Battery seal immersion test apparatus

Abstract

The utility model discloses battery sealed immersion type test equipment, including box, oil supply mechanism, refrigerating system, heat exchange pipeline, test box and circulation pipeline, the box is separated into first box body and second box body through the division, oil supply mechanism installs in second box body and is adjacent to first box body, and oil supply mechanism includes oil tank and first heater, and first heater is located at oil tank, is used for heating the oil in oil tank, heat exchange pipeline is located at oil tank, and refrigerating system installs in second box body and communicates with heat exchange pipeline, is used for refrigeration to the oil in oil tank, test box is electrically conductive box, and test box is located in first box body, and test box has the sealed cavity for accommodating battery, and circulation pipeline communicates oil tank and test box, and circulation pipeline passes through the division, and test box is connected with external charge and discharge equipment through the wire. The utility model can improve the authenticity of the environment temperature of analog battery package, and can improve the site utilization.

Description

Technical Field

[0001] This utility model relates to the field of battery testing technology, and in particular to a battery sealed immersion testing device. Background Technology

[0002] During battery development, immersion cooling systems are typically used for battery testing. Existing immersion cooling systems include an oil cooler, test chambers, charge / discharge cabinets, and a housing. The batteries are stored in the test chambers to simulate the charge / discharge cycle performance of the batteries within the battery pack. The oil cooler provides cooling oil circulation to simulate the battery pack cooling system. The test chambers are placed in the housing to simulate the impact of changes in the external environment of the battery pack during different seasons on the testing. The charge / discharge cabinets are used to simulate and test different operating conditions.

[0003] Existing immersion cooling systems have the following problems:

[0004] (1) The oil cooler and the housing are designed separately. The oil pipe is connected to the test box interface in the housing. The oil circuit circulation is long, and there is oil temperature loss. This results in the untimely response to the required temperature and cannot simulate the oil circuit circulation of the battery pack more realistically.

[0005] (2) The oil cooler and the housing are designed separately, which leads to a waste of space and insufficient utilization of the test site. Utility Model Content

[0006] The purpose of this utility model embodiment is to provide a battery sealing immersion test device that can quickly adjust the oil temperature and respond to the required temperature in real time, so as to improve the realism of the simulated ambient temperature of the battery pack and improve the site utilization rate.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A battery sealing immersion test device is provided, comprising:

[0009] The box is divided into a first box and a second box by a partition.

[0010] An oil supply mechanism is installed in the second housing and adjacent to the first housing. The oil supply mechanism includes an oil storage tank and a first heater. The first heater is located in the oil storage tank and is used to heat the oil in the oil storage tank.

[0011] A refrigeration system and a heat exchange pipe, wherein the heat exchange pipe is located inside the oil storage tank, and the refrigeration system is installed inside the second tank and connected to the heat exchange pipe, for cooling the oil in the oil storage tank;

[0012] The test box is a conductive box located inside the first housing and has a sealed cavity for accommodating the battery. The circulation pipeline connects the oil tank and the test box and passes through the partition. The test box is connected to an external charging and discharging device via wires.

[0013] As a further embodiment of the battery sealing immersion test equipment, a temperature chamber is provided inside the first chamber, and at least part of the outer wall of the temperature chamber is spaced from the inner wall of the first chamber to form an air duct. The test box is located inside the temperature chamber, and the temperature chamber has an air inlet and an air outlet that connect the inside of the temperature chamber and the air duct. The battery sealing immersion test equipment also includes a temperature regulation system, which is used to regulate the air temperature inside the air duct.

[0014] As a further embodiment of the battery sealing immersion test equipment, the temperature chamber has a bottom plate and side plates. The bottom plate is spaced from the bottom of the first chamber to form a first channel. The two oppositely arranged side plates of the temperature chamber are spaced from the inner wall of the first chamber to form a second channel. The two second channels and the first channel are connected to form the air duct. The two oppositely arranged side plates are respectively provided with the air inlet and the air outlet.

[0015] As a further embodiment of the battery sealing immersion test equipment, the temperature chamber is equipped with a support, and the test box is mounted on the support, with the test box facing the air inlet or adjacent to the air inlet.

[0016] As a further embodiment of the battery sealing immersion test equipment, the temperature chamber is also equipped with a driving component, which is connected to the support frame and can drive the support frame to move up and down.

[0017] As a further embodiment of the battery sealing immersion test equipment, the oil supply mechanism also includes a replenishment tank and a replenishment pipe disposed in the second tank, wherein the replenishment tank is connected to the oil storage tank through the replenishment pipe.

[0018] As a further embodiment of the battery sealing immersion test equipment, the oil supply mechanism also includes a vent pipe, and the replenishment tank is connected to the top of the oil storage tank through the vent pipe, with an vent opening on the top of the replenishment tank.

[0019] As a further embodiment of the battery sealing immersion test equipment, the refrigeration system includes a cooler, an inlet pipe, an outlet pipe, and a first circulation pump. The cooler is connected to the heat exchange pipeline through the inlet pipe and the outlet pipe, respectively, and the first circulation pump is installed on the inlet pipe.

[0020] As a further embodiment of the battery sealing immersion testing equipment, multiple test boxes are spaced apart inside the first housing; the circulation pipeline includes an oil inlet pipe, an oil return pipe, and a second circulation pump. The oil inlet pipe includes a main oil inlet pipe, a first oil distributor, and multiple oil inlet branch pipes. Each oil inlet branch pipe is connected to one of the test boxes, and the main oil inlet pipe is connected to all the oil inlet branch pipes through the first oil distributor; the oil return pipe includes a main oil return pipe, a second oil distributor, and multiple oil return branch pipes. Each oil return branch pipe is connected to one of the test boxes, and the main oil return pipe is connected to all the oil return branch pipes through the second oil distributor.

[0021] As a further embodiment of the battery sealing immersion test equipment, it also includes a flow meter, a valve, and a pressure sensor, with each of the oil inlet branches equipped with the flow meter, the valve, and the pressure sensor.

[0022] Beneficial effects:

[0023] This invention divides the housing into a first housing and a second housing using a partition. An oil supply mechanism is installed in the first housing, adjacent to the second housing, to deliver oil to the sealed cavity of the test box within the second housing, immersing the battery in oil at a suitable temperature. The oil tank contains a heat exchange pipe, connected to a refrigeration system for cooling the oil. Simultaneously, a first heater directly heats the oil in the tank. Through the combined action of the refrigeration system and the first heater, the oil temperature in the tank is quickly adjusted to the required level. The temperature-adjusted oil is then transported through a circulation pipeline to the sealed cavity of the test box to immerse the battery, thus simulating the temperature of the battery's environment. In this invention, the short distance between the oil tank and the test box, and the short circulation pipeline connecting them, shortens the oil's transport path from the tank to the sealed cavity, reducing oil temperature loss and improving the realism of the simulated battery pack's environmental temperature, resulting in high test accuracy.

[0024] This utility model integrates the oil supply mechanism, refrigeration system, circulation pipeline and temperature chamber for keeping the battery test box warm into one unit. The overall structure is compact, occupies less space, and improves the space utilization rate. Attached Figure Description

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the battery sealing immersion test equipment described in an embodiment of the present invention. Figure 1 ;

[0027] Figure 2 This is a schematic diagram of the battery sealing immersion test equipment described in an embodiment of the present invention. Figure 2.

[0028] In the picture:

[0029] 100. Enclosure; 110. Divider; 111. Wiring hole; 120. First enclosure; 130. Second enclosure; 140. Temperature chamber; 150. Air duct; 160. Bracket; 200. Oil supply mechanism; 210. Oil reservoir; 220. First heater; 230. Liquid replenishment tank; 240. Liquid replenishment pipe; 250. Vent pipe; 300. Refrigeration system; 310. Refrigerator; 320. Liquid inlet pipe; 330. Liquid outlet pipe; 340. First circulation pump; 400. Test Box; 500, Circulation pipeline; 510, Oil inlet pipe; 511, Main oil inlet pipe; 512, First oil distributor; 513, Oil inlet branch pipe; 520, Oil return pipe; 521, Main oil return pipe; 522, Second oil distributor; 523, Oil return branch pipe; 530, Second circulation pump; 600, Temperature control system; 610, Evaporator; 620, Second heater; 630, Fan; 640, Compressor; 700, Flow meter; 800, Pressure sensor; 900, Distribution box. Detailed Implementation

[0030] To make the technical problems solved by this utility model, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0031] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationships shown in the accompanying drawings. They are used solely for ease of description and simplification of operation, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are merely used for distinction in description and have no special meaning.

[0034] like Figure 1 and Figure 2 As shown, the battery sealing immersion test equipment of this embodiment includes a housing 100, an oil supply mechanism 200, a refrigeration system 300, a heat exchange pipe (not shown in the figure), a test box 400, and a circulation pipeline 500.

[0035] The housing 100 is divided into a first housing 120 and a second housing 130 by a partition 110. An oil supply mechanism 200 is installed in the second housing 130 and adjacent to the first housing 120. The oil supply mechanism 200 includes an oil storage tank 210 and a first heater 220. The first heater 220 is located in the oil storage tank 210 and is used to heat the oil in the oil storage tank 210. A heat exchange pipe is located in the oil storage tank 210. A refrigeration system 300 is installed in the second housing 130 and connected to the heat exchange pipe, used to cool the oil in the oil storage tank 210. A test box 400 is a conductive box located in the first housing 120. The test box 400 has a sealed cavity (not shown in the figure) for accommodating a battery. A circulation pipe 500 connects the oil storage tank 210 and the test box 400. The test box 400 is connected to an external charging / discharging device via a wire.

[0036] In this embodiment, the housing 100 is divided into a first housing 120 and a second housing 130 by a partition 110. An oil supply mechanism 200 is installed in the first housing 120 to supply oil to the sealed cavity of the test box 400 in the second housing 130, immersing the battery in oil at a suitable temperature. The oil storage tank 210 contains an oil storage chamber and a heat exchange pipe. A refrigeration system 300 is connected to this heat exchange pipe to cool the oil in the oil storage tank 210. Simultaneously, a first heater 220 can directly heat the oil in the oil storage tank 210. Through the coordinated action of the refrigeration system 300 and the first heater 220, the oil temperature in the oil storage tank 210 is quickly adjusted to the required temperature. Then, the temperature-adjusted oil is transported to the sealed cavity of the test box 400 through a circulation pipe 500 to immerse the battery, thereby simulating the temperature of the battery's environment. In this embodiment, since the distance between the oil tank 210 and the test box 400 is relatively short, the circulation pipeline 500 connecting the two is relatively short. This can shorten the flow path of the cooling oil from the oil tank 210 to the sealed cavity of the test box 400, thereby reducing oil temperature loss and improving the realism of the ambient temperature of the simulated battery pack, resulting in high test accuracy.

[0037] In this embodiment, the oil supply mechanism 200, the refrigeration system 300, and the circulation pipeline 500 are integrated into the first box 120 for heat preservation of the test box 400 within the box 100. The overall structure is compact and occupies little space.

[0038] The separator 110 has a wire hole 111. The battery is located in the sealed cavity and is electrically connected to the wire through the terminal on the test box 400. The wire passes through the wire hole 111 and is connected to the external charging and discharging equipment.

[0039] In a specific example, the partition 110 is an L-shaped structure consisting of a horizontal plate and a vertical plate. The L-shaped partition 110 is connected to the side wall of the housing 100, thereby dividing the housing 100 into a first housing 120 and a second housing 130. The oil supply mechanism 200 is located in the second housing 130 and adjacent to the vertical plate. A wire hole 111 is provided on the vertical plate.

[0040] Furthermore, a temperature chamber 140 is installed inside the first housing 120. At least part of the outer wall of the temperature chamber 140 is spaced from the inner wall of the first housing 120 to form an air duct 150. The test box 400 is installed inside the temperature chamber 140. The temperature chamber 140 has an air inlet and an air outlet that connect the inside of the temperature chamber 140 with the air duct 150. The battery sealing immersion test equipment also includes a temperature regulation system 600, which is used to regulate the air temperature inside the air duct 150.

[0041] In this embodiment, the temperature control system 600 is similar to an existing air conditioning system, including an evaporator 610, a second heater 620, a fan 630, a condenser, a compressor 640, sensors, etc., used to regulate the temperature of the air in the air duct 150. The condenser and other components are not shown in the figure. The compressor 640 is located inside the second housing 130. The fan blades of the evaporator 610, the second heater 620, and the fan 630 are located inside the air duct 150 and below the temperature chamber 140. There can be two fans 630. The drive motors of the fans 630 are located outside the first housing 120 and are connected to the corresponding fan blades to improve the airflow effect in the air duct 150, allowing air to enter the temperature chamber 140 through the air inlet and exit through the air outlet, thereby improving the temperature control efficiency within the temperature chamber 140.

[0042] Furthermore, the temperature chamber 140 has a bottom plate and side plates. The bottom plate is spaced from the bottom of the first chamber 120 to form a first channel. The two oppositely arranged side plates of the temperature chamber 140 are spaced from the inner wall of the first chamber 120 to form a second channel. The two second channels and the first channel are connected to form an air duct 140. An air inlet and an air outlet are respectively opened on the two oppositely arranged side plates.

[0043] It is understood that the air duct 150 has a U-shaped structure. In this embodiment, the air inlet and air outlet are respectively set on two opposite side plates of the temperature chamber 140 (one side plate has an air inlet and the other side plate has an air outlet). The second channel adjacent to the air inlet can be used as an air inlet duct, and the second channel adjacent to the air outlet can be used as a return air duct, which can further improve the air convection effect in the temperature chamber 140.

[0044] Furthermore, the chamber 140 is equipped with a bracket 160, and the test box 400 is mounted on the bracket 160, with the test box 400 facing or adjacent to the air inlet.

[0045] In this embodiment, the position of the test box 400 can be raised by the bracket 160 so that the test box 400 is directly facing the air inlet, so that the temperature-regulated air can blow directly onto the test box 400, or the test box 400 can be placed near the air inlet so that the temperature of the test box 400 can quickly reach the required test environment temperature.

[0046] To enable the temperature chamber 140 to accommodate test boxes 400 of different sizes, this embodiment can also design the support 160 as an adjustable structure. Specifically, the temperature chamber 140 is also equipped with a driving component (not shown in the figure), which is connected to the support 160 and can drive the support 160 to move up and down. The driving component can be a cylinder or a motor, which will not be described in detail here.

[0047] Furthermore, the oil supply mechanism 200 also includes a replenishment tank 230 and a replenishment pipe 240 located in the second housing 130, with the replenishment tank 230 connected to the oil storage tank 210 via the replenishment pipe 240.

[0048] After the test is completed, the battery is removed from the test box 400. Some oil will inevitably be lost. When the oil level in the oil tank 210 is insufficient, the oil in the replenishment tank 230 can be transferred to the oil tank 210 through the replenishment pipe 240.

[0049] Since some air may exist inside the oil reservoir 210, a vent pipe 250 is specifically designed in this embodiment to prevent the air in the oil reservoir 210 from being transported to the sealed cavity of the test box 400 through the circulation pipe 500 and affecting the test results. Specifically, the oil supply mechanism 200 also includes a vent pipe 250, and the replenishment tank 230 is connected to the top of the oil reservoir 210 through the vent pipe 250. The top of the replenishment tank 230 has a vent (not shown in the figure). The air in the oil reservoir 210 is discharged into the replenishment tank 230 through the vent pipe 250 and discharged through the vent in the replenishment tank 230.

[0050] In this embodiment, the refrigeration system 300 includes a refrigerator 310, an inlet pipe 320, an outlet pipe 330, and a first circulation pump 340. The refrigerator 310 is connected to both ends of a heat exchange pipe in the oil storage tank 210 through the inlet pipe 320 and the outlet pipe 330, respectively. The first circulation pump 340 is installed on the inlet pipe 320. The refrigerant cooled by the refrigerator 310 is transported through the inlet pipe 320 to the heat exchange pipe in the oil storage tank 210 under the power of the first circulation pump 340, thereby cooling the oil located inside the oil storage tank 210 but outside the heat exchange pipe. The refrigerant in the heat exchange pipe then flows back to the refrigerator 310 through the outlet pipe 330 for further cooling, and the cycle continues.

[0051] Furthermore, multiple test boxes 400 are spaced apart inside the first housing 120; the circulation pipeline 500 includes an oil inlet pipe 510, an oil return pipe 520, and a second circulation pump 530. The oil inlet pipe 510 includes an oil inlet main pipe 511, a first oil distributor 512, and multiple oil inlet branch pipes 513. The oil inlet branch pipes 513 are connected to the test boxes 400 one by one, and the oil inlet main pipe 511 is connected to the oil inlet branch pipes 513 through the first oil distributor 512; the oil return pipe 520 includes an oil return main pipe 521, a second oil distributor 522, and multiple oil return branch pipes 523. The oil return branch pipes 523 are connected to the test boxes 400 one by one, and the oil return main pipe 521 is connected to the oil return branch pipes 523 through the second oil distributor 522.

[0052] In this embodiment, multiple test boxes 400 are set in the first housing 120. The sealed cavity of each test box 400 is connected to the corresponding oil inlet branch pipe 513 and oil return branch pipe 523. All oil inlet branch pipes 513 are connected to the oil inlet main pipe 511 through the first oil distributor 512, and all oil return branch pipes 523 are connected to the oil return main pipe 521 through the second oil distributor 522. This allows for the simultaneous simulation and testing of the charge and discharge performance of multiple batteries immersed in oil at the same temperature.

[0053] Specifically, the first oil distributor 512 and the second oil distributor 522 are respectively fixed to one side of the partition 110 located in the first housing 120. The first oil distributor 512 and the second oil distributor 522 are respectively provided with connecting ends that connect to their respective branch pipes. The partition 110 is provided with through holes for each connecting end to pass through, and each connecting end passes through the corresponding through hole to connect to the corresponding branch pipe.

[0054] In this embodiment, the battery sealing immersion test equipment also includes a flow meter 700, a valve (not shown in the figure), and a pressure sensor 800. Each oil inlet branch pipe 513 is equipped with a flow meter 700, a valve, and a pressure sensor 800. The flow meter 700 and the pressure sensor 800 can detect the flow rate and velocity of the oil in each corresponding branch pipe, and the valves can be used to adjust the flow rate and velocity in real time, so that the oil is delivered to the sealed cavity of each test box 400 at a suitable flow rate and velocity, thereby more realistically simulating the environment in which the battery pack is located.

[0055] It is understood that, in this embodiment, valves can be installed on pipelines where flow rate needs to be controlled, which will not be elaborated here.

[0056] In this embodiment, the battery sealing immersion test equipment also includes a power distribution box 900, which is installed inside the second housing 130 to facilitate the power connection of various electrical components such as the cooler 310, the first heater 220, the second heater 620, and the evaporator 610.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery sealing immersion test device, characterized in that, include: The box is divided into a first box and a second box by a partition. An oil supply mechanism is installed in the second housing and adjacent to the first housing. The oil supply mechanism includes an oil storage tank and a first heater. The first heater is located in the oil storage tank and is used to heat the oil in the oil storage tank. A refrigeration system and a heat exchange pipe, wherein the heat exchange pipe is located inside the oil storage tank, and the refrigeration system is installed inside the second tank and connected to the heat exchange pipe, for cooling the oil in the oil storage tank; The test box is a conductive box located inside the first housing and has a sealed cavity for accommodating the battery. The circulation pipeline connects the oil tank and the test box and passes through the partition. The test box is connected to an external charging and discharging device via wires.

2. The battery sealing immersion test equipment according to claim 1, characterized in that, The first chamber contains a temperature chamber, at least part of the outer wall of the temperature chamber is spaced from the inner wall of the first chamber to form an air duct, the test box is disposed inside the temperature chamber, and the temperature chamber has an air inlet and an air outlet that connect the inside of the temperature chamber and the air duct; the battery sealing immersion test equipment also includes a temperature regulation system, which is used to regulate the air temperature inside the air duct.

3. The battery sealing immersion test equipment according to claim 2, characterized in that, The incubator has a bottom plate and side plates. The bottom plate is spaced from the bottom of the first box to form a first channel. The two side plates of the incubator, which are arranged opposite to each other, are spaced from the inner wall of the first box to form a second channel. The two second channels and the first channel are connected to form the air duct. The two side panels, which are arranged opposite to each other, are respectively provided with air inlets and air outlets.

4. The battery sealing immersion test equipment according to claim 3, characterized in that, The chamber is equipped with a support frame, and the test box is mounted on the support frame, with the test box facing the air inlet or adjacent to the air inlet.

5. The battery sealing immersion test equipment according to claim 4, characterized in that, The incubator is also equipped with a driving component, which is connected to the support frame and can drive the support frame to move up and down.

6. The battery sealing immersion test apparatus according to any one of claims 1 to 5, characterized in that, The oil supply mechanism also includes a replenishment tank and a replenishment pipe located inside the second tank, and the replenishment tank is connected to the oil storage tank through the replenishment pipe.

7. The battery sealing immersion test equipment according to claim 6, characterized in that, The oil supply mechanism also includes a vent pipe, and the replenishment tank is connected to the top of the oil storage tank through the vent pipe. The top of the replenishment tank is provided with an vent.

8. The battery sealing immersion test apparatus according to any one of claims 1 to 5, characterized in that, The refrigeration system includes a cooler, an inlet pipe, an outlet pipe, and a first circulation pump. The cooler is connected to the heat exchange pipeline through the inlet pipe and the outlet pipe, respectively, and the first circulation pump is installed on the inlet pipe.

9. The battery sealing immersion test apparatus according to any one of claims 1 to 5, characterized in that, The first housing contains a plurality of test boxes spaced apart. The circulation pipeline includes an oil inlet pipe, an oil return pipe, and a second circulation pump. The oil inlet pipe includes a main oil inlet pipe, a first oil distributor, and a plurality of oil inlet branch pipes. Each oil inlet branch pipe is connected to a test box in a corresponding manner. The main oil inlet pipe is connected to all the oil inlet branch pipes through the first oil distributor. The oil return pipe includes a main oil return pipe, a second oil distributor, and a plurality of oil return branch pipes. Each oil return branch pipe is connected to a test box in a corresponding manner. The main oil return pipe is connected to all the oil return branch pipes through the second oil distributor.

10. The battery sealing immersion test equipment according to claim 9, characterized in that, It also includes a flow meter, a valve, and a pressure sensor, with each of the inlet branch pipes equipped with the flow meter, the valve, and the pressure sensor.

Images