Patent Description:
A secondary battery is a battery that is designed to be repeatedly charged and discharged and differs from a primary battery, which is designed to provide an irreversible conversion of chemical energy to electrical energy. A low-capacity secondary battery is often used as a power supply for a small electronic device, such as a mobile phone, a laptop computer, or a camcorder, while a high-capacity secondary battery is often used as a power supply for a hybrid vehicle or the like.

Generally, a secondary battery cell includes an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, a case accommodating the electrode assembly, and an electrode terminal electrically connected to the electrode assembly. An electrolyte solution is injected into the case to enable charging and discharging of the battery cell due to an electrochemical reaction between the positive electrode, the negative electrode, and the electrolyte solution. A shape of the case, such as a cylindrical or rectangular shape, varies depending on the desired use or application of the battery cell.

The secondary battery cell repeatedly contracts and expands due to repeated charging and discharging such that a direct fatigue load is applied to a battery structure. In addition, the secondary battery cell may continuously expand as the electrode assembly deteriorates, and a pressure applied to the battery structure may increase in later life stages of the cell compared with an early life stage of the cell due to the continuous expansion such that a safety problem may occur due to performance degradation and structural deformation.

<CIT> discloses a secondary battery module capable of constantly maintaining a surface pressure of a battery cell. The secondary battery module of the present invention includes a battery stack in which a plurality of battery cells are stacked; a case in which the battery stack is accommodated; a pressure pad disposed to be in contact with the battery cells constituting the battery stack and having a volume which is adjusted; and a pressure adjusting unit that adjusts the volume of the pressure pad in response to a measured pressure, thereby constantly maintaining the pressure applied to the battery cell.

Embodiments of the present disclosure provide a pressure maintenance device for maintaining a constant internal pressure of a battery structure even if a volume of a battery cell changes and a battery system including the pressure maintenance device.

The invention provides a pressure maintenance device and a battery system as set forth in the claims.

Embodiments of the present disclosure will now be described, in detail, in connection with the accompanying drawings. Aspects and features of embodiments, and manners of providing the same, will now be described in detail with the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present disclosure. The embodiments are provided as examples so that the present disclosure may be thorough and complete, and will sufficiently describe aspects and features of the present disclosure to a person skilled in the art.

It will be understood that when an element or layer is referred to as being "on," "connected to," or "coupled to" another element or layer, it may be directly on, connected, or coupled to the other element or layer or one or more intervening elements or layers may also be present. When an element or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. For example, when a first element is described as being "coupled" or "connected" to a second element, the first element may be directly coupled or connected to the second element or the first element may be indirectly coupled or connected to the second element via one or more intervening elements.

In the figures, dimensions of the various elements, layers, etc. may be exaggerated for clarity of illustration. The same reference numerals designate the same elements. Further, the use of "may" when describing embodiments of the present disclosure relates to "one or more embodiments of the present disclosure. " Expressions, such as "at least one of" and "any one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression "at least one of a, b, or c" indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the term "below" may encompass both an orientation of above and below. The device may be otherwise oriented (rotated <NUM> degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

The terminology used herein is for the purpose of describing embodiments of the present disclosure and is not intended to be limiting of the present disclosure. It will be further understood that the terms "includes," "including," "comprises," and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The controller and/or any other relevant devices or components according to embodiments of the present disclosure described herein may be implemented utilizing any suitable hardware, firmware (e.g., an application-specific integrated circuit), software, and/or a suitable combination of software, firmware, and hardware. For example, the various components of the controller may be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of the controller may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a same substrate as the controller. Further, the various components of the controller may be a process or thread, running on one or more processors, in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functionalities described herein. The computer program instructions are stored in a memory which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer readable media such as, for example, a CD-ROM, flash drive, or the like. Also, a person of skill in the art should recognize that the functionality of various computing devices may be combined or integrated into a single computing device or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the embodiments of the present disclosure.

Hereinafter, a pressure maintenance device, according to embodiments of the present disclosure, and a battery system including the pressure maintenance device will be described, in detail, with reference to necessary drawings.

<FIG> is a schematic diagram of a battery system including a pressure maintenance device according to embodiments of the present disclosure.

Referring to <FIG>, the battery system 1a, according to an embodiment, may include a battery module and a pressure maintenance device of the battery module.

The battery module may include a plurality of battery cells <NUM> connected to each other in series and/or in parallel and a module housing <NUM> that is a structure accommodating the plurality of battery cells <NUM>. The plurality of battery cells <NUM> may be disposed in a stacked arrangement inside the module housing <NUM>.

An airtight space (e.g., an inner space or a compartment) <NUM> may be formed inside the module housing <NUM>. The plurality of battery cells <NUM> and a hydraulic device <NUM> of a pressure maintenance device <NUM>, described in more detail below, may be accommodated in the inner space <NUM> of the module housing <NUM>. A buffer plate <NUM> may be arranged between the hydraulic device <NUM> and the battery cells <NUM> in the inner space <NUM> of the module housing <NUM>. The buffer plate <NUM> may be deformed or moved according to a change in a volume of one or more of the battery cells <NUM>. The buffer plate <NUM> may be moved or deformed toward the battery cells <NUM> due to an expansion pressure from the hydraulic device <NUM> if the battery cells <NUM> contract. The buffer plate <NUM> may be moved or deformed toward the hydraulic device <NUM> due to an expansion pressure of the battery cells <NUM> during expansion of the battery cells <NUM>.

The pressure maintenance device, according to an embodiment, may include the hydraulic device <NUM>, an accumulator <NUM>, a fluid pipe <NUM>, a maintenance valve <NUM>, a pressure reducing valve <NUM>, a heater <NUM>, a temperature sensor <NUM>, and a controller <NUM>.

The hydraulic device <NUM> may reduce or minimize a fatigue load of the module housing <NUM> by offsetting (e.g., canceling) pressure change inside the module housing <NUM> due to deformation (e.g., a change in the volume) of the battery cells <NUM>. If the battery cells <NUM> contract (e.g., if one or more of the battery cells <NUM> contract), the hydraulic device <NUM> may expand to move or deform the buffer plate <NUM> toward the battery cells <NUM>. If the battery cells <NUM> expand, the hydraulic device <NUM> may contract by the expansion pressure transferred from the battery cells <NUM> through the buffer plate <NUM>.

The hydraulic device <NUM> may include a device (e.g., a hydraulic bag, a hydraulic cylinder, or the like) configured to expand and contract in response to a hydraulic pressure. The hydraulic device <NUM> may expand or contract through inflow and discharge of fluid (e.g., oil). If the hydraulic device <NUM> contracts, the fluid may be discharged from the hydraulic device <NUM>. If the hydraulic device <NUM> expands, the fluid may flow into the hydraulic device <NUM>.

The accumulator <NUM> may store a pressurized fluid and may offset a hydraulic pressure change caused by expansion and contraction of the hydraulic device <NUM>. For example, if a hydraulic pressure change occurs inside the fluid pipe <NUM> due to the expansion or the contraction of the hydraulic device <NUM>, the accumulator <NUM> may discharge the fluid to the fluid pipe <NUM> or may offset the hydraulic pressure change within the fluid pipe <NUM> by introducing the fluid of the fluid pipe <NUM> into the accumulator <NUM>. If the battery cells <NUM> contract such that the hydraulic device <NUM> expands, the accumulator <NUM> may prevent a decrease in a hydraulic pressure by discharging the fluid to the fluid pipe <NUM>. If the battery cells <NUM> expand so that the hydraulic device <NUM> contracts, the accumulator <NUM> may prevent an increase in the hydraulic pressure by introducing the fluid from the hydraulic device <NUM> into the accumulator <NUM>. In some embodiments, an internal pressure of the accumulator <NUM> may change in proportion to a change in an internal pressure of the battery cells <NUM>. For example, if the internal pressure of the battery cells <NUM> increases (e.g., the battery cells <NUM> expand), a pressure of the accumulator <NUM> may increase due to inflow of the fluid, and if the internal pressure of the battery cells <NUM> decrease (e.g., the battery cells <NUM> contract), the pressure of the accumulator <NUM> may decrease due to discharge of the fluid.

The fluid pipe <NUM> may extend through (or extend into) and may be coupled to the module housing <NUM>. The fluid pipe <NUM> may be respectively connected to a fluid inlet/outlet of the hydraulic device <NUM> and a fluid inlet/outlet of the accumulator <NUM>. The fluid pipe <NUM> may be a passage for fluid exchange between the hydraulic device <NUM> and the accumulator <NUM>.

The maintenance valve <NUM> may be connected to a fluid inlet of the fluid pipe <NUM> to replenish the fluid inside the fluid pipe <NUM>. The maintenance valve <NUM> may be manually or automatically operated.

The maintenance valve <NUM> may be opened by a manual operation of a user to supply the fluid to the inside of the fluid pipe <NUM>.

Opening and closing of the maintenance valve <NUM> may be controlled by the controller <NUM>. For example, if a pressure inside the fluid pipe <NUM> lowers to a reference (or predetermined) value or less or a set period is reached, the controller <NUM> may open the maintenance valve <NUM> so that a fluid stored in a fluid tank is supplied to the inside of the fluid pipe <NUM>. In some embodiments, the pressure maintenance device may further include a pressure sensor <NUM> (see, e.g., <FIG>) configured to detect an internal pressure of the fluid pipe <NUM> or the accumulator <NUM>. If the internal pressure of the fluid pipe <NUM> or the accumulator <NUM> detected by the pressure sensor lowers to the reference value or less, the controller <NUM> may open the maintenance valve <NUM> so that an additional fluid is supplied to the fluid pipe <NUM>.

The pressure reducing valve <NUM> may be connected to a fluid outlet of the fluid pipe <NUM> to discharge the fluid inside the fluid pipe <NUM> to the outside of the fluid pipe <NUM>. The pressure reducing valve <NUM> may be opened if the pressure inside the fluid pipe <NUM> exceeds a reference (or predetermined) value so that the fluid inside the fluid pipe <NUM> is discharged to the outside. The pressure reducing valve <NUM> may be closed if the pressure inside the fluid pipe <NUM> lowers to the reference value or less to stop the discharging of the fluid.

The fluid pipe <NUM> may maintain an airtight state except for when the maintenance valve <NUM> is opened so that the fluid is supplied to the inside of the fluid pipe <NUM> or if the pressure reducing valve <NUM> is opened so that the fluid inside the fluid pipe <NUM> is discharged to the outside. In some embodiments, when the maintenance valve <NUM> and the pressure reducing valve <NUM> are both closed, the fluid inside the fluid pipe <NUM> may be exchanged only between the hydraulic device <NUM> and the accumulator <NUM>.

The heater <NUM> may heat the accumulator <NUM>.

The temperature sensor <NUM> measures an outdoor air temperature (e.g., an outdoor temperature, an external or ambient temperature) outside the accumulator <NUM>.

The controller <NUM> may detect the outdoor air temperature through the temperature sensor <NUM> and may adjust an electric current flowing through the heater <NUM> so that the heater heats the accumulator <NUM>. To prevent a pressure change inside the accumulator <NUM> from occurring due to a temperature change inside the accumulator <NUM>, the controller <NUM> may reduce or minimize a change in an internal temperature of the accumulator <NUM> by controlling an operation of the heater <NUM> according to the detected outdoor air temperature. Because energy necessary to raise <NUM> nitrogen pressurized at <NUM> bar by <NUM> degrees Celsius is approximately <NUM> Wh (watt-hours) if nitrogen is charged inside the accumulator <NUM>, a temperature change inside the accumulator <NUM> may be reduced or minimized with little energy.

According to the above-described embodiments, displacement of the battery cells <NUM> may be absorbed by the pressure maintenance device so that a fatigue load applied to the module housing <NUM> due to charging and discharging of the battery cells <NUM> is reduced or minimized. For example, even if swelling occurs due to deterioration during the life of the battery cells <NUM>, a pressure inside the module housing <NUM> may be kept constant compared with an early life stage of the battery cells <NUM> so that structural deformation of the module housing <NUM> is reduced or minimized. In some embodiments, if the battery module is installed, a fastening force of the battery cells <NUM> may be improved by pressurizing the battery cells <NUM> by using the pressure maintenance device. In some embodiments, the accumulator <NUM>, the heater <NUM>, and the like may be used to respond to an external temperature variable, fluid leakage, or the like.

<FIG> is a schematic diagram of a battery system including a pressure maintenance device according to other embodiments of the present disclosure.

The same reference numerals used to describe the battery system 1b shown in <FIG> as those used to describe the battery system 1a shown in <FIG>, described above, may denote the same component and a redundant description thereof is omitted.

Comparing the embodiment shown in <FIG> with the embodiment shown in <FIG>, the battery system 1b may further include a supplemental pipe <NUM>, an auxiliary accumulator (e.g., a supplemental accumulator) <NUM>, a solenoid valve <NUM>, and pressure sensors <NUM> and <NUM>.

The supplemental pipe <NUM> may be a fluid passage between the solenoid valve <NUM>, the auxiliary accumulator <NUM>, and the maintenance valve <NUM>.

The auxiliary accumulator <NUM> may store a fluid in a pressurized state. If the fluid is supplied to the supplemental pipe <NUM> through the maintenance valve <NUM>, the auxiliary accumulator <NUM> may store the supplied fluid therein. If the solenoid valve <NUM> is opened so that a hydraulic pressure inside the supplemental pipe <NUM> lowers, the auxiliary accumulator <NUM> may supply the fluid to the supplemental pipe <NUM> by discharging the fluid stored in the auxiliary accumulator <NUM>.

Opening of the solenoid valve <NUM> may be controlled by the controller <NUM>, and flow of the fluid between the fluid pipe <NUM> and the supplemental pipe <NUM> may be controlled.

The pressure sensor <NUM> may be coupled to the fluid pipe <NUM> to detect an internal hydraulic pressure P1 of the fluid pipe <NUM>. The pressure sensor <NUM> may be coupled to the supplemental pipe <NUM> to detect an internal hydraulic pressure P2 of the supplemental pipe <NUM>.

The controller <NUM> may compare the pressures detected by the pressure sensors <NUM> and <NUM> and, when the internal hydraulic pressure P1 of the fluid pipe <NUM> is lower than the internal hydraulic pressure P2 of the supplemental pipe <NUM>, may open the solenoid valve <NUM> so that the fluid of the supplemental pipe <NUM> flows into the fluid pipe <NUM>. If the fluid is supplied from the supplemental pipe <NUM> to the fluid pipe <NUM>, the hydraulic pressure inside the supplemental pipe <NUM> may be lowered so that the fluid stored in the accumulator <NUM> is discharged to the supplemental pipe <NUM>.

In the above description, the opening of the solenoid valve <NUM> is controlled by using the pressure sensors <NUM> and <NUM> coupled to the fluid pipe <NUM> and the supplemental pipe <NUM>, but this is merely an example. In another embodiment, the pressure sensors <NUM> and <NUM>, used to determine whether the solenoid valve <NUM> should be opened, may be respectively coupled to the accumulators <NUM> and <NUM>. For example, the pressure sensors <NUM> and <NUM> may respectively detect internal pressures of the accumulator <NUM> and the auxiliary accumulator <NUM>, and the controller <NUM> may compare the internal pressures to determine whether the solenoid valve <NUM> should be opened. In some embodiments, if the internal pressure of the accumulator <NUM> becomes lower than the internal pressure of the auxiliary accumulator <NUM>, the controller <NUM> may open the solenoid valve <NUM> so that the fluid of the supplemental pipe <NUM> flows into the fluid pipe <NUM>.

According to embodiments of the present disclosure, the auxiliary accumulator <NUM> may be used to supplement the fluid if a pressure of an accumulator (e.g., a main or primary accumulator) <NUM> decreases so that a maintenance period is increased.

The same reference numerals used to describe the battery system 1c shown in <FIG> as are used to describe the battery system 1a shown in <FIG>, described above, may denote the same component and a redundant description thereof is omitted.

Comparing the embodiment shown in <FIG> with the embodiment shown in <FIG>, the battery system 1c may further include a pump <NUM> for supplementing the fluid in the fluid pipe <NUM> and a motor <NUM> for driving the pump <NUM> instead of the maintenance valve <NUM>.

If a pressure inside the fluid pipe <NUM> lowers to a reference (or predetermined) value or less or a set period is reached, the controller <NUM> may drive the pump <NUM> by using (or by controlling) the motor <NUM> so that a fluid stored in a fluid tank is supplied to the inside of the fluid pipe <NUM>. In some embodiments, the pressure maintenance device may further include the pressure sensor <NUM> (see, e.g., <FIG>) for detecting an internal pressure of the fluid pipe <NUM> or the accumulator <NUM>. If the internal pressure of the fluid pipe <NUM> or the accumulator <NUM> detected by the pressure sensor lowers to the reference value or less, the controller <NUM> may drive the pump <NUM> so that additional fluid is supplied to the fluid pipe <NUM>.

According to embodiments of the present disclosure, if the pressure maintenance device determines that fluid supplement is necessary to maintain pressure, the pressure maintenance device may drive the pump <NUM> to automatically supplement the fluid in the accumulator <NUM> even during driving of a vehicle to which the battery system is attached.

While embodiments of the present disclosure have been shown and described with reference to the accompanying drawings, the specific terms used herein are only for the purpose of describing these embodiments and are not intended to define the meanings thereof or be limiting of the scope of the present disclosure set forth in the claims. Therefore, a person of ordinary skill in the art will understand that various modifications and other equivalent embodiments of the present disclosure are possible. Consequently, the scope of the present disclosure must be determined based on the appended claims.

pressure sensor <NUM> (see, e.g., <FIG>) for detecting an internal pressure of the fluid pipe <NUM> or the accumulator <NUM>. If the internal pressure of the fluid pipe <NUM> or the accumulator <NUM> detected by the pressure sensor lowers to the reference value or less, the controller <NUM> may drive the pump <NUM> so that additional fluid is supplied to the fluid pipe <NUM>.

While embodiments of the present disclosure have been shown and described with reference to the accompanying drawings, the specific terms used herein are only for the purpose of describing these embodiments and are not intended to define the meanings thereof. Therefore, a person of ordinary skill in the art will understand that various modifications and other equivalent embodiments of the present disclosure are possible. Consequently, the scope of the present disclosure must be determined based on the appended claims.

Claim 1:
A pressure maintenance device comprising:
a hydraulic device (<NUM>) inside a housing (<NUM>) of a battery module together with a plurality of battery cells (<NUM>), the hydraulic device (<NUM>) being configured to change its volume to offset a pressure change inside the housing (<NUM>) due to deformation of the plurality of battery cells (<NUM>);
an accumulator (<NUM>) connected to the hydraulic device (<NUM>) through a pipe (<NUM>), the accumulator (<NUM>) being configured to store fluid and to discharge the fluid to the pipe (<NUM>) or to store the fluid introduced from the pipe (<NUM>) according to a change in a volume of the hydraulic device (<NUM>);
a heater (<NUM>) configured to heat the accumulator (<NUM>)
comprising a temperature sensor (<NUM>) configured to detect the outdoor air temperature; and
a controller (<NUM>) configured to control the heater (<NUM>) according to an outdoor air temperature.