Anti-toppling control method and system for a refrigeration appliance and refrigeration appliance

Abstract

The application discloses a kind of anti-tipping control method of refrigeration equipment, anti-tipping control system and refrigeration equipment.The anti-tipping control method includes the following steps: when drawer needs to be opened or drawer is opened, the first weight data M1 of first weight sensor and the second weight data M2 of second weight sensor are obtained, wherein, and the first weight sensor is located in front of the second weight sensor;Maximum safe travel X1 of drawer is calculated according to first weight data M1 and second weight data M2;When drawer moves to maximum safe travel X1, send alarm signal or make drawer stop moving.Maximum safe travel X1 is used to indicate that there is no risk of tipping within how far distance drawer moves, when drawer has moved to maximum safe travel, then control drawer stops moving forward, or through alarm signal, remind user not to continue to open drawer, thereby effectively prevent refrigeration equipment from tipping.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment, and in particular to an anti-tipping control method, an anti-tipping control system, and refrigeration equipment for refrigeration equipment. Background Technology

[0002] For refrigeration equipment with drawer doors, if there are many items inside the drawer and the drawer is heavily loaded, the center of gravity of the refrigeration equipment will shift forward when the drawer is fully pulled out or pulled out a long distance, posing a risk of tipping over. If the refrigeration equipment tipps over, it is very likely to hit the user in front of the refrigeration equipment. Therefore, existing refrigeration equipment has serious safety hazards. Summary of the Invention

[0003] The purpose of this invention is to provide an anti-tipping control method, an anti-tipping control system, and a refrigeration device for preventing the refrigeration device from tipping over.

[0004] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides an anti-tipping control method for a refrigeration device, comprising the following steps:

[0005] Determine if the drawer is open; Then, the first weight data M1 of the first weight sensor and the second weight data M2 of the second weight sensor are obtained, wherein the first weight sensor and the second weight sensor are located below the drawer, and the first weight sensor is located in front of the second weight sensor. Calculate the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2; An alarm signal is sent when the drawer moves to its maximum safe travel distance X1.

[0006] As a further improvement to one embodiment of the present invention, the "determining whether the drawer is open" specifically means: The system detects whether the drawer has moved forward from its initial position using a distance sensor or a contact switch. If it has, the drawer opens; otherwise, it remains closed.

[0007] As a further improvement to one embodiment of the present invention, the step of "calculating the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2" specifically means: The overweight coefficient K1 is calculated using the first weight data M1 and the second weight data M2. The maximum safe travel distance X1 is determined based on the overload factor K1.

[0008] As a further improvement to one embodiment of the present invention, the step of "calculating the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2" further includes: The drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2. Calculate the maximum safe travel distance X1 based on K1 and K2.

[0009] As a further improvement to one embodiment of the present invention, K1 = 1 - (M - M0) / M0, and K2 = 2 M1 / M; where M = M1 + M2, and M0 is a preset weight threshold; When K1 / K2 is less than or equal to 0, X1 = 0; When K1 / K2 is greater than 0 and less than 1, X1=X0 K1 / K2, where X0 is the maximum travel of the drawer; When K1 / K2 is greater than 1, X1 = X0, where X0 is the maximum travel of the drawer.

[0010] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides an anti-tipping control method for a refrigeration device, comprising the following steps: Received instruction to open drawer; Acquire first weight data M1 from a first weight sensor and second weight data M2 from a second weight sensor, wherein the first weight sensor and the second weight sensor are located below the drawer, and the first weight sensor is located in front of the second weight sensor; Calculate the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2; When the drive unit moves the drawer forward to its maximum safe travel, the control unit shuts off to stop the drawer from moving.

[0011] As a further improvement to one embodiment of the present invention, the step of "calculating the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2" specifically means: The overweight coefficient K1 is calculated using the first weight data M1 and the second weight data M2. The maximum safe travel distance X1 is determined based on the overload factor K1.

[0012] As a further improvement to one embodiment of the present invention, the step of "calculating the maximum safe travel X1 of the drawer based on the first weight data M1 and the second weight data M2" further includes: The drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2. Calculate the maximum safe travel distance X1 based on K1 and K2.

[0013] As a further improvement to one embodiment of the present invention, K1 = 1 - (M - M0) / M0, and K2 = 2 M1 / M; where M = M1 + M2, and M0 is a preset weight threshold; When K1 / K2 is less than or equal to 0, X1 = 0; When K1 / K2 is greater than 0 and less than 1, X1=X0 K1 / K2, where X0 is the maximum travel of the drawer; When K1 / K2 is greater than 1, X1 = X0, where X0 is the maximum travel of the drawer.

[0014] As a further improvement to one embodiment of the present invention, the method further includes, after the statement "when the drive device drives the drawer to move forward to the maximum safe travel, the drive device is controlled to close so that the drawer stops moving", the following method is also included: Determine whether the drawer should continue moving forward; If so, an alarm signal will be sent.

[0015] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides an anti-tipping control system for refrigeration equipment, comprising: A first weight sensor and a second weight sensor are both located below the drawer of the refrigeration equipment, with the first weight sensor located in front of the second weight sensor. A controller, comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, and the processor executes the program to implement the steps of the anti-tipping control method for the refrigeration equipment.

[0016] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a refrigeration device, including a cabinet and a drawer installed inside the cabinet, the drawer being slidable relative to the cabinet in a front-to-back direction, characterized in that it further includes the anti-tipping control system, wherein the first weight sensor and the second weight sensor are both installed on the inner wall of the cabinet.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the maximum safe travel distance X1 is used to indicate how far the drawer can move without the risk of tipping over. When the drawer has moved to the maximum safe travel distance, the drawer is controlled to stop moving forward, or an alarm signal is used to remind the user not to continue opening the drawer, thereby effectively preventing the refrigeration equipment from tipping over. Attached Figure Description

[0018] Figure 1 This is the anti-tipping control method for refrigeration equipment according to the first embodiment of the present invention; Figure 2 This is the anti-tipping control method for refrigeration equipment according to the second embodiment of the present invention; Figure 3 This is a side view of a refrigeration device according to an embodiment of the present invention; Figure 4 This is a front view of a refrigeration device drawer after it has been hidden, according to one embodiment of the present invention; Among them, 10 is the cabinet; 20 is the drawer; 30 is the first weight sensor; and 40 is the second weight sensor. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0020] In the various illustrations of this invention, for ease of illustration, certain dimensions of structures or parts may be enlarged relative to other structures or parts; therefore, only the basic structure of the subject matter of this invention is used to illustrate the invention.

[0021] The first embodiment of the present invention provides an anti-tipping control method for a refrigeration device, applicable to refrigeration devices where the drawer 20 is opened manually.

[0022] Specifically, the refrigeration device includes a housing 10, a drawer 20 installed inside the housing 10, and a first weight sensor 30 and a second weight sensor 40 located below the drawer 20, with the first weight sensor 30 located in front of the second weight sensor 40. The drawer 20 can slide relative to the housing 10 in the front-back direction.

[0023] The anti-tipping control method for the refrigeration equipment includes the following steps: S11. Determine whether drawer 20 is open.

[0024] If the result of S11 is yes, then execute S12 to obtain the first weight data M1 of the first weight sensor 30 and the second weight data M2 of the second weight sensor 40.

[0025] S13. Calculate the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2.

[0026] The maximum safe travel distance X1 is used to indicate how far the drawer 20 can be moved without the risk of tipping over.

[0027] S14. An alarm signal is sent when drawer 20 moves to the maximum safe travel distance X1.

[0028] The overall weight of drawer 20 can be obtained by using the first weight data M1 and the second weight data M2, thereby determining whether the load on drawer 20 is excessive. The weight distribution within drawer 20 can also be determined using the first weight data M1 and the second weight data M2, thus determining the distance drawer 20 can move forward without risk of tipping over. When drawer 20 reaches its maximum safe travel distance, an alarm signal is triggered to remind the user not to continue opening drawer 20, effectively preventing the refrigeration equipment from tipping over.

[0029] The "alarm signal" can be an alarm sound, such as a sound emitted through a voice module to alert the user, or a warning light, such as a warning light illuminating to alert the user.

[0030] The "determining whether drawer 20 is open" specifically means: detecting whether drawer 20 has moved forward from its initial position using a distance sensor or a contact switch; if so, drawer 20 is open; otherwise, drawer 20 is not open.

[0031] The distance sensor can be installed on the rear wall of the housing 10 to detect the position of the drawer 20. When the distance sensor detects that the drawer 20 has moved forward relative to its initial position, it indicates that the drawer 20 has been opened. Alternatively, the housing 10 may have a contact switch for contacting the drawer 20. When the drawer 20 is in its initial position, the contact switch is in contact with the drawer 20; when the drawer 20 moves forward, the contact switch disengages from the drawer 20, indicating that the drawer 20 has been opened.

[0032] In this embodiment, the travel of drawer 20 can be detected by a distance sensor installed on the rear wall of cabinet 10.

[0033] The phrase "calculate the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2" specifically means: calculating the overweight coefficient K1 using the first weight data M1 and the second weight data M2; and determining the maximum safe travel X1 based on the overweight coefficient K1.

[0034] The overload coefficient K1 is used to reflect the weight of drawer 20. The maximum safe travel X1 is determined by K1 so that the calculated maximum safe travel X1 is related to the load of drawer 20.

[0035] The phrase "calculating the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2" also includes: The drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2. Calculate the maximum safe travel distance X1 based on K1 and K2.

[0036] The drawer weight uniformity coefficient K2 is used to reflect whether the center of gravity of drawer 20 is forward or backward. The maximum safe travel X1 is determined by K2 and is related to the load of drawer 20.

[0037] Specifically, K1 = 1 - (M - M0) / M0, and K2 = 2 M1 / M; where M = M1 + M2, M0 is a preset weight threshold, and M is the weight of the drawer. When there is a load inside the drawer 20, M is greater than the preset M0.

[0038] The greater the drawer weight M exceeds the weight threshold M0, the smaller the overweight coefficient K1. The greater the weight in the front area of ​​drawer 20, i.e., the further forward the center of gravity, the larger the value of M1 and the larger the drawer weight uniformity coefficient K2.

[0039] When K1 / K2 is less than or equal to 0, X1 = 0.

[0040] If K1 / K2 is less than or equal to 0, that is, K1 is less than 0, the weight of drawer 20 is much greater than the preset weight threshold, and the load on drawer 20 is overloaded. Even if the drawer 20 is opened with a small stroke, it will still tilt forward. Therefore, the maximum safe stroke is set to zero, that is, the refrigeration unit will send an alarm signal as soon as the user pulls the drawer 20.

[0041] When K1 / K2 is greater than 0 and less than 1, X1=X0 K1 / K2, where X0 is the maximum stroke of drawer 20.

[0042] X0 represents the maximum travel distance that drawer 20 can be opened under no-load conditions. The specific value is determined by the internal structure of the refrigeration equipment. When K1 / K2 is greater than 0 and less than 1, if the drawer weight uniformity coefficient K2 remains constant, the greater the difference between the drawer weight M and the weight threshold M0, the smaller the overload coefficient K1 and the smaller the maximum safe travel distance X1. If the overload coefficient K1 remains constant, the larger the value of M1, the further forward the center of gravity of drawer 20 is, the larger the drawer weight uniformity coefficient K2 and the smaller the maximum safe travel distance X1.

[0043] In summary, the heavier the drawer and the closer the center of gravity is, the smaller the maximum safe travel X1 calculated by the overweight coefficient K1 and the drawer weight uniformity coefficient K2, which effectively prevents the refrigeration equipment from tipping over. Furthermore, while ensuring that the refrigeration equipment will not tip over, the length of the drawer 20 that can be pulled out is as long as possible, reducing the difficulty for users to take items out of the drawer 20.

[0044] When K1 / K2 is greater than 1, X1 = X0.

[0045] Since drawer 20 is in normal use and K1 is less than or equal to 1, if K1 / K2 is greater than 1, it means that the value of K2 is small, that is, the center of gravity of drawer 20 is far back. Therefore, drawer 20 can be opened directly to the maximum stroke without the risk of the refrigeration equipment tipping over.

[0046] The second embodiment of the present invention provides another anti-tipping control method for refrigeration equipment, applicable to refrigeration equipment that automatically opens the drawer 20.

[0047] Specifically, the refrigeration equipment includes a cabinet 10, a drawer 20 installed inside the cabinet 10, a drive device for driving the drawer 20 to move forward or backward, a first weight sensor 30 and a second weight sensor 40 located below the drawer 20, with the first weight sensor 30 located in front of the second weight sensor 40.

[0048] The drive mechanism is existing technology. In one embodiment, the drive mechanism includes a motor, a gear driven to rotate by the motor, and a rack mounted on the drawer and extending in a front-to-back direction. The motor drives the gear to rotate, causing the rack to move in the front-to-back direction, thereby moving the drawer 20 back and forth. The rack is preferably located below the gear to avoid the gear supporting the rack, which would prevent the first and second weight sensors from accurately detecting the weight of the drawer 20.

[0049] A gear mounted on drawer 20 and a rack extending in the front-to-back direction rotate and engage with each other. The rack moves back and forth along its length. The rack is preferably positioned above the gear to avoid the rack supporting the gear and preventing the first and second weight sensors from being properly engaged. The anti-tipping control method for the refrigeration equipment includes the following steps: S21, Received instruction to open drawer 20.

[0050] When this instruction is received, the aforementioned anti-tipping control method is executed. Specifically, this instruction can be sent by the user via a mobile terminal or via the touch panel of the refrigeration unit. Receiving this instruction indicates that the user needs to open drawer 20.

[0051] S22. Obtain the first weight data M1 from the first weight sensor 30 and the second weight data M2 from the second weight sensor 40.

[0052] S23. Calculate the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2.

[0053] The maximum safe travel distance X1 is used to indicate how far the drawer 20 can be moved without the risk of tipping over.

[0054] S24. When the drive unit drives the drawer 20 forward to the maximum safe travel distance, control the drive unit to close so that the drawer 20 stops moving.

[0055] The overall weight of drawer 20 can be obtained using the first weight data M1 and the second weight data M2, thereby determining whether the load on drawer 20 is excessive. The weight distribution within drawer 20 can also be determined using the first weight data M1 and the second weight data M2, thus determining the distance drawer 20 can move forward without risk of tipping over. When drawer 20 reaches its maximum safe travel distance, it is prevented from opening further, effectively preventing the refrigeration equipment from tipping over.

[0056] In this embodiment, the travel of drawer 20 can be detected by a distance sensor provided on the rear wall of the cabinet 10, or determined by the distance the gear moves driven by the drive device.

[0057] The phrase "calculate the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2" specifically means: calculating the overweight coefficient K1 using the first weight data M1 and the second weight data M2; and determining the maximum safe travel X1 based on the overweight coefficient K1.

[0058] The overload coefficient K1 is used to reflect the weight of drawer 20. The maximum safe travel X1 is determined by K1 so that the calculated maximum safe travel X1 is related to the load of drawer 20.

[0059] The phrase "calculating the maximum safe travel X1 of drawer 20 based on the first weight data M1 and the second weight data M2" also includes: The drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2. Calculate the maximum safe travel distance X1 based on K1 and K2.

[0060] The drawer weight uniformity coefficient K2 is used to reflect whether the center of gravity of drawer 20 is forward or backward. The maximum safe travel X1 is determined by K2 and is related to the load of drawer 20.

[0061] Specifically, K1 = 1 - (M - M0) / M0, and K2 = 2 M1 / M; where M = M1 + M2, M0 is a preset weight threshold, and M is the weight of the drawer. When there is a load inside the drawer 20, M is greater than the preset M0.

[0062] The greater the drawer weight M exceeds the weight threshold M0, the smaller the overweight coefficient K1. The greater the weight in the front area of ​​drawer 20, i.e., the further forward the center of gravity, the larger the value of M1 and the larger the drawer weight uniformity coefficient K2.

[0063] When K1 / K2 is less than or equal to 0, X1 = 0.

[0064] If K1 / K2 is less than or equal to 0, that is, K1 is less than 0, the weight of drawer 20 is much greater than the preset weight threshold. The load on drawer 20 is overloaded. Even if the drawer 20 opens with a small stroke, it will still tilt forward. Therefore, the maximum safe stroke is set to zero, that is, the drive device does not drive drawer 20 to move forward.

[0065] When K1 / K2 is greater than 0 and less than 1, X1=X0 K1 / K2, where X0 is the maximum stroke of drawer 20.

[0066] X0 represents the maximum travel distance that drawer 20 can be opened under no-load conditions. The specific value is determined by the specific structure of the refrigeration equipment, such as the length of the rack in the drive unit. When K1 / K2 is greater than 0 and less than 1, if the drawer weight uniformity coefficient K2 remains constant, the greater the difference between the drawer weight M and the weight threshold M0, the smaller the overload coefficient K1 and the smaller the maximum safe travel distance X1. If the overload coefficient K1 remains constant, the larger the value of M1, the further forward the center of gravity of drawer 20 is, the larger the drawer weight uniformity coefficient K2 and the smaller the maximum safe travel distance X1.

[0067] In summary, the heavier the drawer and the closer the center of gravity is, the smaller the maximum safe travel X1 calculated by the overweight coefficient K1 and the drawer weight uniformity coefficient K2, which effectively prevents the refrigeration equipment from tipping over. Furthermore, while ensuring that the refrigeration equipment will not tip over, the length of the drawer 20 that can be pulled out is as long as possible, reducing the difficulty for users to take items out of the drawer 20.

[0068] When K1 / K2 is greater than 1, X1 = X0.

[0069] Since drawer 20 is in normal use and K1 is less than or equal to 1, if K1 / K2 is greater than 1, it means that the value of K2 is small, that is, the center of gravity of drawer 20 is far back. Therefore, drawer 20 can be opened directly to the maximum stroke without the risk of the refrigeration equipment tipping over.

[0070] The description of "controlling the drive device to close so that the drawer 20 stops moving when the drive device drives the drawer 20 to move forward to the maximum safe travel" is followed by: determining whether the drawer 20 continues to move forward; if so, sending an alarm signal.

[0071] When drawer 20 has moved to its maximum safe travel distance, the user may actively pull it out, which poses a risk of the refrigeration unit tipping over. Therefore, if it is detected that drawer 20 continues to move forward after it has reached its maximum safe travel distance, an alarm signal will be sent to alert the user that the refrigeration unit is at risk of tipping over.

[0072] The "alarm signal" can be an alarm sound, such as a sound emitted through a voice module to alert the user, or a warning light, such as a warning light illuminating to alert the user.

[0073] In this embodiment, a distance sensor can be used to detect whether the drawer 20 continues to move forward. Specifically, the distance sensor can be installed on the rear wall of the cabinet 10 to detect the position of the drawer 20.

[0074] The present invention also provides an anti-tipping control system for refrigeration equipment, characterized in that it comprises: A first weight sensor 30 and a second weight sensor 40 are both located below the drawer 20 of the refrigeration equipment, and the first weight sensor 30 is located in front of the second weight sensor 40. The controller includes a memory and a processor. The memory stores a computer program that can run on the processor. The processor executes the program to perform the steps of the anti-tipping control method for the refrigeration equipment described in the first and second embodiments above.

[0075] The present invention also provides a refrigeration device, including a cabinet 10 and a drawer 20 installed inside the cabinet 10. The drawer 20 can slide relative to the cabinet 10 in the front-back direction. In the anti-tipping control system described in the above embodiment, the first weight sensor 30 and the second weight sensor 40 are both installed on the inner wall of the cabinet 10.

[0076] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preventing tipping over a refrigeration device, characterized in that, Includes the following steps: Determine if the drawer is open; Then, the first weight data M1 of the first weight sensor and the second weight data M2 of the second weight sensor are obtained, wherein the first weight sensor and the second weight sensor are located below the drawer, and the first weight sensor is located in front of the second weight sensor. The maximum safe travel X1 of the drawer is calculated based on the first weight data M1 and the second weight data M2, specifically: the overload coefficient K1 is calculated using the first weight data M1 and the second weight data M2; the drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2; where K1 = 1 - (M - M0) / M0, and K2 = 2. M1 / M; where M = M1 + M2, and M0 is a preset weight threshold; when K1 / K2 is less than or equal to 0, X1 = 0; when K1 / K2 is greater than 0 and less than 1, X1 = X0. K1 / K2, where X0 is the maximum travel of the drawer; when K1 / K2 is greater than 1, X1 = X0, where X0 is the maximum travel of the drawer; An alarm signal is sent when the drawer moves to its maximum safe travel distance X1.

2. The anti-tipping control method for refrigeration equipment according to claim 1, characterized in that, The specific meaning of "determining whether the drawer is open" is as follows: The system detects whether the drawer has moved forward from its initial position using a distance sensor or a contact switch. If it has, the drawer opens; otherwise, it remains closed.

3. A method for preventing tipping over a refrigeration device, characterized in that, Includes the following steps: Received instruction to open drawer; Acquire first weight data M1 from a first weight sensor and second weight data M2 from a second weight sensor, wherein the first weight sensor and the second weight sensor are located below the drawer, and the first weight sensor is located in front of the second weight sensor; The maximum safe travel X1 of the drawer is calculated based on the first weight data M1 and the second weight data M2, specifically: the overload coefficient K1 is calculated using the first weight data M1 and the second weight data M2; the drawer weight uniformity coefficient K2 is calculated using the first weight data M1 and the second weight data M2; where K1 = 1 - (M - M0) / M0, and K2 = 2. M1 / M; where M = M1 + M2, and M0 is a preset weight threshold; when K1 / K2 is less than or equal to 0, X1 = 0; when K1 / K2 is greater than 0 and less than 1, X1 = X0. K1 / K2, where X0 is the maximum travel of the drawer; when K1 / K2 is greater than 1, X1 = X0, where X0 is the maximum travel of the drawer; When the drive unit moves the drawer forward to its maximum safe travel, the control unit shuts off to stop the drawer from moving.

4. The anti-tipping control method for refrigeration equipment according to claim 3, characterized in that, The text further includes the following after the statement "when the drive unit drives the drawer forward to the maximum safe travel, control the drive unit to close so that the drawer stops moving"; Determine whether the drawer should continue moving forward; If so, an alarm signal will be sent.

5. An anti-tipping control system for refrigeration equipment, characterized in that, include: A first weight sensor and a second weight sensor are both located below the drawer of the refrigeration equipment, with the first weight sensor located in front of the second weight sensor. A controller, comprising a memory and a processor, the memory storing a computer program executable on the processor, the processor executing the program to implement the steps of the anti-tipping control method for the refrigeration equipment according to any one of claims 1-4.

6. A refrigeration device, comprising a cabinet and a drawer installed inside the cabinet, the drawer being slidable relative to the cabinet in a front-to-back direction, characterized in that, It also includes the anti-tipping control system as described in claim 5, wherein the first weight sensor and the second weight sensor are both installed on the inner wall of the housing.

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