Pressure reducing device and coffee machine using same

Abstract

The pressure reducing device comprises a valve seat, a valve rod, an air inlet nozzle, a floating blocking mechanism and an adjusting knob, a high-pressure cavity and a low-pressure cavity are formed in the valve seat, the air inlet nozzle is installed in the valve seat and separates the high-pressure cavity from the low-pressure cavity, an air inlet channel is formed in the air inlet nozzle, an air hole is formed in the tail end of the air inlet channel, and the valve rod is arranged on the valve seat in a sleeved mode. The floating blocking mechanism is installed at the first end of the valve rod and matched with the air outlet end of the air hole, the floating blocking mechanism can be in elastic contact with the air inlet nozzle all the time, and the adjusting knob is installed at the second end of the valve rod and can drive the valve rod to rotate. According to the pressure reducing device, the floating blocking mechanism is adopted, the floating blocking mechanism has certain pressing force, high-pressure gas in the high-pressure cavity can enter the low-pressure cavity only after overcoming the pressing force, and therefore it can be guaranteed that the gas entering the low-pressure cavity has a stable air pressure value; therefore, the stability of the extraction pressure required by subsequent coffee making is ensured.

Description

Technical Field

[0001] This utility model relates to the field of daily necessities technology, and in particular to a pressure-reducing device and a coffee machine using the same. Background Technology

[0002] Most espresso machines on the market today use pump-press (high-pressure extraction), which works by actively applying pressure through an electric pump or piston device to force hot water to quickly pass through the coffee grounds. These include semi-automatic / fully automatic espresso machines and capsule coffee machines. These machines are characterized by their large size and high cost.

[0003] Some gas cylinder coffee machines have appeared on the market. Compared with traditional espresso machines, they have the advantage of being small in size, while at the same time providing the gas pressure needed for extraction, which can extract the aroma of coffee.

[0004] Gas cylinder-type coffee machines use gas cylinders as their gas source. These cylinders store high-pressure gas, which needs to be depressurized before use. However, existing gas cylinder-type coffee machines typically use depressurization devices that are separate from the machine itself. This means the machine is connected externally to the depressurization device described in patents such as CN204062068U and CN205654929U. As a result, while the coffee machine itself is small, the addition of a depressurization device results in a larger overall size, a less aesthetically pleasing appearance, and an inability to integrate the device seamlessly with the machine. Furthermore, the pressure adjustment knobs on existing coffee machines use threaded connections, requiring considerable force to turn. Some even require an extension handle to adjust the pressure. Existing technology suffers from inconvenient and laborious pressure adjustment. Utility Model Content

[0005] The purpose of this invention is to provide a pressure-reducing device that can at least solve one of the above-mentioned problems.

[0006] According to one aspect of the present invention, a pressure reducing device is provided, comprising a valve seat, a valve stem, an air inlet, a floating blocking mechanism, and an adjusting knob. The valve seat has a high-pressure chamber and a low-pressure chamber formed therein. The air inlet is installed in the valve seat and separates the high-pressure chamber and the low-pressure chamber. An air inlet channel is provided in the air inlet, and an air hole is provided at the end of the air inlet channel. The valve stem is fitted onto the valve seat. The floating blocking mechanism is installed at the first end of the valve stem and cooperates with the air outlet end of the air hole. The floating blocking mechanism can always maintain elastic contact with the air inlet. The adjusting knob is installed at the second end of the valve stem and can drive the valve stem to rotate.

[0007] In some embodiments, the floating plugging mechanism includes a floating rod and an elastic element. One end of the floating rod is movably fitted onto the valve stem, and the other end engages with the air orifice. The elastic element is fitted onto the outer periphery of the floating rod, and its two ends abut against the valve stem and the floating rod, respectively. Under the action of the elastic element, the floating rod always maintains elastic contact with the air inlet.

[0008] In some implementations, the elastic element includes at least one set of disc springs.

[0009] In some embodiments, a limiting boss is formed at the end of the floating rod away from the valve stem. The limiting boss is movably installed in the low-pressure chamber and cooperates with the air hole. The first end of the elastic element abuts against the limiting boss.

[0010] In some embodiments, the pressure reducing device further includes a bearing mounted on the end of the valve stem away from the adjusting knob and fitted around the outer periphery of the floating rod, with the two ends of the elastic element abutting against the bearing.

[0011] In some embodiments, the floating blocking mechanism further includes a blocking plate, which is mounted at the center of the end face of the floating rod near the air inlet and engages with the air hole.

[0012] In some embodiments, the valve stem and the valve seat are threadedly connected, the outer wall of the valve stem is provided with a first threaded connection portion, and the inner wall of the valve seat is provided with a second threaded connection portion that mates with the first threaded connection portion.

[0013] In some embodiments, the air inlet is threadedly connected to the valve seat, the outer wall of the air inlet is provided with a third threaded connection portion, and the inner wall of the valve seat is provided with a fourth threaded connection portion that mates with the third threaded connection portion.

[0014] In some embodiments, the pressure reducing device further includes a sealing cover, which is installed on the end face of the valve seat away from the valve stem and is in sealing fit with the valve seat. The valve seat, the air inlet, and the sealing cover together enclose a high-pressure chamber.

[0015] According to another aspect of the present invention, a coffee machine is also provided, including a main unit, a gas system, and a gas cylinder. The main unit includes a water tank and a coffee extraction chamber. The gas cylinder is connected to the input end of the gas system, and the output end of the gas system is connected to the water tank. The gas system includes a high-pressure pipeline, a gas pressure reducing device, and a low-pressure pipeline. The gas pressure reducing device is the aforementioned pressure reducing device. The input end of the high-pressure pipeline is connected to the gas cylinder, and the output end is connected to the high-pressure chamber of the gas pressure reducing device. The low-pressure chamber of the gas pressure reducing device is connected to the input end of the low-pressure pipeline, and the output end of the low-pressure pipeline is connected to the water tank.

[0016] The beneficial effects of this utility model are:

[0017] This utility model provides a pressure reducing device with a novel structure. This pressure reducing device is used to reduce the pressure of the high-pressure gas output from the gas cylinder to obtain the pressure required for extraction. The pressure reducing device adopts a floating blocking mechanism, which has a certain clamping force. The high-pressure gas in the high-pressure chamber needs to overcome this clamping force before it can enter the low-pressure chamber. Thus, it can ensure that the gas entering the low-pressure chamber has a stable gas pressure value, which ensures the stability of the extraction pressure required for subsequent coffee making.

[0018] This pressure reducing device uses a disc spring as the elastic element. Disc springs have advantages such as short stroke, heavy load, small space requirement, easy maintenance and replacement, and long service life. Compared with the cylindrical helical compression springs used in traditional pressure reducing valves or pressure reducing structures, the elastic element formed by the combination of disc springs has a smaller requirement for axial dimensions, thereby reducing the overall volume of the pressure reducing device. This allows it to be effectively integrated with the coffee machine and achieve a significant pressure reducing effect.

[0019] The pressure relief device is equipped with a bearing, which is a miniature thrust ball bearing. Its function is to bear axial load, and it has the advantages of high axial load and high rigidity. At the same time, it occupies little axial space. More importantly, the bearing enables smooth operation of the adjustment knob, and the turning process is smooth, which greatly improves the user experience.

[0020] This invention also provides a coffee machine with a novel structure. This coffee machine uses the aforementioned pressure-reducing device. As part of the coffee machine, the pressure-reducing device is effectively integrated with the machine body, resulting in a simple structure and an attractive appearance. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the pressure-reducing device of this utility model;

[0022] Figure 2 for Figure 1 The diagram shows a bottom view of the pressure-reducing device.

[0023] Figure 3 for Figure 2 A schematic cross-sectional view of the pressure-reducing device along the AA direction;

[0024] Figure 4 This is a schematic diagram of the exploded structure of the pressure-reducing device of this utility model;

[0025] Figure 5 This is a three-dimensional structural diagram of the valve seat of this utility model;

[0026] Figure 6 This is a three-dimensional structural diagram of the coffee machine of this utility model;

[0027] Figure 7 for Figure 6 The diagram shows the 3D structure of the coffee machine after omitting some structural elements.

[0028] Figure 8 This is a three-dimensional structural diagram of the host unit of this utility model;

[0029] Figure 9 for Figure 8 The diagram shows a top view of the structure.

[0030] Figure 10 for Figure 9 The diagram shows a cross-sectional view along the BB direction.

[0031] Figures 1-10 Figure labels in the diagram:

[0032] a-Main unit; b-Gas system; c-Gas cylinder; d-First housing; e-Second housing; f-Mount; a1-Water tank; a2-Coffee extraction chamber; a3-Mount; a4-Powder container; a5-Mounting base; b1-High-pressure pipeline; b2-Gas pressure reducing device; b3-Low-pressure pipeline; b31-Inlet pipe;

[0033] 1-Valve seat; 2-Valve stem; 3-Air inlet; 4-Floating plugging mechanism; 5-Adjusting knob; 6-Bearing; 7-Sealing cover; 11-High pressure chamber; 12-Low pressure chamber; 13-Second threaded connection; 14-Fourth threaded connection; 15-First connecting hole; 16-Second connecting hole; 21-First threaded connection; 22-Guide groove; 31-Air inlet channel; 32-Air hole; 33-Third threaded connection; 41-Floating rod; 42-Elastic element; 43-Plug plate; 421-Disc spring; 411-Limiting boss. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] Figures 1-5 The pressure-reducing device according to one embodiment of the present invention is shown schematically.

[0037] like Figures 1-5As shown, the pressure reducing device includes a valve seat 1, a valve stem 2, an air inlet 3, a floating blocking mechanism 4, and an adjusting knob 5. The valve seat 1 has a high-pressure chamber 11 and a low-pressure chamber 12. The air inlet 3 is installed in the valve seat 1 and separates the high-pressure chamber 11 and the low-pressure chamber 12. An air inlet channel 31 is provided in the air inlet 3, and an air hole 32 is provided at the end of the air inlet channel 31. The valve stem 2 is fitted onto the valve seat 1. The floating blocking mechanism 4 is installed at the first end of the valve stem 2 and cooperates with the air outlet end of the air hole 32. The floating blocking mechanism 4 can always maintain elastic contact with the air inlet 3. The adjusting knob 5 is installed at the second end of the valve stem 2 and can drive the valve stem 2 to rotate.

[0038] Preferably, the floating blocking mechanism 4 includes a floating rod 41 and an elastic element 42. One end of the floating rod 41 is movably fitted onto the valve stem 2, and the other end cooperates with the air hole 32. The elastic element 42 is fitted onto the outer periphery of the floating rod 41 and its two ends abut against the valve stem 2 and the floating rod 41 respectively. Under the action of the elastic element 42, the floating rod 41 always maintains elastic contact with the air inlet 3.

[0039] Preferably, the end of the valve stem 2 away from the adjusting knob 5 is provided with a guide groove 22 that cooperates with the limit of the floating rod 41.

[0040] Preferably, the elastic element 42 includes at least one set of disc springs 421.

[0041] As a further preferred embodiment, the disc springs 421 in this embodiment are in two sets, and each set of disc springs 421 includes two disc-shaped spring pieces that are combined in an opposing manner.

[0042] Preferably, a limiting boss 411 is formed at the end of the floating rod 41 away from the valve stem 2. The limiting boss 411 is movably installed in the low-pressure chamber 12 and cooperates with the air hole 32. The first end of the elastic member 42 abuts against the limiting boss 411.

[0043] Preferably, the pressure reducing device also includes a bearing 6, which is installed on the end of the valve stem 2 away from the adjusting knob 5 and fitted around the outer periphery of the floating rod 41, with the two ends of the elastic element 42 abutting against the bearing 6.

[0044] As a further preferred option, bearing 6 is a commercially available F4-8M miniature thrust ball bearing. It can achieve high axial load and high stiffness in a very small space.

[0045] Preferably, the floating blocking mechanism 4 also includes a blocking piece 43, which is installed at the center of one end face of the floating rod 41 near the air inlet 3 and cooperates with the air hole 32.

[0046] As a further preferred embodiment, the blocking plate 43 is made of PTFE gasket. PTFE gaskets have excellent properties such as corrosion resistance, aging resistance, and non-conductivity. They also exhibit good mechanical strength between -100℃ and 100℃. In this embodiment, the PTFE gasket enables soft contact with the air inlet 3, which not only avoids direct contact between the floating rod 41 and the air inlet 3, reducing friction and extending service life, but also provides good sealing performance after blocking, preventing air leakage and cross-contamination.

[0047] Preferably, the valve stem 2 is threadedly connected to the valve seat 1.

[0048] As a further preferred embodiment, the outer wall of the valve stem 2 is provided with a first threaded connection portion 21, and the inner wall of the valve seat 1 is provided with a second threaded connection portion 13 that cooperates with the first threaded connection portion 21.

[0049] Preferably, the air inlet 3 is threadedly connected to the valve seat 1.

[0050] As a further preferred embodiment, the outer wall of the air inlet nozzle 3 is provided with a third threaded connection portion 33, and the inner wall of the valve seat 1 is provided with a fourth threaded connection portion 14 that cooperates with the third threaded connection portion 33.

[0051] Preferably, the pressure reducing device also includes a sealing cover 7, which is fixedly installed on the end face of the valve seat 1 away from the valve stem 2 by screws or other fasteners and is sealed to the valve seat 1 by a sealing ring. The valve seat 1, the air inlet 3 and the sealing cover 7 together form a high-pressure chamber 11.

[0052] In addition, to achieve this, the valve seat 1 of this embodiment is also provided with a first connection hole 15 for connecting to the high-pressure pipeline b1 and a second connection hole 16 for connecting to the low-pressure pipeline b3. The first connection hole 15 is connected to the high-pressure chamber 11 and the second connection hole 16 is connected to the low-pressure chamber 12.

[0053] The working principle of this utility model is as follows:

[0054] Taking this embodiment as an example in a coffee machine, this espresso machine uses gas cylinder C as its gas source. Gas cylinder C can be a commercially available 8g small steel cylinder of carbon dioxide, and the pressure range of the high-pressure gas in gas cylinder C is 60-70 bar. Professional espresso machines, on the other hand, mainly use hot water at around 93 degrees Celsius to apply a pressure of 9 bar to impregnate and brew coffee grounds, producing a rich and aromatic espresso.

[0055] The working principle of the pressure reducing device in this embodiment is as follows: Taking the output pressure of gas cylinder c as 65 bar as an example, the pressure of the floating blocking mechanism 4 pressing the air inlet 3 is set to 56 bar by adjusting the adjustment knob 5 and setting the elastic element 42. In this state, the high pressure gas in the high pressure chamber 11 can make the floating rod 41 of the floating blocking mechanism 4 move away from the air inlet 3 and enter the low pressure chamber 12 through the air hole 32. Since the high pressure gas overcomes the pressure of the floating blocking mechanism 4 pressing the air inlet 3, the high pressure gas is passively depressurized, so that the pressure of the gas actually entering the low pressure chamber 12 is reduced to 9 bar. When the output pressure of gas cylinder c is lower than 65 bar or the gas pressure in the low pressure chamber 12 is greater than 9 bar, the floating blocking mechanism 4 can be reset under the action of the elastic element 42 and re-block the air hole 32 of the air inlet 3. In this way, it can be ensured that the gas entering the low pressure chamber 12 can be stabilized at about 9 bar, thereby ensuring that the extraction pressure is stabilized at about 9 bar, which meets the extraction pressure requirements of professional espresso machines.

[0056] The pressure-reducing device of this invention has at least the following advantages over the prior art:

[0057] 1. This utility model provides a pressure reducing device with a novel structure. The pressure reducing device is used to reduce the pressure of the high-pressure gas output from the gas cylinder c to obtain the pressure required for extraction. The pressure reducing device adopts a floating blocking mechanism 4, which has a certain clamping force. The high-pressure gas in the high-pressure chamber 11 needs to overcome the clamping force before it can enter the low-pressure chamber 12. Thus, it can ensure that the gas entering the low-pressure chamber 12 has a stable gas pressure value, which ensures the stability of the extraction pressure required for subsequent coffee making.

[0058] 2. The pressure reducing device uses a disc spring 421 as the elastic element 42. The disc spring 421 has the advantages of short stroke, heavy load, small space requirement, easy maintenance and replacement, and long service life. Compared with the cylindrical helical compression spring used in traditional pressure reducing valves or pressure reducing structures, the elastic element 42 formed by the combination of disc springs 421 has a smaller requirement for axial dimension, thereby reducing the overall volume of the pressure reducing device. This allows it to be effectively combined with the coffee machine and achieve a significant pressure reducing effect.

[0059] 3. The pressure reducing device is equipped with a bearing 6, which is a miniature thrust ball bearing 6. Its function is to bear axial load. It has the advantages of high axial load and high rigidity. At the same time, it occupies little axial space. More importantly, the bearing 6 enables smooth operation of the adjustment knob 5. The turning process is smooth, which greatly improves the user's experience.

[0060] Example 2

[0061] Figures 6-10A coffee machine according to one embodiment of the present invention is shown schematically.

[0062] like Figures 6-10 As shown, the coffee machine includes a main unit a, a gas system b, and a gas cylinder c. The main unit a includes a water tank a1 and a coffee extraction chamber a2 connected by a one-way valve. The gas cylinder c is connected to the input end of the gas system b, and the output end of the gas system b is connected to the water tank a1. The gas system b includes a high-pressure pipeline b1, a gas pressure reducing device b2, and a low-pressure pipeline b3. The gas pressure reducing device b2 is the aforementioned pressure reducing device. The input end of the high-pressure pipeline b1 is connected to the gas cylinder c, and the output end is connected to the high-pressure chamber 11 of the gas pressure reducing device b2. The low-pressure chamber 12 of the gas pressure reducing device b2 is connected to the input end of the low-pressure pipeline b3, and the output end of the low-pressure pipeline b3 is connected to the water tank a1.

[0063] Preferably, the main unit a in this embodiment further includes a fixed base a3, a coffee bowl a4, and a mounting base a5. The fixed base a3 is located at the bottom of the water tank a1, and the mounting base a5 is located at the bottom of the fixed base a3 and is detachably connected to the fixed base a3. The coffee bowl a4 is used to hold coffee powder, and the coffee bowl a4 is fitted into the mounting base a5 and can be pressed tightly against the bottom of the fixed base a3 by the mounting base a5. The coffee bowl a4 and the fixed base a3 together form a coffee extraction chamber a2. An air inlet pipe b31 is installed on the fixed base a3. The first end of the air inlet pipe b31 is connected to the output end of the low-pressure pipe b3, and the second end passes through the water tank a1 and extends to the top of the interior of the water tank a1. Thus, the hot water in the water tank a1 flows out from the bottom of the water tank a1 into the coffee bowl a4, and after contacting the coffee powder in the coffee bowl a4, coffee liquid is obtained. The coffee liquid flows out from the filter hole at the bottom of the coffee bowl a4.

[0064] Preferably, the coffee machine also includes a first housing d, a second housing e, and a base f. The base f is in contact with an external mounting surface. The first housing d is mounted on the upper surface of the base f and extends upward perpendicularly to the base f. The second housing e is mounted on one side of the first housing d and extends horizontally perpendicularly to the first housing d. The main unit a is mounted through the second housing e. One end of the valve seat 1 of the gas pressure reducing device b2 is fixedly connected to the first housing d by screws or other fasteners, and the other end passes through the first housing d and extends into the interior of the second housing e. The adjustment knob 5 is exposed outside the first housing d. The high-pressure pipeline b1 and the low-pressure pipeline b3 are both located inside the first housing d and the second housing e. The gas cylinder c is mounted on the first housing d.

[0065] The working principle of this coffee machine is as follows: After the gas cylinder c is installed and punctured, the high-pressure gas in the gas cylinder c is input to the gas pressure reducing device b2 through the high-pressure pipeline b1 for pressure reduction. The low-pressure gas after pressure reduction is transported to the air inlet pipe b31 through the low-pressure pipeline b3. The low-pressure gas comes out from the outlet of the air inlet pipe b31 and pressurizes the water in the water tank a1. Under the action of air pressure, the water in the water tank a1 breaks through the one-way valve and enters the coffee extraction chamber a2, comes into contact with the coffee powder in the coffee bowl a4, and obtains coffee liquid, which flows out from the bottom of the coffee bowl a4.

[0066] The coffee machine of this invention utilizes the aforementioned pressure-reducing device. As part of the coffee machine, the pressure-reducing device is effectively integrated with the machine body, resulting in a simple structure, attractive appearance, and effective pressure reduction to meet usage requirements.

[0067] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A pressure-reducing device, characterized in that, The device includes a valve seat (1), a valve stem (2), an air inlet (3), a floating blocking mechanism (4), and an adjusting knob (5). The valve seat (1) has a high-pressure chamber (11) and a low-pressure chamber (12). The air inlet (3) is installed in the valve seat (1) and separates the high-pressure chamber (11) and the low-pressure chamber (12). An air inlet channel (31) is provided in the air inlet (3), and an air hole (32) is provided at the end of the air inlet channel (31). The valve stem (2) is fitted onto the valve seat (1). The floating blocking mechanism (4) is installed at the first end of the valve stem (2) and cooperates with the air outlet end of the air hole (32). The floating blocking mechanism (4) can always maintain elastic contact with the air inlet (3). The adjusting knob (5) is installed at the second end of the valve stem (2) and can drive the valve stem (2) to rotate.

2. The pressure reducing device according to claim 1, characterized in that, The floating blocking mechanism (4) includes a floating rod (41) and an elastic element (42). One end of the floating rod (41) is movably fitted onto the valve stem (2), and the other end cooperates with the air hole (32). The elastic element (42) is fitted onto the outer periphery of the floating rod (41), and both ends abut against the valve stem (2) and the floating rod (41) respectively. Under the action of the elastic element (42), the floating rod (41) always maintains elastic contact with the air inlet (3).

3. The pressure reducing device according to claim 2, characterized in that, The elastic element (42) includes at least one set of disc springs (421).

4. The pressure reducing device according to claim 3, characterized in that, The floating rod (41) has a limiting boss (411) at one end away from the valve stem (2). The limiting boss (411) is movably installed in the low-pressure chamber (12) and cooperates with the air hole (32). The first end of the elastic member (42) abuts against the limiting boss (411).

5. The pressure reducing device according to claim 4, characterized in that, It also includes a bearing (6), which is installed on the end of the valve stem (2) away from the adjusting knob (5) and fitted on the outer periphery of the floating rod (41), and the two ends of the elastic element (42) abut against the bearing (6).

6. The pressure-reducing device according to any one of claims 2-5, characterized in that, The floating blocking mechanism (4) further includes a blocking piece (43), which is installed at the center of one end face of the floating rod (41) near the air inlet (3) and cooperates with the air hole (32).

7. The pressure-reducing device according to any one of claims 1-5, characterized in that, The valve stem (2) is threadedly connected to the valve seat (1). The outer wall of the valve stem (2) is provided with a first threaded connection part (21), and the inner wall of the valve seat (1) is provided with a second threaded connection part (13) that cooperates with the first threaded connection part (21).

8. The pressure reducing device according to any one of claims 1-5, characterized in that, The air inlet (3) is threadedly connected to the valve seat (1). The outer wall of the air inlet (3) is provided with a third threaded connection part (33), and the inner wall of the valve seat (1) is provided with a fourth threaded connection part (14) that cooperates with the third thread.

9. The pressure reducing device according to any one of claims 1-5, characterized in that, It also includes a sealing cap (7), which is installed on the end face of the valve seat (1) away from the valve stem (2) and is sealed to the valve seat (1). The valve seat (1), the air inlet (3) and the sealing cap (7) together form the high-pressure chamber (11).

10. A coffee machine, comprising a main unit (a), a gas system (b), and a gas cylinder (c), wherein the main unit (a) includes a water tank (a1) and a coffee extraction chamber (a2), the gas cylinder (c) is connected to the input end of the gas system (b), the output end of the gas system (b) is connected to the water tank (a1), and the gas system (b) includes a high-pressure pipeline (b1), a gas pressure reducing device (b2), and a low-pressure pipeline (b3), characterized in that, The gas pressure reducing device (b2) is the pressure reducing device according to any one of claims 1-9. The input end of the high-pressure pipeline (b1) is connected to the gas cylinder (c), and the output end is connected to the high-pressure chamber (11) of the gas pressure reducing device (b2). The low-pressure chamber (12) of the gas pressure reducing device (b2) is connected to the input end of the low-pressure pipeline (b3), and the output end of the low-pressure pipeline (b3) is connected to the water tank (a1).

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