Patent Description:
The present invention relates to the technical field of battery pack leakage detection, and in particular, to a battery pack leakage detection system and detection method based on tracer gas cumulative test.

With the rapid development of new energy vehicles, the waterproof protection requirement on battery packs is higher and higher, and the protection requirements of IP67 and even IP68 are provided. The traditional gas detection method is influenced by various factors such as environmental temperature change, pack volume change and the like, and is therefore far from meeting the detection requirements. The market needs a detection method with higher precision to realize reliable waterproof grade tests corresponding to IP67 and IP68.

Helium belongs to extremely active gas molecules and is easy to escape from tiny fine leakage positions. In order to detect the tightness of a workpiece, helium is commonly used in industry as a tracer gas, mass spectrometry is carried out on the workpiece in a vacuum box, and high-precision leakage rate measurement is rapidly realized. This method is called box vacuum helium test.

However, the method needs to be carried out under vacuum, but the battery pack is easy to deform and cannot bear larger internal and external pressure difference, so that the capacity of synchronous vacuum inside and outside the battery pack is needed, to cause the internal and external pressure difference to be kept within a design range.

However, this will bring new problem. If the inside of the battery pack is in a vacuum state, the battery cells in the battery pack are placed in the vacuum state, and the battery cells begin to expand under the action of pressure difference, so that the safety gap of the battery cells will be damaged, and the safety of the battery pack is seriously endangered.

A known battery pack leakage detection system and method is disclosed in <CIT>.

In view of the above, the present invention provides a battery pack leakage detection system and detection method based on tracer gas cumulative test.

The present disclosure provides a battery pack leakage detection system and detection method based on tracer gas cumulative test as set out in the appended set of claims.

The beneficial effects of the present invention are: the leakage detection method of the present invention can test the sealing performance of the battery pack under the atmospheric pressure, so that the battery pack can meet the corresponding sealing grade requirements of IP67 and IP68. The method not only solves the problem that the traditional gas detection method cannot meet the test requirements of IP67 and IP68 due to insufficient measurement precision, but also solves the problem that the traditional vacuum helium detection method will damage the battery cells in the battery pack.

Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary but not restrictive manner with reference to the accompanying drawings. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:.

The present invention is further described in detail with reference to the following specific embodiments and the accompanying drawings. The procedures, conditions, experimental methods and the like for carrying out the present invention are general knowledge and common general knowledge in the art except for the contents specifically mentioned below.

Referring to <FIG>, a first embodiment of the present invention relates to a battery pack leakage detection system based on tracer gas cumulative test. The leakage detection system <NUM> is used to detect whether the sealing requirement of the battery pack <NUM> is satisfied or not. The battery pack <NUM> may be typically a vehicle battery pack that can be used in vehicles. The leakage detection system <NUM> includes a test container <NUM>, a gas filling subsystem <NUM>, a gas stirring subsystem <NUM>, and a test analysis subsystem <NUM>.

The gas filling subsystem <NUM> is used to fill an interior of the battery pack <NUM> with a quantity of tracer gas, wherein the tracer gas may be helium or hydrogen or other gases which can serve as a tracer gas. Specifically, in this embodiment, the gas filling subsystem <NUM> includes a vacuumizing device <NUM> (such as a vacuum pump) used to vacuumize the interior of the battery pack <NUM>, a gas filling device <NUM> used to fill the tracer gas into the interior of the battery pack <NUM>, a pressure monitoring device <NUM> used to monitor the pressure of the tracer gas in the interior of the battery pack <NUM>, and a concentration monitoring device <NUM> used to monitor the concentration of the tracer gas in the interior of the battery pack <NUM>. Because the internal volume of the battery pack <NUM> is relatively large and the inner structure of the battery pack <NUM> is relatively complicated, the gas filling subsystem <NUM> needs to guarantee the filled tracer gas to be evenly distributed in the battery pack <NUM>.

After the tracer gas is filled into the battery pack <NUM>, the internal pressure of the interior of the battery pack <NUM> is greater than the pressure in the test cavity <NUM>, and the tracer gas is distributed evenly in the battery pack <NUM>, wherein the pressure in the test cavity <NUM> is atmospheric pressure. In an example, the battery pack <NUM> is filled with the tracer gas before it is placed into the test cavity <NUM>. In another example, the battery pack <NUM> is filled with the tracer gas after it is placed into the test cavity <NUM>. That is, filling the tracer into the battery pack <NUM> can be done either outside the test cavity <NUM> or inside the test cavity <NUM>.

The test container <NUM> is used to carry out the cumulative test on the battery pack <NUM> filled with the tracer gas, so as to determine whether the sealing requirement of the battery pack <NUM> is satisfied or not. A test cavity <NUM> used to accommodate the battery pack <NUM> is provided inside the test container <NUM>. If the sealing performance of the battery pack <NUM> is not good, the filled tracer gas will leak out from the leakage hole of the battery pack <NUM> to the test cavity <NUM>, the leaked tracer gas will accumulate in the test cavity <NUM>, and the content of the tracer gas in the test cavity <NUM> will increase.

The gas stirring subsystem <NUM> is arranged in the test cavity <NUM> of the test container <NUM>. The gas stirring subsystem <NUM> is used to stir the air in the test cavity <NUM>, so that the leaked tracer gas that leaks out from the battery pack <NUM> into the test cavity <NUM>, if any, is accelerated to mix with the air in the test cavity <NUM> for rapidly realizing the uniform distribution of the leaked tracer gas in the test cavity <NUM>. Specifically, in this embodiment, the gas stirring subsystem <NUM> includes at least one stirring fan <NUM> used for stirring the leaked tracer gas so that the leaked tracer gas is uniformly distributed in the test cavity <NUM>. In a specific embodiment, there are a plurality of stirring fans <NUM> arranged and distributed in the test cavity <NUM>, and the position distribution and the opening frequency of the stirring fans <NUM> can be adjusted according to different sizes and/or shapes of the test container <NUM>. The stirring fans <NUM> are mounted to an inner surface of a top plate (not labelled) of the test container <NUM>. During testing, the stirring fans <NUM> are started in a specific frequency and mode to stir the air in the test cavity <NUM> to accelerate air mixing, so that the leaked tracer gas will be quickly and uniformly distributed in the test cavity <NUM>.

The test container <NUM> is a closed box for gas stirring and accumulation testing. Specifically, the test container <NUM> is provided with a door <NUM> at one side thereof for the entrance and exit of the battery pack <NUM>. The upper side of the test container <NUM> is provided with a gas exhaust port <NUM> used to discharge the leaked tracer gas out of the test cavity <NUM> after the leakage detection testing is finished, so that before the next leakage detection testing begins, there is no any tracer gas in the test cavity <NUM>. The gas exhaust port <NUM> may be provided through the top plate of the test container <NUM>. A support frame <NUM> is provided below the test container <NUM>, and the test container <NUM> is supported on the support frame <NUM>. Further, a conveying mechanism <NUM> is provided in the test cavity <NUM>, and the conveying mechanism <NUM> is used to convey the battery pack <NUM> to enter or leave the test cavity <NUM>.

After the tracer gas is filled into the battery pack <NUM>, the battery pack <NUM> filled with the tracer gas is placed into the test cavity <NUM>, and the gas stirring subsystem <NUM> starts to work to accelerate the gas flow in the test cavity <NUM>. Because the internal pressure of the interior of the battery pack <NUM> is greater than the pressure in the test cavity <NUM>, the tracer gas in the battery pack <NUM> will leak into the test cavity <NUM> through the potential leakage hole of the battery pack <NUM> under the action of pressure difference and is mixed with the air in the test cavity <NUM>. Under the stirring action of the gas stirring subsystem <NUM>, the mixing between the leaked tracer gas and the air in the test cavity <NUM> is quicker and more uniform, so that the leaked tracer gas is uniformly distributed in the test cavity <NUM>.

The test analysis subsystem <NUM> is used to sample the mixed gas in the test cavity <NUM> and analyze the sampled gas to obtain the content of the leaked tracer gas in the test cavity <NUM>, so as to determine whether the sealing requirement of the battery pack <NUM> is satisfied or not according to the content of the leaked tracer gas in the test cavity <NUM>. The test analysis subsystem <NUM> may be typically a mass spectrum test analysis subsystem. In this embodiment, the test analysis subsystem <NUM> includes a mass spectrometer <NUM> which may be a helium mass spectrometer or a hydrogen mass spectrometer and a computing device <NUM> which may be a computer. The mass spectrometer <NUM> is used to sample the mixed gas in the test cavity <NUM> and perform mass spectrum analysis on the sampled gas to determine the content of the leaked tracer gas in the test cavity <NUM>. The computing device <NUM> is used to calculate by the following formula to obtain the product leakage rate of the battery pack <NUM>.

Based on the above leakage detection system, the present invention further provides a battery pack leakage detection method based on tracer gas cumulative test, which will be described below.

Referring to <FIG>, a second embodiment of the present invention relates to a battery pack leakage detection method based on tracer gas cumulative test. In this embodiment, the battery pack <NUM> is filled with the tracer gas before it is placed into the test cavity <NUM>. That is, the battery pack <NUM> is filled with the tracer gas at the outside of the test container <NUM>, and after being filled with the tracer gas, the battery pack <NUM> is then placed into the test container <NUM> for leakage detection testing. The leakage detection method includes the following steps:.

Through the above leakage detection testing, if the product leakage rate is lower than a specified value, then it is determined that the sealing requirement of the battery pack is satisfied; if the product leakage rate is greater than the specified value, then it is determined that the sealing requirement of the battery pack is not satisfied.

Referring to <FIG>, a third embodiment of the present invention relates to a battery pack leakage detection method based on tracer gas cumulative test. In this embodiment, the battery pack <NUM> is filled with the tracer gas after it is placed into the test cavity <NUM>. That is, the battery pack <NUM> without being filled with the tracer gas is placed into the test container <NUM>, and then the battery pack <NUM> is filled with the tracer gas at the inside of the test container <NUM>. The leakage detection method includes the following steps:.

Claim 1:
A battery pack leakage detection system (<NUM>), comprising:
a test container (<NUM>) provided with a test cavity (<NUM>) configured for accommodating the battery pack (<NUM>) therein;
a gas filling subsystem (<NUM>) configured for filling an interior of the battery pack (<NUM>) with a quantity of tracer gas;
a gas stirring subsystem (<NUM>) arranged in the test cavity (<NUM>) and configured for stir the air in the test cavity (<NUM>), such that the leaked tracer gas that leaks out from the battery pack (<NUM>) into the test cavity (<NUM>) is accelerated to mix with the air in the test cavity (<NUM>) for realizing the uniform distribution of the leaked tracer gas in the test cavity (<NUM>); and
a test analysis subsystem (<NUM>) configured for sampling the mixed gas in the test cavity (<NUM>) and analyzing the sampled gas to obtain the content of the leaked tracer gas in the test cavity (<NUM>), so as to determine whether the sealing requirement of the battery pack (<NUM>) is satisfied or not according to the content of the leaked tracer gas in the test cavity (<NUM>);
wherein the test container (<NUM>) is a closed box for housing the battery pack (<NUM>) during test of the battery pack (<NUM>),
characterized in that:
a support frame (<NUM>) is provided below the test container (<NUM>), and the test container (<NUM>) is supported on the support frame (<NUM>);
the test container (<NUM>) is provided with a door (<NUM>) at one lateral side thereof for the entrance and exit of the battery pack (<NUM>), the gas stirring subsystem (<NUM>) comprises at least one stirring fan (<NUM>) mounted to an inner surface of a top plate of the test container (<NUM>), a conveying mechanism (<NUM>) is provided in the test cavity (<NUM>) and arranged on an inner surface of a bottom plate of the test container (<NUM>), and the conveying mechanism (<NUM>) is configured for conveying the battery pack (<NUM>) to enter or leave the test cavity (<NUM>) via the door (<NUM>).