JP2010223261A - Lubricating structure of power transmission section - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating structure of power transmission section which can stably lubricate and cool a power transmission element for a long period of time. <P>SOLUTION: The lubricating structure 10 of power transmission section includes a power transmission element 12, a compound fluid 22 consisting of a lubricating oil 24 for lubricating the power transmission element 12 and refrigerant 26 non-compatible with the lubricating oil 24, and gear 20 for stirring the compound fluid 22 lubricating the power transmission element 12 in connection with an operation of gear train 16 constructing the power transmission element 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lubricating structure of a power transmission unit lubricated with a lubricating liquid.

  O / W / O type composite emulsion automotive lubricants are known that are used as engine oils for automobiles and have a higher cooling performance and equivalent lubricity compared to general lubricating oils (for example, Patent Document 1). reference).

Japanese Patent No. 2513318

  However, the conventional techniques as described above use emulsions containing water that is thermodynamically unstable, freezes easily, and perishes easily, and therefore it is difficult to stably achieve each performance of lubrication and cooling over a long period of time. Met.

  An object of the present invention is to obtain a lubrication structure for a power transmission unit that can stably lubricate and cool a power transmission element over a long period of time.

  The lubricating structure of the power transmission unit according to the invention of claim 1 is a power transmission element, a composite fluid of a lubricating liquid for lubricating the power transmission element, a refrigerant incompatible with the lubricating liquid, and the And a stirring element that stirs the composite fluid that is used for lubrication of the power transmission element.

  In the lubricating structure of the power transmission unit according to the first aspect, the composite fluid stirred by the stirring element is supplied to the power transmission element. As a result, the power transmission element is satisfactorily cooled by contact with the refrigerant while being well lubricated by the lubricating liquid. Here, since the lubricating fluid and the refrigerant of the composite fluid are incompatible with each other, the lubricating liquid and the refrigerant can stably perform their functions independently of each other. That is, in the lubrication structure of the power transmission unit, there is no risk of performance degradation due to, for example, the coupling between the lubricating liquid and the refrigerant, the release of the coupling, and the like.

  Thus, in the lubricating structure of the power transmission unit according to the first aspect, the components of the power transmission unit can be stably lubricated and cooled over a long period of time.

  According to a second aspect of the present invention, in the power transmission unit lubricating structure, a refrigerant having a viscosity lower than that of the lubricating liquid is used as the refrigerant.

  In the lubricating structure of the power transmission unit according to claim 2, since the refrigerant of the composite fluid has a lower viscosity than the lubricating liquid, the flow resistance (shearing force) of the composite fluid is reduced as compared with the case of using a single lubricant. Is done. Thereby, reduction of power transmission loss is achieved.

  According to a third aspect of the present invention, there is provided a lubricating structure for a power transmission unit according to the first or second aspect, wherein a fluorine-based refrigerant is used as the refrigerant.

  In the lubricating structure of the power transmission unit according to claim 3, the fluorine-based refrigerant is not easily corroded itself, hardly corrodes the power transmission element (components thereof), and is not easily frozen (has a low pour point). It can be. For this reason, in the lubricating structure of this power transmission part, the component of a power transmission part can be lubricated and cooled more stably over a longer period of time.

  According to a fourth aspect of the present invention, there is provided a lubrication structure for a power transmission unit according to any one of the first to third aspects, wherein the power transmission element is accommodated and the composite is disposed at the bottom. A housing for storing fluid is further provided, and the stirring element includes a rotating member that is immersed in the composite fluid stored in the bottom of the housing and forms a part of the power transmission element.

  In the lubricating structure of the power transmission unit according to claim 4, the composite fluid stored in the bottom of the housing is agitated by the rotating member constituting a part of the power transmission element, and this composite fluid is used for lubricating the power transmission element. Provided. Since the power transmission element itself forms a stirring element, it is possible to achieve both lubricity and cooling performance by the composite fluid without increasing the number of parts.

  According to a fifth aspect of the present invention, there is provided a lubricating structure for a power transmission unit according to any one of the first to fourth aspects, wherein the coolant is an operating temperature of the power transmission element as the refrigerant. In addition, a refrigerant having a low boiling point is used, and further includes a pressure adjusting element that can be expanded by the pressure of the vaporized refrigerant, and a cooling element for cooling the vaporized refrigerant.

  In the lubricating structure of the power transmission unit according to the fifth aspect, the refrigerant that has contacted the power transmission element that has reached a normal operating temperature (operation temperature) evaporates while taking away latent heat from the power transmission element. For this reason, the cooling structure of the power transmission element is further enhanced in the lubricating structure of the power transmission unit. Further, when the refrigerant evaporates, the pressure adjusting element is prevented from expanding and the internal pressure is prevented from becoming excessive, and the evaporated refrigerant is deprived of latent heat by the cooling element and is liquefied (returns to the liquid phase).

  As described above, the lubricating structure of the power transmission unit according to the present invention has an excellent effect that the power transmission element can be stably lubricated and cooled over a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically schematic structure of the lubrication structure of the power transmission part which concerns on the 1st Embodiment of this invention, (A) is typical sectional drawing of a power transmission element, (B) is composite liquid. It is a perspective view at the time of stationary. 1 is a front view schematically showing a block-on-ring friction and wear tester used for evaluating a composite liquid constituting a lubricating structure of a power transmission unit according to a first embodiment of the present invention. It is a figure which shows the abrasion evaluation result of the block 34 by the said block on-ring friction abrasion tester, Comprising: (A) is a photograph which shows the abrasion state at the time of using only lubricating oil, (B) is the case where only a refrigerant | coolant is used. (C) is a photograph which shows a wear state at the time of using the composite liquid which comprises the lubrication structure of the power transmission part which concerns on the 1st Embodiment of this invention. It is a side view which shows typically the heat dissipation capability testing machine used in evaluating the composite liquid which comprises the lubrication structure of the power transmission part which concerns on the 1st Embodiment of this invention. (A) is a diagram showing the relationship between the heat dissipation performance and the stirring speed for each liquid under test calculated from the measurement results of the heat dissipation capability tester, and (B) is the temperature of the iron ingot in the heat dissipation capability tester. It is a diagram for demonstrating that heat dissipation performance can be calculated from a change. It is a figure which shows the temperature measurement result of each part by the said block on-ring friction abrasion test machine, Comprising: (A) is a diagram which shows the result at the time of using only lubricating oil, (B) is 1st implementation of this invention It is a diagram which shows the result at the time of using the composite liquid which comprises the lubrication structure of the power transmission part which concerns on a form. It is a side view which shows typically the load test apparatus used in evaluating the composite liquid which comprises the lubrication structure of the power transmission part which concerns on the 1st Embodiment of this invention. About the drag torque measurement result accompanying the rotation of the rotating disk by the load test device, the case where only the lubricating oil is used and the composite liquid constituting the lubricating structure of the power transmission unit according to the first embodiment of the present invention are used. It is a graph which compares and shows the case where it was. It is a figure which shows the fluid dragging state to the rotating disk by the said load test apparatus, Comprising: (A) is a photograph at the time of using only lubricating oil, (B) is the power transmission which concerns on the 1st Embodiment of this invention. It is a photograph at the time of using the composite liquid which comprises the lubricating structure of a part. It is sectional drawing which shows typically schematic structure of the lubrication structure of the power transmission part which concerns on the 2nd Embodiment of this invention.

  A power transmission lubricating structure 10 according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1A, a schematic overall configuration of a lubricating structure 10 of a power transmission unit is shown in a schematic cross-sectional view. As shown in this drawing, the lubricating structure 10 of the power transmission unit is applied to lubrication and cooling of the power transmission element 12.

  The power transmission element 12 illustrated in FIG. 1A includes a housing 14 and a gear train 16 disposed in the housing 14. At the bottom of the housing 14 is formed a liquid reservoir 18 in which a composite fluid 22 described later is stored. The gear 20 that forms part of the gear train 16 is immersed in the liquid reservoir 18 at least in the lower part in the direction of gravity. Therefore, in the lubricating structure 10 of the power transmission unit, the composite fluid 22 is agitated when the gear 20 rotates around its own axis. That is, in the example of FIG. 1, the gear 20 corresponds to the stirring element and the rotating member in the present invention.

  In this embodiment, the composite fluid 22 is agitated by the rotation of the gear 20 and is sprinkled (scattered) in the housing 14, and the other gears constituting the gear train 16, the shaft 16 </ b> A of the gear train 16. It is supplied to the bearing portion 16B and the like. The composite fluid 22 used for lubricating the gear train 16 is returned to the liquid reservoir 18 by gravity.

  As shown in FIG. 1B, the composite fluid 22 is configured by mixing a lubricating oil 24 as a lubricating liquid and a refrigerant 26. The lubricating oil 24 is a general lubricating oil corresponding to an application (kind of the power transmission element 12) based on, for example, mineral oil or synthetic oil. The refrigerant 26 is made incompatible with the lubricating oil 24 (insoluble) and does not melt (is mechanically separable and forms an interface in the separated state).

  The composite fluid 22 is separated up and down by gravity as shown in FIG. 1B in an unloaded state (without stirring by the gear 20). In this embodiment, the refrigerant 26 has a higher density than the lubricating oil 24. For this reason, the stationary composite fluid 22 has a configuration in which the interface of the refrigerant 26 is covered with the lubricating oil 24.

  In this embodiment, a fluorine-based refrigerant is used as the refrigerant 26. Thus, the refrigerant 26, which is a fluorine-based refrigerant, is chemically stable and hardly corroded, for example, compared with a refrigerant such as water, and the steel gear train 16 and the housing 14 are not easily deteriorated (such as rust generation). The pour point is low and it is difficult to freeze. The refrigerant 26 has a lower viscosity than the lubricating oil 24.

More specifically, in this embodiment (an experimental example described later), Fluorinert FC-84 manufactured by Sumitomo 3M Co., Ltd. is employed as the refrigerant 26. Fluorinert FC-84 has a pour point of −95 [° C.], a viscosity at 25 [° C.] of about 0.0009515 [Pa · s], and a density at 25 [° C.] of about 1730 [kg / m ³ ]. Supplementing the viscosity of Fluorinert FC-84, where viscosity μ = density ρ × kinematic viscosity ν, the kinetic viscosity of Fluorinert FC-84 is approximately 0.55 × 10 ⁻⁶ [m ² / s].
μ = ρ × ν
= 1730 [kg / m ³ ] × 0.55 × 10 ⁻⁶ [m ² / s]
= 0.0009515 [Pa · s]
It is said. The viscosity and density at 25 [° C.] of the lubricating oil 24 according to this embodiment are approximately 0.043 [Pa · s] and approximately 844.7 [kg / m ³ ], respectively. Further, the boiling point of the refrigerant 26 according to this embodiment is approximately 80 [° C.] at atmospheric pressure.

  The lubricating structure 10 of the power transmission unit described above includes, for example, a bearing, a crankshaft, a valve system of an internal combustion engine and an external combustion engine as the power transmission element 12, and a transmission for an automobile (manual transmission, automatic transmission, (Including continuously variable transmission), and gearboxes for general machinery. Further, for example, in an example in which the power transmission lubrication structure 10 is applied to an automobile transmission, a final gear or a differential gear (in the case of a FF vehicle transmission) can be employed as the gear 20 that is a stirring element. .

  Next, the operation of this embodiment will be described.

  In the power transmission element 12 to which the lubricating structure 10 of the power transmission unit having the above configuration is applied, the composite fluid 22 is agitated by rotating the gear 20 of the gear train 16 in accordance with the operation thereof, and the lubricating oil 24 and the refrigerant are mixed. 26 is mixed (melted) without melting. The composite fluid 22 in which the lubricating oil 24 and the refrigerant 26 are turbid in this way is scattered (spread up) in the housing 14 and supplied to the gear train 16 other than the gear 20 to lubricate the gear train 16. Provided for cooling.

  Here, since the lubricating structure 10 of the power transmission unit uses the composite fluid 22 of the lubricating oil 24 and the refrigerant 26, for example, the same lubricating performance is ensured as compared with a configuration in which the lubricating oil 24 alone is used for lubrication. However, the cooling performance is improved. Further, since the lubricating structure 10 of the power transmission unit uses the composite fluid 22 of the refrigerant 26 and the lubricating oil 24 having a viscosity lower than that of the lubricating oil 24, for example, compared with a configuration in which the lubricating oil 24 alone is used for lubrication. The flow resistance of the lubricant is low, which contributes to the reduction of transmission power loss.

  Hereinafter, these effects will be described with reference to experimental results. FIG. 2 is a schematic side view of a block-on-ring friction and wear tester (LFW-1) 30 described in ASTM D2714. The block-on-ring friction and wear testing machine 30 measures the rotational torque of the ring 32 while pressing the block 34 with a predetermined load (surface pressure) F against the ring 32 rotating at a predetermined peripheral speed v around its own axis. It is. The lower portion of the ring 32 is immersed in the liquid under test, and the sliding portion between the ring 32 and the block 34 is lubricated with the liquid under test.

  First, the lubrication characteristics of each liquid under test using this block-on-ring friction and wear tester 30 will be described. Specifically, the friction coefficient was calculated based on the pressing load of the block 34 and the measured value of the rotational torque of the ring 32, and the wear state of the block 34 after the test was confirmed. Three types of liquids to be tested were used: lubricating oil 24 alone, refrigerant 26 alone, and composite fluid 22 (mixing ratio of lubricating oil 24 and refrigerant 26 was 50% by volume).

  Table 1 shows the friction coefficient and the wear depth (maximum) when each liquid under test is used. Moreover, the abrasion state of the block 34 using each liquid under test is shown in FIG. 3A shows a case where the lubricating oil 24 alone is used as the liquid under test, FIG. 3B shows a case where the refrigerant 26 alone is used as the liquid under test, and FIG. 3C shows a composite fluid 22 as the liquid under test. Each case is shown. The test conditions were set such that the pressing load F of the block 34 was F = 444 [N], the peripheral speed v of the ring 32 was 1.2 [m / s], the total amount of liquid was 50 [ml], and the measurement time was 30 [min]. The friction coefficient was an average value of 1 [min] immediately before the end of measurement.

From Table 1 and FIG. 3, it was confirmed that when the composite fluid 22 was used, at least equivalent lubricating performance was obtained compared to the case of the lubricating oil 24 alone.

  Next, the cooling characteristics of each liquid under test using the heat dissipation capability tester 40 shown in FIG. 4 will be described. The heat radiation capacity tester 40 stirs the liquid to be tested in the container 44 with the stirrer 42, immerses the iron lump 46 heated to lower temperature in the liquid to be tested, and changes the internal temperature of the iron lump 46 over time. Is measured by a thermocouple 48. FIG. 5 (A) shows the heat dissipation performance Phr [W / K] for each liquid under test obtained from the measurement results by the heat dissipation capability tester 40 and the stirring speed by the stirrer 42 (the rotation speed [rpm] of the stirrer 42A). It is a diagram which shows a relationship. From FIG. 5 (A), when the composite fluid 22 is used, compared with the case where the lubricating oil 24 is used alone, at each stirring speed (the condition of natural convection shown as stirring speed 0 and forced convection) Under each condition, it can be seen that the heat dissipation performance Phr is high. This is presumably because when the composite fluid 22 is used, a heat dissipation effect to the refrigerant 26 is obtained by the fluid contact of the refrigerant 26 having a higher heat transfer coefficient than the lubricating oil 24 with the iron block 46. . In the measurement by the heat radiation capability tester 40, boiling of the composite fluid 22 (the lubricating oil 24 and the refrigerant 26) and the lubricating oil 24 alone is not observed.

Supplementing the heat dissipation performance Phr, the heat dissipation performance Phr is calculated as the product (α × A) of the heat transfer coefficient α [W / (m ² · K)] and the heat dissipation area A [m ² ] of the liquid under test. . On the other hand, the temperature change of the iron block 46 in the liquid under test is as shown in FIG. Here, assuming that the temperature change shown in FIG. 5B is a mass system (large heat conduction, specific heat, and mass is limited for the iron block 46), the temperature change of the iron block 46 in the liquid to be tested is
T ′ = exp (−τ)
Satisfy the relationship. If the temperature (variable) of the iron block 46 is T, the initial temperature is T0, and the saturation temperature is Tsat,
T ′ = (T−T0) / (Tsat−T0)
Therefore, the temperature T of the iron block 46 is
T = T0 + (Tsat−T0) × exp (−τ)
It becomes.

Further, when the specific heat of the iron ingot 46 is C, the density is ρ, the volume is V, and the time is t,
τc = C × ρ × V / (α × A)
As
τ = t / τc
Therefore, the temperature T of the iron block 46 is
T = T0 + (Tsat−T0) × exp (−t / τc)
I understand that

  And the time change of the temperature T of this iron ingot 46 is obtained as shown in FIG. 5 (B) by measuring with the heat dissipation capability tester 40, so that the heat dissipation performance Phr for each stirring speed of each liquid under test. = (Α × A) can be calculated.

  Further, the cooling characteristics of each liquid under test using the block-on-ring friction wear tester 30 (see FIG. 2) will be described. 6A and 6B show a liquid thermometer 36 that measures the temperature of the liquid under test and a block thermometer 38 that measures the temperature of the block 34 during the operation of the block-on-ring friction and wear tester 30. , And each measured temperature by a room temperature meter (not shown). The block thermometer 38 is disposed at a position where the distance D from the contact point between the ring 32 and the block 34 is approximately 1 mm. 5A shows the results when the lubricant 24 alone is used as the liquid under test, and FIG. 5B shows the results when the composite fluid 22 is used as the liquid under test.

  As can be seen from these figures, the room temperature during testing of both fluids to be tested is constant. Further, as described above, since the friction coefficients of the fluids to be tested are the same, it is estimated that the heat generation amount is substantially constant due to the friction between the ring 32 and the block 34 during the test. The reason why the temperature of the block 34 changes stepwise is that the pressing load F of the block 34 increases stepwise, and after approximately 600 seconds from the start of the test, the pressing load F of the block 34 = A steady test state of 444 [N] is set.

  6 (A) and FIG. 6 (B), when the composite fluid 22 is used, the liquid temperature and the block in the steady test state are compared with the case where the lubricating oil 24 is used alone. It was confirmed that both of the 34 temperatures were lower. In this experiment, when the composite fluid 22 is used, the temperature of the block 34 is lower than that of the case of the lubricating oil 24 alone, because the refrigerant 26 having a higher heat transfer coefficient than the lubricating oil 24 is in fluid contact with the block 34. Heat dissipation effect on the refrigerant 26 (described with reference to FIG. 5A) and boiling cooling due to the vaporization (evaporation) of the refrigerant 26 having a boiling point of 80 ° C. in contact with the block 34 having a temperature exceeding 80 ° C. This is due to any one or combination of effects.

  The liquid temperature of the composite fluid 22 is lower than that of the lubricating oil 24 alone because the refrigerant 26 is cooled (better than the lubricating oil 24) by contact with the housing of the testing machine. it is conceivable that.

  As described above (results of FIGS. 3, 5, and 6), when the composite fluid 22 is used, the cooling performance is improved while ensuring the same lubricity as compared with the case of using the lubricating oil 24 alone. It was confirmed that Therefore, in the lubrication structure 10 of the power transmission unit using the composite fluid 22, the cooling performance of the gear train 16 and the like is improved while ensuring equivalent lubrication performance as compared with the configuration in which lubrication is performed only with the lubricating oil 24. . In addition, since the cooling effect by boiling cooling of the refrigerant | coolant 26 is large with respect to the cooling effect by the fluid contact of the refrigerant | coolant 26, the bigger cooling effect can be acquired by setting it as the boiling-cooling of the refrigerant | coolant 26 being easy to produce.

  Furthermore, the flow resistance of each liquid under test will be described using the load test apparatus 50 shown in FIG. The load test apparatus 50 rotates an aluminum rotating disk 54 in a transparent housing 52 in which a liquid to be tested is stored in a lower portion, and a load torque (fluid drag torque) of the rotating disk 54 is provided on a shaft 54A. Measured with the strain gauge 54B.

  FIG. 8 is a graph in which drag torque when each liquid under test is used is plotted for each rotation speed of the aluminum rotating disk 54 (showing the minimum value, maximum value, and average value measured multiple times). . From this figure, it was confirmed that when the composite fluid 22 was used, drag torque was reduced at each rotational speed as compared with the case of the lubricating oil 24 alone. The drag torque reduction rate varies depending on the rotation speed (the higher the rotation speed, the smaller the drag torque). However, in the results shown in FIG. 8, the drag torque is reduced by about 30% on average.

  Such a drag torque reduction effect can be visually confirmed from the experimental situation shown in FIG. 9A shows a flow state of the lubricating oil 24 alone when the aluminum rotating disk 54 rotates in the direction of the arrow, and FIG. 9B shows the aluminum rotating disk 54 having the arrow. The flow state of the composite fluid 22 when rotated in the direction is shown. From the comparison of these figures, it can be seen that when the composite fluid 22 is used, the change in the liquid level due to the rotation of the aluminum rotating disk 54 is smaller than when the lubricating oil 24 is used alone.

  From the above, it can be seen that when the composite fluid 22 is used, the load accompanying the rotation of the rotating disk 54 is reduced. Therefore, in the lubrication structure 10 of the power transmission unit using the composite fluid 22, the load associated with the rotation of the gear train 16 (particularly the gear 20) is reduced as compared with a configuration in which lubrication is performed only with the lubricating oil 24, and transmission power is reduced. It can be seen that this contributes to the reduction of loss.

  And in the lubricating structure 10 of a power transmission part, since the composite fluid 22 of the lubricating oil 24 and the refrigerant | coolant 26 incompatible with this lubricating oil 24 is used, each said effect is acquired stably over a long period of time. be able to. For example, when an emulsion in which water and oil are emulsified and dispersed is used as a lubricant, the following problems are concerned. First, since the emulsion is thermodynamically unstable, the emulsified dispersion state tends to deteriorate with time. Secondly, in an emulsion in which water and oil are uniformly dispersed, moisture, which is a refrigerant component, is exposed to the atmosphere and is easily lost by vaporization. Third, the water in the emulsion freezes below freezing. Fourthly, moisture in the emulsion is likely to deteriorate (corrode) with time. Fifth, moisture in the emulsion corrodes the components (steel parts) of the power transmission element 12.

  On the other hand, in the lubricating structure 10 of the power transmission unit, the composite fluid 22 of the lubricating oil 24 and the refrigerant 26 that are incompatible with each other is used by being agitated and mixed by the gear 20 when the power transmission element 12 is operated. Therefore, the composite fluid does not deteriorate with time unlike the first problem in the emulsion. Further, when the power transmission element 12 is stopped, the composite fluid 22 in the liquid reservoir 18 is covered with the lubricating oil 24 at the interface of the refrigerant 26 having a relatively high density. Is prevented or effectively suppressed.

  Furthermore, since the refrigerant 26, which is a fluorine-based refrigerant, has a pour point of −95 ° C. as described above, it does not freeze under the assumed use environment (design lower limit temperature) of the power transmission element 12. Moreover, since this refrigerant | coolant 26 is a fluorine-type refrigerant | coolant, it itself does not corrode and it is hard to corrode the component parts (steel parts, such as the gear train 16 and the housing 14) of the power transmission element 12.

  As described above, the lubricating structure 10 of the power transmission unit using the composite fluid 22 stably exhibits the above-described effect of improving the cooling performance and the effect of reducing the flow resistance while ensuring the lubrication performance. Can do.

  Thus, in the lubricating structure 10 of the power transmission unit according to the first embodiment, the components including the gear train 16 of the power transmission element 12 can be stably lubricated and cooled over a long period of time.

  In addition, although the example which can show | play the boiling cooling effect of the refrigerant | coolant 26 was shown in 1st Embodiment, this invention is not limited to this, The refrigerant | coolant with a higher boiling point as the refrigerant | coolant 26 (for example, boiling point is 174 degreeC) It is also possible to use a structure such as Fluorinert FC-43 manufactured by Sumitomo 3M Co., Ltd., which exhibits a cooling effect by fluid contact (see FIG. 4) regardless of boiling cooling.

  On the other hand, when boiling cooling is used, for example, in order to condense the vaporized refrigerant 26 by heat exchange with the housing 14, a heat radiating fin may be provided on the outer surface of the housing 14.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. Note that portions that are basically the same as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted. FIG. 10 is a schematic cross-sectional view corresponding to FIG. 1 showing a lubricating structure 60 for a power transmission unit according to a second embodiment of the present invention. As shown in this figure, the power transmission unit lubrication structure 60 includes a buffer unit 62 as a pressure adjusting element communicating with the housing 14, and thus the power transmission unit lubrication structure 10 according to the first embodiment. Is different.

  Specifically, the buffer unit 62 according to this embodiment communicates with the upper space of the housing 14 via the communication pipe 64 and is disposed above the upper space of the housing 14 in the gravitational direction. For example, the buffer 62 is formed in an accordion shape so that the capacity of the buffer chamber, which is the internal space, can be expanded or reduced. The buffer unit 62 may be configured such that the capacity of the buffer chamber can be changed by displacement of a diaphragm, a movable lid (piston), or the like.

  And in the lubricating structure 60 of the power transmission part which concerns on this embodiment, the boiling point of the refrigerant | coolant 26 is set lower than the operating temperature (normal operating temperature) of the power transmission element 12. FIG. In this embodiment, the boiling point of the refrigerant 26 is set to 80 ° C. with respect to the operating temperature of the power transmission element 12, which is 140 ° C. (the operating temperature when only the lubricating oil 24 is used for lubrication). Thereby, in the lubricating structure 60 of the power transmission unit, the power transmission element 12 (the gear train 16) is mainly cooled by the boiling cooling effect accompanying the vaporization of the refrigerant 26. As such a refrigerant 26, for example, Fluorinert FC-84 manufactured by Sumitomo 3M Co., Ltd. can be used.

  In the lubrication structure 60 of the power transmission unit, the refrigerant 26 that has contacted the gear train 16 that is operating at a normal operation temperature is vaporized, and the vaporized refrigerant 26 is introduced into the buffer chamber of the buffer unit 62 through the communication pipe 64. It has become so. The buffer unit 62 is configured to prevent the internal pressure of the housing 14 from increasing beyond a predetermined pressure by expanding the capacity of the buffer chamber by the pressure of the gas-phase refrigerant 26. The refrigerant 26 is configured to have a boiling point lower than the operating temperature of the power transmission element 12 at a pressure equal to or lower than the predetermined pressure.

  Further, the lubricating structure 60 of the power transmission unit includes a heat exchanger (condenser) 56 as a cooling element for cooling and liquefying the vaporized refrigerant 26. In this embodiment, the heat exchanger 66 is provided in the communication pipe 64. More specifically, the heat exchanger 66 is configured as an air-cooled condenser that dissipates heat to the outside air by providing fins 66 </ b> A on the outer periphery of the communication pipe 64. The heat exchanger 66 may be provided with a fan that guides cooling air to the fins 66A. For example, in an automobile application, the traveling air may be guided to the fins 66A. Further, the communication pipe 64 is provided so as to form a downward slope without a partial low portion from the buffer part 62 toward the housing 14 in order to return the liquefied refrigerant 6 to the liquid reservoir 18 in the housing 14 by gravity. It has been.

  About the effect | action of the lubricating structure 60 of the power transmission part demonstrated above, the part different from the effect | action of the lubricating structure 10 of a power transmission part is mainly demonstrated.

  In the power transmission element 12 to which the lubrication structure 60 of the power transmission unit is applied, the composite fluid 22 is agitated by rotating the gear 20 of the gear train 16 in accordance with its operation, and the lubricating oil 24 and the refrigerant 26 are mixed. It is mixed (melted) without melting. The composite fluid 22 in which the lubricating oil 24 and the refrigerant 26 are thus turbid is scattered (spread up) in the housing 14 and supplied to the gear train 16 other than the gear 20 to lubricate and cool the gear train 16. To be served.

  Since the boiling point of the refrigerant 26 in the composite fluid 22 is lower than the operating temperature of the power transmission element 12, the refrigerant 26 in contact with the gear train 16 of the power transmission element 12 is vaporized (evaporated), and the heat of vaporization is generated from the gear train 16. Take away (latent heat). That is, in the lubricating structure 60 of the power transmission unit, the gear train 16 is cooled by boiling cooling.

  The vaporized refrigerant 26 is led to the buffer chamber of the buffer unit 62 through the communication pipe 64 and expands the buffer chamber. Therefore, the pressure in the housing 14 becomes higher than a predetermined pressure due to vaporization of the refrigerant 26. Is prevented. A part of the refrigerant 26 cooled by the heat exchanger 66 along with the flow of the communication pipe 64 is liquefied (condensed) and returned to the liquid reservoir 18 by gravity. In addition, after the operation of the power transmission element 12 is stopped, the refrigerant 26 in the buffer chamber is cooled and liquefied and collected in the liquid reservoir 18.

  Thus, the lubrication structure 60 of the power transmission unit is different from the lubrication structure 10 of the power transmission unit in that the power transmission element 12 is cooled mainly by boiling cooling of the refrigerant 26. This is common with the effect of the lubricating structure 10 of the power transmission unit. Therefore, the power transmission unit lubrication structure 60 according to the second embodiment can basically obtain the same effect by the same operation as that of the power transmission unit lubrication structure 10.

  In particular, in the lubricating structure 60 of the power transmission unit, since the refrigerant 26 cools the power transmission element 12 by boiling cooling, the cooling performance of the power transmission element 12 is high. Since the lubrication structure 60 for the power transmission unit includes the buffer unit 62 into which the vaporized refrigerant 26 is introduced, an excessive pressure increase in the housing 14 is prevented, and the bearings 16B and the like are sealed against the internal pressure of the housing 14. Sex is secured. In other words, in the power transmission unit lubrication structure 60 including the buffer unit 62, the cooling performance can be improved by actively utilizing the boiling cooling effect of the refrigerant 26.

  In the second embodiment, the example in which the fins 66A are provided in the communication pipe 64 and the heat exchanger 66 is configured is shown. However, the present invention is not limited to this, and, for example, the outer periphery of the communication pipe 64 is cooled. The heat exchanger 66 may be configured by covering with a water jacket or introducing a cooling water pipe into the buffer section 62 or the communication pipe 64.

  Further, in each of the above-described embodiments, an example in which a fluorine-based refrigerant is used as the refrigerant 26 constituting the composite fluid 22 is shown, but the present invention is not limited to this, and various refrigerants that are incompatible with the lubricating oil 24 are used. Can be adopted.

  Furthermore, in each of the above-described embodiments, the example in which the gear 20 constituting the gear train 16 that is the object of lubrication and cooling functions as the stirring element has been described. However, the present invention is not limited to this, and for example, the liquid reservoir 18 You may provide the stirring apparatus only for stirring (spreading) in the inside. Further, the present invention is not limited to the configuration in which the composite fluid 22 is spun up and supplied to the gear train 16. For example, the composite fluid 22 in the liquid reservoir 18 is pumped up by an oil pump and flows down from above the gear train 16. May be supplied. In this case, an oil pump may be used as a stirring element, and a stirring element such as a stirrer may be provided downstream of the oil pump. In the latter case, the stirrer may be configured to stir the composite fluid 22 by external power, or may be configured to stir the composite fluid 22 by the flow of the composite fluid 22.

DESCRIPTION OF SYMBOLS 10 Lubricating structure of power transmission part 12 Power transmission element 14 Housing 16 Gear train (power transmission element)
20 Gear (stirring element, rotating member)
22 Complex fluid 24 Lubricating oil 26 Refrigerant 60 Lubricating structure of power transmission unit 62 Buffer unit (pressure adjusting element)
66 Heat exchanger (cooling element)

Claims (5)

A power transmission element;
A composite fluid of a lubricating liquid for lubricating the power transmission element and a refrigerant incompatible with the lubricating liquid;
A stirring element that stirs the composite fluid that is provided for lubrication of the power transmission element;
A power transmission lubrication structure with   The lubricating structure for a power transmission unit according to claim 1, wherein a refrigerant having a viscosity lower than that of the lubricating liquid is used as the refrigerant.   The lubricating structure for a power transmission unit according to claim 1 or 2, wherein a fluorine-based refrigerant is used as the refrigerant. A housing for accommodating the power transmission element and storing the composite fluid at a bottom;
The said stirring element is immersed in the said composite fluid stored at the bottom part of the said housing, and is comprised including the rotation member which comprises a part of said power transmission element. The lubrication structure of the power transmission part described in the item. As the refrigerant, a refrigerant having a boiling point lower than the operating temperature of the power transmission element is used,
The lubrication of the power transmission unit according to any one of claims 1 to 4, further comprising: a pressure adjusting element that is expandable by the pressure of the vaporized refrigerant; and a cooling element for cooling the vaporized refrigerant. Construction.