An extractor hood and a method for protecting an oil cup of the extractor hood

Abstract

The application discloses an oil fume extractor and an oil cup protection method of the oil fume extractor. The oil fume extractor comprises a lower box body and an air inlet body. The air inlet body can be lifted relative to the lower box body. The bottom of the air inlet body is provided with an oil cup. In a non-working state of the oil fume extractor, the air inlet body and the oil cup are folded in the lower box body. In a working state of the oil fume extractor, the air inlet body and the oil cup are exposed below the lower box body. In the working state of the oil fume extractor, the oil cup is completely stored in the lower box body, so that the occupied space in the non-working state is further reduced, and the user's bad experience caused by the exposure of the oil cup is avoided.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to a range hood and a method for protecting the oil cup of the range hood. Background Technology

[0002] Range hoods have become an indispensable kitchen appliance in modern homes. They operate on the principles of fluid dynamics, using a centrifugal fan inside to draw in cooking fumes and a filter to remove some grease particles. The centrifugal fan consists of a casing, an impeller housed within the casing, and a motor that drives the impeller. As the impeller rotates, a negative pressure is generated at the center of the fan, drawing in the cooking fumes from below. After being accelerated by the fan, the fumes are collected by the casing and guided outdoors.

[0003] Changing the working form of a range hood can achieve both effective smoke extraction during operation and a sleek, aesthetically pleasing design when off. The lift-type range hood represents a significant direction in this design evolution. Existing lift-type range hoods, such as the concealed range hood disclosed in Chinese Patent Application No. 201821783223.X, include a fan cabinet and a smoke collection hood. The smoke collection hood and fan cabinet are connected, and a first lifting mechanism is provided between them. This first lifting mechanism drives the smoke collection hood to move up and down. The smoke collection hood also includes a movable smoke gathering hood, and a second lifting mechanism is provided within the inner cavity of the smoke collection hood. This second lifting mechanism drives the movable smoke gathering hood to move up and down along a channel.

[0004] However, the oil cup of this type of range hood cannot be completely stored. Furthermore, current range hood lifting mechanisms are typically controlled by methods such as running time, mechanical limit switches, and motor stall current. Time-based control of the lifting mechanism only achieves basic motion control and cannot protect against abnormalities that occur during operation, such as failure to detect mechanism stall or drive motor damage. Limit switch control can only detect whether the moving mechanism has reached the limit switch's position; if multiple positions need to be detected, multiple limit switches are required, resulting in lower cost and reliability. Drive motor current detection is a commonly used method for stall protection and motor damage protection. However, factors such as the motor commutator and winding connection cause current fluctuations, leading to poor detection accuracy and response speed. Additionally, due to the influence of load torque at different positions throughout the movement, the motor's operating current may vary significantly, and relying solely on current detection for stall detection or hand-clamp protection may result in false alarms.

[0005] The inability to effectively protect against or promptly address potential anomalies during lifting can lead to product structural damage or potential safety hazards. For example, in patent 202122871206.X, the oil cup holder stops rotating when it reaches the sensor at the designated position during lifting. However, if foreign objects obstruct contact with the sensor in other locations, the stop control cannot be achieved, posing a risk of malfunction. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a range hood that reduces the space occupied by the range hood when it is not in operation.

[0007] The second technical problem to be solved by the present invention is to provide a method for protecting the oil cup of the above-mentioned range hood.

[0008] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: a range hood, comprising a lower housing and an air inlet, wherein the air inlet is movable relative to the lower housing, and an oil cup is provided at the bottom of the air inlet; characterized in that:

[0009] When the range hood is not in operation, the air inlet and oil cup are retracted into the lower housing;

[0010] When the range hood is in operation, the air inlet and oil cup are exposed below the lower housing.

[0011] By ensuring that the oil cup is completely retracted into the lower housing when the range hood is in operation, the space occupied when not in operation is further reduced, and the unpleasant experience caused by the exposed oil cup is avoided.

[0012] Furthermore, the range hood also includes an upper housing, and the lower housing and the air inlet can be raised and lowered relative to the upper housing, thereby further expanding the lifting range and making the air inlet closer to the smoke source, thus improving the smoke extraction effect.

[0013] Furthermore, the lower housing is fitted over the outer side of the upper housing, and the lower end of the upper housing extends from the upper end of the lower housing into the lower housing, thereby reducing oil leakage into the upper housing.

[0014] Furthermore, the lower housing is fitted outside the air inlet body, and the upper end of the air inlet body extends from the lower end of the lower housing into the lower housing body, thereby facilitating the air inlet body to be retracted when not in operation.

[0015] Furthermore, the air intake includes an air inlet on the front side, and a smoke baffle is provided at the bottom of the lower housing, thereby expanding the smoke collection range.

[0016] Furthermore, to facilitate the driving of the air intake, the range hood also includes a motor for driving the air intake to rise and fall.

[0017] Furthermore, to facilitate motor control, the range hood also includes a motion control module, which includes a control chip and a drive circuit. The drive circuit receives control signals from the control chip and is used to drive the motor to rotate forward or in reverse.

[0018] Furthermore, to facilitate the detection of motor parameters for the protection of the oil cup, the motion control module also includes a motion detection circuit for detecting motor speed and stroke, and a current detection circuit for detecting motor current.

[0019] Furthermore, to facilitate user input of control commands, the motion control module also includes a user operation input unit for inputting commands to the control chip.

[0020] The technical solution adopted by the present invention to solve the second technical problem mentioned above is: a method for protecting the oil cup of a range hood as described above, characterized by comprising the following steps:

[0021] 1) Determine if the range hood is rising or falling;

[0022] 2) Read or calculate the current motor speed V', drive circuit i', and stroke position l';

[0023] 3) Determine if it is an upward motion. If yes, proceed to step 4); otherwise, return to step 1.

[0024] 4) Determine L H ≥l≥L L Is this condition met? If so, record the current speed V. x If not, return to step 1);

[0025] 5) Calculate the sum of current velocities within period t: ∑v=V0'+V1'…+V n ', where n is the number of records, and ∑V is the sum of reference speeds. ref =V ref0 +V ref1 …+V refn V ref0 …V ref1 …V refn This is a preset reference value;

[0026] 6) Calculate V бmax =V refx '-V x The maximum value in ' is used to determine if the oil cup is abnormal and to stop raising and lowering when one of the following conditions is met:

[0027] ∑V ref -∑v≥K1;

[0028] Vбmax ≥K2.

[0029] Wherein, K1 is the first preset difference and K2 is the second preset difference.

[0030] Preferred, V ref0 …V ref1 …V refn The methods to obtain it include the following steps:

[0031] 1) Determine if the range hood is rising or falling;

[0032] 2) Read or calculate the current motor speed V, drive circuit i, and stroke position l;

[0033] 3) Determine if it is an upward motion. If yes, proceed to step 4); otherwise, return to step 1.

[0034] 4) In I Max ≥i≥I min And L H ≥l≥L L If all conditions are met, record n ​​running speeds {V0, V1…V...} x …V n}, x = 1 to n, then proceed to step 5):

[0035] When |V x -V x+1 |≤V б If the data set is confirmed to be valid and saved, the current position is recorded. x The speed V at that time x V б To determine the allowable variation in operating speed, store the corresponding speeds {V0, V1, ..., Vn} for l0, l1, ..., ln. n Otherwise, return to step 1);

[0036] Where L H and L L Given the upper and lower limits of the motor travel range for normal lifting motion, I max and I min The upper and lower limits of the motor operating current for a given normal lifting and lowering motion;

[0037] Otherwise, return to step 1);

[0038] 6) After recording i sets of effective velocity values, we obtain {V0, V1…V...} n}、{V 10 V 11 …V 1n}…{V i0 V i1 …V in}, thus obtaining the reference velocity value {V} corresponding to each position. ref0 …V refx …V refn}, V ref0 According to {V0, V1…V n} We get V ref0 According to {V0, V 10 …Vi0} obtains…V refn According to {V n V 1n …Vi n}get.

[0039] Preferred, V ref0 Let {V0, V} 10 The mean of ...Vi0}, V refx For {V x V 1x …Vi x The mean of}...V refn For {V n V 1n …Vi n The mean of}

[0040] Preferably, before each operation, initialization is performed first: the control chip controls the motor to drive the air intake body to rise, and at the same time obtains or calculates the current current i and the current running speed V of the motor. When i≥I0 and V≤V0, the rising stops, and the current position is marked as point 0, thereby completing the initialization. Here, I0 and V0 are the default current and minimum movement speed threshold at the 0 point position.

[0041] Preferably, if the initialization process exceeds T0 without completing normal initialization, it is judged as a system fault and a prompt is issued, where T0 is the longest initialization time for system operation.

[0042] Compared with existing technologies, the advantages of this invention are as follows: When the range hood is in operation, the oil cup is completely retracted into the lower housing, further reducing the space occupied when not in operation and avoiding the unpleasant user experience caused by the exposed oil cup; by setting up a motion control module, combined with motor current detection, time control, and other comprehensive judgments, more accurate and faster judgments are achieved to solve the problem of the oil cup potentially getting stuck during the range hood's movement; by introducing stroke parameters, abnormal protection within a specified range is achieved, only checking for stalls in the movement range where oil cup jamming might occur, greatly reducing the probability of false judgments; by introducing lifting speed parameters and self-learning the operating speed within a specified stroke range, deviations caused by differences in individual machines and installation environments are resolved; by using two judgment conditions—the maximum speed difference and the sum of speed differences—rapid detection can be achieved, and it can also correctly identify slow speed changes due to decreased structural rigidity. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the working state of the range hood according to an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the oil cup of the range hood in an embodiment of the present invention about to collide.

[0045] Figure 3 This is a schematic diagram of the non-working state of the range hood according to an embodiment of the present invention;

[0046] Figure 4 This is a cross-sectional view of the range hood in its non-working state according to an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the non-working state of the range hood of this embodiment, showing the hidden upper and lower housing parts.

[0048] Figure 6 This is a schematic diagram of the motion control module of the range hood according to an embodiment of the present invention;

[0049] Figure 7 This is a flowchart illustrating the initialization process of the range hood according to an embodiment of the present invention.

[0050] Figure 8 This is a flowchart illustrating the calculation of the reference speed of the range hood according to an embodiment of the present invention;

[0051] Figure 9 This is a flowchart illustrating the jamming protection judgment process of a range hood according to an embodiment of the present invention. Detailed Implementation

[0052] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Since the embodiments disclosed in this invention can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0054] See Figures 1-5 A range hood includes an upper housing 1, a lower housing 2, and an air inlet 3, wherein the upper housing 1 is fixed and cannot be moved, such as being fixed to a wall, and a fan (not shown) is installed inside it.

[0055] The lower housing 2 and the air inlet 3 can move up and down relative to the upper housing 1. The upper housing 1 and the lower housing 2 are sleeved together, and the lower housing 2 and the air inlet 3 are sleeved together. In this embodiment, the lower housing 2 is sleeved on the outside of the upper housing 1 and the outside of the air inlet 3. The lower end of the upper housing 1 extends from the upper end of the lower housing 2 into the lower housing 2, and the upper end of the air inlet 3 extends from the lower end of the lower housing 2 into the lower housing 2.

[0056] In its non-operating state, the upper casing 1 and the air inlet 3 are partially or completely retracted into the lower casing 2, resulting in a smaller overall size, occupying less kitchen space, and being more aesthetically pleasing. (See attached image) Figure 3 and Figure 4 In the operating state of the entire unit, the lower housing 2 and the air inlet 3 descend to a position closer to the smoke source, thereby ensuring the performance requirements of the entire unit. The range hood's motion mechanism for driving the lower housing 2 and the air inlet 3 to rise and fall has a motor 65 (described in detail below). Reference can be made to existing two-stage lifting range hoods, such as those disclosed in Chinese Patent Application No. 201821783223.X, or to the Chinese Patent Application No. 202010123977.8 disclosed by the applicant, which will not be elaborated further here.

[0057] The air inlet 3 includes an air inlet 31 on the front side. A smoke baffle 5 can be installed at the bottom of the lower housing 2. In this embodiment, the smoke baffle 5 is horizontally arranged and fixed to the lower housing 2. In the working state, the air inlet 31 is located below the rear bottom of the smoke baffle 5, and the smoke baffle 5 can guide the fumes into the air inlet 31. In this embodiment, the air inlet 3 is generally flat (the depth in the front-to-back direction is much smaller than the width in the left-to-right direction), thus forming an ultra-thin design, which can reduce the space occupied in the working state.

[0058] An oil cup 4 is provided at the bottom of the air inlet 3. In this embodiment, when not in operation, the oil cup 4 can be completely stored inside the lower housing 2. (See Figure 2) Figure 3 and Figure 4 At this time, the bottom of the oil cup 4 is not lower than the bottom of the lower box 2.

[0059] See Figure 5 and Figure 6 The range hood also includes a motion control module, comprising a control chip 61, a drive circuit 62, a motion detection circuit 63, a current detection circuit 64, a motor 65, and a user input unit 66. The drive circuit 62 receives control signals from the control chip 61 to drive the motor 65 in forward and reverse rotation. The motor 65 can cooperate with other transmission mechanisms to drive the air intake 3 to rise and fall. Other transmission mechanisms include lead screws, nuts, gears, and racks. The control chip 61 also detects the current of the motor 65 in real time through the current detection circuit 64 and obtains information on the motor's speed and stroke through the motion detection circuit 63. The aforementioned current detection and motion detection can use existing circuits for detecting motor operating information; for example, the motion detection circuit 63 can be implemented using a Hall effect sensor and a magnet.

[0060] If the oil cup 4 is not installed properly or for other reasons, it may interfere with the oil cup storage structure of the whole machine (as shown at the bottom of the lower casing 2) during its upward movement. If the range hood's control system fails to recognize this abnormal state and continues to rise, it may eventually cause the oil cup to deform, be damaged, or fall off, creating a safety hazard. By setting up a motion control module, abnormal lifting movements can be quickly detected to avoid subsequent risks.

[0061] See Figure 7 When the range hood is powered on, it first performs a position initialization process, which includes the following steps:

[0062] 1) Start, system initialization;

[0063] 2) The control chip 61 controls the motor 65 to drive the air intake body 3 to rise. At the same time, it acquires or calculates the current current i and the current operating speed V of the motor 65. When i≥I0 and V≤V0, the rising stops and the current position is marked as point 0, that is, the current position l=0, thus completing the initialization.

[0064] If the initialization process fails to complete normally within T0, it is considered a system fault and a prompt will be displayed. Here, I0 and V0 are the default zero-point current and minimum movement speed thresholds, and T0 is the longest initialization time for system operation.

[0065] See Figure 8 After initialization, the range hood performs a reference speed calculation:

[0066] 1) Determine if the range hood is rising or falling. Rising or falling is an externally input command. For example, the range hood will fall when the user presses the fall button, or it will fall automatically when the user turns on the fan speed.

[0067] 2) Read or calculate the current operating speed V of motor 65, drive circuit i, and stroke position l;

[0068] 3) Based on the data from step 2), determine whether it is an upward movement. If yes, proceed to step 4); otherwise, return to step 1.

[0069] 4) In I Max ≥i≥I min And L H ≥l≥L L If all conditions are met, record n ​​running speeds {V0, V1…V...} x …V n}, x = 1 to n, then proceed to step 5), where L H and L L Given the upper and lower limits of the motor's stroke range for normal lifting motion (65), if this range is exceeded, the motor needs to enter the stroke range of the oil cup 4 lifting abnormality protection. max and I min Set the upper and lower limits of the operating current of motor 65 for normal lifting and lowering motion; otherwise, return to step 1); during the above recording process, when |V x -V x+1 |≤V б If the data set is confirmed to be valid and saved, the current position is recorded. x The speed V at that time x V б To determine the allowable variation in system operating speed, store the corresponding speeds {V0, V1, ..., Vn} from l0, l1, ..., ln. n Otherwise, return to step 1);

[0070] 6) After recording i sets of effective velocity values, we obtain {V0, V1…V...} n}、{V 10 V 11 …V 1n}…{V i0 Vi1 …V in Then, it checks whether the data update is complete. Once the update is complete, the reference velocity value {V} for each position is obtained. ref0 …V refx …V refn}, such as V ref0 It can be {V0, V} 10 The mean of ...Vi0}, V refx It can be {V x V 1x …Vi x The mean of}, i.e., V refn It can be {V n V 1n …Vi n Find the mean of the median, and then complete the calculation. The mean can also be replaced by the median, etc.

[0071] See Figure 9 After completing the above position parameter calculations, the range hood enters normal operation mode. During this normal operation, the oil cup protection method includes the following steps:

[0072] 1) Determine if the range hood is rising or falling. Rising or falling is an externally input command. For example, the range hood will fall when the user presses the fall button, or it will fall automatically when the user turns on the fan speed.

[0073] 2) Read or calculate the current operating speed V' of motor 65, drive circuit i', and stroke position l';

[0074] 3) Based on the data from step 2), determine whether it is an upward movement. If yes, proceed to step 4); otherwise, return to step 1.

[0075] 4) Determine L H ≥l≥L L Is this condition met? If so, record the current speed V. x If not, return to step 1);

[0076] 5) Calculate the sum of current velocities within period t: ∑v=V0'+V1'…+V n ', the sum of reference velocities ∑V ref =V ref0 +V ref1 …+V refn ;

[0077] 6) Calculate V бmax =V refx '-V x The maximum value in '' indicates an oil cup malfunction. If one of the following conditions is met, the oil cup is judged to be abnormal, and the lifting and lowering process is stopped, entering protection mode:

[0078] ∑Vref -∑v≥K1;

[0079] V бmax ≥K2.

[0080] Wherein, K1 is the first preset difference and K2 is the second preset difference, which can be obtained through experiments.

[0081] The method described above in this invention has the following advantages:

[0082] 1. By introducing stroke parameters, abnormal protection within a specified range is achieved. Stall judgment is only performed on the movement range where oil cup jamming may occur, greatly reducing the probability of false judgment.

[0083] 2. Introduce lifting speed parameters and perform self-learning on the operating speed within a specified stroke range to resolve deviations caused by differences in individual machines and installation environments;

[0084] 3. By using the two judgment conditions of the maximum speed difference and the sum of speed differences, rapid detection can be achieved, and it can also be used to identify slow speed changes caused by a decrease in structural rigidity.

Claims

1. A range hood, comprising a lower cabinet (2) and an air inlet body (3) capable of being lifted relative to the lower cabinet (2), the bottom of the air inlet body (3) being provided with an oil cup (4); characterized in that: in a non-working state of the range hood, the air inlet body (3) and the oil cup (4) are folded in the lower cabinet (2); in a working state of the range hood, the air inlet body (3) and the oil cup (4) are exposed below the lower cabinet (2); the range hood further comprises a motor (65) for driving the air inlet body (3) to lift; the range hood further comprises a motion control module for controlling the motor (65) and judging whether the oil cup (4) is abnormally lifted by detecting the motor (65), the motion control module comprising: a control chip (61); a driving circuit (62) for driving the motor (65) to rotate forward or reverse according to a control signal received by the control chip (61); a motion detection circuit (63) for detecting the speed and stroke of the motor (65); and a current detection circuit (64) for detecting the current of the motor (65), the stroke and the current being used to judge whether the oil cup (4) is in a range requiring lifting protection, and the speed being used to judge whether the oil cup (4) is abnormal. The range hood further comprises an upper cabinet (1), and the lower cabinet (2) and the air inlet body (3) are capable of being lifted relative to the upper cabinet (1), respectively. The lower cabinet (2) is sleeved outside the upper cabinet (1), and the lower end of the upper cabinet (1) extends into the lower cabinet (2) from the upper end of the lower cabinet (2). The lower cabinet (2) is sleeved outside the air inlet body (3), and the upper end of the air inlet body (3) extends into the lower cabinet (2) from the lower end of the lower cabinet (2). The air inlet body (3) comprises an air inlet (31) opened in the front side, and the bottom of the lower cabinet (2) is provided with a smoke baffle (5). The motion control module further comprises a user operation input unit (66) for inputting a command to the control chip (61). The method comprises the following steps: 1) judging whether the range hood is in lifting or lowering; 2) reading or calculating the current speed V', driving current i' and stroke position l' of the motor (65); 2. The hood according to claim 1, characterized in that: 3) judging whether it is lifting motion, if yes, entering step 4), if no, returning to step 1); 3. The hood according to claim 2, characterized in that: wherein K1 is a first preset difference value, and K2 is a second preset difference value.

4. The hood according to claim 2, characterized in that: 1) judging whether the range hood is in lifting or lowering; 5. The hood according to claim 1, characterized in that: 2) reading or calculating the current speed V, driving current i and stroke position l of the motor (65); 6. The hood according to claim 1, characterized in that: 3) judging whether it is lifting motion, if yes, entering step 4), if no, returning to step 1); 7. A method of protecting an oil cup of a range hood as claimed in any one of claims 1 to 6, characterized in that: otherwise, returning to step 1); Before each operation, initialization is performed first: the control chip (61) controls the motor (65) to drive the air inlet body (3) to lift, and at the same time, the current current i and the current running speed V of the motor (65) are obtained or calculated, when i≥I0 and V≤V0, the lifting is stopped, and the current position is marked as 0 point, thereby completing the initialization, wherein I0 and V0 are the default 0 point position to position current and minimum motion speed threshold. ​ ​ 4) judging L H ≥ l ≥ L L if yes, recording the current speed V x ', if no, returning to step 1); wherein, L H and L L are the upper and lower limit values of the motor (65) stroke range of the given normal lifting movement; 5) Calculate the sum of current speeds ∑v = V0' + V1'... +V n n, the number of records, the sum of reference speeds ∑V ref = V ref0 + V ref1 ... +V refn ; V ref0 ... V ref1 ... V refn are preset reference values; 6) Calculate V бmax = V refx ’- V x ’ the maximum value in, when one of the following conditions is met, the oil cup is judged to be abnormal, stop lifting: ∑V ref -∑v ≥ K1; V бmax ≥ K2; ​ 8. The method of claim 7, wherein: V ref0 …V ref1 …V refn The manner of obtaining includes the following steps: ​ ​ ​ 4) In I Max ≥i≥I min and L H ≥l≥L L If all the above conditions are met, record n running speeds { V0, V1…V x … V n}, x = 1 ~ n, and then go to step 5): When |V x -V x+1 |≤V б , the data set is confirmed valid and saved, and the speed V x at the current position l x is recorded, where V б is the allowable variation of running speed, and the positions l0, l1…ln and the corresponding speeds {V0, V1…V n} are saved; otherwise, return to step 1). where L H and L L are the upper and lower limits of the motor (65) travel range for the given normal lift motion, I max and I min are the upper and lower limits of the motor (65) operating current for the given normal lift motion. ​ 5) When recording the "group effective speed value", get { V0, V1…V n }、{ V 10 ,V 11 …V 1n }…{ V i0 ,V i1 …V in }, get the reference speed value corresponding to each position { V ref0 …V refx …V refn }, V ref0 According to { V0, V1…V n }, V ref0 According to { V0, V 10 …Vi0},…V refn According to { V n ,V 1n …Vi’’ n }.

9. The method of claim 8, wherein: V ref0 is the mean of { V0, V 10 …Vi0}, V refx is the mean of { V x , V 1x …Vi x }. V refn is the mean of { V n , V 1n …Vi n }.

10. The method of claim 7, wherein: ​ 11. The method of claim 10, wherein: When the initialization process does not complete normal initialization beyond T0, the system is judged to be in failure and a prompt is given, T0 being the longest initialization time of the system.

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