shape. Heaters 14a and 14b are built in the pair of holding members 11a and 11b, respectively. The holding member 11a has a structure in which, for example, a film heater (planar heating element) constituting the heater 14a is sandwiched between two thin aluminum plates, and these are integrated by bonding or the like. The thickness of the aluminum plate constituting the holding member 11a is, for example, about 1 to 2 mm. The planar size of the holding member 11 a is at least equivalent to the planar size of the measurement sample 8. The same applies to the holding member 11b. The heaters 14 a and 14 b correspond to “first heaters” that heat the first holding unit 1.

  The first holding unit 1 is provided with a sample heater 12 and a temperature sensor 13. The sample heater 12 heats the measurement sample 8 held by the first holding unit 1. The sample heater 12 is configured using, for example, a film heater. The sample heater 12 has a heating surface having the same size as the planar size of the measurement sample 8 or a larger size.

  The temperature sensor 13 corresponds to a “first temperature sensor” that measures the temperature in the first holding unit 1 that holds the measurement sample 8, and more specifically, between the pair of holding members 11a and 11b. The temperature of the measurement sample 8 held between the two is measured. The temperature sensor 13 is a temperature sensor using a thermocouple, for example. When the measurement sample 8 is set in the first holding unit 1, the temperature sensor 13 is disposed between the sample heater 12 and the holding member 11 b so as to be in thermal (physical) contact with the measurement sample 8. Yes.

(Second holding unit)
The second holding unit 2 has the same heat capacity as the first holding unit 1 described above, including the heater attached thereto. Specifically, the 2nd holding unit 2 has a pair of holding members 16a and 16b which consist of the same structure as a pair of holding members 11a and 11b mentioned above. That is, the second holding unit 2 has substantially the same configuration as the first holding unit 1. However, the second holding unit 2 is substantially empty and does not hold the measurement sample 8. For this reason, when the measurement sample 8 is held in the first holding unit 1, the first holding unit 1 has a larger heat capacity than the second holding unit 2 by the heat capacity of the measurement sample 8. Heaters 19a and 19b are built in the pair of holding members 16a and 16b, respectively.

  The second holding unit 2 is provided with a dummy heater (hereinafter referred to as “dummy heater”) 17 and a temperature sensor 18. The dummy heater 17 has the same structure (shape and size) as the sample heater described above. The temperature sensor 18 corresponds to a “second temperature sensor” that measures the temperature in the second holding unit 2 that does not hold the measurement sample 8, and more specifically, between the pair of holding members 16a and 16b. The temperature of the empty sample 10 held between the two is measured.

  The empty sample 10 is interposed between the dummy heater 17 and the holding member 16b. The empty sample 10 is composed of an aluminum laminate film used for sealing a lithium ion battery to be the measurement sample 8. The reason for providing the empty sample 10 in the second holding unit 2 in this way is to measure the specific heat of the lithium ion battery itself excluding the laminate film portion. However, when the specific heat of the measurement sample 8 including the laminate film portion is measured, or when the influence of the heat capacity of the laminate film is so small as to be negligible when measuring the specific heat of the lithium ion battery, the second holding unit 2 It is not necessary to provide the empty sample 10 inside.

  The temperature sensor 18 is, for example, a temperature sensor using a thermocouple, similar to the temperature sensor 13 described above. The temperature sensor 18 is disposed between the dummy heater 17 and the holding member 16b while being in thermal contact with the empty sample 10.

  In the present embodiment, the plate-like structure is used as the measurement sample 8, and accordingly, the first holding unit 1 and the second holding unit 2 are also entirely plate-like unit structures. Yes.

(Insulated wall)
The heat insulating wall 3 forms an accommodation space for accommodating the first holding unit 1 and the second holding unit 2. The heat insulating wall 3 has a housing structure corresponding to the shape and size of the first holding unit 1 and the second holding unit 2. Incidentally, in FIG. 1, the cross section of the heat insulating wall 3 is represented by a shape close to a square in order to clearly show each component part in an easy-to-understand manner. However, actually, since the first holding unit 1 and the second holding unit 2 are plate-like, the size of the heat insulating wall 3 in the left-right direction is sufficiently smaller than the size in the vertical direction (flat housing structure) )It has become.

  The heat insulating wall 3 is formed using a heat insulating material such as rock wool, for example. Inside the heat insulating wall 3 (or the inner surface), temperature sensors 20a, 20b and heaters 21a, 21b for heat insulation control are provided. The temperature sensors 20 a and 20 b correspond to “third temperature sensors” that measure the temperature of the heat insulating wall 3. The temperature sensor 20a is disposed on a part of the heat insulating wall 3 facing (facing) the first holding unit 1. The temperature sensor 20b is disposed on a part of the heat insulating wall 3 facing (facing) the second holding unit 2.

  The heaters 21 a and 21 b correspond to a “third heater” that heats the heat insulating wall 3. The heater 21a is disposed so as to include at least the wall surface of the heat insulating wall 3 facing the first holding unit 1 as a heating target. The heater 21b is arranged to include at least the wall surface of the heat insulating wall 3 facing the second holding unit 2 as a heating target.

(Heater drive unit)
The heater driving unit 4 drives the sample heater 12 according to predetermined conditions. The heater driving unit 4 is configured using a constant current circuit 22. The constant current circuit 22 supplies a constant current to the sample heater 12. When the constant current circuit 22 supplies a current to the sample heater 12, the sample heater 12 generates heat in response to the current.

(First temperature control unit)
The first temperature control unit 5 corresponds to “first temperature control means” that controls the driving of the heaters 21a and 21b based on the measurement results of the temperature sensor 13, the temperature sensor 18, and the temperature sensors 20a and 20b. Is. The temperature sensor 13 outputs a measurement signal S1 serving as temperature measurement data. The temperature sensor 18 outputs a measurement signal S2 serving as temperature measurement data. The temperature sensor 20a outputs a measurement signal S3 serving as temperature measurement data, and the temperature sensor 20b outputs a measurement signal S4 serving as temperature measurement data.

  The first temperature control unit 5 includes a temperature difference detection circuit 23 that detects temperature differences ΔT1 and ΔT2, which will be described later, and a control circuit 24 that performs current control based on the temperature differences ΔT1 and ΔT2 detected by the temperature difference detection circuit 23. And a current circuit 25 that supplies current to the heaters 21a and 21b in accordance with a control command from the control circuit 24.

  The temperature difference detection circuit 23 uses the measurement signal S2 corresponding to the temperature Tr measured using the temperature sensor 18, the measurement signal S3 corresponding to the temperature Tout1 measured using the temperature sensor 20a, and the temperature sensor 20b. The measurement signal S4 corresponding to the measured temperature Tout2 is used as an input signal. The temperature difference detection circuit 23 outputs a temperature difference detection signal S5 based on the temperature difference ΔT1 between the temperature Tr and the temperature Tout1, and outputs a temperature difference detection signal S6 based on the temperature difference ΔT2 between the temperature Tr and the temperature Tout2. To do.

  The control circuit 24 receives the temperature difference detection signal S5 given from the temperature difference detection circuit 23 as an input signal and generates a control signal S7 corresponding to this input signal, while the temperature difference detection signal S6 given from the temperature difference detection circuit 23. Is an input signal, and a control signal S8 corresponding to this input signal is generated. The current circuit 25 supplies current to the heater 21a based on the control signal S7 given from the control circuit 24, and supplies current to the heater 21b based on the control signal S8 given from the control circuit 24.

(Second temperature control unit)
The second temperature control unit 6 corresponds to “second temperature control means” that controls the driving of the heaters 14 a and 14 b and the heaters 19 a and 19 b based on the measurement results of the temperature sensor 13 and the temperature sensor 18. It is. The first temperature control unit 5 includes a temperature difference detection circuit 27 that detects a temperature difference ΔT0 described later, a control circuit 28 that performs current control based on the temperature difference ΔT0 detected by the temperature difference detection circuit 27, and the current In accordance with a control command from the circuit 28, the heaters 14a and 14b and the current circuit 29 for supplying current to the heaters 19a and 19b are used.

  The temperature difference detection circuit 27 receives the measurement signal S1 corresponding to the temperature Ts measured using the temperature sensor 13 and the measurement signal S2 corresponding to the temperature Tr measured using the temperature sensor 18 as input. A temperature difference detection signal S9 based on the temperature difference ΔT0 is output. The control circuit 28 uses the temperature difference detection signal S9 given from the temperature difference detection circuit 27 as an input signal, and generates a control signal S10 corresponding to this input signal. The current circuit 29 supplies the same current to the heaters 14a and 14b and the heaters 19a and 19b, respectively, based on the control signal S10 supplied from the control circuit 28.

(Signal processing part)
The signal processing unit 7 receives the measurement signal S1 corresponding to the temperature Ts measured using the temperature sensor 13 described above, and uses this input signal to perform various processes (including arithmetic processing) related to specific heat measurement. Is what you do. Specific processing contents will be described later.

<2. Specific heat measurement method>
Subsequently, the specific heat measurement method according to the embodiment of the present invention will be described. This specific heat measurement method is performed using the specific heat measurement apparatus 100 described above.

  FIG. 2 is a flowchart showing an example of the procedure of the specific heat measurement method according to the embodiment of the present invention. First, a measurement sample 8 to be subjected to specific heat measurement is prepared, and the measurement sample 8 is set in the first holding unit 1 (step St1). Here, as an example, it is assumed that the heat capacity of the measurement sample 8 is 600 (J: Joule), the mass of the laminate film (empty sample 10) is 10 g, and the mass of the measurement sample 8 (excluding the mass of the laminate film) is 200 g. . The mass of the laminate film and the measurement sample 8 can be handled as known information by measuring in advance using a mass meter (not shown). Here, it is assumed that measurement data obtained by measuring the mass of the measurement sample 8 is stored in advance in a storage means (such as a RAM) as electronic data. The storage means is one of the functions provided in the signal processing unit 7.

Next, in a state where the first holding unit 1 and the second holding unit 2 are housed in the housing space formed by the heat insulating wall 3, the housing space is changed to a heat insulating state (step St2). The “adiabatic state” described here refers to a state that satisfies the following four requirements.
(1) The temperature of the first holding unit 1 (including the measurement sample 8) and the temperature of the second holding unit 2 are the same.
(2) There is no heat transfer between the first holding unit 1 and the second holding unit 2.
(3) There is no heat transfer between the first holding unit 1 and the heat insulating wall 3.
(4) There is no heat transfer between the second holding unit 2 and the heat insulating wall 3.
In short, there is no heat balance between the measured sample temperature and the holding unit temperature.

  The heat insulation state of the accommodation space described above is maintained until the temperature rise of the measurement sample 8 due to the input of the heat amount described later stops. As the heat insulation control for that purpose, the first temperature control unit 5 performs the following processing. That is, the temperature difference detection circuit 23 takes in the measurement signals S2, S3, S4 of the temperature sensor 18 and the temperature sensors 20a, 20b at predetermined time intervals. The temperature difference detection circuit 23 indicates the temperature Tr indicated by the measurement signal S2 output from the temperature sensor 18 and the measurement signal S3 output from the temperature sensor 20a every time the measurement signals S2, S3, S4 are captured. A temperature difference ΔT1 from the temperature Tout1 is detected. The temperature difference detection circuit 23 detects a temperature difference ΔT2 between the temperature Tr indicated by the measurement signal S2 output from the temperature sensor 18 and the temperature Tout2 indicated by the measurement signal S4 output from the temperature sensor 20b.

  In contrast, when the temperature difference ΔT1 detected by the temperature difference detection circuit 23 is equal to or greater than a predetermined threshold Sh1, the control circuit 24 sends a control signal S7 to turn on the heater 21a to the current circuit 25. If the temperature difference ΔT1 is less than the threshold value Sh1, a control signal S7 for turning off the heater 21a is sent to the current circuit 25. Similarly, when the temperature difference ΔT2 detected by the temperature difference detection circuit 23 is equal to or greater than a predetermined threshold Sh2, the control circuit 24 sends a control signal S8 to turn on the heater 21b to the current circuit 25, When the temperature difference ΔT2 is less than the threshold value Sh2, a control signal S8 for turning off the heater 21b is sent to the current circuit 25.

  Thereby, the current circuit 25 supplies a current to the heater 21a only when the temperature difference ΔT1 becomes equal to or greater than the threshold value Sh1. The current circuit 25 supplies current to the heater 21b only when the temperature difference ΔT2 becomes equal to or greater than the threshold value Sh2. For this reason, the drive of the heater 21a is controlled so that a temperature difference (heat transfer) does not occur between the first holding unit 1 and the heat insulating wall 3. Similarly, the drive of the heater 21b is controlled so that a temperature difference (heat transfer) does not occur between the second holding unit 2 and the heat insulating wall 3. Basically, the same value can be applied to the threshold value Sh1 and the threshold value Sh2.

  Next, the temperature Ts of the measurement sample 8 set in the first holding unit 1 is measured under the above-described heat insulation state (step St3). The temperature of the measurement sample 8 is measured using the temperature sensor 13. Specifically, the signal processing unit 7 takes in the measurement signal S1 output from the temperature sensor 13, and stores the electronic data of the temperature Ts indicated by the measurement signal S1 in the storage unit of the signal processing unit 7 itself.

  Next, the measurement sample 8 is heated by passing a current from the constant current circuit 22 to the sample heater 12 (step St4). The timing at which current flows through the sample heater 12 is the timing after the above-described heat insulation state is stabilized. Further, in order to handle the amount of heat input to the measurement sample 8 as known information (Q), a predetermined amount of current is passed through the sample heater 12. For example, power of 2.00 (W: watt) is supplied to the sample heater 12 for a predetermined time. Then, due to the heat generated by the sample heater 12, the temperature of the measurement sample 8 rises at a rate of 0.01 ° C. per 3 seconds, for example. By the way, in the present embodiment, it is assumed that the amount of heat (Q = 120 J) is input with a power of 2 W for a total of 60 seconds by supplying a current to the sample heater 12. The amount of heat Q input in step St4 corresponds to the “specified amount of heat”. This amount of heat Q may be stored in the storage means of the signal processing unit 7 before a calculation process (described later) for obtaining specific heat.

  The heat generated by the sample heater 12 is applied to the measurement sample 8 held in the first holding unit 1. However, when the sample heater 12 is simply heated, the amount of heat Q input to the measurement sample 8 is diffused not only to the measurement sample 8 but also to unit constituent members (holding members 11a, 11b, etc.) in the vicinity thereof. Is consumed. Then, the specific heat of the measurement sample 8 cannot be accurately measured due to the diffusion of heat to the unit constituent members. Therefore, in the present embodiment, the following temperature control process is adopted.

  First, the temperature difference detection circuit 27 measures the temperature Ts of the measurement sample 8 using the temperature sensor 13 at a predetermined time interval, and measures the temperature Tr of the empty sample 10 using the temperature sensor 18 ( Step St5). At this time, the temperature difference detection circuit 27 detects the temperature difference ΔT0 between the temperatures Ts and Tr measured using the temperature sensors 13 and 18, and outputs the detection result to the control circuit 28 as a temperature difference detection signal S9.

  Then, the control circuit 28 determines whether or not there is a temperature difference depending on whether or not the temperature difference ΔT0 detected by the temperature difference detection circuit 27 is equal to or greater than a predetermined threshold value Sh3 (step St6). At this time, when the control circuit 28 determines that the temperature difference is “present” (when the temperature difference ΔT is greater than or equal to the threshold value Sh3), the control circuit 28 outputs a control signal S10 for turning on the heaters 14a and 14b and the heaters 19a and 19b. When the temperature difference is determined to be “none” (when the temperature difference ΔT is less than the threshold value Sh3), a control signal S10 for turning off the heaters 14a and 14b and the heaters 19a and 19b is sent to the current circuit 25. To send. In contrast, when the control circuit 28 determines that there is a temperature difference, the current circuit 29 supplies the same current to the heaters 14a and 14b and the heaters 19a and 19b, respectively (step St7). Thereafter, the processes of steps St6 and St7 are repeated until the temperature difference ΔT0 becomes substantially zero (the condition of ΔT0 <Sh3 is satisfied).

  Thus, the current circuit 29 supplies the same current to the heaters 14a and 14b and the heaters 19a and 19b only when the temperature difference ΔT detected by the temperature difference detection circuit 27 is equal to or greater than the threshold value Sh3. For this reason, the temperature of the measurement sample 8 in the first holding unit 1 rises due to the heating of the measurement sample 8 in step St3 (input of the amount of heat), and the threshold temperature Sh3 is added to the measurement temperatures Ts, Tr of the temperature sensors 13, 18. When the above temperature difference ΔT0 occurs, the same current is supplied continuously or intermittently (intermittently) to the heaters 14a, 14b and the heaters 19a, 19b each time.

  When the same current is supplied to the heaters 14a and 14b and the heaters 19a and 19b in this way, the same amount of heat is given to the first holding unit 1 and the second holding unit 2, respectively. For this reason, both the temperature in the 1st holding | maintenance unit 1 and the temperature in the 2nd holding | maintenance unit 2 rise. However, the measurement sample 8 is set in the first holding unit 1, and the empty sample 10 is set in the second holding unit 2. For this reason, the heat capacity of the entire second holding unit 2 is smaller than the heat capacity of the entire first holding unit 1 by the heat capacity of the measurement sample 8.

  Therefore, when the same amount of heat is applied to the first holding unit 1 and the second holding unit 2, the second holding unit 2 has a higher rate of temperature rise than the first holding unit 1. For this reason, the temperature Ts of the measurement sample 8 rises due to the heating of the measurement sample 8 in step St3 (input of a prescribed amount of heat), and thereby the temperature Ts, Tr of each of the temperature sensors 13, 18 exceeds the threshold value Sh3. Even if the difference ΔT0 occurs, the temperature Tr catches up with the temperature Ts by supplying the same current to the heaters 14a and 14b and the heaters 19a and 19b. As a result, the temperature Ts of the measurement sample 8 in the first holding unit 1 and the temperature Tr of the empty sample 10 in the second holding unit 2 change in the same manner. This will be described in detail later.

  Note that the above-described temperature difference ΔT0 is set to a slight difference that is substantially close to zero by setting the threshold value Sh3 to be compared with this to a very small value. Therefore, the second temperature control unit 6 uses the heaters 14a and 14b so that a substantial temperature difference ΔT0 does not occur between the temperature Ts measured by the temperature sensor 13 and the temperature Tr measured by the temperature sensor 18. In addition, a temperature control process for supplying the same current to both the heaters 19a and 19b is performed.

  Thereafter, in step St6, the control circuit 28 determines that the temperature difference is “none”, and if this state continues for a predetermined time (determined as Yes in step St8), the temperature Ts of the measurement sample 8 at that stage. Is measured (step St9). Specifically, as in step St3, the signal processing unit 7 takes in the measurement signal S1 output from the temperature sensor 13, and stores the electronic data of the temperature Ts indicated by the measurement signal S1 in the signal processing unit 7 itself. Store in the means.

  Next, the signal processing unit 7 calculates the specific heat of the measurement sample 8 using the electronic data of the two measurement temperatures Ts stored in the storage unit in Steps St3 and St9 (Step St10). Here, for convenience of explanation, the temperature Ts of the measurement sample 8 measured in step St3 is defined as a first sample temperature Ts1, and the temperature Ts of the measurement sample 8 measured in step St9 is defined as a second sample temperature Ts2. In such a case, the signal processing unit 7 obtains a temperature difference ΔTs between the second sample temperature Ts2 and the first sample temperature Ts1 by calculation. This temperature difference ΔTs corresponds to a temperature change amount (temperature increase amount) in the first holding unit 1 accompanying the input of the heat quantity Q. Here, as an example, it is assumed that ΔTs = 0.2 ° C. is calculated. Then, the signal processing unit 7 calculates the specific heat (constant pressure specific heat) Cp of the measurement sample 8 based on the following equation (1).

Cp = Q / (ΔTs × m) (1)
Cp is the specific heat of the measurement sample (J / K · g)
Q is the amount of heat input to the measurement sample (J)
m is the mass of the measurement sample (g)

  Here, the numerical values of Q = 120J and m = 200 g stored in advance in the storage means of the signal processing unit 7 are substituted into the above equation (1), and ΔTs = 0.2 ° C. obtained by the above calculation is satisfied. When a numerical value is substituted, it is obtained as Cp = 3.0 (J / K · g).

  FIG. 3 is a diagram showing how the temperature in the first holding unit 1 and the temperature in the second holding unit 2 change when the specific heat measurement method according to the embodiment of the present invention is performed. It is. The temperature Ts in the figure is the temperature in the first holding unit 1 measured by the temperature sensor 13 and is substantially the temperature of the measurement sample 8. The temperature Tr is a temperature in the second holding unit 2 measured by the temperature sensor 18 and is substantially the temperature of the empty sample 10. In addition, timing t1 in the figure indicates the timing at which the input heat quantity Q is applied by the sample heater 12, and timing t2 indicates the timing at which the rise in the temperature Ts stops and the transition to the equilibrium state starts. A period Lt until t2 indicates a period during which the temperature Ts continues to rise (hereinafter referred to as “temperature rise period”).

  As can be seen from the figure, when a constant current is passed through the sample heater 12 in step St3, the temperature Ts starts to rise. During this temperature rise, the adiabatic state is maintained by supplying the current to the heaters 21a and 21b described above. Further, when a temperature difference ΔT0 occurs between the temperature Ts and the temperature Tr, the same current is supplied to the heaters 14a and 14b and the heaters 19a and 19b so as to be zero. For this reason, when the temperature Ts starts to rise, the temperature Tr also starts to rise following the temperature Ts.

  At this time, the amount of heat given to the first holding unit 1 by supplying current to the heaters 14 a and 14 b corresponds to the amount of heat loss due to the heat capacity of the portion excluding the measurement sample 8. This point will be described in detail below.

First, the total heat capacity of the first holding unit 1 is C1, the heat capacity of the measurement sample 8 is C2, and the heat capacity of the portion excluding the measurement sample 8 is C3. In such a case, the relationship between these heat capacities is as shown in the following equation (2).
C1 = C2 + C3 (2)

  If the heat capacity of the second holding unit 2 is C4, the heat capacity C4 is equal to the heat capacity C3 of the portion excluding the measurement sample 8 in the heat capacity C1 of the first holding unit 1.

  Further, as a form of temperature control in the heat insulating wall 3, when the temperature Ts rises with the input of the heat quantity Q, the heaters 14a and 14b are set such that the temperature difference ΔT0 between the temperature Ts and the temperature Tr becomes zero. When the same current is supplied to the heaters 19a and 19b, the heat loss due to the heat capacity C3 of the portion excluding the measurement sample 8 is compensated each time.

  Then, in the temperature rise period Lt, if the temperature Tr is raised so as to follow the rise in the temperature Ts accompanying the application of the input heat quantity Q, and the temperature difference ΔT0 is controlled to be eliminated, this temperature rise At the timing t2 when the period Lt ends, all the heat loss caused by the heat capacity c3 excluding the measurement sample 8 is compensated.

  For this reason, the temperature Ts2 when the rise in the temperature Ts stops and transitions to the equilibrium state is the measurement sample 8 excluding the heat capacity C3 of the heat capacity C1 of the first holding unit 1 other than the measurement sample 8. It corresponds to only the heat capacity C2. Therefore, the above-described temperature difference ΔTs between the second sample temperature Ts2 and the first sample temperature Ts1 is measured when the heat quantity Q generated by supplying the current to the sample heater 12 is input only to the measurement sample 8. It shows the temperature change of the sample 8 itself. Therefore, if this temperature difference ΔTs is substituted into the above equation (1), the specific heat of the measurement sample 8 can be accurately obtained.

<3. Effects of the embodiment>
According to the specific heat measuring apparatus and the specific heat measuring method according to the embodiment of the present invention, the following effects can be obtained.

  That is, when an object that needs to be held as the measurement sample 8 is used as a target for specific heat measurement, such as the large-sized lithium ion battery described above, the specific heat of the measurement sample 8 can be accurately measured. More specifically, when the measurement sample 8 to be subjected to the specific heat measurement is a plate-like structure and the measurement sample 8 is sandwiched and held between the pair of holding members 11a and 11b, the holding members 11a and 11a, The amount of temperature change of the measurement sample 8 accompanying the input of the prescribed heat quantity can be obtained while compensating for the heat loss caused by the heat capacity such as 11b. For this reason, in the adiabatic specific heat measurement, the specific heat of the measurement sample 8 can be directly and accurately measured without correcting the heat capacity of the first holding unit 1 holding the measurement sample 8.

  Further, when the measurement sample 8 to be measured for specific heat is a lithium ion battery laminated with a film, a film made of the same structure as this film is held in the second holding unit 2 as an empty sample 10. I have to. For this reason, when the measurement sample 8 is a lithium ion battery, the specific heat of the lithium ion battery itself is eliminated in the form of eliminating the influence of the heat capacity of the laminate film, compared to the case where the empty sample 10 is not provided in the second holding unit 2. Can be measured accurately.

<4. Modified example>
The technical scope of the present invention is not limited to the above-described embodiments, and various modifications and improvements may be added within the scope of deriving specific effects obtained by the constituent requirements of the invention and combinations thereof. Including.

  For example, in FIG. 1 described above, the current is individually supplied from the current circuit 29 to the heaters 14a and 14b and the heaters 19a and 19b. However, the present invention is not limited to this, and is as follows. Various configurations may be adopted. That is, although not shown, the heaters 14a and 14b and the heaters 19a and 19b are connected in series, and current is supplied from a common current circuit 29 to the heaters 14a and 14b and the heaters 19a and 19b connected in series. Also good. If this configuration is adopted, the same current can be supplied to the heaters 14a and 14b and the heaters 19a and 19b almost simultaneously with a simpler circuit configuration.

  Further, the measurement sample to be subjected to the specific heat measurement is not limited to the above-described lithium ion battery, and objects of various shapes and sizes can be used as the measurement sample. In addition, the respective configurations (shape, size, etc.) of the first holding unit, the second holding unit, and the heat insulating wall can be variously modified according to the shape, size, etc. of the measurement sample. For example, the first holding unit, the second holding unit, and the heat insulating wall may each be substantially cylindrical. In addition, an adiabatic rise temperature curve in a completely adiabatic state is obtained for a measurement sample that causes a self-heating reaction.

DESCRIPTION OF SYMBOLS 1 ... 1st holding unit 2 ... 2nd holding unit 3 ... Heat insulation wall 4 ... Heater drive part 5 ... 1st temperature control part 6 ... 2nd temperature control part 7 ... Signal processing part 8 ... Measurement sample 10 ... Empty sample 11a, 11b, 16a, 16b ... holding member 12 ... sample heater 13, 18, 20a, 20b ... temperature sensor 14a, 14b, 19a, 19b, 21a, 21b ... heater 17 ... dummy heater 22 ... constant current circuit 23, 27 ... Temperature difference detection circuit 24, 28 ... Control circuit 25, 29 ... Current circuit 100 ... Specific heat measuring device

Claims (5)

A first holding unit for holding a measurement sample to be measured for specific heat;
A substantially empty second holding unit that has the same heat capacity as the first holding unit and does not hold the measurement sample;
A heat insulating wall forming an accommodation space for accommodating the first holding unit and the second holding unit;
A first temperature sensor for measuring a temperature in the first holding unit for holding the measurement sample;
A second temperature sensor that measures the temperature in the second holding unit that does not hold the measurement sample;
A third temperature sensor for measuring the temperature of the heat insulating wall;
A sample heater for heating the measurement sample held in the first holding unit;
A first heater for heating the first holding unit;
A second heater for heating the second holding unit;
A third heater for heating the heat insulation wall;
First temperature control means for controlling the driving of the third heater based on the measurement results of the first temperature sensor, the second temperature sensor, and the third temperature sensor;
Second temperature control means for controlling the driving of the first heater and the second heater based on the measurement results of the first temperature sensor and the second temperature sensor;
And calculating means for calculating specific heat of the measurement sample by calculation,
The first temperature control means includes a heat transfer between the first holding unit and the heat insulating wall and a heat transfer between the second holding unit and the heat insulating wall in the housing space formed by the heat insulating wall. Controlling the drive of the third heater so as to maintain a heat insulation state without
The second temperature control means is configured to input the prescribed amount of heat to the measurement sample by driving the sample heater in a state where the accommodation space is maintained in the heat insulating state. The same current is supplied to both the first heater and the second heater so that there is no temperature difference between the temperature measured by the sensor and the temperature measured by the second temperature sensor. ,
When the specified heat amount is input to the measurement sample in a state in which the accommodation space is maintained in the heat insulating state, the calculation means is configured to input the first temperature sensor based on a measurement result of the first temperature sensor. A specific heat measuring device, wherein a temperature change amount in the holding unit is obtained, and a specific heat of the measurement sample is calculated based on the temperature change amount. Connecting the first heater and the second heater in series;
2. The specific heat measurement according to claim 1, wherein the second temperature control unit includes a current circuit that supplies current to the first heater and the second heater connected in series. apparatus. The measurement sample is a plate-like structure,
The first holding unit has a pair of holding members that hold the measurement sample in a sandwich shape,
The specific heat measuring apparatus according to claim 1, wherein the second holding unit has a pair of holding members made of the same structure as the pair of holding members. The measurement sample is a lithium ion battery laminated with a film,
The specific heat measuring apparatus according to claim 3, wherein the second holding unit holds a film made of the same structure as the film as an empty sample. A first holding unit that holds a measurement sample to be subjected to specific heat measurement, and a substantially empty second holding unit that has the same heat capacity as the first holding unit and does not hold the measurement sample. A first step of housing the in a housing space surrounded by a heat insulating wall;
After the first step, the housing space is changed to a heat insulating state in which there is no heat transfer between the first holding unit and the heat insulating wall and heat transfer between the second holding unit and the heat insulating wall. Two steps,
After the second step, a predetermined amount of heat is input to the measurement sample while maintaining the accommodation space in the heat insulating state, and the temperature in the first holding unit and the first amount are input by inputting the predetermined amount of heat. A third step of supplying the same amount of heat to both the first holding unit and the second holding unit so as not to cause a temperature difference with the temperature in the two holding units;
In the third step, obtaining a temperature change amount in the first holding unit that occurs when the prescribed heat amount is input to the measurement sample, and calculating a specific heat of the measurement sample based on the temperature change amount. Specific heat measurement method.

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