JP5461166B2 - Gear motor for freezer - Google Patents

Description

  The present invention relates to a gear motor for a freezer used in a freezer.

  Since the inside of the freezer for storing fresh food and the like is set at an extremely low temperature, the storage shelf and the carriage that are movably installed inside the freezer have some form of good operation of the gear motor as a driving source. It is necessary to secure in. The “gear motor” in the present invention includes both those in which the motor and the speed reducer are directly integrated from the design stage, and those in which the motor and the reduction gear are integrated afterwards using a coupling or the like.

  In patent document 1, the heat retention apparatus which accommodated the gear motor in the heat retention box with a heating means is provided. In this heat retaining device, the heating means is operated when the temperature in the heat retaining box is lowered to a predetermined control temperature.

JP 2005-300085 A

  However, the method including the above-described heat retaining device requires a heat retaining box and a heating control device in addition to the gear motor. In addition, when the gear motor is not used for a long period of time, a large amount of wasted electric power is required in order to keep the heat retaining device constantly operated so that the gear motor can be used immediately at any time. Of course, when it is clear that the gear motor will not be used for a long period of time, it is possible to turn off the power of the heat retaining device each time. However, in this case, when the gear motor is used, the operation itself cannot be started unless the gear motor is heated by the heating means via the heat retaining device and the grease or the like can function well.

  Therefore, it is considered to design a gear motor that can be used as it is in a freezer by using a lubricant and an oil seal (for example, acrylic rubber, hydrogenated nitrile rubber, etc.) that have been developed so that they can be used at lower temperatures. It is done. However, in reality, when a gear motor using a lubricant and an oil seal that was developed as being usable up to the target temperature of the freezer was operated in the freezer (the operation itself could certainly be performed without any problems. However, it was confirmed that there was a problem that the lubricant sometimes leaked from the oil seal part.

  However, even if the manufacturer takes back the gear motor in which this problem has occurred and examines the oil seal etc. in detail, there may be no particular abnormality in the oil seal itself, and the cause is not necessarily clear. It was a fact.

  The present invention was made based on the knowledge obtained by examining the cause of the oil leakage in such a situation, and without installing a heat retaining device, a heating means, etc. Therefore, it is possible to operate the gear motor as it is, to prevent the leakage of the lubricant, and to maintain the life of the oil seal high.

  The present invention is a gear motor that integrates a motor that operates in a freezer and a speed reducer, and can seal to a temperature that is at least 10 ° C. lower than a target refrigeration temperature as an oil seal that seals the rotating shaft of the speed reducer. The above problem has been solved by incorporating a cryogenic oil seal into the speed reducer.

  As a result of scrutinizing the characteristics of the oil seal of the gear motor used in the freezer, the rotation shaft (input shaft or output shaft) of the speed reducer is used to use the gear motor in the freezer without a heat retention device or warm-up operation. For example, when the target refrigeration temperature is −T ° C., a cryogenic oil seal having a sealing performance lower than − (T + 10) ° C. is used. In short, for example, if the target refrigeration temperature is −30 ° C., a cryogenic oil seal that is guaranteed to be used at −40 ° C. or lower is used.

  As a result, the gear motor can be used directly in the freezer, and the occurrence of oil leakage can be prevented. The specific reason for preventing this oil leakage will be described in detail later.

  The present invention is a gear motor in which a motor used in a freezer and a speed reducer are integrated, and includes an oil seal that seals the rotation shaft of the speed reducer, and the oil seal is at least at a target refrigeration temperature. It is a cryogenic oil seal capable of sealing to a temperature lower than 10 ° C., and the gear motor is operated intermittently so that the temperature around the cryogenic oil seal does not exceed 0 ° C. It can also be considered as a freezer gear motor.

  Further, the present invention is a gear motor in which a motor used in a freezer and a reduction gear are integrated, and includes an oil seal that seals a rotation shaft of the reduction gear, and the oil seal is at least at a target refrigeration temperature. An oil seal for cryogenic temperatures that can be sealed to a temperature lower than 10 ° C, and the temperature around the oil seal for cryogenic temperatures does not exceed a predetermined time that is set shorter than expected to exceed 0 ° C. In addition, the gear motor can be regarded as a freezer gear motor that is operated intermittently.

  According to the present invention, the gear motor can be operated as it is in the freezer, and the leakage of the lubricant can be effectively prevented.

Sectional drawing which shows an example of the gear motor for freezers to which the operating method which concerns on embodiment of this invention is applied. Expanded sectional view of the oil seal on the input side of the gear motor for the freezer Graph of temperature test example around oil seal and enlarged view Flow chart showing an example of operation control of the gear motor Flowchart showing an example of another operation control of the gear motor

  Hereinafter, an example of an embodiment of the present invention will be described in detail based on the drawings.

  First, before describing specific embodiments, the principle of solving the problems of the present invention will be described in detail.

  For example, acrylic rubber is well known as a material excellent in low-temperature sealing performance. Since this material was also described as catalog values that can be used up to -25 ° C, the inventor initially adopted an oil seal according to this material as an oil seal for a freezer gear motor in a freezer with a target refrigeration temperature of -25 ° C. I tried to. However, in reality, sometimes a lubricant leak occurred.

  As a result of scrutinization, it was inferred that when trying to function in the freezer, the hardness remained at the initial stage of operation, so that it was not able to follow the shaft's subtle fluctuations and vibrations well. This can be inferred from the fact that no abnormality was found even when the gear motor was brought home and the oil seal or the like was examined at room temperature. This seems to be due to the lack of elasticity at the beginning of driving and a decrease in tightness. This point can be said to be a situation unique to a gear motor for a freezer that is different from a simple O-ring or the like, and is considered to be a problem particularly in an oil seal of a rotating shaft such as an input shaft that rotates at high speed.

  For this reason, an oil seal for cryogenic temperature having a low temperature characteristic that is one step superior, that is, an extremely low temperature sealing performance that can be handled at a temperature of − (T + 10) ° C. or lower when the target freezing temperature is −T ° C. An attempt was made to use a low temperature oil seal (specifically, for example, nitrile rubber), and good results were obtained, confirming that the inference was correct.

  The present invention has been made based on this finding.

  Even when such a further cryogenic oil seal was used as an oil seal of a gear motor for a freezer, lubricant leakage could be newly confirmed by long-term use.

  At the stage of exploring countermeasures, it was speculated that one of the causes was the effect of temperature rise. FIG. 3 shows an increase in the temperature around the oil seal when the motor rotation speed (speed of the input shaft of the speed reducer) is 1800 rpm in a freezer having a temperature in the freezer (target freezing temperature) of −25 ° C. An experimental example is shown in which As can be seen from this experimental example, when the temperature in the freezer is −25 ° C., the temperature around the oil seal is about 10 minutes after the start of operation and is larger than that at room temperature (in the actual measurement result, about It can be confirmed that the temperature rises rapidly to around 0 ° C. at 1.3 times), exceeds 0 ° C. in 10 minutes, and then gradually increases and becomes almost constant after 40 minutes.

  This result shows that the oil seal periphery goes back and forth around the boundary of 0 ° C. when it is repeatedly stopped after being continuously operated for more than 10 minutes from the start of operation. It is considered that the temperature increase / decrease around 0 ° C. due to the operation / stop causes the problem of condensation.

  However, especially when a gear motor is newly introduced or maintained, when it is brought into the freezer from the outside of the freezer after a test operation at room temperature, or when the storage shelf or transport stand is once outside the freezer door. In the case of a freezer with a structure that comes out and enters again, it is considered that outside air (air containing moisture) is likely to be brought into the freezer together with the gear motor. As a result, condensation around the oil seal condenses and repeats solidification and melting It will be.

  In view of this, the gear motor according to the present invention incorporates a cryogenic oil seal that is guaranteed to be used at least at-(T + 10) ° C when the target refrigeration temperature is -T ° C. Preferably, the gear motor is operated intermittently so that the temperature around the oil seal does not exceed 0 ° C. Alternatively, the gear motor is operated intermittently so as not to exceed a predetermined time set shorter than a time when the temperature around the cryogenic oil seal is predicted to exceed 0 ° C. This eliminates the “phase change” of water around the cryogenic oil seal, prevents repeated condensation, solidification, and melting, and makes the gear motor use environment very stable.

  A configuration in which the humidity of the freezer is managed so as to be kept low or the oil seal is contrived so that condensation does not become a problem is also effective.

  Hereinafter, a more specific example of the embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a cross-sectional view of a gear motor for a freezer according to an example of an embodiment of the present invention. Note that the target freezing temperature of the freezer (not shown) is −25 ° C. in this example.

  The freezer gear motor 10 is an integrated motor 12 and speed reducer 14. In general, when referring to a “gear motor”, the motor 12 and the speed reducer 14 are generally integrated (from the design stage) as in this embodiment, but the gear motor according to the present invention is often referred to. For example, an independently designed motor and a reduction gear may be integrated through a coupling or a connecting bolt. The present invention can be similarly applied when there is a situation where it is not desired to leak oil outside the reduction gear (for example, in the coupling).

  The speed reducer 14 includes an input shaft (rotary shaft) 16 that also serves as a motor shaft of the motor 12, a hypoid pinion 18 that is integrally formed with the input shaft 16, and a hypoid gear 20 that meshes with the hypoid pinion 18. The hypoid gear 20 is incorporated in the intermediate shaft 22, and an intermediate pinion 24 integrally formed with the intermediate shaft 22 meshes with the output gear 26. Then, the rotation of the output gear 26 is output to the outside as the rotation of the hollow type output shaft (rotating shaft) 27.

  The freezer gear motor 10 includes an oil seal that seals the input shaft 16 and the output shaft 27 of the speed reducer 14. This oil seal is a cryogenic oil seal 30 that can be sealed to a temperature that is at least 10 ° C. lower than the target refrigeration temperature, and the temperature around the cryogenic oil seal 30 does not exceed 0 ° C. The gear motor 10 is operated intermittently.

  More specifically, the input side of the speed reducer 14 includes a cryogenic oil seal 30 (according to an embodiment of the present invention) disposed adjacent to the bearing 28 of the input shaft 16, and the cryogenic oil seal 30. The oil seal 30 is hermetically sealed by a room temperature oil seal 32 (for dust removal) incorporated in parallel on the inside of the speed reducer. The output side of the speed reducer 14 is sealed by a cryogenic oil seal 36 (according to the embodiment of the present invention) disposed adjacent to the bearing 34 of the output shaft 27. The output-side cryogenic oil seal 36 has a structure similar to that of the input-side cryogenic oil seal 30 although the diameter is different. Therefore, for the sake of convenience, the description will be made by paying attention to the cryogenic oil seal 30 on the input side.

  The cryogenic oil seal 30 is made of nitrile rubber. Nitrile rubber has a low-temperature sealing property that is sufficient for a target refrigeration temperature of −25 ° C. (can be sufficiently sealed to −40 ° C. (below) lower than the target refrigeration temperature of −25 ° C. by 10 ° C. or more). . In addition, since it is resistant to mineral oil and has wear resistance, it is suitable for use as a gear motor for a freezer. In fact, this nitrile rubber does not cause the problem of the initial hardness even if the direct operation is started without the warm-up operation in the freezer. In addition to nitrile rubber, silicone rubber, ethylene propylene rubber, styrene butadiene rubber, ethylene tetrafluoride resin, fabric, and the like also have good low-temperature characteristics as the material for the cryogenic oil seal of the present invention. Among these, silicone rubber is preferable in that it can also effectively cope with the point that it may be operated outside the freezer because it has relatively heat resistance.

  As shown in FIG. 2 in an enlarged manner, the cryogenic oil seal 30 has a simple structure mainly having a main lip 30A (although the material itself is expensive), and the cost is reduced. On the other hand, in the case of the gear motor 10 operated in the freezer, it has been confirmed that dust problems such as abrasion powder are likely to occur (particularly, a test operation at room temperature was performed at the time of introduction or maintenance of the gear motor 10). The generation of this dust is likely to be further reduced by the operation according to the present embodiment (maintaining below 0 ° C.), but in this embodiment, the oil for cryogenic temperature is further reduced. Since a normal temperature oil seal 32 for dust removal is incorporated in parallel with the inside of the speed reduction mechanism of the seal 30, the dust removal function is further strengthened.

  This room temperature oil seal 32 is literally used at room temperature, and has a dust lip 32B in addition to the main lip 32A. This room temperature oil seal 32 functions as a so-called oil seal when performing a room temperature test operation at the time of introduction (inevitable in this kind of gear motor for a freezer) or a room temperature inspection operation during maintenance outside the freezer. In addition, the cryogenic oil seal 30 is surely protected from dust such as abrasion powder. On the other hand, during normal cryogenic operation in a freezer, much of the dust is caught here, but the hardness increases and the function as an oil seal is reduced. However, since the sliding loss is hardly increased by that amount, even though two oil seals are provided, it is possible to maintain high operating efficiency and to generate a small amount of heat (especially for the present embodiment). It has.

  This freezer gear motor 10 is operated intermittently so that the temperature around the cryogenic oil seal 30 does not exceed 0 ° C. Although this specific operation control is not particularly limited, in this embodiment, a temperature sensor 40 composed of a thermocouple is incorporated in the vicinity of the cryogenic oil seal 30, and the temperature around the cryogenic oil seal 30. Can be detected.

  In this embodiment, the output-side cryogenic oil seal 36 does not incorporate a temperature sensor, thereby reducing costs. This is because the temperature of the output-side cryogenic oil seal 36 is always lower than the temperature of the input-side cryogenic oil seal 30 (because the rotational speed of the output shaft 27 is slow). This is because it is sufficient to monitor.

  The following is an example of operation control. The operation of the gear motor 10 for the freezer is performed according to a flowchart as shown in FIG. 4, for example.

  When the power of the gear motor 10 is turned on in step S2, the temperature around the cryogenic oil seal 30 is detected by the temperature sensor 40 using a thermocouple in step S4. In step S6, it is determined whether or not this temperature is higher than -4 ° C. with some allowance from 0 ° C. When it is determined that the temperature is −4 ° C. or lower, there is no possibility that the condensed condensation that has solidified is melted, so the process returns to step S4 and the temperature monitoring and the operation of the gear motor 10 are continued. However, when it is determined in step S6 that the temperature around the cryogenic oil seal 30 has become higher than −4 ° C., the process proceeds to step S8 where a warning by a lamp (not shown) or the like is given. Further, in step S10, it is confirmed whether or not the temperature is higher than -2 ° C. If it is determined that the temperature around the cryogenic oil seal 30 is −2 ° C. or lower, the temperature monitoring in step S4 is repeated once again. If it is determined in step S10 that the temperature is higher than −2 ° C., step S12 is performed. Proceed to, and the power is shut off. During this time, whenever the operator manually stops the operation of the gear motor 10, the process proceeds to step S12, where the gear motor 10 is stopped. When the power is turned on next time, the flow starts again from step S2. .

  Thus, when the temperature around the cryogenic oil seal 30 is −2 ° C. or lower, the operation can be continued as it is, but when it is determined that the temperature around the cryogenic oil seal 30 is higher than −2 ° C. At that time, the operation is stopped. Therefore, the oil seals 30, 32, 34 in the gear motor 10 are reliably maintained below freezing point, and the condensed condensation that has solidified does not melt (of course, there is no re-condensation). Can always maintain good sealing performance in a stable environment, and can greatly extend the service life.

  In this example, in addition to the warning threshold value (−4 ° C.), the power cutoff threshold value (−2 ° C.) is slightly higher and lower than 0 ° C., but there is only one threshold value. (No warning) or a timer may be activated instead of the second threshold setting. The threshold value itself is not limited to -4 ° C and -2 ° C.

  Note that the control (that is, the driving method according to the present embodiment) may be manually turned off in consideration of the fact that there is a case where it is desired to drive urgently even at the expense of some life.

  By the way, what is important in the present invention is that the gear motor 10 is intermittently operated so that the temperature around the cryogenic oil seal 30 does not exceed 0 ° C. The temperature sensor 40 is not necessarily an essential requirement. Absent. For example, the gear motor 10 may be operated intermittently so as not to exceed a predetermined time set shorter than a time when the temperature around the cryogenic oil seal is predicted to exceed 0 ° C. .

  FIG. 5 shows an example of operation control according to this configuration example.

  In this operation control, instead of directly detecting the temperature in the vicinity of each cryogenic oil seal 30, the oil seals 30, 32, 36 is protected. Therefore, when relying on this operation control, the temperature sensor 40 of the gear motor 10 is unnecessary.

  When the power is turned on in step S20, it is determined whether or not the third timer t3 started (reset & count start) in step S32 described later at the time of the previous power-off has passed for 5 minutes or more. If 5 minutes or more have elapsed, the process immediately proceeds to step S24, and the power is actually turned on. If 5 minutes have not yet elapsed, the process waits until 5 minutes have elapsed, and then proceeds to step S24. At this time, the power is turned on for the first time. In step S24, the first timer t1 is started (reset & count is started) simultaneously with turning on the power.

  Thereafter, in step S26, it is determined whether or not the first timer (that is, the continuous operation time) t1 has exceeded a predetermined time, for example, 8 minutes (the temperature around the cryogenic oil seal 30 does not reach 0 ° C.). The From the time the power is turned on, that is, as long as 8 minutes have not passed since the gear motor 10 actually started operation, the operation goes around step S26 and the operation is continued as it is.

  However, if it is determined that the first timer t1 has exceeded 8 minutes, the process proceeds to step S28, where a warning by a lamp (not shown) or the like is given, and the second timer t2 is started (reset & count start). If it is determined in step S30 that two minutes have elapsed since the start of the second timer t2, the power is turned off in step S32, and at the same time, the third timer t3 is started (reset & count start). The third timer t3 is used to secure a 5-minute interval (re-operation prohibition period) until the power is actually turned on when the next power-on operation is performed (step S20 described above). (Step S22 described above). With the function of the third timer t3, even when the power of the gear motor 10 is turned on immediately after continuous operation, it is reliably prevented that the temperature reaches 0 ° C. or higher as a result.

  The re-operation prohibition period (5 minutes in this example) may be changed as appropriate depending on the heat dissipation characteristics around the oil seal of the gear motor 10 and the ambient temperature (target freezer temperature). In addition, it is better to variably set depending on the time of continuous operation immediately before. Naturally, when the last continuous operation time is short, the re-operation prohibition period may be short. As a result, the operation at a temperature lower than 0 ° C. can be performed more reliably while reducing the frequency of interruption.

  In this embodiment, the threshold value of the first timer t1 is set to 8 minutes and the threshold value of the second timer t2 is set to 2 minutes, as long as the continuous operation time is 10 minutes or less according to the above-described experiment. This is because the oil seals 30, 32, and 36 are presumed not to be at 0 ° C., and therefore, it is considered that there is no possibility that the condensed condensation will melt. The threshold value of the first timer t1 is appropriately set depending on the actual target temperature of the freezer or the amount of heat generated around the oil seal of the gear motor. Incidentally, even if it is other than the freezer which concerns on this embodiment, if it is less than 10 minutes, it will not generally exceed 0 degreeC.

  As described above, the present invention does not necessarily need to physically measure the temperature. However, it is not always necessary to actually measure the continuous operation time with a timer and then automatically turn off the gear motor. There is no need to do. That is, for example, the gear motor is consciously considered for the continuous operation time and the re-operation prohibition time so that the continuous operation time does not exceed 10 minutes (even in the absence of the timer means or the like). May be operated intermittently. Even with such a configuration, oil leakage can be effectively prevented and the life (of the oil seal) can be significantly increased, and the gear motor for a freezer can be used as it is in the freezer while minimizing cost increase. Can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Gear motor for freezer 12 ... Motor 14 ... Reduction gear 30, 36 ... Oil seal for cryogenic temperature 32 ... Oil seal for normal temperature 40 ... Temperature sensor

Claims (4)

A gear motor that integrates a motor and a reducer used in a freezer,
An oil seal that seals the rotating shaft of the speed reducer;
The oil seal is a cryogenic oil seal that can be sealed to a temperature that is at least 10 ° C. lower than the target refrigeration temperature, and the gear motor is designed so that the temperature around the cryogenic oil seal does not exceed 0 ° C. A freezer gear motor that is operated intermittently. A gear motor that integrates a motor and a reducer used in a freezer,
An oil seal that seals the rotating shaft of the speed reducer;
The oil seal is a cryogenic oil seal that can be sealed to a temperature that is at least 10 ° C. lower than the target refrigeration temperature, and the temperature around the cryogenic oil seal is expected to exceed 0 ° C. The gear motor for a freezer, wherein the gear motor is operated intermittently so as not to exceed a predetermined time set short. In claim 2 ,
The predetermined time is set to 10 minutes or less. A freezer gear motor. In any one of claims 1 to 3,
The freezer gear motor, wherein the cryogenic oil seal is selected from nitrile rubber, silicone rubber, ethylene propylene rubber, styrene butadiene rubber, tetrafluoroethylene resin, and fabric.

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