WO1998022758A1

WO1998022758A1 - Damper device and method for driving the same

Info

Publication number: WO1998022758A1
Application number: PCT/JP1997/004155
Authority: WO
Inventors: Ichiroh Ohnishi
Original assignee: Matsushita Refrigeration Company
Priority date: 1996-11-15
Filing date: 1997-11-14
Publication date: 1998-05-28
Also published as: AU4965597A; CN1212755A; JPH10141835A; CN1114074C; JP3930082B2; TW357252B

Abstract

A damper device (104) includes a first flap (105); a second flap (106); and a driving section (107) for driving the first flap (105) and the second flap (106). The first flap (105) and the second flap (106) are provided so as to interpose the driving section (107) therebetween along a direction of a driving shaft (108a) of the driving section (107). A pivoting shaft (105a) of the first flap (105) and a pivoting shaft (106a) of the second flap (106) are parallel to each other and arranged in a direction other than parallel to the direction of the driving shaft (108a) of the driving section (107), and the first flap (105) and the second flap (106) are driven by the driving shaft (108a). The first flap (105) pivots between a first state and a second state, and the second flap (106) pivots between a first state and a second state.

Description

DESCRIPTION

DAMPER DEVICE AND METHOD FOR DRIVING THE SAME

TECHNICAL FIELD

The present invention relates to a damper device for adjusting the temperature in a refrigerator by blocking and unblocking the path of cold air, and a method for driving such a damper device.

BACKGROUND ART

Conventionally, a damper device has been adopted in order to adjust the temperature of two refrigeration chambers in a refrigerator. A damper device controls the amount of cold air flowing into each refrigeration chamber by opening and closing, by a flap, the path of cold air leading to each refrigeration chamber. Specif- ically, this type of damper device is described in Japanese Publication for Opposition Nos. 4-8709 and 6- 92862.

Hereinafter, a conventional damper device will be described with reference to Figures 11, 12 and 13.

As shown in Figure 11, the conventional damper device operates in the following manner. Cams 12a and 12b are rotated by a motor 3, and thus the driving pins 15a and 15b are driven ( in a linear vertical manner as shown in Figure 11) via driving pins 15a and 15b. In this manner, the flaps 2a and 2b are opened and closed. The motor 3 also drives a switch cam 13. As shown in Figure 12, the switch cam 13, together with a switch 14, forms a position detector for detecting the operation mode of the flaps 2a and 2b based on the driving amount of the motor 3. The switch cam 13 has a high portion 13H and a low portion 13L along the outer periphery thereof with a central angle being 180 degrees. As shown by the cam diagram in Figure 13, the cams 12a and 12b have outer surfaces represented by trapezoidal lines with respect to the rotation angle, which are offset with respect to each other by 90 degrees. By arranging the cams 12a and 12b and the switch cam 13 so that the central angle of the switch cam 13 corresponds to operation modes a, b, c and d in Figure 13, the flaps 2a and 2b can be independently controlled based on the operation position of the switch 14.

However, the above-described conventional damper device has the following drawbacks.

( 1 ) Since the flaps 2a and 2b cannot be separately replaced, the freedom of design is relatively low.

(2) The large volume thereof restricts the possible places to put the damper device and/or requires an increase in the size of the refrigerator.

(3) Since the position detector is required, the number of components are increased and thus the costs are raised.

DISCLOSURE OF THE INVENTION

According to an aspect of the invention, a damper device includes a first flap; a second flap; and a driving section for driving the first flap and the second flap. The first flap and the second flap are provided so as to interpose the driving section therebetween along a direction of a driving shaft of the driving section. A pivoting shaft of the first flap and a pivoting shaft of the second flap are parallel to each other and arranged in a direction other than parallel to the direction of a driving shaft of the driving section, and the first flap and the second flap are driven by the driving shaft. The first flap pivots between a first state and a second state, and the second flap pivots between a first state and a second state.

In one embodiment of the invention, the pivoting shaft of the first flap and the pivoting shaft of the second flap are located along a single line.

In one embodiment of the invention, the first flap and the second flap are put into an initial state, where the first flap and the second flap are both in either the first state or the second state, within a prescribed time period after the driving section starts driving.

In one embodiment of the invention, there is a period in which only one of the first flap and the second flap pivots from the time when driving section starts driving until the initial state is realized.

In one embodiment of the invention, the driving section includes a motor having the driving shaft which is rotatable in a first direction and a second direction opposite to the second direction; a first transmission section for transmitting a turning force of the driving shaft to the first flap; and a second transmission section for transmitting the turning force of the driving shaft to the second flap.

In one embodiment of the invention, the first transmission section transmits the turning force of the driving shaft to the first flap only during a first period from the time when the driving shaft starts rotating in the first direction until the first flap is put into the first state, and during a second period from the time when the driving shaft starts rotating in the second direction until the first flap is put into the second state.

In one embodiment of the invention, the second transmission section transmits the turning force of the driving shaft to the second flap only during a third period from the time when the first flap is put into the first state by the rotation of the driving shaft in the first direction until the second flap is put into the first state, and during a fourth period from the time when the second flap is put into the second state by the rotation of the driving shaft in the second direction until the second flap is put into the second state.

In one embodiment of the invention, the first transmission section includes a first subordinate gear and a first driving gear for transmitting the turning force of the driving shaft to the first flap through the first subordinate gear, and a second ransmission section includes a second subordinate gear and a second driving gear for transmitting the turning force of the driving shaft to the second flap through the second subordinate gear.

In one embodiment of the invention, when the driving shaft rotates in the second direction in the state where the first flap and the second flap are both in the first state, only the first flap pivots in the second direction; after the first flap is put into the second state, the first flap is maintained in the second state and the second flap pivots in the second direction; and after the second flap is put into the second state, the first flap and the second flap are both maintained in the second state. When the driving shaft rotates in the first direction in the state where the first flap and the second flap are both in the second state, only the first flap pivots in the first direction; after the first flap is put into the first state, the first flap is maintained in the first state and the second flap pivots in the first direction; and after the second flap is put into the first state, the first flap and the second flap are both maintained in the first state.

In one embodiment of the invention, when the driving shaft rotates in the first direction by at least a first prescribed amount, the first flap and the second flap are both put into the first state. When the driving shaft rotates in the second direction thereafter by a second prescribed amount which is smaller than the first prescribed amount, the first flap is put into the second state and the second flap is maintained in the first state. In one embodiment of the invention, when the driving shaft rotates in the second direction by at least the first prescribed amount, the first flap and the second flap are both put into the second state. When the driving shaft rotates in the first direction thereafter by the second prescribed amount which is smaller than the first prescribed amount, the first flap is put into the first state and the second flap is maintained in the second state.

In one embodiment of the invention, the driving section further includes a decelerating gear array for transmitting a turning force of the driving shaft to the second driving gear.

In one embodiment of the invention, the driving section further includes a first subordinate gear, a first driving gear for pivoting the first flap through the first subordinate gear, a second subordinate gear, a second driving gear for pivoting the second flap through the second subordinate gear, and a decelerating gear array for transmitting a turning force of the driving shaft to the second driving gear. The damper device further includes a turning force transmission section for transmitting a turning force of the second driving gear to the first driving gear in a period until the first flap is put into the second state while the driving shaft is rotating in the second direction and in a period until the first flap is put into the first state while the driving shaft is rotating in the first direction and for preventing transmission of the turning force of the second driving gear to the first driving gear in a period after the first flap is put into the second state while the driving shaft is rotating in the second direction and in a period after the first flap is put into the first state while the driving shaft is rotating in the first direction; a transmission prevention section for prevent- ing the turning force of the second driving gear from being transmitted to the second subordinate gear while the second flap is in the second state and the second driving gear is rotating in such a direction as to put the second flap into the second state and while the second flap is in the first state and the second driving gear is rotating in such a direction as to put the second flap into the first state; and a transmission start section for releasing the prevention of the transmission of the turning force of the second driving gear to the second subordinate gear when the second driving gear rotates in such a direction as to put the second flap to the first state while the second flap is in the second state and the first flap is in the first state and when the second driving gear rotates in such a direction as to put the second flap to the second state while the second flap is in the first state and the first flap is in the second state.

In one embodiment of the invention, the driving section includes a first driving gear having a first gear section having a plurality of teeth; a second driving gear having a second gear section for receiving a turning force of the driving shaft through a decelerating gear array and for retaining the first driving gear by a gear shaft so as to prevent forcible rotation of the first driving gear when a prescribed load torque acts on the first driving gear, the second gear section having a plurality of teeth, the second driving gear also having a cylindrical section adjacent to the second gear section and having a diameter which is equal or greater than a diameter of an addendum circle of the second gear section, the cylindrical section having a notch which forms a long groove together with one of root portions of the second gear section; a fan-shaped first subordinate gear for transmitting a turning force of the driving shaft to the first flap, first subordinate gear having teeth along an arc-shaped periphery which are always engaged with the first gear section; a fan-shaped second subordinate gear for transmitting a turning force of the driving shaft to the second flap, second subordinate gear having long teeth respectively provided at two ends of an arc-shaped periphery which are engageable with the long groove and a plurality of short teeth provided along the arc-shaped periphery between the long teeth and engageable only with the second gear section; a loading device associated with the first subordinate gear for loading the second subordinate gear in such a direction as to pivot the first subordinate gear when a relative pivot angle of the first subordinate gear with respect to the second subordinate gear exceeds a prescribed angle; and a stopper for stopping the first subordinate gear from pivoting when the first flap is in a prescribed state.

In one embodiment of the invention, the damper device further includes a first frame having an opening which is closable by the first flap and a second frame having an opening which is closable by the second flap. The first flap, the second flap, the first frame and the second frame are independently detachable from the driving section. According to another aspect of the invention, a method for driving a damper is provided. The damper includes a first flap, a second flap, and a driving section for driving the first flap and the second flap. The first flap and the second flap are provided so as to interpose the driving section therebetween along a direction of a driving shaft of the driving section. A pivoting shaft of the first flap and a pivoting shaft of the second flap are parallel to each other and ar- ranged in a direction other than parallel to the direction of a driving shaft of the driving section, and the first flap and the second flap are driven by the driving shaft. The first flap pivots between a first state and a second state, and the second flap pivots between a first state and a second state. The method includes the step of putting the first flap and the second flap into an initial state, where the first flap and the second flap are both in either the first state or the second state, within a prescribed time period after the driving section starts driving.

In one embodiment of the invention, there is a period in which only one of the first flap and the second flap pivots from the time when the driving section starts driving until the initial state is realized.

Thus, the invention described herein makes possible an advantage of providing a compact damper device which can sufficiently control the two flaps and thus solves at least one of the drawbacks, and a method for driving the same. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is an isometric view of a part of a refrigerator including a damper device in an example according to the present invention;

Figure 2 is a partially cut front view of a driving section of the damper device shown in Figure 1 in the state where a first flap and a second flap are both open;

Figure 3 is a partially cut cross-sectional view of the driving section shown in Figure 2 in a direction of arrow III in Figure 1;

Figure 4 is a partial isometric view of the driving section in the state where the first flap and the second flap are both open;

Figure 5 is a partially cut cross-sectional view of the driving section in the state where the first flap and the second flap are both closed;

Figure 6 is a partially cut cross-sectional view of the driving section in the state where the first flap is closed and the second flap is open;

Figure 7 is a partially cut cross-sectional view of the driving section in the state where the first flap is open and the second flap is closed;

Figure 8 is a timing chart illustrating the state of the first flap and the second flap when a motor is rotated forward for 7 seconds and then rotated in reverse for 3 seconds;

Figure 9 is a timing chart illustrating the state of the first flap and the second flap when a motor is rotated in reverse for 7 seconds and then rotated forward for 3 seconds;

Figure 10 is an isometric view of a damper device in another example according to the present invention;

Figure 11 is a plan view of a conventional damper device;

Figure 12 is a cycle diagram showing the relationship between a position detector including a switch cam and a switch and operation modes of the conventional damper device shown in Figure 11; and

Figure 13 is a cam diagram showing the operation of the conventional damper device shown in Figure 11.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way of illustrative examples with reference to the attached figures .

( Example 1 ) Figure 1 is an isometric view of a part of a refrigerator including a damper device in a first example according to the present invention. Shown in Figure 1 is a duct 101 through which cold air flows in and out. The duct 101 includes an air path 102 having a relatively small cross section, an air path 103 having a relatively large cross section, and a partition 101a for separating the two air paths 102 and 103 from each other.

A damper device 104 is attached to the duct 101. The damper device 104 includes a first flap 105 for opening and closing the air path 102, a second flap 106 for opening and closing the air path 103, and a driving section 107 for driving the first flap 105 and the second flap 106.

The driving section 107 is accommodated in the partition 101a. The first flap 105 and the second flap 106 are located so as to interpose the driving section 107. A pivoting shaft 105a (Figure 3) of the first flap 105 and a pivoting shaft 106a (Figure 3) of the second flap 106 are parallel to each other and arranged in a direction other than parallel to a direction of a driving shaft 108a of a motor 108 (Figure 2) of the driving section 107. The pivoting shaft of the first flap and the pivoting shaft of the second flap can, for example, also be located along a single line. When driven by the driving section 107, the first flap 105 pivots between a first state and a second state, and the second flap 106 pivots between a first state and a second state. For example, the first state is the state where the first flap 105 opens the air path 102 and the second state is the state where the first flap 105 closes the air path 102. For example, the first state is the state where the second flap 106 opens the air path 103 and the second state is the state where the second flap 106 closes the air path 103.

Figure 2 is a partially cut front view of the driving section 107 in the state where the first flap 105 and the second flap 106 are both open. Figure 3 is a partially cut cross-sectional view of the driving section 107 in a direction of arrow III in Figure 1, and Figure 4 is a partial isometric view of the driving section 107 in the state where the first flap 105 and the second flap 106 are both open.

Figure 5 is a partially cut cross-sectional view of the driving section 107 in the state where the first flap 105 and the second flap 106 are both closed. Figure 6 is a partially cut cross-sectional view of the driving section 107 in the state where the first flap 105 is closed and the second flap 106 is open. Figure 7 is a partially cut cross-sectional view of the driving section 107 in the state where the first flap 105 is open and the second flap 106 is closed.

As shown in Figures 2, 5, 6 and 7, the driving section 107 includes a motor 108 and a decelerating gear array 109 located therein. The motor 108 includes a driving shaft 108a, which is rotatable in a first direction and a second direction opposite to the first direction. For example, the first direction is a direction for opening the first flap 105, and the second direction is a direction for closing the first flap 105. For example, the first direction is a direction for opening the second flap 106, and the second direction is a direction for closing the second flap 106. With reference to Figure 4, the driving section 107 will be described in more detail.

A first driving gear 110 includes a first gear section 110a including a plurality of teeth, and ring- shaped retaining members 110b and 110c interposing the first gear section 110a and arranged in an axial direction thereof. The first gear section 110a has a central through-hole llOd running along a central axis thereof.

A second driving gear 111, to be provided with a turning force of a motor 108 through the decelerating gear array 109, includes a second gear section Ilia including a plurality of teeth, a cylindrical section 111b having a diameter which is slightly larger than the diameter of an addendum circle of the second gear section Ilia, and a gear shaft 111c having a diameter which is slightly smaller than the diameter of a dedendum circle. The cylindrical section 111b is adjacent to the second gear section Ilia concentrically and has a notch llle, which forms a long groove llld together with one of a plurality of root portions between the teeth of the second gear section Ilia.

The through-hole llOd of the driving gear 110 has a diameter which is slightly larger than the diameter of the gear shaft 111c of the second driving gear 111. The retaining members 110b and 110c of the first driving gear 110 each have an arc having a diameter which is slightly smaller than the diameter of the gear shaft 111c of the second driving gear 111.

When the gear shaft 111c is inserted into the through-hole llOd of the first driving gear 110, the retaining members 110b and 110c tighten the gear shaft 111c. Accordingly, unless a load torque having a level exceeding a prescribed level (i.e., a load torque surpassing the static friction between the retaining members 110b, 110c and the gear shaft 111c) acts on the first driving gear 110, the first driving gear 110 and the second driving gear 111 rotate concentrically and at an identical angular velocity.

Accordingly, unless the above-mentioned load torque acts on the first driving gear 110, the first driving gear 110 is rotated by the rotation of the second driving ge_°r 111.

A fan-shaped first subordinate gear 112 includes a first gear region 112a engageable with the first gear section 110a of the first driving gear 110, and an output shaft 112b for transmitting the pivoting of the first gear region 112a to the first flap 105. The first gear region 112a has an arc-shaped periphery, along which a plurality of teeth are provided. The first driving gear 110 and the first subordinate gear 112 act together as a first transmission section for transmitting the rotation of the driving shaft 108a to the first flap 105.

Since the first gear section 110a of the first driving gear 110 and the first gear region 112a of the first subordinate gear 112 are always engaged with each other, the first subordinate gear 112 pivots simultaneously with the rotation of the first driving gear 110. The first subordinate gear 112, after pivoting at a prescribed angle, contacts a stopper 107a or a stopper 107b (Figure 2) of the driving section 107 and stops. At this point, the first driving gear 110 also stops. In the case where the second driving gear 111 is rotating, the gear shaft 111c slides on the retaining members 110b and 110c. Thus, although the gear shaft 111c rotates, but the first driving gear 110 does not resume rotating.

A fan-shaped second subordinate gear 113 includes a second gear region 113a engageable with the second gear section Ilia of the second driving gear 111, and an output shaft 113b for transmitting the pivoting of the second gear region 113a to the second flap 106. The second gear region 113a has an arc-shaped periphery, along which a plurality of teeth are provided. The second driving gear 111 and the second subordinate gear 113 act together as a second transmission section for transmitting the rotation of the driving shaft 108a to the second flap 106.

The number of teeth of the second gear region 113a is greater by one than the number of teeth of the second gear section Ilia of the second driving gear 111. As best shown in Figure 6, teeth of the second gear region 113a, except for two teeth respectively provided at two ends of the arc-shaped periphery, are short teeth 113c engageable only with the second gear section Ilia, and the two teeth provided at two ends are long teeth 113d engageable with the long groove llld as well as the second gear section Ilia.

The second subordinate gear 113 is not in engage- ment with the second gear section Ilia while either one of the long teeth 113d is in contact with the cylindrical section 111b of the second driving gear 111. When either one of the long teeth 113d engages the long groove llld, the second subordinate gear 113 starts rotating. When the number of rotations of the second subordinate gear 113 exceeds one, the other long tooth 113d is disengaged from the long groove llld, which stops the rotation of the second subordinate gear 113.

In this manner, the second subordinate gear 113 stops rotating after rotating to a prescribed angle due to the disengagement thereof from the second driving gear 111. The second subordinate gear 113 does not resume rotating until one of the teeth 113d of the second subordinate gear 113 is forcibly engaged with the long groove llld of the second driving gear 111.

Returning to Figure 4, a leaf spring acting as a loading device 114 includes elastic cantilevers 114a and 114b, and a holder 114c for connecting the cantilevers 114a and 114b to the first subordinate gear 112.

In the state where the second flap 106 is fully open and the first flap 105 is closed by the first subordinate gear 112, the cantilever 114a contacts a projection 113e of the second subordinate gear 113, and thus presses one long tooth 113d-l, which is movable in such a direction as to close the second flap 106, against the cylindrical section 111b so as to put the long tooth 113d-l into engagement with the long groove llld.

In the state where the second flap 106 is fully open and the first flap 105 is fully open by the first subordinate gear 112, the cantilever 114b contacts a projection 113f of the second subordinate gear 113, and thus presses the other long tooth 113d-2, which is movable in such a direction as to open the second flap 106, against the cylindrical section 111b so as to put the long tooth 113d-2 into engagement with the long groove llld.

With reference to Figures 8 and 9, the operation of the damper device 104 having the above-described structure will be described. In cases 1 through 8 below, there are various combinations of states of the first and second flaps 105 and 106 when the motor 108 starts rotating. In cases 1 through 4, when the motor 108 rotates for a prescribed time period (from tO until t5; e.g., 7 seconds), both the first and second flaps 105 and 106 are put into a first state (e.g., open). In cases 5 through 8, when the motor 108 rotates for a prescribed time period (from tO until t5; e.g., 7 seconds), both the first and second flaps 105 and 106 are put into a second state (e.g., closed). The state where both the first and second flaps 105 and 106 are in the first state or the second state after the motor 108 starts rotating is referred to as an "initial state". In whichever state each of the first flap 105 and the second flap 106 may be when the motor 108 starts rotating, the initial state is realized after the motor 108 rotates for a prescribed time period.

The retaining members 110b and 110c and the gear shaft 111c act together as a turning force transmission section. The cantilever 114a, the projection 113e, the long groove llld including the notch llle act together as a transmission start section. The cantilever 114b, the projection 113f , the long groove llld including the notch llle act together as a transmission start section,

Case 1

In case 1, in the state where the first flap 105 and the second flap 106 are fully open (Figure 2), the motor 108 is rotated forward for 7 seconds and rotated in reverse for 3 seconds.

When the motor 108 starts rotating forward at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The first driving gear 110 is urged to rotate by the frictional force between the retaining members 110b, 110b of the first driving gear 110 and the gear shaft llle of the second driving gear 111.

However, the first flap 105 is already fully open at this point and thus one end 112c of the first subordinate gear 112 is in contact with the stopper 107a of the driving section 107. Accordingly, the first subordinate gear 112 cannot rotate further in such a direction as to open the first flap 105.

The first gear section 110a of first driving gear 110 is in engagement with the first gear region 112a of the first subordinate gear 112. The force for preventing the rotation of the first driving gear 110 generated by the con .act between the stopper 137a and the first subordinate gear 112 surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the first driving gear 110. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

The second flap 106 is already fully open at this point. Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle, the cantilever 114a of the loading device 114 does not load the projection 113e in such a direction for pressing the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111.

At this point, the second driving gear 111 is rotated in such a direction as to move the long teeth 113d and the short teeth 113c so as to open the second flap 106. Accordingly, even when the rotation of the second driving gear 111 carries the long groove llld to such a position as to face the long tooth 113d-l and some force acts to put the long tooth 113d-l into engagement with the long groove llld, the long tooth 113d-l is soon disengaged. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully open, and the only the second driving gear 111 and the decelerating gear array 109 are rotated by the turning force of the motor 108.

After the motor 108 stops rotating forward at tδ, which is 7 seconds after tO, the motor 108 starts rotating in reverse at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c and the gear shaft llle, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 does not load the projection 113e in such a direction for pressing the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully closed by the rotation of the first driving gear 110 at t8, the rotation of the first subordinate gear 112 is stopped by the contact between the first flap 105 and an inner wall of the duct 101 (Figure 1) defining the air path 102, and also by the contact between the other end 112d of the first subordinate gear 112 and the stopper 107b of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such contacts surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accord- ingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

Slightly before the first flap 105 is fully closed, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds the prescribed angle. This causes the cantilever 114a of the loading device 114 to load the projection 113e in such a direction as to press the long tooth 113d- 1 against the cylindrical section 111b.

At t9 (3 seconds after t7 ) before the long groove llld reaches such a position as to face the long tooth

113d-l by the rotation of the second driving gear 111, the motor 108 stops rotating in reverse. Figure 6 shows this state. As described above, when the motor 108 is rotated forward for 7 seconds in the state where the first flap 105 and the second flap 106 are fully opened (Figure 2), both the first flap 105 and the second flap 106 are maintained fully open. When the motor 108 is rotated in reverse for 3 seconds after that, only the first flap 105 is closed and the second flap 106 is maintained fully open ( Figure 6 ) .

Case 2

In case 2, in the state where the first flap 105 is fully closed and the second flap 106 is fully open (Figure 6), the motor 108 is rotated forward for 7 seconds and rotated in reverse for 3 seconds.

When the motor 108 starts rotating forward at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c of the first driving gear 110 and the gear shaft llle of the second driving gear 111, thus causing the first driving gear 110 to rotate. Accordingly, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 to pivot in such a direction to open the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds a prescribed angle. There- fore, the cantilever 114a of the loading device 114 loads the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. The second driving gear 111 is rotated in such a direc- tion as to move the long teeth 113d and the short teeth 113c so as to open the second flap 106. Accordingly, even when the rotation of the second driving gear 111 carries the long groove llld to such a position as to face the long tooth 113d-l and the long tooth 113d-l is put into engagement with the long groove llld, the long tooth 113d-l is soon disengaged. Thus, the long tooth 113d-l again contacts the cylindrical section 111b, and neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. In conse- quence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t2 (Figure 2), the rotation of the first subordinate gear 112 is stopped by the contact between one end 112c of the first subordinate gear 112 and the stopper 107a of the driving section 107. Since the force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the retaining member 110b, 110c, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open .

Slightly before the first flap 105 is fully opened, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 becomes smaller than a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 stops loading the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Therefore, the second flap 106 is maintained fully open.

After the motor 108 stops rotating forward at t6, which is 7 seconds after tO, the motor 108 starts rotating in reverse at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c and the gear shaft llle, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 does not load the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. in consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully closed by the rotation of the first driving gear 110 at t8, the rota- tion of the first subordinate gear 112 is stopped by the contact between the first flap 105 and the inner wall of the duct 101 (Figure 1) defining the air path 102 and also by the contact between the other end 112d of the first subordinate gear 112 and the stopper 107b of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such contacts surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the retaining members 110b, 110c of the first driving gear 110. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

113d-l by the rotation of the second driving gear 111, the motor 108 stops rotating in reverse. Figure 6 shows this state.

As described above, when the motor 108 is rotated forward for 7 seconds in the state where the first flap 105 is closed and the second flap 106 is fully opened (Figure 6), the first flap 105 is fully opened and the second flap 106 is maintained fully open (Figure 2). When the motor 108 is rotated in reverse for 3 seconds after that, only the first flap 105 is closed and the second flap 106 is maintained fully open (Figure 6).

Case 3

In case 3, in the state where the first flap 105 and the second flap 106 are fully closed (Figure 5), the motor 108 is rotated forward for 7 seconds and rotated in reverse for 3 seconds.

When the motor 108 starts rotating forward at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the gear shaft llle of the second driving gear 111 and the retaining members 110b, 110c of the first driving gear 110, causing the first driving gear 110 to rotate. Thus, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to open the air path 102.

Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordi- nate gear 113 does not exceed a prescribed angle, the cantilever 114b of the loading device 114 does not load the projection 113f of the second subordinate gear 113 in such a direction as to press the long tooth 113d-2, which is movable in such a direction as to open the second flap 106, against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t2 (Figure 7), the rotation of the first subordinate gear 112 is stopped by the contact between one end 112c of the first subordi- nate gear 112 and the stopper 107a of the driving section 107. Since the force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the retaining member 110b, 110c, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

Slightly before the first flap 105 is fully opened, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds a prescribed angle. Accordingly, the cantilever 114b of the loading device 114 loads the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b.

At t4, the rotation of the second driving gear 111 carries the long groove llld to such a position as to face the long tooth 113d-2. The long tooth 113d-2 is put into engagement with the long groove llld by the loading force of the lever 114b. Thus, the long tooth 113d-2 and the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. As a result, the turning force of the second driving gear 111 is transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 pivots in such a direction as to open the air path 103.

When the second flap 106 is fully opened by the rotation of the second driving gear 111 at t5 (Figure 2), the second subordinate gear 113 moves from the original position (a position for closing the second flap 106) to the opposite position (a position for opening the second flap 106 ) based on the rotation of the second driving gear 111. Accordingly, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. As a result, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

After the motor 108 stops rotating forward at t6, which is 7 seconds after tO, the motor 108 starts rotating in reverse at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c of the first driving gear 110 and the gear shaft llle of the second driving gear 111, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate genr 113 does not exceed a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 does not load the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully closed by the rotation of the first driving gear 110 at t8, the rotation of the first subordinate gear 112 is stopped by the contact between the first flap 105 and the inner wall of the duct 101 (Figure 1) defining the air path 102 and also by the contact between the other end 112d of the first subordinate gear 112 and the stopper 107b of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such contacts surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

Slightly before the first flap 105 is fully closed, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds the prescribed angle. This causes the cantilever 114a of the loading device 114 to load the projection 113e in such a direction as to press the long tooth 113d- 1 against the cylindrical section 111b. At t9 (3 seconds after t7 ) before the long groove llld reaches such a position as to face the long tooth

As described above, when the motor 108 is rotated forward for 7 seconds in the state where the first flap 105 and the second flap 106 are fully closed (Figure 5), both the first flap 105 and the second flap 106 are fully open (Figure 2). When the motor 108 is rotated in reverse for 3 seconds after that, only the first flap 105 is closed and the second flap 106 is maintained fully open ( Figure 6 ) .

Case 4

In case 4, in the state where the first flap 105 is fully open and the second flap 106 is fully closed (Figure 7), the motor 108 is rotated forward for 7 seconds and rotated in reverse for 3 seconds.

When the motor 108 starts rotating forward at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The first driving gear 110 is urged to rotate by the frictional force between the retaining members 110b, 110c of the first driving gear 110 and the gear shaft llle of the second driving gear 111.

The first gear section 110a of first driving gear 110 is engaged with the first gear region 112a of the first subordinate gear 112. The force for preventing the rotation of the first driving gear 110 generated by the contact between the stopper 107a and the first subordinate gear 112 surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the first driving gear 110. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordi- nate gear 113 exceeds a prescribed angle, the cantilever 114b of the loading device 114 loads the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b.

At tl, the rotation of the second driving gear

111 carries the long groove llld to such a position as to face the long tooth 113d-2. The long tooth 113d-2 is put into engagement with the long groove llld by the loading force of the lever 114b. Thus, the long tooth 113d-2 and the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. As a result, the turning force of the second driving gear 111 is transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 pivots in such a direction as to open the air path 103.

When the second flap 106 is fully opened by the rotation of the second driving gear 111 at t3 (Figure 2), the second subordinate gear 113 moves from the original position based on the rotation of the second driving gear 111 (a position for closing the second flap 106) to the opposite position (a position for opening the second flap 106). Accordingly, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. As a result, the turning force of the second driving gear 111 is not transmitted to the second subor- dinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

After the motor 108 stops rotating forward at t6, which is 7 seconds after tO, the motor 108 starts rotat- ing in reverse at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c and the gear shaft llle, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 does not load the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. in consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully opened.

At t9 (3 seconds after t7 ) before the long groove llld reaches such a position as to face the long tooth 113d-l by the rotation of the second driving gear 111, the motor 108 stops rotating in reverse. Figure 6 shows this state.

As described above, when the motor 108 is rotated forward for 7 seconds in the state where the first flap 105 is fully open and the second flap 106 is fully closed (Figure 7), the first flap 105 is maintained open and the second flap 106 is fully opened ( Figure 2 ) . When the motor 108 is rotated in reverse for 3 seconds after that, only the first flap 105 is closed and the second flap 106 is maintained fully open (Figure 6).

Case 5

In case 5, in the state where the first flap 105 and the second flap 106 are fully open (Figure 2), the motor 108 is rotated in reverse for 7 seconds and rotated forward for 3 seconds.

When the motor 108 starts rotating in reverse at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear

111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c of the first driving gear 110 and the gear shaft llle of the second driving gear 111, thus causing the first driving gear 110 to rotate. The first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle, the cantilever 114a of the loading device 114 does not load the projection 113e of the second subordinate gear 113 in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. i such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully closed by the rotation of the first driving gear 110 at t2 (Figure 6), the rotation of the first subordinate gear 112 is stopped by the contact between the first flap 105 and the inner wall of the duct 101 (Figure 1) defining the air path 102 and the contact between the other end 112 of the first subordinate gear 112 and the stopper 107b of the driving section 107. Since the force for preventing the rotation of the first driving gear 110 generated by such contacts surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the retaining member 110b, 110c, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

Slightly before the first flap 105 is fully closed, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds a prescribed angle. Accordingly, the cantilever 114a of the loading device 114 loads the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b.

At t4, the rotation of the second driving gear

111 carries the long groove llld to such a position as to face the long tooth 113d-l. The long tooth 113d-l is put into engagement with the long groove llld by the loading force of the lever 114a. Thus, the long tooth 113d-l and the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. As a result, the turning force of the second driving gear 111 is transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordi- nate gear 113 pivots in such a direction as to close the air path 103.

When the second flap 106 is fully closed by the rotation of the second driving gear 111 at t5 (Figure 5), the second subordinate gear 113 moves from the original position based on the rotation of the second driving gear 111 (a position for opening the second flap 106) to the opposite position (a position for closing the second flap 106). Accordingly, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. As a result, the turning force of the second driving gear 111 is not transmitted to the second subor- dinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

After the motor 108 stops rotating in reverse at t6, which is 7 seconds after tO, the motor 108 starts rotating forward at t7. The turning force of the motor

108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c of the first driving gear

110 and the gear shaft llle of the second driving gear

111, thus causing the first driving gear 110 to rotate.

As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to open the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114b of the loading device 114 does not load the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. in consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t8, the rota- tion of the first subordinate gear 112 is stopped by the contact between the first subordinate gear 112 and the stopper 107a. The force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

Slightly before the first flap 105 is fully opened, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds the prescribed angle. This causes the cantilever 114b of the loading device 114 to load the projection 113f in such a direction as to press the long tooth 113d- 2 against the cylindrical section 111b. At t9 (3 seconds after t7 ) before the long groove llld reaches such a position as to face the long tooth

113d-2 by the rotation of the second driving gear 111, the motor 108 stops rotating forward. Figure 7 shows this state.

As described above, in the state where the first flap 105 and the second flap 106 are fully open (Figure 2), when the motor 108 is rotated in reverse for 7 seconds both the first flap 105 and the second flap 106 are fully closed (Figure 5). When the motor 108 is rotated forward for 3 seconds after that, only the first flap 105 is opened and the second flap 106 is maintained fully closed (Figure 7).

Case 6

In case 6, in the state where the first flap 105 is fully open and the second flap 106 fully closed (Figure 6), the motor 108 is rotated in reverse for 7 seconds and rotated forward for 3 seconds.

When the motor 108 starts rotating in reverse at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The first driving gear 110 is urged to rotate by the frictional force between the retaining members 110b, 110c of the first driving gear 110 and the gear shaft llle of the second driving gear 111.

However, the first flap 105 is already fully open at this point. Thus, the first flap 105 is in contact with the inner wall of the duct 101 (Figure 1) defining the air path 102, and the other end 112d of the first subordinate gear 112 is in contact with the stopper 107b of the driving section 107. Accordingly, the first subordinate gear 112 cannot rotate further in such a direction as to close the first flap 105.

The first gear section 110a of first driving gear

110 is engaged with the first gear region 112a of the first subordinate gear 112. The force for preventing the rotation of the first driving gear 110 generated by the contact between the above-mentioned contacts surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the first driving gear 110. Accordingly, the turning force of the second driving gear

111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds a prescribed angle, the cantilever 114a of the loading device 114 loads the projection 113e in such a direction as to press the long tooth 113d-l against the cylindrical section 111b.

At tl, the rotation of the second driving gear 111 carries the long groove llld to such a position as to face the long tooth 113d-l. The long tooth 113d-l is put into engagement with the long groove llld by the loading force of the cantilever 114a. Thus, the long tooth 113d- 1 and the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. As a result, the turning force of the second driving gear 111 is transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 pivots in such a direction as to close the air path 103.

When the second flap 106 is fully closed by the rotation of the second driving gear 111 at t3 (Figure 5), the second subordinate gear 113 moves from the original position based on the rotation of the second driving gear 111 (a position for opening the second flap 106) to the opposite position (a position for closing the second flap 106). Accordingly, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. As a result, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

After the motor 108 stops rotating in reverse at t6, which is 7 seconds after tO, the motor 108 starts rotating forward at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c and the gear shaft llle, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to open the air path 102. At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114b of the loading device 114 does not load the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t8, the rotation of the first subordinate gear 112 is stopped by the contact between one end 112c of the first subordinate gear 112 and the stopper 107a of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

Slightly before the first flap 105 is fully opened, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds the prescribed angle. This causes the cantilever 114b of the loading device 114 to load the projection 113f in such a direction as to press the long tooth 113d- 2 against the cylindrical section 111b.

As described above, when the motor 108 is rotated in reverse for 7 seconds in the state where the first flap 105 is fully closed and the second flap 106 is fully opened (Figure 6), the first flap 105 is maintained fully closed and the second flap 106 is fully closed (Figure 5 ) . When the motor 108 is rotated forward for 3 seconds after that, only the first flap 105 is opened and the second flap 106 is maintained fully closed (Figure 7).

Case 7

In case 7, in the state where the first flap 105 and the second flap 106 are fully closed (Figure 5), the motor 108 is rotated in reverse for 7 seconds and rotated forward for 3 seconds.

However, the first flap 105 is already fully closed at this point. Thus, the first flap 105 is in contact with the inner wall of the duct 101 defining the air path 102, and the other end 112d of the first subordinate gear 112 is in contact with the stopper 107b of the driving section 107. Accordingly, the first subordinate gear 112 cannot rotate further in such a direction as to close the first flap 105.

The first gear section 110a of first driving gear

110 is engaged with the first gear region 112a of the first subordinate gear 112. The force for preventing the rotation of the first driving gear 110 generated by the above-mentioned contacts surpasses the frictional force between the gear shaft llle of the second driving gear

111 and the first driving gear 110. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

The second flap 106 is already fully closed at this point. Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle, the cantilever 114b of the loading device 114 does not load the projection 113f in such a direction for pressing the long tooth 113d-2 against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111.

At this point, the second driving gear 111 is rotated in such a direction as to move the long teeth 113d and the short teeth 113c so as to close the second flap 106. Accordingly, even when the rotation of the second driving gear 111 carries the long groove llld to such a position as to face the long tooth 113d-2 and some force acts to put the long tooth 113d-2 into engagement with the long groove llld, the long tooth 113d-2 is soon disengaged. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully closed, and the only the second driving gear 111 and the decelerating gear array 109 are rotated by the turning force of the motor 108.

After the motor 108 stops rotating in reverse at t6, which is 7 seconds after tO, the motor 108 starts rotating forward at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c and the gear shaft llle, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 in engagement with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to open the air path 102.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t8, the rotation of the first subordinate gear 112 is stopped by the contact between the other end 112d of the first subordi- nate gear 112 and the stopper 107a of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

At t9 (3 seconds after t7 ) before the long groove llld reaches such a position as to face the long tooth 113d-2 by the rotation of the second driving gear 111, the motor 108 stops rotating forward. Figure 7 shows this state.

As described above, when the motor 108 is rotated in reverse for 7 seconds in the state where the first flap 105 and the second flap 106 are fully closed (Figure 5 ) , both the first flap 105 and the second flap 106 are maintained fully closed. When the motor 108 is rotated forward for 3 seconds after that, only the first flap 105 is opened and the second flap 106 is maintained fully closed (Figure 7).

Case 8

In case 8, in the state where the first flap 105 is fully open the second flap 106 is fully closed (Figure 7), the motor 108 is rotated in reverse for 7 seconds and rotated forward for 3 seconds.

When the motor 108 starts rotating in .averse at tO, the turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the gear shaft llle of the second driving gear 111 and the retaining members 110b, 110c of the first driving gear 110, causing the first driving gear 110 to rotate. Thus, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to close the air path 102.

Since the relative pivot angle of the first subordinate gear 112 with respect to the second subordi- nate gear 113 does not exceed a prescribed angle, th<~ cantilever 114a of the loading device 114 does not load the projection 113e of the second subordinate gear 113 in such a direction as to press the long tooth 113d-l against the cylindrical section 111b. In such a state, the long tooth 113d-l is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear 111 is not transmitted to the second subordinate gear 113, and the second flap 106 associated with the second subordinate gear 113 is maintained fully open.

When the first flap 105 is fully closed by the rotation of the first driving gear 110 at t2 (Figure 5), the rotation of the first subordinate gear 112 is stopped by the contact between the first flap 105 and the inner wall of the duct 101 (Figure 1) defining the air path 102 and also by the contact between the other end 112d of the first subordinate gear 112 and the stopper 107b of the driving section 107. Since the force for preventing the rotation of the first driving gear 110 generated by such contacts surpasses the frictional force between the gear shaft llle of the second driving gear 111 and the retaining member 110b, 110c, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully closed.

Slightly before the first flap 105 is fully closed, the relε ive pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 becomes smaller than a prescribed angle. Accordingly, the cantilever 114b of the loading device 114 stops loading the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Therefore, the second flap 106 is maintained fully closed.

After the motor 108 stops rotating in reverse at t6, which is 7 seconds after tO, the motor 108 starts rotating forward at t7. The turning force of the motor 108 is transmitted to the second driving gear 111 through the decelerating gear array 109. The turning force of the second driving gear 111 is transmitted to the first driving gear 110 by the frictional force between the retaining members 110b, 110c of the first driving gear

110 and the gear shaft llle of the second driving gear 111, thus causing the first driving gear 110 to rotate. As a result, the first subordinate gear 112 engaged with the first gear section 110a of the first driving gear 110 rotates, and thus the first flap 105 associated with the first subordinate gear 112 pivots in such a direction as to open the air path 102.

At this point, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 does not exceed a prescribed angle. Accordingly, the cantilever 114b of the loading device 114 does not load the projection 113f in such a direction as to press the long tooth 113d-2 against the cylindrical section 111b. In such a state, the long tooth 113d-2 is only slightly in contact with, or out of contact with the cylindrical section 111b. Thus, neither the long teeth 113d nor the short teeth 113c are engaged with the second gear section Ilia of the second driving gear 111. In consequence, the turning force of the second driving gear

111 is not transmitted to the second subordinate gear 113. Thus, the second flap 106 associated with the second subordinate gear 113 is maintained fully closed.

When the first flap 105 is fully opened by the rotation of the first driving gear 110 at t8, the rotation of the first subordinate gear 112 is stopped by the contact one end 112c of the first subordinate gear 112 and the stopper 107a of the driving section 107. The force for preventing the rotation of the first driving gear 110 generated by such a contact surpasses the frictional force between the gear shaft llle and the retaining members 110b, 110c. Accordingly, the turning force of the second driving gear 111 is not transmitted to the first driving gear 110. In other words, the first driving gear 110 stops rotating although the second driving gear 111 keeps rotating. Thus, the first flap 105 is maintained fully open.

Slightly before the first flap 105 is fully opened, the relative pivot angle of the first subordinate gear 112 with respect to the second subordinate gear 113 exceeds the prescribed angle. This causes the cantilever 114b of the loading device 114 to load the projection 113f in such a direction as to press the long teeth 113d- 2 against the cylindrical section 111b.

As described above, when the motor 108 is rotated in reverse for 7 seconds in the state where the first flap 105 is fully open and the second flap 106 is fully closed (Figure 7), the first flap 105 is fully closed and the second flap 106 is maintained fully closed (Figure 5). When the motor 108 is rotated forward for 3 seconds after that, only the first flap 105 is opened and the second flap 106 is maintained fully closed (Figure 7).

The operation mode ( the manner of driving the motor 108) and the open/closed state of the first flap 105 and the second flap 106 are shown in Table 1. Table 1

( Example 2 ) Figure 10 is an isometric view of a damper device in a second example according to the present invention. The damper device in this example includes a first frame 115 for pivotally supporting the first flap 105 and a second frame 116 for pivotally supporting the second flap 106. The first frame 115 and the second frame 116 are attached to the driving section 107 by screws 117.

By the design of detachably attaching the frames to the driving section by screws, different sizes of frames can be relatively easily attached in conformity to the size of the duct and also the specification of the refrigerator. For example, the larger frame 116 can be exchanged with the smaller frame 115. Two frames 115 can be used, or two frames 116 can be used. Alternatively, various other sizes of frames can be used in various combinations.

The driving section 107 has depressions for accepting the screws 117. Such a design prevents the screws from projecting from the side surfaces of the driving section 107. This is advantageous for easy attachment of the damper to the refrigerator.

The driving section 107 also has grooves to be engaged with the frames for facilitated and reliable attachment of the frames.

A motor device according to the present invention operates, for example, in the following manner. When the motor 108 is rotated forward for 7 seconds, both the first flap 105 and the second flap 106 are opened ( first mode); and when the motor 108 is rotated in reverse for 3 seconds after that, the first flap 105 is closed and the second flep 106 is maintained open (second mode). When the motor 108 is rotated in reverse for 7 seconds, both the first flap 105 and the second flap 106 are closed (third mode); and when the motor 108 is rotated forward for 3 seconds after that, the first flap 105 is opened and the second flap 106 is maintained closed ( fourth mode) .

By such a structure, the two flaps 105 and 106 can be put into any state by controlling the rotation direction and rotation time of the motor 108 without a and 106.

The first direction and the second direction can be set to either the forward direction or the reverse direction of the motor rotation. The first state and the second state as the initial state can be set to the open state or the closed state, respectively.

The method for rotating the driving shaft is not limited to use of a motor, but any other device, for example, a belt can be used.

In the above-described examples, description regarding the start of the motor is omitted. The motor can be started by use of a known method, for example, based on a signal from a temperature sensor.

A damper device and a method for driving the same are preferably used for a refrigerator, but also widely applicable as a damper device for controlling the flow rate or flow direction of a fluid (gas or liquid) and a method for driving the same.

INDUSTRIAL APPLICABILITY

A damper device according to the present invention includes a first flap; a second flap; and a driving section for driving the first flap and the second flap. The first flap and the second flap are provided so as to interpose the driving section therebetween along a direction of a driving shaft of the driving section. A pivoting shaft of the first flap and a pivoting shaft of the second flap are parallel to each other and arranged in a different direction from the direction of a driving shaft of the driving section, and the first flap and the second flap are driven by the driving shaft. The first flap pivots between a first state and a second state, and the second flap pivots between a first state and a second state.

Accordingly, the first flap and second flap can be separately replaced, which improves the freedom of design. Since the damper device can be provided at the air path which can be opened and closed by the first flap and the second flap, the damper device can be compact and thus does not restrict the place where the damper device is placed or increase the size of the refrigerator.

In the case where the first flap and the second flap are put into an initial state, where the first flap and the second flap are both in either the first state or the second state, within a prescribed time period after the driving section starts driving, the two flaps can be separately controlled to be put into a desired state without a position detector. Thus, the number of components and costs are reduced.

Claims

1. A damper device, comprising: a first flap; a second flap; and a driving section for driving the first flap and the second flap, wherein: the first flap and the second flap are provided so as to interpose the driving section therebetween along a direction of a driving shaft of the driving section, a pivoting shaft of the first flap and a pivoting shaft of the second flap are parallel to each other and arranged in a direction other than parallel to the direction of a driving shaft of the driving section, and the first flap and the second flap are driven by the driving shaft, and the first flap pivots between a first state and a second state, and the second flap pivots between a first state and a second state.

2. A damper device according to claim 1, wherein the pivoting shaft of the first flap and the pivoting shaft of the second flap are located along a single line.

3. A damper device according to claim 1, wherein the first flap and the second flap are put into an initial state, where the first flap and the second flap are both in either the first state or the second state, within a prescribed time period after the driving section starts driving.

4. A damper device according to claim 3, wherein there is a period in which only one of the first flap and the second flap pivots from the time when driving section starts driving until the initial state is realized.

5. A damper device according to claim 1, wherein the driving section includes: a motor having the driving shaft which is rotat- able in a first direction and a second direction opposite to the first direction; a first transmission section for transmitting a turning force of the driving shaft to the first flap; and a second transmission section for transmitting the turning force of the driving shaft to the second flap.

6. A damper device according to claim 5, wherein the firs+" transmission section transmits the turning force of the driving shaft to the first flap only during a first period from the time when the driving shaft starts rotating in the first direction until the first flap is put into the first state, and during a second period from the time when the driving shaft starts rotating in the second direction until the first flap is put into the second state.

7. A damper device according to claim 6, wherein the second transmission section transmits the turning force of the driving shaft to the second flap only during a third period from the time when the first flap is put into the first state by the rotation of the driving shaft in the first direction until the second flap is put into the first state, and during a fourth period from the time when the second flap is put into the second state by the rotation of the driving shaft in the second direction until the second flap is put into the second state.

8. A damper device according to claim 5, wherein the first transmission section includes a first subordinate gear and a first driving gear for transmitting the turning force of the driving shaft to the first flap through the first subordinate gear, and a second transmission section includes a second subordinate gear and a second driving gear for transmitting the turning force of the driving shaft to the second flap through the second subordinate gear.

9. A damper device according to claim 3, wherein: when the driving shaft rotates in the second direction in the state where the first flap and the second flap are both in the first state, only the first flap pivots in the second direction; after the first flap is put into the second state, the first flap is maintained in the second state and the second flap pivots in the second direction; and after the second flap is put into the second state, the first flap and the second flap are both maintained in the second state; and when the driving shaft rotates in the first direction in the state where the first flap and the second flap are both in the second state, only the first flap pivots in the first direction; after the first flap is put into the first state, the first flap is maintained in the first state and the second flap pivots in the first direction; and after the second flap is put into the first state, the first flap and the second flap are both maintained in the first state.

10. A damper device according to claim 3, wherein: when the driving shaft rotates in the first direction by at least a first prescribed amount, the first flap and the second flap are both put into the first state; and when the driving shaft rotates in the second direction thereafter by a second prescribed amount which is smaller than the first prescribed amount, the first flap is put into the second state and the second flap is maintained in the first state.

11. A damper device according to claim 10, wherein: when the driving shaft rotates in the second direction by at least the first prescribed amount, the first flap and the second flap are both put into the second state; and when the driving shaft rotates in the first direction thereafter by the second prescribed amount which is smaller than the first prescribed amount, the first flap is put into the first state and the second flap is maintained in the second state.

12. A damper device according to claim 8, wherein the driving section further includes a decelerating gear array for transmitting a turning force of the driving shaft to the second driving gear.

13. A damper device according to claim 4, wherein: the driving section further includes a first subordinate gear, a first driving gear for pivoting the first flap through the first subordinate gear, a second subordinate gear, a second driving gear for pivoting the second flap through the second subordinate gear, and a decelerating gear array for transmitting a turning force of the driving shaft to the second driving gear, the damper device further includes: a turning force transmission section for transmitting a turning force of the second driving gear to the first driving gear in a period until the first flap is put into the second state while the driving shaft is rotating in the second direction and in a period until the first flap is put into the first state while the driving shaft is rotating in the first direction and for preventing transmission of the turning force of the second driving gear to the first driving gear in a period after the first flap is put into the second state while the driving shaft is rotating in the second direction and in a period after the first flap is put into the first state while the driving shaft is rotating in the first direction; a transmission prevention section for preventing the turning force of the second driving gear from being transmitted to the second subordinate gear while the second flap is in the second state and the second driving gear is rotating in such a direction as to put the second flap into the second state and while the second flap is in the first state and the second driving gear is rotating in such a direction as to put the second flap into the first state; and a transmission start section for releasing the prevention of the transmission of the turning force of the second driving gear to the second subordinate gear when the second driving gear rotates in such a direction as to put the second flap to the first state while the second flap is in the second state and the first flap is in the first state and when the second driving gear rotates in such a direction as to put the second flap to the second state while the second flap is in the first state and the first flap is in the second state.

14. A damper device according to claim 3, wherein the driving section includes: a first driving gear having a first gear section having a plurality of teeth, a second driving gear having a second gear section for receiving a turning force of the driving shaft through a decelerating gear array and for retaining the first driving gear by a gear shaft so as to prevent forcible rotation of the first driving gear when a prescribed load torque acts on the first driving gear, the second gear section having a plurality of teeth, the second driving gear also having a cylindrical section adjacent to the second gear section and having a diameter which is equal or greater than a diameter of an addendum circle of the second gear section, the cylindrical section having a notch which forms a long groove together with one of root portions of the second gear section, a fan-shaped first subordinate gear for transmitting a turning force of the driving shaft to the first flap, first subordinate gear having teeth along an arc- shaped periphery which are always engaged with the first gear section, a fan-shaped second subordinate gear for transmitting a turning force of the driving shaft to the second flap, second subordinate gear having long teeth respectively provided at two ends of an arc-shaped periphery which are engageable with the long groove and a plurality of short teeth provided along the arc-shaped periphery between the long teeth and engageable only with the second gear section, a loading device associated with the first subordinate gear for loading the second subordinate gear in such a direction as to pivot the first subordinate gear when a relative pivot angle of the first subordinate gear with respect to the second subordinate gear exceeds a prescribed angle, and a stopper for stopping the first subordinate gear from pivoting when the first flap is in a prescribed state.

15. A damper device according to claim 1, further comprising a first frame having an opening which is closable by the first flap and a second frame having an opening which is closable by the second flap, wherein the first flap, the second flap, the first frame and the second frame are independently detachable from the driving section.

16. A method for driving a damper including a first flap, a second flap, and a driving section for driving the first flap and the second flap, wherein: the first flap and the second flap are provided so as to interpose the driving section therebetween along a direction of a driving shaft of the driving section, a pivoting shaft of the first flap and a pivoting shaft of the second flap are parallel to each other and arranged in a direction other than parallel to the direction of a driving shaft of the driving section, and the first flap and the second flap are driven by the driving shaft, and the first flap pivots between a first state and a second state, and the second flap pivots between a first state and a second state, the method comprising the step of: putting the first flap and the second flap into an initial state, where the first flap and the second flap are both in either the first state or the second state, within a prescribed time period after the driving section starts driving.

17. A method for driving the damper device according to claim 16, wherein there is a period in which only one of the first flap and the second flap pivots from the time when the driving section starts driving until the initial state is realized.