Annular electric heating metal honeycomb carrier

Abstract

The invention relates to an annular electric heating metal honeycomb carrier, and relates to the field of tail gas emission treatment devices.The annular electric heating metal honeycomb carrier comprises a carrier body and a heating element, the heating element comprises an outer cylinder and a heating disc, the heating disc is installed on the outer cylinder, an annular plate is installed on the outer cylinder, an outer thread is formed in the outer surface of the annular plate, and the heating disc is installed on the outer cylinder; the annular plate is in threaded connection with a driving ring through the external threads, an elastic piece is arranged on the edge of the annular plate, the elastic piece is provided with a clamping block, and the driving ring is used for extruding the elastic piece to deform, so that the clamping block is clamped to the carrier body. The electric heating device has the effect that the electric heating element and the honeycomb carrier can be conveniently disassembled, assembled and overhauled.

Description

Technical Field

[0001] The present application relates to the field of tail gas emission treatment devices, and in particular to an annular electrically heated metal honeycomb carrier. Background Art

[0002] When cars and motorcycles are driving, the engine burns fuel to produce exhaust gas, which contains a variety of harmful substances, which are very harmful to the environment and human health. It is usually necessary to install an exhaust gas purification system in cars and motorcycles to treat the exhaust gas. Metal honeycomb carrier, as a new type of functional composite material, plays a great role in the exhaust gas purification system.

[0003] The electrically heated metal honeycomb carrier is a type of metal honeycomb carrier. Due to its unique electric heating function, it is particularly suitable for scenarios with high requirements on exhaust gas temperature, such as automobile exhaust purification in cold regions, specific industrial waste gas treatment, etc. In addition, in some occasions that require rapid startup and high-efficiency purification effects, the electrically heated metal honeycomb carrier also has significant advantages.

[0004] The electric heating element in the existing electric heating metal honeycomb carrier is integrally connected to the honeycomb carrier, usually by welding, which results in a long time for disassembly and assembly of the electric heating element and the honeycomb carrier. Therefore, it is troublesome to inspect and repair the electric heating element or the honeycomb panel separately. Summary of the invention

[0005] In order to facilitate the disassembly, assembly and maintenance of the electric heating element and the honeycomb carrier, the present application provides a ring-shaped electric heating metal honeycomb carrier.

[0006] The present application provides a ring-shaped electrically heated metal honeycomb substrate adopts the following technical solution: A ring-shaped electrically heated metal honeycomb carrier comprises a carrier body and a heating element, wherein the heating element comprises an outer cylinder and a heating plate, wherein the heating plate is mounted on the outer cylinder, a ring plate is mounted on the outer cylinder, an outer surface of the ring plate is provided with an external thread, a driving ring is threadedly connected to the ring plate via the external thread, an elastic sheet is arranged at the edge of the ring plate, a clamping block is arranged on the elastic sheet, and the driving ring is used to squeeze the elastic sheet to deform, thereby clamping the clamping block on the carrier body.

[0007] By adopting the above technical solution, the heating plate is installed on the outer cylinder, and the ring plate is installed on the outer cylinder. The outer surface of the ring plate is provided with an external thread. The driving ring connected to the ring plate by rotating the thread is used to squeeze the elastic sheet, and the elastic sheet is clamped on the carrier body by the clamping block installed on the elastic sheet. Therefore, the heating element and the carrier body can be quickly connected and removed by rotating the driving ring, thereby facilitating the disassembly, assembly and maintenance of the electric heating element and the honeycomb carrier.

[0008] In a specific possible implementation manner, a protrusion is provided on the outer surface of the carrier body, a groove is provided on the protrusion corresponding to the clamping block, and the clamping block can be clamped in the groove.

[0009] By adopting the above technical solution, a concave block is provided on the outer surface of the carrier body, and a groove is provided on the concave block corresponding to the snap-in block. The snap-in block can be snapped into the groove to replace the snap-in block being snapped on the outer surface of the carrier body, thereby improving the firmness of the connection between the heating element and the carrier body.

[0010] In a specific implementation scheme, a plurality of elastic sheets are provided, and the plurality of elastic sheets are evenly arranged along the circumference of the ring plate, and a clamping block is provided on each of the elastic sheets. The protrusion is correspondingly arranged in a ring shape, and a plurality of grooves are provided on the protrusion.

[0011] By adopting the above technical solution, a number of elastic sheets are set, and the several elastic sheets are evenly installed in the circumferential part of the ring plate, and the protrusions are correspondingly set in a ring shape, so that the several elastic sheets can be evenly clamped on the circumferential part of the outer surface of the carrier body, thereby further ensuring the firmness of the connection between the heating element and the carrier body.

[0012] In a specific possible implementation manner, it further comprises an electrode, wherein the electrode is mounted on the outer cylinder, and the electrode is used to electrically heat the heating disk.

[0013] In a specific possible implementation scheme, two electrodes are provided, both electrodes are installed on the outer cylinder, the conductive ends of the two electrodes penetrate the side wall of the outer cylinder, and the two electrodes are respectively connected to the two ends of the heating plate to serve as the positive and negative poles of the heating plate.

[0014] In a specific possible implementation mode, two electrodes are provided, and both electrodes are installed on the outer cylinder, wherein the conductive end of one of the electrodes penetrates the side wall of the outer cylinder and is connected to one end of the heating disk, and the other end of the heating disk is connected to the outer cylinder wire, and the other electrode is electrically connected to the outer cylinder, so that the outer cylinder serves as the positive electrode or negative electrode of the heating disk.

[0015] In a specific possible implementation mode, the electrode includes an electrode column, a steel sleeve, and an insulating filler. The electrode column is arranged in the steel sleeve, and the insulating filler is arranged between the electrode column and the steel sleeve. The steel sleeve is arranged on the outer cylinder, and the outer cylinder is provided with a mounting hole. The electrode column passes through the mounting hole and is electrically connected to the heating plate.

[0016] By adopting the above technical solution, when installing the electrode, the electrode column is inserted into the installation hole and connected to the heating plate, and then the steel sleeve is installed on the outer cylinder to complete the installation of the electrode. The insulating filler can make the electrode have a certain insulation.

[0017] In a specific possible implementation scheme, it also includes a circulation device, which includes an air inlet pipe, an air outlet hood and a circulation hood, the air inlet pipe is installed on the air outlet hood, the air outlet hood is clamped on the side of the carrier body away from the heating plate, the circulation hood is clamped on the side of the ring plate away from the carrier body, and the air inlet pipe passes through the heating plate and the carrier body and extends to the circulation hood.

[0018] By adopting the above technical solution, the intake pipe is installed on the exhaust hood, one end of the intake pipe is connected to the engine outlet, and the other end of the intake pipe passes through the heating plate and the carrier body and extends into the circulation hood. After the gas passes through the heating plate and the carrier body, it impacts the side wall of the circulation hood, and then enters the heating plate through the side wall of the circulation hood for heating, and then enters the carrier body, and is discharged through the exhaust hood, thereby ensuring a better catalytic effect while buffering the impact of the airflow.

[0019] In a specific feasible implementation scheme, the outer cylinder is provided with a support bar extending toward its own center position, the support bar is provided with a plurality of support members, the plurality of support members are arranged along the length direction of the support bar, and each of the support members is connected to the heating plate.

[0020] By adopting the above technical solution, when installing the heating plate, the support bar is first installed on the outer cylinder, and then the heating plate is inserted into the outer cylinder and connected to the support bar through multiple support members. Compared with the traditional honeycomb support body, this solution makes the exhaust gas flow more smoothly through the cooperation of the support retaining ring and the support bar, thereby reducing the pressure difference on both sides of the heating plate and reducing the back pressure of the heating plate, so that the engine has higher output power and lower energy consumption.

[0021] In a specific possible implementation scheme, it also includes a support member, which includes a support needle, an insulating ceramic, and a metal capillary. The support needle is connected to the support bar, the insulating ceramic is arranged on the support needle, and the metal capillary is arranged on the insulating ceramic. The metal capillary can be inserted into the honeycomb hole and welded to the heating plate.

[0022] By adopting the above technical solution, when installing the heating plate, the support bar is first installed on the outer cylinder, and then the heating plate is inserted into the outer cylinder and connected to the support bar through multiple support members. Compared with the traditional honeycomb support body, this solution makes the exhaust gas flow more smoothly through the cooperation of the support retaining ring and the support bar, thereby reducing the pressure difference on both sides of the heating plate and reducing the back pressure of the heating plate, so that the engine has higher output power and lower energy consumption.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. The heating plate is installed on the outer cylinder, and a ring plate is installed on the outer cylinder. The outer surface of the ring plate is provided with an external thread. The driving ring connected to the ring plate by the thread is rotated, so that the driving ring is installed to squeeze the elastic sheet, and the elastic sheet is clamped on the carrier body by the clamping block installed on the elastic sheet. Therefore, the heating element and the carrier body can be quickly connected and removed by rotating the driving ring, so that the disassembly and maintenance of the electric heating element and the honeycomb carrier are convenient; 2. The air intake pipe is installed on the air outlet hood, one end of the air intake pipe is connected to the air outlet of the engine, and the other end of the air intake pipe passes through the heating plate and the carrier body and extends into the circulation hood. After the gas passes through the heating plate and the carrier body, it impacts the side wall of the circulation hood, and then enters the heating plate through the side wall of the circulation hood for heating, and then enters the carrier body, and is discharged through the air outlet hood, thereby ensuring a better catalytic effect while buffering the impact of the airflow; 3. When installing the heating plate, first install the support bar on the outer cylinder, then insert the heating plate into the outer cylinder, and connect it to the support bar through multiple support members. Compared with the traditional honeycomb support body, this solution makes the exhaust gas flow more smoothly through the cooperation of the support retaining ring and the support bar, thereby reducing the pressure difference on both sides of the heating plate and reducing the back pressure of the heating plate, so that the engine has higher output power and lower energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of Example 1 of the present application.

[0025] Figure 2 This is a structural schematic diagram of the connection relationship between the slide plate and the carrier body in Example 1 of the present application.

[0026] Figure 3 This is a schematic diagram of the structure of the heating element in Example 1 of the present application.

[0027] Figure 4 This is a cross-sectional view showing the connection relationship between the support member and the heating plate in Example 1 of the present application.

[0028] Figure 5 This is a cross-sectional view of the electrode in Example 1 of the present application.

[0029] Figure 6 This is a cross-sectional view showing the connection relationship between the electrode and the heating plate according to Example 1 of the present application.

[0030] Figure 7 This is an exploded structural diagram of the circulation device in Example 1 of the present application.

[0031] Figure 8 This is a cross-sectional view showing the connection relationship between the electrode and the heating plate according to Example 2 of the present application.

[0032] Explanation of the reference numerals: 1. carrier body; 11. bump; 12. groove; 2. heating element; 21. outer cylinder; 22. heating plate; 3. circulation device; 31. air inlet pipe; 32. air outlet hood; 33. circulation hood; 4. support retaining ring; 41. support bar; 42. support member; 421. support needle; 422. insulating ceramic; 423. metal capillary; 5. electrode; 51. electrode column; 52. steel sleeve; 53. insulating filler; 6. ring plate; 61. elastic sheet; 62. drive ring; 63. snap-in block. DETAILED DESCRIPTION

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] In this specification, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or suggesting relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features.

[0035] The embodiment of the present application discloses a ring-shaped electrically heated metal honeycomb carrier.

[0036] Example 1 like Figure 1 and 2 As shown, the annular electrically heated metal honeycomb carrier includes a carrier body 1, a heating element 2 and a circulation device 3. The carrier body 1 can adopt a common metal honeycomb carrier commonly used in the market, the heating element includes an outer cylinder 21 and a heating plate 22, the heating plate 22 is installed in the outer cylinder 21, and the circulation device 3 is installed on the heating element 2 and the carrier body 1. The circulation device 3 is used to guide the exhaust gas to prevent the exhaust gas from directly impacting the heating plate 22 and the carrier body 1, thereby reducing the impact force on the heating plate 22 and the carrier body 1.

[0037] like Figure 2 As shown, a ring plate 6 is provided on the outer cylinder 21, and a plurality of elastic sheets 61 are provided on one side of the outer surface of the ring plate 6. The plurality of elastic sheets 61 are evenly installed on the circumferential portion of the edge of the ring plate 6. An external thread is provided on the outer surface of the ring plate 6 adjacent to the elastic sheet 61. A driving ring 62 is threadedly connected to the ring plate 6 through the external thread. A clamping block 63 is provided on the inner side of the side of the elastic sheet 61 away from the ring plate 6. A protrusion 11 is provided on the outer surface of the carrier body 1. The protrusion 11 is formed integrally with the outer cylinder 21 of the carrier body 1. The protrusion 11 is arranged as an annular block and is arranged coaxially with the carrier body 1. A groove 12 is provided on the protrusion 11 corresponding to the clamping block 63, and the clamping block 63 can be clamped in the groove 12.

[0038] The heating plate 22 is installed on the outer cylinder 21, and the ring plate 6 is installed on the outer cylinder 21. The outer surface of the ring plate 6 is provided with an external thread. The driving ring 62 connected to the thread on the ring plate is rotated, so that the driving ring 62 squeezes the elastic sheet 61, and is clamped on the carrier body 1 through the clamping block 63 installed on the elastic sheet 61. Therefore, by rotating the driving ring 62, the heating element 2 and the carrier body 1 can be quickly connected and removed, thereby facilitating the disassembly, assembly and maintenance of the electric heating element 2 and the honeycomb carrier.

[0039] like Figure 3 and 4 As shown, a support retaining ring 4 is provided in the outer cylinder 21, and the support retaining ring 4 is arranged along the circumference of the inner wall of the outer cylinder 21. The support retaining ring 4 is directly welded to the outer cylinder 21, and the support retaining ring 4 is located on one side of the heating plate 22. A plurality of support bars 41 are provided on the support retaining ring 4, and the support bars 41 and the support retaining ring 4 are processed and formed by an integrated laser cutting process of high-temperature resistant materials. The middle support bar 41 is in a circular ring shape, and the remaining support bars 41 are evenly spaced along the circumference of the support retaining ring 4, and the middle support bar 41 is connected to the support retaining ring 4. The support bars 41 arranged along the circumference of the support retaining ring 4 are spiral, and each support bar 41 is provided with a plurality of support members 42. The support members 42 in this embodiment It includes a support needle 421, an insulating ceramic 422, and a metal capillary 423. The insulating ceramic 422 is fixedly sleeved on one end of the support needle 421 away from the support bar 41. The metal capillary 423 is arranged on the insulating ceramic 422. Each support needle 421 is arranged along the axial direction of the outer cylinder 21. Each support needle 421 is welded to the support bar 41 by electric welding. A honeycomb hole is provided on the heating plate 22. The honeycomb hole is surrounded by a corrugated foil strip on the heating plate 22. The honeycomb hole corresponds to the support needle 421 one by one. Solder is coated on the support needle 421, and the support needle 421 is inserted into the honeycomb hole. Then, the support needle 421 is connected to the heating plate 22 by vacuum brazing.

[0040] When installing the heating plate 22, first solder the support needle 421 to the slot position and then install it on the support bar 41, then weld the support retaining ring 4 to the outer cylinder 21, and apply solder on the metal capillary 423. The setting of the metal capillary 423 facilitates the coating of solder; then insert the heating plate 22 into the outer cylinder 21, so that the metal capillary 423 is inserted into the honeycomb hole, and finally complete the connection between the support needle 421 and the heating plate 22 by vacuum brazing. When the exhaust gas is heated by passing through the heating plate 22, compared with the traditional honeycomb support body, this solution can reduce the exhaust gas flow resistance through the cooperation of the support retaining ring 4 and the support bar 41, so that the exhaust gas flows more smoothly, thereby reducing the pressure difference on both sides of the heating plate 22, and reducing the back pressure of the heating plate 22, so that the engine has higher output power and lower energy consumption.

[0041] like Figure 5 and 6 As shown, in the embodiment of the present application, it also includes an electrode 5, two electrodes 5 are provided, and the two electrodes 5 are both installed on the ring plate 6. The conductive ends of the two electrodes 5 penetrate the ring plate 6 and the side wall of the outer cylinder 21 and extend to the inner part of the outer cylinder 21. The two electrodes 5 are respectively connected to the two ends of the heating disk 22, serving as the positive and negative poles of the heating disk 22. The electrode 5 includes an electrode column 51, a steel sleeve 52, and an insulating filler 53. The electrode column 51 is arranged in the steel sleeve 52, and the insulating filler 53 is arranged between the electrode column 51 and the steel sleeve 52. The steel sleeve 52 is arranged on the ring plate 6, and the outer cylinder 21 is provided with a mounting hole. The electrode column 51 passes through the mounting hole and is electrically connected to the heating disk 22.

[0042] As shown in the figure, the circulation device 3 includes an air inlet pipe 31, an air outlet hood 32 and a circulation hood 33. The air inlet pipe 31 is installed on the air outlet hood 32. The air outlet hood 32 is clamped on the side of the ring plate 6 away from the carrier body 1. The circulation hood 33 is clamped on the side of the carrier body 1 away from the heating plate 22. The air inlet pipe 31 passes through the heating plate 22 and the carrier body 1 and extends to the circulation hood 33. The air inlet pipe 31 is installed on the air outlet hood 32. One end of the air inlet pipe 31 is connected to the engine air outlet, and the other end of the air inlet pipe 31 passes through the heating plate 22 and the carrier body 1 and extends into the circulation hood 33. After passing through the heating plate 22 and the carrier body 1, the gas impacts the side wall of the circulation hood 33, and then enters the heating plate 22 through the side wall of the circulation hood 33 for heating and then enters the carrier body 1, and is discharged through the air outlet hood 32, thereby ensuring a better catalytic effect while buffering the impact of the airflow.

[0043] The implementation principle of an annular electrically heated metal honeycomb carrier in the embodiment of the present application is as follows: a heating disk 22 is mounted on an outer cylinder 21, and a ring plate 6 is mounted on the outer cylinder 21. An external thread is provided on the outer surface of the ring plate 6. A driving ring 62 connected to the annular plate by rotating the thread causes the driving ring 62 to squeeze the elastic sheet 61, and the driving ring 62 is clamped on the carrier body 1 by a clamping block 63 installed on the elastic sheet 61. Thus, by rotating the driving ring 62, the heating element 2 and the carrier body 1 can be quickly connected and removed, thereby facilitating the disassembly, assembly and maintenance of the electric heating element 2 and the honeycomb carrier. Then, by energizing the electrode 5, the heating disk 22 is heated, and the gas passes through the heating disk 22 and the carrier body 1 and then impacts the side wall of the circulation cover 33, and then passes through the side wall of the circulation cover 33 to enter the heating disk 22 for heating and then enter the carrier body 1, and is discharged through the gas outlet cover 32, thereby ensuring a better catalytic effect while buffering the impact of the airflow.

[0044] Example 2 like Figure 7 As shown, the difference between this embodiment and embodiment 1 is that the two electrodes 5 in this embodiment are both installed on the ring plate 6, wherein the conductive end of one electrode 5 penetrates the ring plate 6 and the side wall of the outer cylinder 21 and is connected to one end of the heating disk 22, and the other end of the heating disk 22 is electrically connected to the outer shell, and the other electrode 5 penetrates the side wall of the ring plate 6 and is electrically connected to the outer cylinder 21, so that the outer cylinder 21 serves as the positive electrode or negative electrode of the heating disk 22.

[0045] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A ring-shaped electrically heated metal honeycomb carrier, characterized in that: The invention comprises a carrier body (1) and a heating element (2), wherein the heating element (2) comprises an outer cylinder (21) and a heating disk (22), wherein the heating disk (22) is mounted on the outer cylinder (21), wherein a ring plate (6) is mounted on the outer cylinder (21), wherein an outer surface of the ring plate (6) is provided with an external thread, wherein a driving ring (62) is threadedly connected to the ring plate via the external thread, wherein an elastic sheet (61) is arranged at the edge of the ring plate (6), wherein the elastic sheet (61) is provided with a clamping block (63), wherein the driving ring (62) is used for squeezing the elastic sheet (61) to deform, thereby clamping the clamping block (63) on the carrier body (1).

2. The annular electrically heated metal honeycomb carrier according to claim 1 is characterized in that: The outer surface of the carrier body (1) is provided with a protrusion (11), and a groove (12) is provided on the protrusion (11) corresponding to the clamping block (63), and the clamping block (63) can be clamped in the groove (12).

3. The annular electrically heated metal honeycomb carrier according to claim 2 is characterized in that: A plurality of elastic sheets (61) are provided, and the plurality of elastic sheets (61) are evenly arranged along the circumference of the ring plate (6). A clamping block (63) is provided on each of the elastic sheets (61). The convex block (11) is correspondingly arranged in a ring shape, and a plurality of grooves (12) are provided on the convex block (11).

4. The annular electrically heated metal honeycomb carrier according to claim 1 is characterized in that: It also comprises an electrode (5), wherein the electrode (5) is mounted on the outer cylinder (21), and the electrode (5) is used to electrically heat the heating disk (22).

5. The annular electrically heated metal honeycomb carrier according to claim 4 is characterized in that: Two electrodes (5) are provided, and both electrodes (5) are mounted on the outer tube (21). One conductive end of the two electrodes (5) penetrates the side wall of the outer tube (21). The two electrodes (5) are respectively connected to the two ends of the heating plate (22) to serve as the positive and negative electrodes of the heating plate (22).

6. The annular electrically heated metal honeycomb carrier according to claim 4, characterized in that: Two electrodes (5) are provided, and both electrodes (5) are installed on the outer tube (21). One of the electrodes (5) has a conductive end that penetrates the side wall of the outer tube (21) and is connected to one end of the heating disk (22). The other end of the heating disk (22) is connected to the outer tube (21) by an electric wire. The other electrode (5) is electrically connected to the outer tube (21), so that the outer tube (21) serves as the positive electrode or negative electrode of the heating disk (22).

7. The annular electrically heated metal honeycomb carrier according to claim 4, characterized in that: The electrode (5) comprises an electrode column (51), a steel sleeve (52), and an insulating filler (53); the electrode column (51) is arranged in the steel sleeve (52); the insulating filler (53) is arranged between the electrode column (51) and the steel sleeve (52); the steel sleeve (52) is arranged on the outer cylinder (21); a mounting hole is provided on the outer cylinder (21); the electrode column (51) passes through the mounting hole and is electrically connected to the heating plate (22).

8. The annular electrically heated metal honeycomb carrier according to claim 1, characterized in that: The invention also comprises a circulation device (3), wherein the circulation device (3) comprises an air inlet pipe (31), an air outlet hood (32) and a circulation hood (33); the air inlet pipe (31) is mounted on the air outlet hood (32); the air outlet hood (32) is clamped on a portion of the carrier body (1) on a side away from the heating plate (22); the circulation hood (33) is clamped on a portion of the ring plate (6) on a side away from the carrier body (1); the air inlet pipe (31) passes through the heating plate (22) and the carrier body (1) and extends to the circulation hood (33).

9. The annular electrically heated metal honeycomb carrier according to claim 1, characterized in that: The outer cylinder (21) is provided with a support bar (41) extending towards its own center position, and the support bar (41) is provided with a plurality of support members (42). The plurality of support members (42) are arranged along the length direction of the support bar (41), and each of the support members (42) is connected to the heating plate (22).

10. The annular electrically heated metal honeycomb carrier according to claim 9, characterized in that: The heating plate (22) is provided with honeycomb holes, and the honeycomb holes correspond to the support member (42) one by one. The support member (42) is plugged into the heating plate (22) by being inserted into the heating plate (22). The support member (42) comprises a support needle (421), an insulating ceramic (422), and a metal capillary (423). The support needle (421) is connected to the support bar (41). The insulating ceramic (422) is arranged on the support needle (421). The metal capillary (423) is arranged on the insulating ceramic (422). The metal capillary (423) can be inserted into the honeycomb holes and welded to the heating plate (22).

Images