JP2017167050A - Voltage detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect disconnection of a cell voltage detection wiring by reducing the number of samplings as compared with the conventional case. A plurality of discharge circuits B1 to B12 are respectively connected in parallel to a plurality of battery cells C1 to C12, and a plurality of transmission lines S1 to S13 that transmit terminal voltages of terminals of the plurality of battery cells C1 to C12. In a voltage detection device A including cell voltage detection units D1 to D12 that detect the cell voltages of a plurality of battery cells C1 to C12 by sampling the terminal voltages input from the transmission lines S1 to S13 in a predetermined cycle. , A pair of cell voltages related to the pair of battery cells C1 and C2 detected by the cell voltage detectors D1 and D2 when the discharge circuits B1 and B2 of the pair of adjacent battery cells C1 and C2 are discharged at different duty ratios. The disconnection of the transmission line S2 regarding the pair of battery cells C1 and C2 is determined based on whether or not V1 and V2 show opposite change tendencies in a plurality of samplings. Equipped with a microcomputer M. [Selection diagram] Figure 1

Description

  The present invention relates to a voltage detection device.

  The following Patent Document 1 includes a discharge circuit that includes a series circuit of a bypass resistor and a switching element and is connected in parallel to each of a plurality of battery cells that form a battery, and a voltage detection circuit that detects each voltage of the battery cells. And a control unit that controls each switching element so that the voltage of each battery cell becomes uniform based on the voltage detection result of each battery cell obtained from the voltage detection circuit, the control unit includes: The switching elements of the discharge circuit connected to the adjacent battery cells are controlled with different duty ratios, and the disconnection of the cell voltage detection wiring drawn from each terminal of each battery cell based on the potential difference between the adjacent battery cells A cell balance control device for detecting the above is disclosed.

JP 2013-085354 A

  The above-described prior art performs disconnection determination of each cell voltage detection wiring using the potential difference (differential pressure) between adjacent battery cells, and there is a problem that it takes time to determine disconnection of the cell voltage detection wiring. . That is, in the conventional technique, the determination threshold value must be set to 1 volt or more (for example, 1.3 V) because it is necessary to ensure the reliability of the disconnection determination, and the differential pressure exceeds the determination threshold value. In the meantime, it is necessary to sample the cell voltage of adjacent battery cells several tens of times.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to detect a disconnection of a cell voltage detection wiring by reducing the number of samplings compared to the conventional art.

  In order to achieve the above object, in the present invention, as a first solution means for a voltage detection device, a plurality of discharge circuits respectively connected in parallel to a plurality of battery cells, and a terminal of each terminal of the plurality of battery cells A voltage detection apparatus comprising: a plurality of transmission lines that transmit voltages; and a cell voltage detection unit that detects cell voltages of the plurality of battery cells by sampling the terminal voltage input from the transmission lines at a predetermined period. When the discharge circuits of a pair of adjacent battery cells are discharged at different duty ratios, the pair of cell voltages related to the pair of battery cells detected by the cell voltage detector are reversed over a plurality of samplings. A means is provided that includes a disconnection determination unit that determines disconnection of the transmission line related to the pair of battery cells based on whether or not a change tendency is exhibited.

  In the present invention, as a second solving means relating to the voltage detecting device, in the first solving means, the disconnection determining unit may determine whether the pair of cell voltages have a reverse change tendency in a plurality of consecutive samplings. Based on the above, a means for determining disconnection of the transmission line with respect to the pair of battery cells is adopted.

  In the present invention, as a third solving means relating to the voltage detection device, in the first or second solving means, a charge balance adjusting unit that adjusts a charging balance of the plurality of battery cells by controlling the discharge circuit. The means of further comprising is adopted.

 According to the present invention, when a discharge circuit of a pair of adjacent battery cells is in a discharge state with a different duty ratio, a pair of cell voltages related to a pair of battery cells detected by the cell voltage detection unit is over a plurality of samplings. Since the disconnection of the transmission line related to a pair of battery cells is determined based on whether or not it shows a reverse change tendency, the number of samplings is reduced as compared to the conventional case, that is, the transmission line (cell voltage detection wiring) is earlier than the conventional one. Disconnection can be detected.

It is a circuit diagram which shows the structure of the cell balance control apparatus A which concerns on one Embodiment of this invention. It is a timing chart which shows the whole operation | movement of the cell balance control apparatus A which concerns on one Embodiment of this invention. It is a flowchart which shows the disconnection detection process in one Embodiment of this invention. It is a timing chart which shows the disconnection detection process in one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the cell balance control device A according to the present embodiment is a device that detects voltages (cell voltages) of a total of twelve battery cells C1 to C12 that constitute an assembled battery, and prints of a predetermined size. 12 discharge circuits B1 to B12 mounted on the substrate, 13 transmission lines S1 to S13, 13 CR filters F1 to F13, 12 cell voltage detectors D1 to D12, temperature sensor TS, microcomputer M (Disconnection determination part, charge balance adjustment part) and the insulation element IR are provided.

  The twelve battery cells C1 to C12 are connected in series in a line, the plus terminal of the battery cell C1 is the plus terminal of the assembled battery, and the minus terminal of the battery cell C12 is the minus terminal of the assembled battery. That is, twelve battery cells C1 to C12 are connected in series in the order of battery cell C1 → battery cell C2 → (omitted) → battery cell C11 → battery cell C12, and the total cell voltage of each battery cell C1 to C12. The value is the output voltage of the battery pack.

  The twelve discharge circuits B1 to B12 are respectively connected in parallel to the twelve battery cells C1 to C12, and each is a series circuit of a bypass resistor and a switching element. The discharge circuits B1 to B12 are in a discharge state when the switching element is turned on, and are in a non-discharge state when the switching element is turned off.

  That is, the discharge circuit B1 is connected in parallel to the battery cell C1, and the discharge circuit B2 is connected in parallel to the battery cell C2. The discharge circuit B3 is connected in parallel to the battery cell C3, and the discharge circuit B4 is connected in parallel to the battery cell C4. The discharge circuit B5 is connected in parallel to the battery cell C5, and the discharge circuit B6 is connected in parallel to the battery cell C6. The discharge circuit B7 is connected in parallel to the battery cell C7, and the discharge circuit B8 is connected in parallel to the battery cell C8. The discharge circuit B9 is connected in parallel to the battery cell C9, and the discharge circuit B10 is connected in parallel to the battery cell C10. Further, the discharge circuit B11 is connected in parallel to the battery cell C11, and the discharge circuit B12 is connected in parallel to the battery cell C12.

  The 13 transmission lines S1 to S13 are wires (cell voltage detection wires) that transmit the terminal voltages of the 12 battery cells C1 to C12 to the 12 cell voltage detectors D1 to D12. The terminals (total 13) of the battery cells C1 to C12 and the input terminals (total 13) of the 12 cell voltage detectors D1 to D12 are connected to each other.

  That is, the transmission line S1 connects the positive terminal of the battery cell C1 and one input end 1a of the cell voltage detector D1, and the transmission line S2 is a connection point between the negative terminal of the battery cell C1 and the positive terminal of the battery cell C2. And the other input terminal 1b of the cell voltage detection unit D1 and one input terminal 2a of the cell voltage detection unit D2.

  The transmission line S3 connects a connection point between the negative terminal of the battery cell C2 and the positive terminal of the battery cell C3, the other input end 2b of the cell voltage detection unit D2, and one input end 3a of the cell voltage detection unit D3. The transmission line S4 (not shown) includes a connection point between the negative terminal of the battery cell C3 and the positive terminal of the battery cell C4, the other input terminal 3b of the cell voltage detector D3, and one input terminal of the cell voltage detector D4 (not shown). 4a is connected.

  Further, the transmission line S5 (not shown) is connected to the other input terminal 4b of the cell voltage detector D4 (not shown) and one of the cell voltage detectors D5 as well as the connection point between the minus terminal of the battery cell C4 and the plus terminal of the battery cell C5. The transmission line S6 (not shown) is connected to the input terminal 5a, and the other input terminal 5b of the cell voltage detector D5 (not shown) and the cell voltage are connected to the negative terminal of the battery cell C5 and the positive terminal of the battery cell C6. One input terminal 6a of the detection unit D6 is connected.

  The transmission line S7 (not shown) is connected to the other input terminal 6b of the cell voltage detector D6 (not shown) and one input terminal of the cell voltage detector D7 as well as the connection point between the negative terminal of the battery cell C6 and the positive terminal of the battery cell C7. The transmission line S8 (not shown) is connected to the other input terminal 7b of the cell voltage detector D7 (not shown) and the cell voltage detector as well as the connection point between the minus terminal of the battery cell C7 and the plus terminal of the battery cell C8. One input terminal 8a of D8 is connected.

  The transmission line S9 (not shown) includes the other input terminal 8b of the cell voltage detector D8 (not shown) and one input terminal of the cell voltage detector D9, as well as the connection point between the negative terminal of the battery cell C8 and the positive terminal of the battery cell C9. The transmission line S10 (not shown) is connected to the other input terminal 9b of the cell voltage detector D9 (not shown) and the cell voltage detection, similarly to the connection point between the minus terminal of the battery cell C9 and the plus terminal of the battery cell C10. One input terminal 10a of the part D10 is connected.

  A transmission line S11 (not shown) is connected to the other input terminal 10b of the cell voltage detector D10 (not shown) and one input terminal of the cell voltage detector D11 as well as the connection point between the negative terminal of the battery cell C10 and the positive terminal of the battery cell C11. 11a, the transmission line S12 is connected to the connection point between the negative terminal of the battery cell C11 and the positive terminal of the battery cell C12, the other input terminal 11b of the cell voltage detection unit D11 (not shown), and one of the cell voltage detection unit D12. Are connected to the input terminal 12a. The transmission line S13 connects the negative terminal of the battery cell C12 and the other input end 12b of the cell voltage detection unit D12.

  The thirteen CR filters F1 to F13 are noise-removing low-pass filters provided on the thirteen transmission lines S1 to S13, respectively, and are composed of a filter resistor and a filter capacitor. The filter resistor is connected in series to each of the 13 transmission lines S1 to S13. The filter capacitor has one end connected to each of the 13 transmission lines S1 to S13 and the other end connected to GND (grounding). Potential).

  That is, the CR filter F1 is provided on the transmission line S1, the CR filter F2 is provided on the transmission line S2, the CR filter F3 is provided on the transmission line S3, and the CR filter F4 is provided on the transmission line S4. The CR filter F5 is provided on the transmission line S5, the CR filter F6 is provided on the transmission line S6, the CR filter F7 is provided on the transmission line S7, and the CR filter F8 is provided on the transmission line S8. CR filter F9 is provided in transmission line S9, CR filter F10 is provided in transmission line S10, CR filter F11 is provided in transmission line S11, and CR filter F12 is provided in transmission line S10. The CR filter F13 is provided on the transmission line S13.

  The twelve cell voltage detectors D1 to D12 are provided corresponding to the twelve battery cells C1 to C12, and each battery input from each transmission line S1 to S13 via each CR filter F1 to F13. By sampling the terminal voltages of the cells C1 to C12 at a predetermined cycle, the voltage between the terminals (cell voltage) of each of the battery cells C1 to C12 is detected. That is, each cell voltage detection part D1-D12 detects the difference (difference voltage) of each terminal voltage of each battery cell C1-C12 as cell voltage V1-V12, and outputs it to the microcomputer M.

  For example, the cell voltage detector D1 detects the cell voltage V1 of the battery cell C1 based on a pair of terminal voltages input via the transmission line S1 and the transmission line S2. The cell voltage detector D2 detects the cell voltage V2 of the battery cell C2 based on a pair of terminal voltages input via the transmission line S2 and the transmission line S3. The cell voltage detector D3 detects the cell voltage V3 of the battery cell C3 based on a pair of terminal voltages input via the transmission line S3 and the transmission line S4. The cell voltage detector D4 detects the cell voltage V4 of the battery cell C4 based on a pair of terminal voltages input via the transmission line S4 and the transmission line S5.

  The cell voltage detector D5 detects the cell voltage V5 of the battery cell C5 based on a pair of terminal voltages input via the transmission line S5 and the transmission line S6. The cell voltage detector D6 detects a cell voltage V6 of the battery cell C6 based on a pair of terminal voltages input via the transmission line S6 and the transmission line S7. The cell voltage detector D7 detects the cell voltage V7 of the battery cell C7 based on a pair of terminal voltages input via the transmission line S7 and the transmission line S8. The cell voltage detector D8 detects the cell voltage V8 of the battery cell C8 based on a pair of terminal voltages input via the transmission line S8 and the transmission line S9.

  The cell voltage detector D9 detects the cell voltage V9 of the battery cell C9 based on a pair of terminal voltages input via the transmission line S9 and the transmission line S10. The cell voltage detector D10 detects the cell voltage V10 of the battery cell C10 based on a pair of terminal voltages input via the transmission line S10 and the transmission line S11. The cell voltage detector D11 detects the cell voltage V11 of the battery cell C11 based on a pair of terminal voltages input via the transmission line S11 and the transmission line S12. The cell voltage detector D12 detects the cell voltage V12 of the battery cell C12 based on a pair of terminal voltages input via the transmission line S12 and the transmission line S13.

  The temperature sensor TS detects the temperature (substrate temperature) of the printed circuit board described above, and outputs a temperature signal indicating the substrate temperature to the microcomputer M. The temperature sensor TS is mounted on the printed circuit board in the vicinity of the cell voltage detection units D1 to D12 and the microcomputer M, which are liable to be destroyed or malfunction due to temperature rise. Such a temperature sensor TS is, for example, a thermistor.

  The microcomputer M is a so-called one-chip microcomputer in which a CPU (Central Processing Unit), a memory, an input / output interface, etc. are integrated, and exhibits a predetermined function by executing a voltage detection program stored in the internal memory. To do.

  Such a microcomputer M obtains sample values by sampling the cell voltages V1 to V12 input from the cell voltage detectors D1 to D12 at a predetermined sampling period and performing A / D conversion. The microcomputer M stores the sample values (digital values of the cell voltages V1 to V12) in the internal memory and performs predetermined processing according to the voltage detection program, thereby charging the battery cells C1 to C12. A state balance control process and a disconnection diagnosis process for each of the transmission lines S1 to S13 are performed.

  That is, the microcomputer M functions as a charge balance adjustment unit that adjusts the charge balance of the plurality of battery cells C1 to C12 by controlling the discharge circuits B1 to B12. The microcomputer M controls the discharge circuits B1 to B12 so that the cell voltages V1 to V12 of the battery cells C1 to C12 are equal.

  The microcomputer M also functions as a disconnection determination unit. The microcomputer M outputs an open / close signal to the switching elements T1 to T12 of the discharge circuits B1 to B12, thereby causing the discharge circuits of a pair of adjacent battery cells to be in a discharge state with different duty ratios. Based on whether or not the pair of cell voltages corresponding to the battery cells show opposite change trends over a plurality of sample values, the disconnection of the transmission line related to the pair of battery cells is determined. The disconnection diagnosis process by the microcomputer M is a main feature of the present embodiment, and will be described in detail in the operation description to be described later.

  The microcomputer M is connected to an external battery ECU via an insulating element IR so as to be communicable, and notifies the external battery ECU of the disconnection diagnosis result. The insulating element IR is an element for isolating the microcomputer M and the battery ECU, and is, for example, a photocoupler.

  Next, the operation of the cell balance control apparatus A according to the present embodiment will be described with reference to FIGS.

  In the cell balance control apparatus A according to the present embodiment, as shown in FIG. 2, the microcomputer M performs disconnection diagnosis of each transmission line S <b> 1 to S <b> 13 and each cell in the disconnection detection period and the actual discharge period that are alternately repeated at a constant period. The voltages V1 to V12 are alternately made uniform. That is, the microcomputer M controls the switching elements of the discharge circuit connected to a pair of adjacent battery cells with different duty ratios in the disconnection detection period (for example, 150 ms) from time t1 to t2.

  For example, the microcomputer M switches the switching elements T1, T3,... B11 connected to the odd-numbered battery cells C1, C3,. , T11 is turned ON / OFF at a duty ratio (first duty ratio) of 4%, and switching elements of discharge circuits B2, B4,..., B12 connected to even-numbered battery cells C2, C4,. T2, T4,..., T12 are turned ON / OFF at a 96% duty ratio (second duty ratio).

  Here, when a disconnection occurs in any of the 13 transmission lines S1 to S13, the cell voltages of the pair of battery cells related to the disconnected line and adjacent to each other differ from the pair of discharge circuits as described above. When controlled by the duty ratio, a reverse change tendency is shown because CR filters F1 to F12 are provided in the transmission lines S1 to S13.

  For example, a case where a disconnection occurs in the transmission line S2 that connects the connection point between the battery cell C1 and the battery cell C2 and the cell voltage detection unit D1 and the cell voltage detection unit D2 will be described. A pair of adjacent battery cells is a battery cell C1 and a battery cell C2. Therefore, after the start time t1 of the disconnection detection period, that is, after the control of the pair of discharge circuits B1 and B2 related to the pair of battery cells C1 and C2 with different duty ratios, the pair related to the pair of battery cells C1 and C2 is started. Among the cell voltages V1 and V2, one cell voltage V1 gradually rises, and the other cell voltage V2 shows a tendency to gradually fall.

  As shown in the flowchart of FIG. 3, the microcomputer M samples a plurality of sample values of a pair of cell voltages of adjacent battery cells with respect to the sample values of the cell voltages V1 to V12 sampled after the start time t1 of the disconnection detection period. The disconnection diagnosis of each of the transmission lines S1 to S13 is performed by evaluating whether or not the reverse change tendency is exhibited.

  In other words, when the microcomputer M acquires the sample values Vx1 to Vx12 of the cell voltages V1 to V12 at the sample time tx after the start time t1 (step S1), the sample values Vx1 to Vx12 are the previous sample time tx−. The sample value detected by taking, for example, a difference with respect to each sample value Vx1-1 to Vx12-1 acquired in 1 is increased by a predetermined value or more, or the detected sample value is decreased by a predetermined value or more. It is determined whether or not the sample value is changing with the same tendency (step S2).

  Then, the microcomputer M determines that each sample value Vx1 acquired at the previous sample time tx-1 is the sample value Vx1 to Vx12 acquired at the sample time tx when the determination in step S2 is "Yes". When it changes with the same tendency with respect to -1 to Vx12-1, the values N1 to N12 of the voltage change counter are incremented (step S3). Then, the microcomputer M includes cell voltage pairs in a pair of adjacent battery cells, that is, cell voltage pairs V1, V2, cell voltage pairs V2, V3, cell voltage pairs V3, V4, cell voltage pairs V4, V5, cell voltage pairs. V5, V6, cell voltage pair V6, V7, cell voltage pair V7, V8, cell voltage pair V8, V9, cell voltage pair V9, V10, cell voltage pair V10, V11, cell voltage pair V11, V12, It is determined whether the voltage change counter values N1 to N12 are equal to or greater than a predetermined threshold value Q (step S4).

  That is, the microcomputer M stores the sample values Vx1 to Vx12 in the internal memory when the determination in step S4 is (No), that is, when the values N1 to N12 of the voltage change counter are smaller than the predetermined threshold value Q. (Step S6), and Step S1 is repeated. If the determination in step S2 is “No”, that is, if the sample values Vx1-1 to Vx12-1 do not change or if the change tendency changes, the voltage change counter is not changed. Is reset (step S5), the sample values Vx1 to Vx12 are stored in the internal memory (step S6), and step S1 is repeated.

  The microcomputer M determines that the determination in step S4 is (Yes), that is, the cell voltage pair V1, V2, the cell voltage pair V2, V3, the cell voltage pair V3, V4, the cell voltage pair V4, V5, the cell voltage pair. V5, V6, cell voltage pair V6, V7, cell voltage pair V7, V8, cell voltage pair V8, V9, cell voltage pair V9, V10, cell voltage pair V10, V11, cell voltage pair V11, V12 When the values N1 to N12 of the change counter reach the threshold value Q, it is determined that the transmission line at the connection point of the pair of battery cells corresponding to the cell voltage pair that has reached the threshold value Q is disconnected.

  For example, as shown in FIG. 1, when the transmission line S2 at the connection point of the pair of battery cells C1 and C2 is disconnected, the cell voltage pair V1 and V2 related to the pair of battery cells C1 and C2 is as shown in FIG. One cell voltage V1 gradually increases, and the other cell voltage V2 gradually decreases. Accordingly, the sample values Vx1 and Vx2 of the cell voltage pair V1 and V2 continuously change in the reverse direction after the start time t1 of the disconnection detection period as shown in FIG. Is set to “3”, the values N1 and N2 of the voltage change counter reach the threshold value Q in the fourth sample value sequentially sampled after the start time t1, so that the timing td is earlier than the conventional timing td. The disconnection of the transmission line S2 can be detected.

  According to such a cell balance control apparatus A according to the present embodiment, although it depends on the setting of the threshold value Q, it is not necessary to sample the cell voltage at least several tens of times as in the prior art. Disconnection of the transmission lines S2 to S12 can be detected at an earlier timing.

  When the disconnection detection process in the disconnection detection period from time t1 to t2 is completed, the microcomputer M detects the substrate temperature Ta and each battery obtained from the temperature sensor TS in the next actual discharge period (for example, 500 ms) at time t2-t3. Based on the voltage detection results V1 to V2 of the cells C1 to C12, the switching elements T1 to T12 of the discharge circuits B1 to B12 are controlled so that the voltages of the battery cells C1 to C12 are uniform.

  Then, when the cell balance control in the actual discharge period from time t2 to t3 is completed, the microcomputer M differs from the disconnection detection period from time t1 to t2 described above in the disconnection detection period at the next time t3-t4. , And B11 switching elements T1, T3,..., T11 connected to the battery cells C1, C3,. Open circuit detection is performed by turning on / off switching elements T2, T4,..., T12 of discharge circuits B2, B4,..., B12 connected to cells C2, C4,.

  In other words, the microcomputer M performs the disconnection detection process by alternately switching the first duty ratio and the second duty ratio for each disconnection detection period, thereby preventing one of the adjacent battery cells from being overdischarged. To do. In addition, as shown in FIG. 2, even if the values of the first duty ratio and the second duty ratio are switched, the change tendency of the cell voltage V1 of the battery cell C1 and the cell voltage V2 of the battery cell C2 is only reversed. Yes, disconnection of the transmission lines S2 to S12 can be detected in the same manner as the disconnection detection period at the times t1 to t2.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) The above embodiment relates to a case where the present invention is applied to the cell balance control apparatus A, but the present invention is not limited to this. The present invention is also applicable to a voltage detection device that simply detects cell voltages of a plurality of battery cells, for example.

(2) In the above embodiment, when the discharge circuits of a pair of adjacent battery cells are in a discharge state with different duty ratios, a pair of cell voltages detected by the pair of cell voltage detection units corresponding to the pair of battery cells Although the disconnection of the transmission line regarding a pair of battery cells was determined based on whether or not the cell voltage shows an opposite change tendency over a plurality of consecutive samplings, the present invention is not limited to this. For example, instead of successive sample values, attention may be paid to every other sample value, and it may be evaluated whether or not every other sample value shows a reverse change tendency over a plurality.

A cell balance control device B1 to B12 discharge circuit C1 to C12 battery cell D1 to D12 cell voltage detection unit F1 to F12 CR filter M microcomputer (disconnection determination unit, charge balance adjustment unit)
R1-R12 Bypass resistance S1-S13 Transmission line

Claims (3)

A plurality of discharge circuits each connected in parallel to a plurality of battery cells, a plurality of transmission lines for transmitting terminal voltages of terminals of the plurality of battery cells, and the terminal voltages input from the transmission lines at a predetermined cycle In a voltage detection apparatus comprising a cell voltage detection unit that detects cell voltages of a plurality of the battery cells by sampling,
When a discharge circuit of a pair of adjacent battery cells is in a discharge state with a different duty ratio, a pair of cell voltages related to the pair of battery cells detected by the cell voltage detection unit tend to reversely change over a plurality of samplings. A voltage detection device comprising: a disconnection determination unit that determines disconnection of the transmission line related to the pair of battery cells based on whether or not   The disconnection determination unit determines disconnection of the transmission line with respect to the pair of battery cells based on whether or not the pair of cell voltages show reverse trends in a plurality of consecutive samplings. Item 2. The voltage detection device according to Item 1.   The voltage detection apparatus according to claim 1, further comprising a charge balance adjustment unit that adjusts a charge balance of the plurality of battery cells by controlling the discharge circuit.

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