JP3620818B2 - Weight detector and microwave oven - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a weight detection device that electrically detects a weight in a thrust direction, and to an improvement in a microwave oven using the weight detection device.
[0002]
[Prior art]
In recent years, in microwave ovens, sensors for measuring temperature and weight are used as sensors for automatic cooking. Conventionally, various types such as a capacitance type and a piezoelectric element type have been adopted as a weight detection device as a weight sensor, but at present, the capacitance type is mainly used. In this weight detection device based on capacitance, a slight displacement amount of an output shaft (thrust shaft) that is displaced by the weight of a cooked product placed on a turntable is based on a change in capacitance between parallel plates. To detect.
[0003]
[Problems to be solved by the invention]
However, the conventional electrostatic capacity type weight detection apparatus includes an oscillation circuit and is configured to change the electrostatic capacity of the variable capacitor according to the distance between the electrodes. Therefore, it may be affected by stray capacitance generated in the wiring pattern on the printed circuit board, and in order to cope with this, it is necessary to secure a certain capacitance or more. In addition, in consideration of variations in component dimensions, a certain distance between electrodes is required. For this reason, the opposing area between electrodes increases and there exists a problem that an apparatus enlarges.
[0004]
Further, when such a conventional weight detection device is applied to a microwave oven, the displacement amount in the thrust direction of the turntable is detected, and a rotation drive means and a weight detection device for driving the turntable to rotate. Each has an independent configuration, and after assembling each of them separately, both are combined, so the number of assembly steps increases. In addition, the shape after combining the two tends to be difficult to be compact and large. Furthermore, if a load spring is used when restoring the displacement of the turntable in the thrust direction, the detection accuracy is deteriorated unless the engagement between the thrust shaft of the turntable and the load spring is good.
[0005]
Accordingly, the present invention provides a weight detection device that enables downsizing, eliminates problems when using a load spring, and enables stable and accurate weight detection, and a microwave oven using the weight detection device. The purpose is to do.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the weight detection device of the present invention is provided with a thrust shaft that is received by a load spring and is displaced in the thrust direction according to the weight to be detected, and a relative displacement provided by being engaged with the thrust shaft. Rotation displacement means for rotating the detection member by a predetermined amount according to the displacement amount of the thrust shaft, rotation drive means for rotating the relative displacement detection member integrally with the thrust shaft, and a relative displacement detection member The relative displacement amount of the detected object, the detector that is disposed in the detectable range of the detected object, detects the detected object, and the relative displacement detection member detected by the detector is weighted. And a transmission member for indirectly transmitting the movement in the thrust direction according to the weight of the thrust shaft to the load spring at the end of the thrust shaft on the load spring side.
[0007]
A weight detection device according to another aspect of the invention includes a thrust shaft that is received by a load spring and is displaced in the thrust direction according to the weight to be detected, and a relative displacement detection member provided by being engaged with the thrust shaft. Rotation displacement means for rotating and displacing a predetermined amount according to the displacement amount of the thrust shaft, rotation drive means for rotating the relative displacement detection member integrally with the thrust shaft, and detection target provided on the relative displacement detection member A body, a detector that is arranged in a detectable range of the detected object, detects the detected object, and a relative displacement amount of the relative displacement detection member detected by the detector is converted into a weight. Conversion means, and the bottom of the load spring is fixed to a case for holding the load spring.
[0008]
In another invention, in addition to the weight detection device of the above-described invention, the thrust shaft is moved to the end of the thrust spring on the load spring side so that the movement in the thrust direction according to the weight of the thrust shaft is indirectly transmitted to the load spring. A member is provided. Furthermore, in another invention, in addition to the weight detection device of each invention described above, the transmission member has a cap shape, and the load spring is a coil spring. Furthermore, in another invention, in addition to the weight detection device of each invention described above, when the load spring repeatedly compresses and expands, the size of each member is set so that the load spring and the transmission member do not contact the case that holds the load spring. Is set.
[0009]
In another invention, the load spring and the transmission member are fixed in addition to the weight detection device of each invention described above. In another invention, in addition to the above-described weight detection devices, an interposition member is further disposed between the transmission member and the thrust shaft. Furthermore, in another invention, in addition to the weight detection device of each of the above-described inventions, as an interposed member, a resin cap made of resin covers the tip of the resin cap so as to rotate integrally with the thrust shaft, and is placed on a load spring. The resin cap is received inside the bottom of the metal cap made of metal.
[0010]
In another invention, in addition to the weight detection device of the above-described invention, a lubricant is applied to a portion where the metal cap and the resin cap abut. In another invention, in addition to the weight detection device of the above-mentioned invention, the resin cap is arranged so that the outer peripheral side surface thereof faces the inner side surface of the metal cap, and the gap between the opposing portions is set to 50 to 500 μm. Furthermore, in another invention, in addition to the weight detection device of each of the above-described inventions, the tip on the load spring side of the thrust shaft is made thinner.
[0011]
According to another invention, in addition to the weight detection device of each of the above-described inventions, first and second relative displacement detections are provided in which the thrust shaft is made of ceramic and the relative displacement detection member is engaged with the thrust shaft. These two relative displacement detection members are rotated and displaced relative to each other by a predetermined amount according to the displacement amount of the thrust shaft by the rotation displacement means, and the first and second relative displacement detection members are respectively covered. A detection body is provided, and the weight conversion means converts the relative displacement amounts of the first and second relative displacement detection members detected by the detector as weight. In another invention, in addition to the weight detection device of the above-described invention, position holding means for holding the positional relationship in the rotation direction of the first and second relative displacement detection members is provided.
[0012]
Further, the microwave oven of the present invention has a weight detection device that allows the turntable to be displaced in the thrust direction according to the weight applied to the turntable and detects the weight applied to the turntable based on the amount of displacement. The weight detection device described in each claim is provided as a weight detection device.
[0013]
In the weight detection device of the present invention, when a weight is applied, the load spring contracts and the thrust shaft is displaced in the thrust direction. Then, the relative displacement detecting member is relatively rotated by a predetermined rotation angle about the thrust shaft according to the displacement amount of the thrust shaft. This operation is detected by a detector, and the relative displacement amount of the relative displacement detection member is converted into weight by the weight conversion means.
[0014]
For example, the relative displacement detection member is a first and second relative displacement detection member provided by engaging with a thrust shaft, and the first relative displacement detection member is relative to the second relative displacement detection member. A signal proportional to the displacement amount (for example, a signal having a time interval proportion proportional to the relative displacement amount) is output as a weight detection signal, and the weight is detected based on the weight detection signal.
[0015]
Thus, unlike the capacitance type weight detection device, the weight detection device of the present invention has various problems that the capacitance type conventionally has, for example, floating that occurs in a wiring pattern on a printed circuit board. In order to cope with the influence on the capacity, it is necessary to secure a certain capacitance or more, so that the facing area between the electrodes increases, the problem of increasing the size of the apparatus does not occur, and the weight is small and accurate. Detection is possible. Furthermore, since the position is reliably held, the displacement value can be stably supplied.
[0016]
In addition, a microwave oven using such a weight detection device as a weight detection device for measuring the weight of a cooked product placed on a turntable can reduce the weight detection portion, and reduce the size of the entire microwave oven. Can be planned. In particular, if the second relative displacement detection member is also used as an output gear of a reduction gear train for reducing the rotational force from the turntable drive source, the rotation drive means and the weight detection portion can be integrated. As a result, the size can be reduced and the number of assembling steps can be reduced as compared with the conventional one in which the rotation driving means and the weight detection portion are separated.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Examples of embodiments of the present invention will be described below with reference to FIGS. In this embodiment, an example in which the weight detection device is applied to a microwave oven will be described. When applied to a microwave oven, as described above, the amount of displacement of the turntable on which the food is placed is taken out as a signal indicating the weight of the food, and the microwave irradiation time is determined based on the signal indicating the weight. Control such as determination.
[0018]
First, the overall configuration will be described with reference to FIGS. The weight detection device 1 can be broadly divided into a rotation driving means 12 for rotating the turntable 11 and rotating first and second relative displacement detection members 42 and 43, which will be described later, integrally with the thrust shaft 41, and a turn. The table 11 includes a weight detection unit 13 that detects the amount of displacement in the thrust direction, and each of these components is housed in a single metal casing 14. The casing 14 includes a case main body 14a and a case lid 14b. The first and second relative displacement detection members 42 and 43 are vertically moved by the bottom surface of the case main body 14a and the inner surfaces of the case lid 14b. It is arranged to sandwich. That is, the bottom surface of the case main body 14 a and the case lid 14 b are both top plates of the casing 14.
[0019]
The rotation driving means 12 includes a motor 20 as a drive source (here, a synchronous motor is used), a first gear 31 as a reduction gear train that decelerates the rotational force of the motor 20 and transmits it to the turntable 11, The second gear 32, the third gear 33, the second relative displacement detecting member 43 serving as an output gear, the reverse rotation preventing lever 34a for preventing the motor 20 from rotating in reverse, and the reverse rotation preventing lever disposed coaxially with the reverse rotation preventing lever 34a. A rotation gear 34. The reverse rotation prevention lever 34a and the reverse rotation prevention lever rotation gear 34 are urged in the thrust direction by a spring 34b.
[0020]
The motor 20 includes a coil 21, a rotor 22, a fixed shaft 23, a pinion 24 fixed to the rotor 22, a center plate 25, and the like. The root portion of the pinion 24 is provided with protrusions 24a and 24a for preventing the reverse rotation of the rotor 22 by contacting the reverse rotation prevention lever 34a when the rotor 22 is reversely rotated. Therefore, when the rotor 22 rotates in the forward direction, the protrusion 24a of the rotor 22 and the protrusion 34c of the reverse rotation prevention lever 34a do not engage with each other, and the rotor 22 rotates freely. The protrusion 34c of the reverse rotation prevention lever 34a hits the protrusion 24a and prevents the rotor 22 from rotating.
[0021]
The first gear 31 and the second gear 32 are attached between the intermediate plate 25 and the case lid 14b by shafts 31a and 32a, respectively, and the third gear 33 is attached between the case main body 14a and the case lid 14b by a shaft 33a. ing. The pole teeth constituting the stator of the motor 20 are erected from the case main body 14a toward the rotor 22, but a label 26 is attached to the case main body 14a in order to close the remaining hole forming the pole teeth. ing.
[0022]
The weight detection unit 13 is fixed to the center of the turntable 11 and has a thrust shaft 41 that is displaced in the thrust direction according to the weight applied to the turntable 11 and a first shaft that is engaged with the thrust shaft 41. And second relative displacement detecting members 42 and 43, and rotational displacement means 44 for relatively rotating the two relative displacement detecting members 42 and 43 by a predetermined amount in accordance with the displacement amount of the thrust shaft 41, and The biasing spring 45 as a position holding means for holding the positional relationship in the rotational direction of the first and second relative displacement detection members 42, 43, a weight detection signal output means to be described later, and the thrust shaft 41 A coil spring 46 serving as a load spring disposed on the distal end side is a main component. The signal output from the weight detection signal output means is converted into weight by weight conversion means (not shown) made of a microcomputer.
[0023]
The first and second relative displacement detection members 42 and 43 are coaxially provided on the thrust shaft 41 so as to make a pair with each other. The first relative displacement detection member 42 rotates according to the displacement of the thrust shaft 41 in the thrust direction, and the second relative displacement detection member 43 depends on the displacement of the thrust shaft 41 in the thrust direction. It does not rotate but rotates by receiving a rotational driving force from the rotational driving means 12. That is, the second relative displacement detection member 43 serves as an output gear that is a part of a reduction gear train that constitutes the rotation drive unit 12 and that engages with another gear.
[0024]
The rotational displacement means 44 engages the first and second relative displacement detection members 42 and 43 and the thrust shaft 41, and when the thrust shaft 41 is displaced in the thrust direction, the first relative displacement detection member 44 The member 42 is rotated by a predetermined rotation angle about the thrust shaft 41 according to the displacement amount of the thrust shaft 41, and the second relative displacement detection member 43 is rotated by receiving the driving force from the rotation driving means 12. At that time, the rotational force can be transmitted to the thrust shaft 41. The rotational displacement means 44 includes oblique grooves 42 b and 42 c formed in the first relative displacement detection member 42 and axial grooves 43 b and 43 c formed in the second relative displacement detection member 43. A pin 44a that is attached to the thrust shaft 41 and that fits into the overlapping portions of the grooves 42b and 43b and the grooves 42c and 43c when the first and second relative displacement detection members 42 and 43 are fitted together. , Is composed of. Details of these will be described later.
[0025]
The urging spring 45 is a coil spring and serves as a position holding means for holding the positional relationship in the rotation direction of the first and second relative displacement detection members 42 and 43. In other words, the urging spring 45 gives a circumferential force to the first relative displacement detection member 42 when the first and second relative displacement detection members 42 and 43 are fitted together. The urging force holds the relative displacement amounts of the first and second relative displacement detection members 42 and 43, that is, holds both positions. If the position is not held by the urging spring 45, variations are likely to occur during weight measurement, but may be omitted depending on the required accuracy.
[0026]
In this embodiment, the reverse rotation prevention lever 34a prevents the rotor 22 from rotating in the reverse direction, and the turntable 11 rotates in one direction. This is because there is no need to rotate in both directions in a microwave oven.
[0027]
Specifically, as shown in FIG. 6, the position holding means described above is configured such that the biasing spring 45 biases the first relative displacement detection member 42 in the circumferential direction, whereby the pin 44 a and the first The contact position W1 with the grooves 42b and 42c provided in the relative displacement detection member 42 is set to be the sides 42c1 and 42b1 on one side of the grooves 42b and 42c. On the other hand, the contact position W2 between the pin 44a and the grooves 43b and 43c provided in the second relative displacement detection member 43 when the turntable 11 rotates is on the other sides 43b2 and 43c2 of the grooves 43b and 43c. It will always be located. As a result, the pin 44a is restrained from rattling in the overlapping grooves, and the positional relationship in the circumferential direction between the first and second relative displacement detection members 42 and 43 is always maintained in the same state. It is like that.
[0028]
The biasing spring 45 includes a protrusion 51d of the first relative displacement detection member 42 and a storage wall 52d and a pressing protrusion of the second relative displacement detection member 43 formed on the same radius with the thrust shaft 41 as the center. Both ends are supported in a compressed state in the storage portion 52e.
[0029]
Accordingly, the biasing spring 45 applies a biasing force in the circumferential direction to the first relative displacement detection member 42. This urging force causes the first relative displacement detecting member 42 to generate a force F1 toward the reference surface, which will be described later, by contacting the pin 44a. For this reason, the first relative displacement detection member 42 is always at a constant position in the axial direction (= a position in contact with the reference plane).
[0030]
The weight detection signal output means outputs a signal corresponding to the relative displacement amount of the first and second relative displacement detection members 42 and 43 as a weight detection signal. As shown in FIG. 7, the weight detection signal output means includes three magnets B1, B2, B3 that are to be detected provided on the first relative displacement detection member 42 side, and a second relative displacement. Three magnets A1, A2, A3 to be detected provided on the detection member 43 side, and a casing 14 serving as a detector for converting the magnetism generated by these magnets B1-B3, A1-A3 into electric signals And a Hall IC 47 which is a Hall element fixedly disposed on the substrate. Details of these will be described later.
[0031]
The first gear 31, the second gear 32, and the third gear 33 as the reduction gear train determine the gear ratio so that the rotor 22 of the motor 20 rotates an integer with respect to one rotation of the thrust shaft 41. Thus, when the position change amount in the rotation direction does not change, that is, when a predetermined weight is added and the relative displacement amounts of the first and second relative displacement detection members 42 and 43 are constant and rotating. The leakage magnetic field from the motor 20 always has the same phase for each predetermined position of the thrust shaft 41, and can be measured under the same conditions.
.
[0032]
For example, the rotational position of the rotor 22 at the timing of detecting the magnetic force of the signal magnet A1 detected once per rotation is always the same. For this reason, the influence of the magnetic flux from the rotor 22 and the magnetic flux from the stator in the motor 20 on the Hall IC 47 is the same regardless of how many times the thrust shaft 41 rotates. Such a relationship is the same for the other magnets A2, A3, B1, B2, B3 and the motor 20. Further, the influence of vibration by the rotor 22 is always the same condition. This eliminates variations in measurement results and enables accurate detection.
[0033]
In order to always make the influence of the rotor 22 and the like the same, in addition to the method of determining the gear ratio so that the rotor 22 rotates an integer for one rotation of the thrust shaft 41, two rotations of the thrust shaft 41 are performed. Alternatively, a method of determining the gear ratio so that the rotor 22 rotates an integer by three rotations can be employed. However, in such a case, the measurement accuracy is stabilized by performing the measurement twice (including a multiple of two times) or three times (including a multiple of three times).
[0034]
Next, the weight detection unit 13 will be described in more detail. As described above, one end (rear end) of the thrust shaft 41 is engaged with or fixed to the turntable 11, the rotational force of the motor 20 is transmitted to the turntable 11, and the cooked product is placed on the turntable 11. As a result, it is lowered together with the turntable 11 in the thrust direction.
[0035]
On the other end (tip) side of the thrust shaft 41, a resin resin cap 48 serving as an interposed member for pushing down the coil spring 46 serving as a load spring and a metal serving as a transmission member for receiving the resin cap 48 are provided. A metal cap 49 is attached. This is because the thrust shaft 41 is generally made of ceramic, and if it is directly received by the metal cap 49, the metal side is worn and the vertical position of the thrust shaft 41 changes. For the purpose of preventing this wear, the end portion of the thrust shaft 41 is covered with a resin cap 48 and rotated integrally with the thrust shaft 41. The coil spring 46 is housed in a case that is a protruding cylindrical portion 14c that is screwed to the case body 14a. Further, grease R1 as a lubricant is applied between the resin cap 48 and the metal cap 49 in order to further reduce wear.
[0036]
When the coil spring 46 moves in the front-rear and left-right directions and the rotational direction of the thrust shaft 41, the vertical position of the thrust shaft 41 changes and the measured value of the weight changes. For this reason, the bottom of the coil spring 46 is fixed to the projecting cylindrical portion 14c so that the coil spring 46 does not move in the front-rear and left-right directions and the rotational direction of the thrust shaft 41. In this fixing, the coil spring 46 is brought into contact with the rising portion 14d provided at the center inside the projecting cylindrical portion 14c so that the coil spring 46 cannot be moved back and forth and left and right, and the bottom of the coil spring 46 and the bottom portion of the projecting cylindrical portion 14c are adhered. It is fixed by applying grease R2 and preventing rotation. For this fixing, other methods such as fixing by an adhesive or plasma welding can be employed without providing the rising portion 14d.
[0037]
Further, when the position of the metal cap 49 is shifted, the vertical position of the thrust shaft 41 is changed, and the measured value is changed. In order to prevent this, the metal cap 49 is fixed to the coil spring 46 by plasma welding R3 so that the position of the metal cap 49 does not shift. In addition to the plasma welding R3, other fixing methods such as fixing with an adhesive can be used for this fixing.
[0038]
Further, when the metal cap 49 comes into contact with the inner surface of the protruding cylindrical portion 14c other than the bottom portion of the coil spring 46, a part of the weight applied to the thrust shaft 41 is not applied to the coil spring 46, so that correct measurement cannot be performed. For this reason, when the coil spring 46 repeats compression and extension, the size of each member is set so that the coil spring 46 and the metal cap 49 do not contact the inner surface of the protruding cylindrical portion 14c. That is, a sufficient gap g1 is provided so that the outer diameter portion of the coil spring 46 and the outer diameter portion of the metal cap 49 do not contact the inner surface of the protruding cylindrical portion 14c. The gap g1 is 0.2 to 1.5 mm so as to be a sufficient gap even in consideration of the plasma welding R3.
[0039]
Further, the resin cap 48 is disposed so that the outer peripheral side surface thereof faces the inner side surface of the metal cap 49, and the gap g2 between the opposing portions is set to 50 to 500 μm. If this gap g2 is large, the radial contact portion between the resin cap 48 and the metal cap 49 may be moved by an external impact. When the contact portion moves, the vertical position of the thrust shaft 41 changes and the measured value changes. In order to prevent this, the gap g2 between the opposing portions is set to 50 to 500 μm so that the thrust shaft 41 can be rotated smoothly and the amount of movement when the thrust shaft 41 is moved is reduced. If the gap g <b> 2 is too small, the resin cap 48 comes into contact with the metal cap 49 too much, causing a problem in the rotation of the thrust shaft 41.
[0040]
The coil spring 46 is a coil spring called a square coil spring having a quadrilateral cross section, and applies a biasing force against the thrust shaft 41 to the thrust shaft 41. That is, the thrust shaft 41 is supported by the coil spring 46 and is displaced in the thrust direction against the restoring force of the coil spring 46 according to the weight. Each end of the coil spring 46 is made thin so that the upper and lower end faces are horizontal.
[0041]
The load characteristics of the coil spring 46 are such that the compression length changes in direct proportion to the load, and the variation is only about 3 mm even when a 7 kg load is applied. As described above, the rectangular coil spring has a small displacement even under a high load, and is advantageous when there is a space limitation, a space in the displacement direction is suppressed, and a high load is to be supported.
[0042]
Further, as shown in FIG. 4, the first relative displacement detection member 42 has a cylindrical shape, and a hole 42 a through which the thrust shaft 41 passes is formed at the center thereof. A pair of grooves 42b and 42c are formed in the side cylindrical portion at positions facing each other across the central axis. The grooves 42b and 42c are formed obliquely with a predetermined angle with respect to the central axis direction. The oblique grooves 42b and 42c are formed in a spline shape by resin molding with a mold having a turning-out structure. By forming in a spline shape, the vertical change of the pin 44a can be smoothly converted into a change in the rotation direction in a linear relationship.
[0043]
In addition, magnet loading portions 51a, 51b, and 51c for loading magnets B1, B2, and B3 arranged at intervals of 120 ° are provided outside the side cylindrical portion. The magnet loading part 51a, which is one of these magnet loading parts 51a, 51b, 51c, holds the positional relationship in the rotational direction of the first and second relative displacement detection members 42, 43. A protrusion 51 d that locks one end of the biasing spring 45 is provided. Note that the other end side of the biasing spring 45 is loaded into a storage portion including a storage wall 52d and a pressing protrusion 52e provided in the second relative displacement detection member 43.
[0044]
On the other hand, as shown in FIG. 5, the second relative displacement detecting member 43, which also serves as an output gear, has a cylindrical shape with one end having a bottom and the other end being open, and the inner diameter thereof is the first relative displacement detecting member. It has a slightly larger diameter than the outer diameter of 42, and has an inner cylindrical portion 43a formed concentrically inside. The outer diameter of the inner cylindrical portion 43a is slightly smaller than the inner diameter of the first relative displacement detecting member 42, and a pair of axial directions are located on the side cylindrical portion at positions facing the central axis of the cylinder. Grooves 43b and 43c that are notched are formed.
[0045]
A hole 43 d through which the thrust shaft 41 passes is formed in the center portion on the bottomed end side of the second relative displacement detection member 43. The second relative displacement detection member 43 has a gear formed on the outer surface thereof, meshes with the third gear 33 of the rotation driving means 12, and also functions as an output gear.
[0046]
One end of the second relative displacement detection member 43 is in contact with a leaf spring 50 that is a metal plate-like spring member. The leaf spring 50 is disposed between the first and second relative displacement detection members 42 and 43 and the inner surface of the case lid 14 b serving as one top plate of the casing 14. The leaf spring 50 serves as a biasing unit that biases the first and second relative displacement detection members 42 and 43 in the thrust direction.
[0047]
The first relative displacement detection member 42 and the second relative displacement detection member 43 include an end portion where the inlet portions of the grooves 42b and 42c of the first relative displacement detection member 42 are provided, and a second relative displacement detection member 42. The first relative displacement detection member 42 is inserted into the second relative displacement detection member 43 so as to face the open end of the displacement detection member 43. As a result, the inner cylindrical portion 43 a of the second relative displacement detection member 43 is inserted into the first relative displacement detection member 42.
[0048]
A cylindrical protrusion 43e (see FIG. 2) protruding outward is formed at the bottomed end of the second relative displacement detection member 43, and the cylindrical protrusion 43e is a leaf-shaped spring 50. Abut. Thereby, the second relative displacement detection member 43 is urged by the urging force F2 on the bottom surface side of the case main body 14a. A flat washer 54 is disposed between the inner surface of the case body 14a and the first and second relative displacement detection members 42 and 43 on the opening end side of the second relative displacement detection member 43. ing. Thus, the second relative displacement detecting member 43 is biased by the leaf spring 50 from one side and pressed against the washer 54 from the other side, so that the vertical movement is restricted.
[0049]
The first relative displacement detection member 42 is pressed against the washer 54 side by the urging force F <b> 2 via the second relative displacement detection member 43. The second relative displacement detection member 42 is also pressed against the washer 54 by F1 generated from the biasing force of the biasing spring 45.
[0050]
As described above, the washer 54 has the first and second relative displacement detection members 42 when no weight is applied to the turntable 11 (that is, in an initial state) or when the cooking member is not placed on the turntable 11. 43 are in contact with each other. That is, the washer 54 serves as a reference surface that receives the end surfaces of the first and second relative displacement detection members 42 and 43 urged by the leaf spring 50 serving as a biasing means in the initial state or during cooking. The first and second relative displacement detection members 42 and 43 are relatively displaced from the reference surface in accordance with the weight applied to the turntable 11. With this configuration, the relative displacement amount of both due to the weight is stabilized, and it is possible to reliably detect the weight without error.
[0051]
Although the end faces of the first and second relative displacement detection members 42 and 43 biased by the leaf spring 50 are in contact with the washer 54 at the same time, the first relative displacement detection is performed. A configuration may be adopted in which only the working member 42 contacts the washer 54. When only the second relative displacement detection member 43 is in contact with the washer 54, the first relative displacement detection member 42 is also in contact with the washer 54 by the biasing force F 1 of the biasing spring 45. It will be. The washer 54 is provided so that the first and second relative displacement detection members 42 and 43 rotate smoothly. However, the washer 54 is eliminated, and the bottom surface of the case main body 14a is directly used as the reference plane. It is also good.
[0052]
In the present embodiment, the first and second relative displacement detection members 42 and 43 are urged in the thrust direction by the leaf spring 50 and the urging spring 45 as described above, and the washer 54 serving as a reference surface is used to It is configured to receive an end face. When there is a leaf spring, the actual weight and the measured conversion value almost coincide with each other and there is almost no variation, whereas when there is no leaf spring, the actual weight and the measured conversion value vary. In this way, the leaf spring 50 urges the first and second relative displacement detection members 42 and 43 in the thrust direction and reliably abuts against the washer 54 serving as a reference surface. The weight detection device 1 according to the embodiment has an effect that more accurate weight detection can be performed.
[0053]
In addition, the pin 44a is attached to the thrust shaft 41 so as to cross the central axis of the thrust shaft 41 at a right angle so that both ends of the pin 44a protrude on both sides (referred to as left and right). The left and right projecting portions of the pin 44a engage with axial grooves 43b and 43c formed in the inner cylindrical portion 43a of the second relative displacement detection member 43, and the first relative displacement detection Engage with diagonal grooves 42b and 42c formed in the member 42. Furthermore, one end of the pin 44a engages with a groove 43b formed in the inner cylindrical portion 43a of the second relative displacement detection member 43 and a slit 43f disposed opposite to the first relative displacement detection member 42. doing.
[0054]
The thrust shaft 41 has its tip penetrating from the case body 14 through the washer 54 and the bearing member 53a to reach the metal cap 49 disposed in the protruding cylindrical portion 14c, and pushes the metal cap 49 by the weight applied to the turntable 11. An operation of compressing the coil spring 46 is performed. At this time, the tip of the thrust shaft 41 is in contact with the resin cap 48 and is rotatable together with the resin cap 48. The rear end side of the thrust shaft 41 penetrates the bearing member 53b from the case lid 14b and projects outward, and is engaged or fixed to the turntable 11.
[0055]
The thrust shaft 41 is attached in such a state. That is, as described above, the pin 44a attached to the thrust shaft 41 is formed in the grooves 43b and 43c on the second relative displacement detection member 43 side (formed in the same direction as the central axis, that is, in the axial direction). And is engaged with grooves 42b and 42c on the first relative displacement detection member 42 side (which are formed obliquely at a predetermined angle with respect to the central axis direction). Therefore, when the thrust shaft 41 is operated to be pushed down, the pin 44a passes through the grooves 43b and 43c on the second relative displacement detection member 43 side and the grooves 42b and 42c of the first relative displacement detection member 42. Try to move down. At this time, the second relative displacement detection member 43 is not rotated because the movement in the rotational direction is restricted and the grooves 43b and 43c are the same as the axial direction. On the other hand, the first relative displacement detection member 42 moves in the rotational direction about the thrust shaft 41 as the pin 44a moves downward. This will be described with reference to FIG.
[0056]
The state of FIG. 6 (A) is the groove of the pin 44a and the first and second relative displacement detecting members 42, 43 when the thrust shaft 41 is in the initial state (the state where the cooked product is not placed on the turntable 11). The relationship of 42b, 42c, 43b, 43c is shown. FIG. 6B shows the pin 44a and the grooves 42b, 42c of the first and second relative displacement detection members 42, 43 in a state where the cooked product is placed on the turntable 11 and the thrust shaft 41 is lowered to the maximum. The relationship between 43b and 43c is shown. As can be seen from FIGS. 6A and 6B, the first relative displacement detecting member 42 is rotated by a predetermined angle, and the grooves 42b and 42c are moved by the distance L in the circumferential direction on the circumference (rotation). ).
[0057]
As described above, when a load is applied to the turntable 11, the thrust shaft 41 is displaced (lowered) in proportion to the load, and accordingly, the first relative displacement detection member 42 rotates by a distance L at the maximum. It can move in the direction. The state of FIG. 6B shows a state in which a maximum load (here, 7 kg) is applied to the turntable 11.
[0058]
When the turntable 11 is rotationally driven, if the motor 20 is energized, the rotational force is transmitted from the first gear 31 to the third gear 33, and further, the third gear 33 has teeth. It is transmitted to the second relative displacement detecting member 43. When the second relative displacement detecting member 43 rotates, the rotational force is transmitted to the thrust shaft 41 through the contact position W2 by the pin 44a, whereby the turntable 11 can be rotated.
[0059]
As described above, the thrust shaft 41 has the pin 44a and the grooves 42b and 42c provided on the first relative displacement detection member 42 side and the grooves 43b and 43c provided on the second relative displacement detection member 43 side. When displaced in the thrust direction, the first relative displacement detecting member 42 is rotated by a predetermined rotation angle about the thrust shaft 41 according to the displacement amount of the thrust shaft 41. Then, when the second relative displacement detection member 43 is rotated by receiving the driving force from the rotation driving unit 12, the pin 44 a and the like perform an operation that allows the rotational force of the motor 20 to be transmitted to the thrust shaft 41. That is, the pins 44a and the like constitute the above-described displacement direction converting means.
[0060]
Next, means for outputting an electrical signal corresponding to the magnitude of the load applied to the turntable 11 by the relative movement of the first relative displacement detection member 42 relative to the second relative displacement detection member 43, that is, weight detection. The signal output means will be described.
[0061]
In the first relative displacement detection member 42, three magnets A1, A2, A3 are arranged on the same plane at equal intervals. These magnets are separated by 120 °. On the other hand, in the second relative displacement detection member 43, three magnets B1, B2, B3 are arranged at equal intervals on the same plane. These magnets are separated by 120 °. When the first and second relative displacement detection members 42 and 43 are fitted so as to be coaxial as described above, the six magnets A1, A2, A3, B1, B2, and B3 described above are Corresponding magnets, that is, magnet A1 and magnet B1, magnet A2 and magnet B2, and magnet A3 and magnet B3 are arranged on the same plane so as to be separated from each other by a predetermined angle, 33.24 ° in this embodiment.
[0062]
In the vicinity of the magnet, a Hall IC 47 that is a Hall element that converts the magnetism into an electrical signal and outputs the signal is fixed to the casing 14. Specifically, the Hall IC 47 is fixed in a recess below a support column 56a extending as a vertical wall to a holder 56, which is a resin molded part, and passes through a hole provided in the bottom surface of the case body 14a. It is configured to protrude into the casing 14. The three terminals of the Hall IC 47 protrude outside the case body 14a and are soldered to the printed circuit board. Also, components such as connectors and chip capacitors are attached on the printed circuit board.
[0063]
The holder 56 for fixing the Hall IC 47 is fixed to the case main body 14a and has a structure positioned with respect to the upper case 14b. That is, a protrusion is provided at the tip edge of the support column 56a inserted from a hole provided in the bottom surface of the case body 14a, whereas an engagement hole is provided in the upper case lid 14b. The holder 56 is fixed to the case main body 14a, and at the same time, the projection of the holder 56 is fitted into the engagement hole, whereby the support column 56a is positioned and fixed so that there is no inclination.
[0064]
As a result, the intervals between the magnets A1, A2, A3 and the magnets B1, B2, B3 are fixed to a predetermined gap, so that the Hall IC 47 works accurately. Since the support column 56a also serves as a support wall between the upper case lid 14b and the lower case body 14a of the casing 14, it is possible to simultaneously prevent the interval between the opposing surfaces from changing (narrowing) due to thermal deformation or the like. Playing a role. The holder 56 may be made by shaving or pressing a metal in addition to the resin.
[0065]
8A and 8B are diagrams for explaining the positional relationship between the magnets A1, A2, A3, magnets B1, B2, B3, and the Hall IC 47, and are schematic diagrams for the sake of clarity. There are also portions that do not directly represent the structure shown in FIGS. 1 to 7 used in the above description.
[0066]
The magnets A1, A2 and A3 are respectively loaded in magnet loading portions 51a, 51b and 51c provided at equal intervals on the circumferential portion of the second relative displacement detecting member 43, and fixed by heat welding of a resin or an adhesive. Is done. Similarly, the magnets B1, B2, and B3 are loaded into magnet loading portions 52a, 52b, and 52c provided at equal intervals on the circumferential portion of the first relative displacement detection member 42, respectively, and heat welding or adhesion of resin is performed. Fixed by the material. Magnets A1, A2, A3 and magnets B1, B2, B3 are alternately arranged on the same plane. In other words, the magnet A1, the magnet B1, the magnet A2, the magnet B2, the magnet A3, and the magnet B3 are alternately arranged, and each has a structure arranged on the same plane.
[0067]
8A shows the positional relationship corresponding to the state of FIG. 6A, and the positional relationship when the thrust shaft 41 is in the initial state (the state in which the cooked product is not placed on the turntable 11). It is. Further, FIG. 8B shows a positional relationship corresponding to the state of FIG. 6B, and the positional relationship in a state where 7 kg of the cooked product is placed on the turntable 11 and the thrust shaft 41 is lowered to the maximum. Is shown.
[0068]
In FIG. 8A, the interval between a pair of magnets (for example, magnet A1 and magnet B1) arranged at close positions is a predetermined interval Y1. When the cooked product (7 kg) is placed on the turntable 11 and the thrust shaft 41 is lowered to the maximum extent, the first relative displacement detecting member 42 is rotated to the maximum extent and FIG. It becomes a state like this. Then, as shown in FIG. 8B, the magnets B1, B2, B3 of the first relative displacement detection member 42 move in the circumferential direction, respectively. Therefore, as described above, an interval between a pair of magnets (for example, the magnet A1 and the magnet B1) arranged in the close position in the initial state is opened.
[0069]
In such a configuration, the operation will be described. First, when the cooked product is not placed on the turntable 11, the relationship between the first relative displacement detection member 42 and the second relative displacement detection member 43 is as shown in FIG. It has become. In this state, the magnets A1, A2, A3 and the magnets B1, B2, B3 are in a positional relationship as shown in FIG.
[0070]
If the motor 20 rotates in this state, the second relative displacement detection member 43 also starts to rotate, and an output as shown in FIG. 9A is obtained from the Hall IC 47. In other words, signals are output from the Hall IC 47 at time intervals proportional to the angle between adjacent magnets. That is, if attention is paid to the magnets A1, B1, A2, the magnets A1, A2 are separated by an angle W, and the angle between the magnets A1, B1 is Y1, so the angle between the magnets B1, A2 is , W−Y1 = Z1.
[0071]
Here, when considering only the magnets A1, A2, and A3 in the second relative displacement detection member 43, the signal As1 of the Hall IC 47 by the magnet A1 and the signal of the Hall IC 47 by the magnet A2 as the turntable 11 rotates. If the time up to As2 (the time between the centers of the time widths in each signal) is t, this time t is unchanged and becomes the time corresponding to the angle W. Therefore, when the cooked product is not placed on the turntable 11, the signal As1 is first output from the Hall IC 47 between the magnet A1 and the magnet B1, and when the time corresponding to the angle Y1 has elapsed, the signal Bs1 is output. The relationship between the magnet A2 and the magnet B2 and between the magnet A3 and the magnet B3 is the same as this relationship.
[0072]
At this time, even in the case of only the magnet A1 and the magnet B1, that is, only one pair of magnets, the time ratio corresponding to the angle between the two magnets A1 and B1 with respect to one cycle is calculated. If the inclinations of the thrust shaft 41 and the holder 56 are not the same, the difference in inclination appears in the measured value. In the present embodiment, since there are a plurality of pairs of magnets, a pair in which the detected value of the position change is increased and a pair in which the detected value of the position change is increased due to the inclination of the thrust shaft 41, and the average is close to the correct value.
[0073]
In this embodiment, next, the signal Bs1 is output from the Hall IC 47 between the magnet B1 and the magnet A2, and when the time corresponding to the angle Z1 has elapsed, the signal As2 is output. The relationship between the magnet B2 and the magnet A3 and the relationship between the magnet B3 and the magnet A1 are the same as this relationship.
[0074]
In addition, as a method of measuring the time between signals output from the Hall IC 47, as described above, the length between the centers of the signals (the center of the signal width) is measured and each obtained by one round. Three values are averaged. The reason for measuring the length between the signal centers (the center of the signal width) is that the width of the output signal of the Hall IC 47 may vary depending on the temperature, and the average is the inclination of the thrust shaft 41. It is for dealing with.
[0075]
On the other hand, when some cooked product is placed on the turntable 11 and cooking is started, the turntable 11 starts rotating, and the thrust shaft 41 is lowered together with the turntable 11 by the weight of the cooked product.
[0076]
As a result, the first relative displacement detecting member 42 rotates in proportion to the descending amount of the turntable 11, and the inter-magnet angle between adjacent magnets such as the magnet B1 with respect to the magnet A1 and the magnet B2 with respect to the magnet A2 is increased. Change. At this time, since the turntable 11 is in a rotating state, from the Hall IC 47, the signal As1 for the magnet A1, the signal Bs1 for the magnet B1, the signal As2 for the magnet A2, and the signal As2 for the magnet B2. A signal is output corresponding to the passage of each magnet, such as signal Bs2. However, the time interval between the signals As1 and Bs1 at this time is longer than the time interval in the initial state described above. On the other hand, the time interval between the signals Bs1 and As2 is shorter than the time interval in the initial state described above.
[0077]
For example, as an extreme example, when a 7 kg cooked product is placed on the turntable 11, the magnets A1, A2, A3 on the second relative displacement detection member 43 side and the magnets on the first relative displacement detection member 42 side The relationship between B1, B2, and B3 is the positional relationship as shown in FIG. That is, the angle between the magnets in the close position in the initial state of the magnet on the first relative displacement detection member 42 side and the magnet on the second relative displacement detection member 43 side (for example, the angle between the magnets of the magnet A1 and the magnet B1). ) Spreads to Y2 and the angle with the magnet (for example, magnet A2 for magnet B1) arranged at a position that is not close to each other becomes narrow, so that an output as shown in FIG. 9B is obtained from the Hall IC 47. .
[0078]
As can be seen from FIG. 9B, the time interval between the signal As1 for the magnet A1 and the signal Bs1 for the magnet B1 is longer than the corresponding interval in FIG. 9A. That is, in the initial state (a state in which the cooked product is not placed on the turntable 11), the time interval between the signal As1 and the signal Bs1 is short, but when a 7 kg cooked product is placed on the turntable, the signal As1. And the time interval between the signals Bs1 are widened, and signals having different time intervals can be extracted from the Hall IC 47 in accordance with the weight of the cooked product. Therefore, the weight of the cooked product can be measured using the output of the Hall IC 47. The displacement amount is converted into weight by a microcomputer (not shown).
[0079]
FIG. 10 shows the load applied to the turntable (the weight of the cooked product) and the magnet B1 on the first relative displacement detection member 42 side with respect to the Hall IC output by the magnet A1 on the second relative displacement detection member 43 side. The time interval of the Hall IC output is expressed as a percentage, and each time interval t between the magnets A1, A2 and A3 is 100%, and is a percentage with respect to this t. The relationship between the magnet B2 for the magnet A2 and the magnet B3 for the magnet A3 is the same. As can be seen from FIG. 15, when the load is 0, it is 28% (0.28 t), when the load is 1 kg, it is about 30% (0.30 t), and when the load is 4 kg, it is about 38% (0. 38t), the time interval becomes longer in proportion to the load, and at the maximum load (7 kg), it becomes about 44% (0.44 t).
[0080]
On the other hand, FIG. 11 shows the magnet on the second relative displacement detection member 43 side with respect to the load applied to the turntable (weight of the cooked product) and the Hall IC output by the magnet B1 on the first relative displacement detection member 42 side. The time interval of Hall IC output by A2 is expressed as a percentage, and each time interval t between the magnets A1, A2 and A3 is 100%, and is a percentage with respect to t. The relationship between the magnet A3 with respect to the magnet B2 and the relationship between the magnet A1 with respect to the magnet B3 is the same. As can be seen from FIG. 16, when the load is 0, it is 72% (0.72 t), when the load is 1 kg, it is about 70% (0.70 t), and when the load is 4 kg, it is about 62% (0. 62t), the time interval decreases in proportion to the load, and at the maximum load (7 kg), the time interval is about 56% (0.56 t).
[0081]
Based on such a relationship, the weight of the cooked product can be detected, and if the weight of the cooked product is known, the cooking time or the like considering that can be automatically set.
[0082]
By the way, in the explanation so far, the magnet on the second relative displacement detection member 43 side and the magnet on the first relative displacement detection member 43 side are each constituted by three pairs of three, Alternatively, for example, a pair may be used. In principle, the amount of displacement of the turntable 11 is determined by the time of the Hall IC 47 even with only one pair of magnets on the second relative displacement detection member 43 side and the first relative displacement detection member 42 side. It can be taken out as a displacement of the interval. However, in order to enable use regardless of the difference between the 50 kHz region and the 60 kHz region, a reference time (in this case, between the magnets A1, A2, and A3 on the second relative displacement detection member 43 side). It is preferable to express the displacement (= ratio) with respect to the time interval t). Therefore, in order to obtain the displacement amount, the magnets of the first and second relative displacement detection members 42 and 43 may be paired, but it is necessary to calculate at least two intervals.
[0083]
As described above, in the above-described embodiment, the displacement amount in the thrust direction of the turntable 11 is converted into the displacement amount in the rotation direction of the first relative displacement detection member 42 and is proportional to the displacement amount in the rotation direction. The output of the Hall IC 47 is obtained, and the weight of the cooked product placed on the turntable 11 is detected based on the displacement amount of the output of the Hall IC 47. Also, these weight detection operations can be performed while the turntable 11 is rotating by placing a cooked product on the turntable 11 and starting cooking. Therefore, efficient weight detection becomes possible.
[0084]
Further, when the turntable 11 is rotated, the first and second relative displacement detection members 42 and 43 are held in the circumferential positional relationship by the biasing spring 45 and are also relative to the washer 54 serving as a reference surface. It is pressed by the leaf spring 50. Therefore, the positional relationship does not shift during rotation, and an accurate displacement amount, that is, accurate weight detection can be performed.
[0085]
Further, the rotation drive means 12 for rotating the turntable 11 and the weight detection unit 13 for detecting the weight are housed in one casing 14, in other words, the weight detection unit 13 is connected to the rotation drive means 12. Since the weight detection unit 13 and the rotation driving means 12 are assembled separately and then combined together, the number of assembly steps can be reduced and the overall size can be reduced. It is possible to reduce the cost.
[0086]
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the turntable 11 has been described as rotating only in one direction, but the turntable 11 may be capable of bidirectional rotation. In that case, in the present invention, as described above, the biasing spring 45 as the position holding means is configured to hold the position of the first and second relative displacement detection members 42 and 43 in the circumferential direction. The measurement value does not vary, and can be dealt with only by correcting the fixed value according to the rotation direction, so that the effect as the detection device is further exhibited.
[0087]
Further, when the friction is small and the wear is small, the lubricant between the resin cap 48 and the metal cap 49 may be omitted. Furthermore, as shown in FIG. 12, it is good also as a structure which mounts the sheet | seat 61 with good abrasion resistance on the metal cap 49 as an interposed member. In this case, it is preferable to provide a hemispherical protrusion 41a at the tip of the thrust shaft 41 and make the tip thin, but a flat shape may be used as long as wear is small. In the example shown in FIG. 12, the protruding cylindrical portion 14c is a case whose upper side is widened, and the coil spring 46 and the metal cap 49 are fixed and the coil spring 46 and the protruding cylindrical portion 14c are fixed by the adhesive R4. Yes.
[0088]
Furthermore, the transmission member may not be a metal, but may be another member, for example, a resin material, and the shape thereof may not be a cap shape but may be another shape such as a flat plate shape. The metal cap 49 may be fixed to the coil spring 46 by press-fitting or bonding. Furthermore, the metal cap 49 may have a shape with a lower center as shown in FIG. In this case, it is preferable to provide a hemispherical protrusion 48 a on the bottom surface of the resin cap 48 so that the protrusion 48 a always abuts against the center of the metal cap 49.
[0089]
The thrust shaft 41 on the turntable 11 side protrudes from the cylindrical burring portion of the case lid 14b constituting the other top plate of the casing 14, and the thrust shaft 41 is connected to the case lid 14b at the base end. Alternatively, preload may be applied from the outer peripheral direction by a reel spring or the like serving as a tilt prevention means with the pin fixed. If there is a backlash of the thrust shaft 41, the measured value of the weight varies depending on the inclination of the thrust shaft 41. However, with this structure, the backlash of the thrust shaft 41 is eliminated and the detection error can be eliminated. In addition to the reel spring, the member that applies the preload to the thrust shaft 41 may be a plate spring, a resin having a spring property, a rubber material, or the like.
[0090]
In the above-described embodiment, the three pairs of magnets A1, A2, A3, B1, B2, and B3 are used. However, only one pair may be used, or another number of pairs such as two or four pairs may be used. Furthermore, in the above-described embodiment, the displacement amount is detected by the magnetic detection means by the magnet and the Hall IC 47, but this can be realized by other means. For example, a plurality of overlapping slits are provided on both the first relative displacement detection member 42 and the second relative displacement detection member 43, and the length of the overlapping slits changes as the thrust shaft is displaced in the thrust direction. You may make it do.
[0091]
In the case of this configuration, the photoelectric conversion means such as a photodiode and a phototransistor are arranged to face each other with the slit interposed therebetween, and the thrust shaft is displaced in the thrust direction, whereby the slit length of the overlapping slit is changed. Then, a change in the slit length of the overlapping slits can be taken out as an interval of output signals from the phototransistor, and weight detection can be performed based on this. Also by this, the weight can be detected as in the above-described embodiment.
[0092]
In the above-described embodiment, the first relative displacement detection member 42 is rotationally displaced by the displacement of the thrust shaft 41 in the thrust direction, and the second relative displacement detection member 43 is not displaced. Both members 42 and 43 may be displaced together, or only the second relative displacement detecting member 43 may be displaced. Moreover, you may employ | adopt other shapes and structures, such as making the magnet into the structure which made the outer peripheral part of the circular rubber magnet convex.
[0093]
Further, the coil spring 46 may be a circular or other shape coil spring instead of a square coil spring. Furthermore, instead of a coil spring, another spring such as a plate spring or a disc spring may be used, or another elastic member such as a rubber material or a plastic material may be used. Further, the biasing spring 45 may be rubber or another elastic member instead of the coil spring. In addition to the leaf spring 50, other biasing means such as a disc spring or a rubber member may be disposed at the position of the leaf spring 50.
[0094]
Further, in the above-described embodiment, the case where the weight of the cooked product in the microwave oven is detected has been described as an example. However, the present invention is not limited to the microwave oven, and the weight of other devices such as an oven and a toaster are not limited. It can also be applied to detection. The present invention can also be applied to detection of the weight of other articles other than cooked products.
[0095]
【The invention's effect】
As described above, in the weight detection device of the present invention, the thrust shaft received by the load spring and displaced in the thrust direction according to the weight to be detected, and the relative displacement detection provided by being engaged with the thrust shaft. A relative displacement detecting member provided with rotational displacement means for rotationally displacing the member for a predetermined amount according to the displacement amount of the thrust shaft, and rotational drive means for rotating the relative displacement detection member integrally with the thrust shaft; Since a signal corresponding to the relative displacement amount is output as a weight detection signal, highly accurate weight detection is possible with a simple configuration, and the size can be reduced as compared with a conventional capacitance type weight detection device. .
[0096]
In the first aspect of the present invention, the transmission member for indirectly transmitting the movement in the thrust direction according to the weight of the thrust shaft to the load spring is provided at the end of the thrust shaft on the load spring side. The operation of the spring becomes stable, and wear is less likely to occur between the thrust shaft and the load spring, so that stable weight measurement can be performed for a long time.
[0097]
According to the second aspect of the present invention, since the bottom of the load spring is fixed to the case for holding the load spring, the load spring does not move in the front-rear and left-right directions and the rotational direction of the thrust shaft. As a result, it is possible to prevent the weight measurement value from changing. Furthermore, in the invention according to claim 3, as in the invention according to claim 1, the operation of the load spring becomes stable, and wear is less likely to occur between the thrust shaft and the load spring. Measurement is possible.
[0098]
In the invention according to claim 4, since the transmission member is in the shape of a cap and the load spring is a coil spring, the bottom of the cap can be fitted into the center of the coil spring to easily combine the two. Further, the thrust shaft can be inserted into the cap-shaped recess, which is advantageous in terms of vertical space. Further, since the thrust shaft is restricted from moving in the lateral direction by the bearing of the device, the outer periphery of the thrust shaft enters the recess, so that the coil spring is held at the center. In addition, wear prevention grease or the like can be put in the recess.
[0099]
In the invention according to claim 5, when the load spring repeatedly compresses and expands, the size of each member is set so that the load spring and the transmission member do not contact the case holding the load spring. Correct measurement will always be possible. In the invention according to claim 6, since the transmission member is fixed to the load spring, the position of the transmission member does not shift and the vertical position of the thrust shaft does not change. For this reason, a measurement value does not change and accurate weight detection can be performed.
[0100]
Further, in the invention described in claim 7, since the interposition member is further arranged between the transmission member and the thrust shaft, wear is further generated by using the interposition member as a sheet or a resin cap having a low friction coefficient. This makes it possible to measure the weight stably for a long time.
Further, in the invention described in claim 8, as the interposition member, a resin cap made of resin is placed on the tip of the cap so as to rotate integrally with the thrust shaft, and a metal metal cap as a transmission member placed on the load spring is used. Since the resin cap is received inside the bottom portion, the operation of the load spring is further stabilized, wear is less likely to occur, and stable weight measurement can be performed for a long period of time. The thrust shaft is supported at a portion other than the tip, and the tip is held at a fixed position (center) by the action of the bearing, and the metal cap that receives the resin cap is also naturally fixed at the center. The As a result, the load spring is also arranged in the center, and contact with the case side in which the load spring is incorporated is prevented.
[0101]
Further, in the invention according to claim 9, since the lubricant is applied to the portion where the metal cap and the resin cap abut, the wear is further reduced, and stable weight measurement can be performed for a long time. In the invention according to claim 10, since the resin cap is disposed so that the outer peripheral side surface thereof faces the inner side surface of the metal cap and the gap between the opposing portions is 50 to 500 μm, the vertical position of the thrust shaft is The measurement value does not change, and the measured value becomes accurate. If this gap is large, the radial contact portion between the resin cap and the metal cap may be moved by an external impact. When the contact portion moves, the vertical position of the thrust shaft changes and the measured value changes. However, in the present invention, large movement of the contact portion is prevented. In the invention according to claim 11, since the tip of the thrust shaft on the load spring side is made thin, wear is further reduced.
[0102]
Furthermore, in the invention described in claim 12, the thrust shaft is made of ceramic, and the relative displacement detection member is the first and second relative displacement detection members provided by being engaged with the thrust shaft. The displacement detecting member is rotated and displaced relative to the thrust shaft by a predetermined amount according to the amount of displacement of the thrust shaft, and the first and second relative displacement detecting members are provided with detected bodies, respectively. Since the relative displacement amounts of the first and second relative displacement detection members detected by the detector are converted as weights, accurate weight measurement can be performed with a simple structure. In addition, stable measurement can be performed for a long time.
[0103]
Furthermore, in the invention described in claim 13, since the position holding means for holding the positional relationship in the rotation direction of the first and second relative displacement detection members is provided, the first and second relative displacement detections are provided. The positional relationship of the working member in the circumferential direction is held by the position holding means. For this reason, accurate weight detection can be performed even during rotation.
[0104]
In the microwave oven according to the fourteenth aspect, the weight detection device for detecting the weight of the cooked product can be made small, so that the microwave oven itself is downsized. In addition, since it is possible to detect the weight with high accuracy, it is possible to set an appropriate cooking time when performing control for automatically setting the cooking time with respect to the weight of the cooked product.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an embodiment of a weight detection device of the present invention, and is a view showing a detector holder omitted.
FIG. 2 is an exploded perspective view of the weight detection apparatus shown in FIG.
FIG. 3 is a partially enlarged view of a portion where a coil spring as a load spring used in the weight detection device shown in FIG. 1 is disposed.
4 is a perspective view illustrating in detail the first relative displacement detection member shown in FIGS. 1 and 2. FIG.
FIG. 5 is a perspective view illustrating in detail the second relative displacement detection member shown in FIGS. 1 and 2;
6 is a diagram for explaining a relationship between a first relative displacement detection member and a second relative displacement detection member of the weight detection device shown in FIG. 1, and FIG. 6A shows a load applied from a turntable. (B) is a front view when the load from the turntable is applied to the maximum.
7 is a cross-sectional view taken along the line AA in FIG.
8 is a view for explaining the positional relationship between each magnet on the first relative displacement detection member side and each magnet on the second relative displacement detection member side of the weight detection apparatus shown in FIG. 1 and the arrangement of the Hall ICs. (A) is a figure which shows the case where the load is not applied to the turntable, (B) is the figure which shows the case where the maximum load is applied to the turntable.
9 is a diagram showing an output signal of a Hall IC used in the weight detection device shown in FIG. 1, and FIG. 9 (A) is a diagram showing an output signal when no load is applied to the turntable; ) Is a diagram showing an output signal when the maximum load is applied to the turntable.
FIG. 10 is a diagram showing a first relative displacement detection member-side magnet with respect to a Hall IC output by a magnet on the second relative displacement detection member side, with a horizontal axis representing a load applied from the turntable to the weight detection device shown in FIG. Is a graph in which the value (= phase difference between magnets A and B) indicating the time interval of Hall IC output as a percentage is indicated on the vertical axis.
FIG. 11 shows a magnet on the second relative displacement detection member side with respect to the Hall IC output by the magnet on the first relative displacement detection member side, with the load applied from the turntable to the weight detection device shown in FIG. 1 as the horizontal axis. Is a graph in which the value (= phase difference between magnets A and B) indicating the time interval of Hall IC output as a percentage is indicated on the vertical axis.
FIG. 12 is a partially enlarged view showing another example of a structure of a portion where a coil spring as a load spring of the weight detection device of the present invention is arranged.
FIG. 13 is a partially enlarged view showing still another example of a structure of a portion where a coil spring as a load spring of the weight detection device of the present invention is arranged.
[Explanation of symbols]
1 Weight detector
11 Turntable
12 Rotation drive means
13 Weight detector
14 Casing
14a Case body
14b Case lid
14c Projecting cylindrical part (case)
20 Motor (part of rotation drive means)
41 Thrust shaft
42 1st member for relative displacement detection
43 Second member for detecting relative displacement
44 Rotating displacement means
44a pin
45 Biasing spring (position holding means)
46 Coil spring (load spring)
47 Hall IC (detector)
48 Resin cap (intervening member)
49 Metal cap (Transmission member)
55 Printed circuit board (circuit board)
56 Holder
AI, A2, A3 Second relative displacement detecting member side magnet (detected body)
B1, B2, B3 First relative displacement detecting member side magnet (detected body)

Claims (14)

A thrust shaft that is received by the load spring and is displaced in the thrust direction according to the weight to be detected, and a relative displacement detection member that is provided by engaging with the thrust shaft are set in a predetermined amount according to the displacement amount of the thrust shaft. Rotational displacement means for rotational displacement, rotational drive means for rotating the relative displacement detection member integrally with the thrust shaft, a detected body provided on the relative displacement detection member, and the detected body A detector for detecting the detected object, and a weight conversion means for converting a relative displacement amount of the relative displacement detection member detected by the detector as a weight, A weight detection device, wherein a transmission member for indirectly transmitting movement in a thrust direction corresponding to the weight of the thrust shaft to the load spring is provided at an end of the thrust shaft on the load spring side. A thrust shaft that is received by the load spring and is displaced in the thrust direction according to the weight to be detected, and a relative displacement detection member that is provided by engaging with the thrust shaft are set in a predetermined amount according to the displacement amount of the thrust shaft. Rotational displacement means for rotational displacement, rotational drive means for rotating the relative displacement detection member integrally with the thrust shaft, a detected body provided on the relative displacement detection member, and the detected body A detector for detecting the detected object, and a weight conversion means for converting a relative displacement amount of the relative displacement detection member detected by the detector as a weight, A weight detecting device, wherein the bottom of the load spring is fixed to a case for holding the load spring. The transmission member for indirectly transmitting the movement in the thrust direction according to the weight of the thrust shaft to the load spring is provided at an end of the thrust shaft on the load spring side. Weight detection device. The weight detecting device according to claim 1 or 3, wherein the transmission member has a cap shape, and the load spring is a coil spring. The size of each member is set so that the load spring and the transmission member do not contact a case holding the load spring when the load spring repeatedly compresses and expands. Or the weight detection apparatus of 4. 6. The weight detection device according to claim 1, wherein the load spring and the transmission member are fixed. 7. The weight detection apparatus according to claim 1, further comprising an interposition member disposed between the transmission member and the thrust shaft. As the interposition member, a resin cap made of resin is put on the tip of the thrust shaft so as to rotate integrally with the thrust shaft, and the resin cap is placed inside the bottom of the metal cap made of metal as the transmission member placed on the load spring. 8. The weight detection apparatus according to claim 7, wherein The weight detection apparatus according to claim 8, wherein a lubricant is applied to a portion where the metal cap and the resin cap are in contact with each other. The weight detection device according to claim 8 or 9, wherein the resin cap is disposed so that an outer peripheral side surface thereof faces an inner side surface of the metal cap, and a gap between the opposing portions is set to 50 to 500 µm. 11. The weight detection device according to claim 1, wherein a tip of the thrust shaft on the load spring side is thinned. The thrust shaft is made of ceramic, the relative displacement detection member is a first and second relative displacement detection member provided by engaging with the thrust shaft, and these two relative displacement detection members are connected to the rotating shaft. The first and second relative displacement detection members are provided with the detected bodies, respectively, by a relative displacement by a dynamic displacement means in accordance with a displacement amount of the thrust shaft, and the weight conversion means, 12. The relative displacement amount of the first and second relative displacement detection members detected by the detector is converted as a weight. Weight detection device. 13. The weight detection apparatus according to claim 12, further comprising position holding means for holding the positional relationship in the rotation direction of the first and second relative displacement detection members. In the microwave oven having a weight detection device that detects the weight applied to the turntable based on the displacement amount, the turntable can be displaced in the thrust direction according to the weight applied to the turntable. A microwave oven comprising the weight detection device according to any one of claims 1 to 13.

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