A shelf lifting device, a refrigerator, and a control method of a shelf lifting device

Abstract

This invention discloses a shelf lifting device, a refrigerator, and a control method for the shelf lifting device. The shelf lifting device includes guide rails arranged on both sides and a shelf that can move up and down along the guide rails. It also includes a pressure sensor located at the lower end of each guide rail. The pressure sensor is electrically connected to a controller, which controls the shelf lifting speed to maintain a uniform and stable speed based on the real-time weight change of the shelf and the food on it, as measured by the pressure sensor. This invention effectively solves the vibration caused by changes in shelf lifting speed due to changes in food weight; it prevents the shelf from tilting and food from rolling off; and it overcomes the risk of shelf or motor damage caused by the shelf hitting the top, which may not be easily detected.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and in particular to a shelf lifting device and its control method used in refrigerator compartments. Background Technology

[0002] With the progress of the times and the rapid development of science and technology, people's requirements for quality of life have also increased. For household refrigerators, people no longer only require large capacity, but also have corresponding demands in terms of function and intelligence. Currently, most refrigerators on the market have fixed shelves, and users cannot easily adjust the distance between shelves according to changes in the height and volume of refrigerated items. This means that after purchasing large items, it is difficult to place them between the shelves, easily leading to low space utilization. Furthermore, with the increasing demand for large-capacity refrigerators and their increasing height, the fixed shelf positions make it inconvenient for users to access food on higher, fixed shelves, affecting the user experience.

[0003] Currently, various refrigerators with adjustable shelves are available on the market, and almost all of them are driven by a motor, which moves a rotating mechanism to raise or lower the shelves, allowing users to adjust the distance between the shelves according to their needs. Figure 1 , Figure 2 As shown, a refrigerator disclosed in the prior art 1 has a shelf 02 with lifting function in the refrigerator compartment. The shelf includes a shelf 4 for placing food and a lifting assembly 3 that can control the lifting of the shelf. The lifting assembly includes: a DC motor 37, a DC motor support frame, a support rod vertically arranged on the DC motor support frame, and a slide rail and pulley structure connected to the DC motor support frame. The DC motor support frame is fixed to the inner wall of the refrigerator, and the top of the support rod is fixedly connected to a connecting frame fixed to the slide rail and pulley structure. The connecting frame can move along the slide rail of the slide rail and pulley structure as the support rod moves up and down. The shelf is fixed to the connecting frame and can move automatically up and down with the connecting frame. For safety, the lifting assembly also includes limit switches to limit the lifting limit of the shelf. That is, the limit switches are set at the two extreme positions of the shelf's up and down travel to control the height and range of the shelf's lifting. When the refrigerator shelf moves upward and touches the upper limit switch, it stops moving; when the refrigerator shelf moves downward until it touches the lower limit switch, it also stops moving. To prevent the partition from colliding and damaging the interior walls of the room.

[0004] However, in daily life, the food on the shelves changes depending on needs or the season, meaning the weight the shelves can bear will change. For example... Figure 3 The figure shows the motor speed-torque curve. The vertical axis represents the motor speed N (r / min) and motor current (A), and the horizontal axis represents the motor torque T (Nm). From... Figure 3The two straight lines sloping to the left represent the speed-torque curves for two different types of DC motors; the straight line sloping to the right represents the current-torque curve for one type of DC motor. These curves show that speed and torque are inversely proportional, while torque and current are directly proportional. That is, the greater the torque, the lower the speed; conversely, if the torque increases, the speed also increases, and therefore the current (power) must also increase. The curves also show that the speed of existing DC motors changes with the weight of the food. If the user increases or decreases the total amount of food in the refrigerator, the speed at which the shelves rise and fall will change accordingly. This variation in the speed of the shelves' movement causes vibration in the moving parts, generating noise and potentially accumulating damage to the transmission mechanism, thus affecting the refrigerator's lifespan. Sometimes, food placed unevenly on the left and right sides of the shelves can easily roll off, causing inconvenience or loss for the user. Furthermore, existing motors cannot automatically stop the shelves from rising if the food reaches the top. This means that the shelf stopped rising before it even touched the upper limit switch because the food on it was too tall and touched the top of the refrigerator compartment. However, the DC motor was still powered on, and its power increased due to the increased load. If not handled promptly, this could damage the shelf and the motor, thus affecting the user experience.

[0005] Therefore, how to overcome the shortcomings of existing refrigerator shelf lifting devices, such as vibration caused by changes in the lifting speed of the shelves due to changes in the weight of food; uneven placement of food on the left and right sides of the shelves, making food easy to roll off the shelves; and the difficulty in noticing when the shelves touch the top, causing damage to the shelves and motor, are problems that need to be solved by those skilled in the art. Summary of the Invention

[0006] This invention addresses the problem of vibration caused by changes in shelf lifting speed due to variations in food weight in existing refrigerators. It provides a shelf lifting device, a refrigerator, and a control method for the shelf lifting device. This invention effectively solves the vibration problem caused by changes in shelf lifting speed due to variations in food weight; it prevents shelves from tilting and food from rolling off; and it overcomes the risk of shelf or motor damage caused by shelves hitting the top, which may not be easily detected.

[0007] The present invention provides a shelf lifting device, comprising guide rails arranged on both sides and a shelf capable of moving up and down along the guide rails. It also includes a pressure sensor located at the lower end of each guide rail, the pressure sensor being electrically connected to a controller. The controller controls the shelf lifting speed to remain uniform and stable based on the real-time weight change of the shelf and the food on it, measured by the pressure sensor.

[0008] Preferably, the shelf lifting device is equipped with a transmission device to drive the shelf to move up and down along the guide rail.

[0009] Preferably, the transmission device includes a horizontal shaft located between the two guide rails at the upper end of the guide rail, a drive motor that drives the horizontal shaft to rotate, and both ends of the horizontal shaft are connected to a longitudinal shaft vertically arranged on the side of the guide rail through a transmission mechanism. Each longitudinal shaft is threadedly connected to a sliding nut, which can slide up and down in the guide rail. The side of the sliding nut is fixedly connected to the shelf.

[0010] Preferably, the transmission mechanism is a pair of bevel gear transmission mechanisms or a worm gear transmission mechanism, through which the transmission between the mutually perpendicular horizontal and vertical axes is realized.

[0011] Preferably, the shelf is further provided with a pressure sensor in the partition plane to sense the pressure from above.

[0012] Preferably, each guide rail is equipped with a limit switch at both the upper and lower ends.

[0013] The present invention provides a refrigerator, characterized in that it includes the aforementioned shelf lifting device.

[0014] The present invention provides a control method for the shelf lifting device, comprising the following steps:

[0015] First, preset the speed of the drive motor to ensure smooth operation;

[0016] The pressure sensor detects the real-time weight G of the shelf and the food on it, and feeds it back to the controller. When the controller detects a change in the real-time weight G, it adjusts the voltage of the drive motor so that the speed of the drive motor matches the preset speed range of the drive motor, so as to keep the shelf moving up and down at a constant speed.

[0017] Preferably, the sum of the limited weight of the shelf and the weight on it is preset to be Gmax; the speed of the drive motor for smooth operation is preset to be three speeds: high, medium and low.

[0018] When G≥Gmax, an alarm is triggered; reduce the amount of food on the shelf until G<Gmax, then cancel the alarm.

[0019] When G < Gmax, the controller adjusts the voltage of the drive motor according to the formula: V = (UI * R) / K, so that the speed of the drive motor is maintained at the preset gear speed and moves at a constant speed.

[0020] Wherein: the real-time weight G = (G1 + G2) / 2 is the average weight; G1 is the weight measured by the pressure sensor on the right side of the shelf, and G2 is the weight measured by the pressure sensor on the left side of the shelf;

[0021] V, U, I, R, and K represent the speed, voltage, current, internal resistance, and reduction ratio of the drive motor, respectively.

[0022] Preferably, when the ratio of the weight G1 measured by the pressure sensor on the right to the weight G2 measured by the pressure sensor on the left is greater than parameter a, i.e., G1 / G2 > a, it indicates that the shelf is tilted to the right; when the ratio of the weight G1 measured by the pressure sensor on the right to the weight G2 measured by the pressure sensor on the left is less than another parameter b, i.e., G1 / G2 < b, it indicates that the shelf is tilted to the left; an alarm is triggered until the shelf returns to balance, at which point the alarm is canceled.

[0023] Where a is the experimentally measured value of the degree to which the shelf tilts to the right; b is the experimentally measured value of the degree to which the shelf tilts to the left.

[0024] Preferably, when the pressure sensor detects no change in the real-time weight G, and the shelf is in the rising phase, the pressure detected by the pressure sensor continues to increase, and the controller stops the drive motor from rotating after two seconds.

[0025] The shelf lifting device provided by this invention uses a DC geared motor and a transmission mechanism to connect two perpendicular shafts for transmission, thereby enabling the shelves in the refrigerator compartment to move up and down. The space above and below the shelves can be adjusted as needed. Specifically, when the lower shelf holds taller food items, the transmission mechanism can adjust the shelf's height, de-energize the motor, and stop the shelf assembly in the desired position, suitable for placing food of different heights. Pressure sensors on both sides can detect and calculate changes in the weight of food on the shelves. After comparison and judgment, the motor speed can be controlled to achieve uniform up-and-down movement of the shelves, avoiding vibration and noise caused by variable speed movement, thus extending the refrigerator's lifespan. The weight data measured by the pressure sensors on both sides of the shelf can determine if it is tilting to the left or right, allowing for timely adjustment to a balanced state and preventing food from rolling off the shelves, causing inconvenience or even loss. Furthermore, pressure sensors on the shelves can effectively detect if food is touching the top, causing increased load, and can promptly de-energize the motor to prevent damage. Attached Figure Description

[0026] Figure 1 This is a 3D schematic diagram of an existing refrigerator;

[0027] Figure 2 This is a schematic diagram of the shelf lifting mechanism used in existing refrigerators;

[0028] Figure 3 It is a graph of the motor's speed versus torque;

[0029] Figure 4 This is a perspective view of an embodiment of the shelf lifting device provided by the present invention;

[0030] Figure 5 yes Figure 4 The left view;

[0031] Figure 6 yes Figure 4 Schematic diagram of the transmission mechanism;

[0032] Figure 7 This is a control principle diagram of the shelf lifting device provided by the present invention;

[0033] Figure 8 This is a flowchart of the control method for the shelf lifting device provided by the present invention;

[0034] Figure 9 This is a schematic diagram of the principle of determining whether a shelf is tilted, provided by the present invention.

[0035] Existing technology Figure 1 , Figure 2 In the middle: 1-Refrigerator, 02-Shelf, 3-Lifting assembly, 4-Divider, 37-DC motor.

[0036] This invention Figures 3-9 In the middle: 01-guide rail, 02-shelf, 03-pressure sensor, 04-horizontal axis, 5-drive motor, 6-transmission mechanism, 7-vertical axis, 8-sliding nut, 9-pressure sensor, 10-limit switch. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0038] Currently, various refrigerators with adjustable shelves are available on the market, and almost all of them are driven by a motor, which moves a rotating mechanism to raise or lower the shelves, allowing users to adjust the distance between the shelves according to their needs. Figure 1 , Figure 2 As shown, a refrigerator 1 disclosed in the prior art has a shelf 02 with a lifting function inside. The shelf includes a shelf 4 for placing food and a lifting assembly 3. The lifting assembly includes: a DC motor 37, a DC motor support frame, a support rod vertically arranged on the DC motor support frame, and a slide rail and pulley structure connected to the DC motor support frame. The top end of the support rod is fixedly connected to a connecting frame fixed on the slide rail and pulley structure. The connecting frame can move along the slide rail in the slide rail and pulley structure as the support rod moves up and down. The shelf is fixed on the connecting frame and can move automatically up and down with the connecting frame.

[0039] However, the speed of the DC motor changes with the weight of the food on the shelves. In other words, increasing or decreasing the total amount of food will cause the shelf's lifting speed to change, resulting in vibration of moving parts, noise, and potential cumulative damage to the transmission mechanism, thus affecting the refrigerator's lifespan. Sometimes, food on the shelves is not placed evenly on both sides, causing it to roll off. Furthermore, in the current design, the shelf may not stop immediately when it reaches the top due to food height, which can damage the shelf and motor, thus impacting the user experience.

[0040] In order to solve the problems caused by the lifting and lowering of existing refrigerator shelves, the present invention provides a shelf lifting device, a refrigerator, and a control method for the lifting and lowering of shelves.

[0041] like Figure 4 , 5 Figure 6 illustrates an embodiment of a shelf lifting device for a refrigerator compartment provided by the present invention. It includes guide rails 01 vertically arranged on both sides and shelves 02 capable of moving up and down along the guide rails. It also includes pressure sensors 03 located at the lower end of each guide rail. These pressure sensors are electrically connected to the refrigerator's controller. The controller controls the shelf lifting speed to remain uniform and stable based on the real-time weight change of the shelf and its weight, measured by the pressure sensors. The shelf lifting device is equipped with a transmission mechanism to drive the shelves to move up and down along the guide rails.

[0042] Please combine Figure 4 , 5 6. The transmission device includes a horizontal shaft 04 located between the two guide rails at their upper ends, a drive motor 5 driving the horizontal shaft to rotate, and both ends of the horizontal shaft connected to a vertical shaft 7 vertically positioned on the side of the guide rail via a transmission mechanism 6. Each vertical shaft is threadedly connected to a sliding nut 8, which can slide up and down in the guide rail. The vertical shaft can actually be a lead screw. The side of the sliding nut is fixedly connected to the shelf. In this embodiment, the transmission mechanism can be a pair of bevel gear transmission mechanisms, or a worm gear transmission mechanism, to achieve transmission between the mutually perpendicular horizontal and vertical shafts. That is, drive motor 5 → horizontal shaft 04 rotates → transmission mechanism 6 drives → vertical shaft 7 rotates → sliding nut 8 slides up and down → shelf 02 moves up and down. The shelf partition plane is also provided with a pressure sensor 9 that senses the pressure of the top of the compartment. For example, the pressure sensor is located on the inner right side of the partition plane (e.g. Figure 4 As shown in the diagram, limit switches 10 are provided at both the upper and lower ends of each guide rail so that the pressure sensor can collect the pressure on the partition. When the shelf moves to the upper and lower limit positions and contacts the limit switches at the upper and lower ends of the guide rail, the drive motor can be de-energized and stopped to prevent damage.

[0043] The shelf lifting device proposed in this invention automatically controls the forward and reverse rotation of the drive motor via a controller, allowing the shelf to move up and down and stop at the desired position. This adjusts the height of the compartment to accommodate food items of different sizes and heights. Pressure sensors located at the lower ends of the guide rails on both sides detect changes in the weight of the food on the shelf and adjust the voltage of the drive motor accordingly, ensuring a uniform lifting speed and preventing vibration and noise caused by variations in food weight. The pressure sensors at the lower ends of the guide rails on both sides can also check for tilting of the shelf partitions, providing timely alerts to remind users to adjust food placement and maintain shelf stability.

[0044] The present invention also provides a refrigerator, wherein the intermediate compartment is provided with the shelf lifting device described in the present invention.

[0045] like Figure 7 As shown, the overall lifting control scheme of the shelf lifting device provided by the present invention is as follows:

[0046] First, the preset speed range for the drive motor to run smoothly is three speed ranges: high, medium, and low, which are represented by M3, M2, and M1 respectively.

[0047] The pressure sensor detects the real-time weight G of the shelf and the food on it, and feeds it back to the refrigerator controller. When the real-time weight G monitored by the controller changes, the voltage of the drive motor is adjusted so that the speed of the drive motor matches the preset speed setting, thereby maintaining the shelf at a uniform speed.

[0048] like Figure 8 As shown, an embodiment of the control method for the shelf lifting device provided by the present invention specifically includes the following steps:

[0049] Step 1: Preset the sum of the shelf and the maximum weight that can be placed on it as Gmax. The specific value can be determined by testing depending on the refrigerator model.

[0050] After the refrigerator is turned on, the pressure sensor detects whether the real-time weight G changes. When the detected real-time weight G changes, it needs to determine whether G > Gmax. If this condition is met, it means that the current shelf is in an overload state, and the refrigerator will issue an alarm to remind the user to reduce the amount of food on the shelf until the condition G < Gmax is met, at which point the overload warning will be canceled.

[0051] Wherein, G = (G1 + G2) / 2 is the calculated average weight; G1 is the weight measured by the pressure sensor on the right side of the shelf; and G2 is the weight measured by the pressure sensor on the left side of the shelf.

[0052] When G < Gmax, the controller adjusts the voltage of the drive motor according to the formula: V = (UI * R) / K, so that the speed of the drive motor is maintained at the preset gear speed and moves at a constant speed.

[0053] In the formula, V, U, I, R, and K represent the speed, voltage, current, internal resistance, and reduction ratio of the drive motor, respectively.

[0054] according to Figure 3 The NT curve of the motor shown indicates that as the torque T increases, the speed N decreases. This means the drive motor meets the requirement: it can drive the maximum shelf load Gmax at the lowest speed (i.e., maximum torque).

[0055] According to the relationship between torque T and rotational speed N: T = 9.55 * (P / N), where P is the power of the drive motor, the rotational speed N = 9.55 * (P / T) can be derived from this formula. When the weight on the shelf increases, the required torque T increases, and the rotational speed N decreases. To maintain a uniform rotational speed N, i.e., to ensure that the rotational speed N does not decrease with the increase of torque T, the power P of the drive motor can be increased accordingly, or the voltage U of the drive motor can be increased accordingly. In other words, when the weight on the shelf increases, the rotational speed V of the drive motor decreases, while the current I, internal resistance R, and reduction ratio K of the motor remain unchanged. According to the formula: V = (UI * R) / K, to maintain a uniform rotational speed V, the voltage U of the drive motor must be increased accordingly. Here, V and N are commonly used symbols in this field to represent the rotational speed of a drive motor; different symbols are used in different formulas. Similarly, when the weight on the shelf decreases, the rotational speed V of the drive motor increases. To maintain a constant speed by keeping the drive motor speed V constant, the drive motor voltage U must be reduced accordingly.

[0056] In actual control, the required adjustment voltage value based on the change value per unit weight measured in the experiment can be used as a reference. The voltage can be adjusted by substituting it into the formula V=(UI*R) / K. Then, fine-tuning of the voltage can be tried until the feedback drive motor speed V reaches the set gear speed, such as the low gear speed M1. Then, voltage adjustment can be stopped.

[0057] Based on pressure sensors installed on both sides, the system can detect and calculate changes in the weight of food on the shelves. After comparison and judgment, it can control the speed of the drive motor to remain constant regardless of changes in shelf weight, thus achieving uniform shelf lifting and lowering. This avoids vibration and noise caused by variable speed movement of the shelves, thereby extending the refrigerator's lifespan.

[0058] like Figure 9 As shown, this invention can determine whether a shelf is tilted based on the weight it bears, detected by a pressure sensor installed at the lower end of the guide rail. The specific method is as follows:

[0059] When the ratio of the weight G1 measured by the pressure sensor on the right side of the shelf to the weight G2 measured by the pressure sensor on the left side is greater than parameter a (G1 / G2 > a), it indicates that the shelf is tilted to the right. When the ratio of the weight G1 measured by the pressure sensor on the right side to the weight G2 measured by the pressure sensor on the left side is less than another parameter b (G1 / G2 < b), it indicates that the shelf is tilted to the left. In both cases, the system will issue an alarm until the shelf returns to balance and the tilt is eliminated, at which point the alarm will be canceled. Here, 'a' represents the experimentally measured degree of tilt to the right, and 'b' represents the experimentally measured degree of tilt to the left.

[0060] By measuring the weight data on both sides of the shelf using pressure sensors installed on both sides, it can be determined whether the shelf is tilted to the left or right, so that the shelf can be adjusted to a balanced state in time, which can prevent food on the shelf from rolling off and causing inconvenience or even loss.

[0061] refer to Figure 4 As shown, when the shelf is in the rising phase, the pressure sensors on both sides of the shelf detect no change in the real-time weight G, but the pressure detected by the pressure-sensitive sensor continues to increase. However, two seconds after this occurs, the controller automatically stops the drive motor from rotating. By installing pressure-sensitive sensors on the partition, it is possible to effectively detect whether the increased load is caused by food that is too tall and touches the top of the compartment, thus promptly cutting off the power to the drive motor to prevent damage.

[0062] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method of a shelf lifting device, characterized by, The shelf lifting device includes guide rails arranged on both sides and a shelf that can move up and down along the guide rails. It also includes a pressure sensor located at the lower end of each guide rail. The pressure sensor is electrically connected to a controller. The controller controls the shelf lifting speed to remain uniform and stable based on the real-time weight change of the shelf and the weight of the food on it measured by the pressure sensor. The control method includes the following steps: The preset speed of the drive motor for uniform operation; the preset weight limit of the shelf and the weight on it is Gmax; When the pressure sensor detects a real-time weight G ≥ Gmax, it sends an alarm to the controller; the amount of food on the shelf is reduced until G < Gmax, and the alarm is canceled. When G < Gmax is detected, the controller adjusts the voltage of the drive motor according to the formula: V = (UI * R) / K, so that the speed of the drive motor is maintained at the preset gear speed, so as to keep the shelf moving up and down at a uniform speed. Where: real-time weight G = (G1+G2) / 2, is the average weight; G1 is the weight measured by the pressure sensor on the right side of the shelf, and G2 is the weight measured by the pressure sensor on the left side of the shelf; V, U, I, R, and K represent the speed, voltage, current, internal resistance, and reduction ratio of the drive motor, respectively.

2. The control method according to claim 1, characterized by, When the ratio of the weight G1 measured by the pressure sensor on the right to the weight G2 measured by the pressure sensor on the left is greater than parameter a, i.e., G1 / G2 > a, it indicates that the shelf is tilted to the right; when the ratio of the weight G1 measured by the pressure sensor on the right to the weight G2 measured by the pressure sensor on the left is less than another parameter b, i.e., G1 / G2 < b, it indicates that the shelf is tilted to the left; an alarm will be triggered until the tilt of the shelf is eliminated, at which point the alarm will be deactivated. Where a is the experimentally measured value of the degree to which the shelf tilts to the right; b is the experimentally measured value of the degree to which the shelf tilts to the left.

3. The control method according to claim 1, characterized by, The shelf is also equipped with a pressure-sensitive sensor in the partition plane.

4. The control method according to claim 3, characterized by, When the pressure sensor detects no change in the real-time weight G, and the shelf is in the rising phase, the pressure detected by the pressure sensor continues to increase, and the drive motor stops rotating after two seconds.

5. The control method according to claim 1, characterized by, The speed range is divided into three levels: high, medium, and low.

6. The control method as described in claim 1, characterized in that, The shelf lifting device is equipped with a transmission device to drive the shelf to move up and down along the guide rail.

7. The control method as described in claim 6, characterized in that, The transmission device includes a horizontal shaft located between the two guide rails at the upper end of the guide rail, a drive motor that drives the horizontal shaft to rotate, and both ends of the horizontal shaft are connected to a vertical shaft erected on the side of the guide rail through a transmission mechanism. Each vertical shaft is threadedly connected to a sliding nut, which can slide up and down in the guide rail. The side of the sliding nut is fixedly connected to the shelf.

8. The control method as described in claim 7, characterized in that, The transmission mechanism is a pair of bevel gear transmission mechanisms or a worm gear transmission mechanism, which realizes the transmission between the horizontal axis and the vertical axis.

9. The control method as described in claim 1, characterized in that, Each of the guide rails is equipped with a limit switch at both the upper and lower ends.

10. The control method according to any one of claims 1 to 9, characterized in that, The shelf lifting device is located inside the refrigerator.

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