KR19990006304A - Damper - Google Patents

Abstract

Provided is a damper capable of obtaining a large braking force even when an orifice is formed at the time of molding a piston or an occluding member even if the area of the orifice hole is made small.

An opening 13a in which a groove 13b is formed in the periphery is provided in the flat plate portion 12 of the piston cam body 11 and the closing member 31 having the frustum- (b) side to the chamber (a) side to leave the groove 13b with the truncated cone portion 32 to close the opening 13a.

Description

Damper

The present invention relates to a damper that applies a braking force to the rotation of a tiltable member.

Conventionally, when the rotary body rotatably provided on one end of the housing is rotated as the above damper, the piston accommodated in the housing so as to be movable in the axial direction moves and is moved from one chamber on the side of the rotary body partitioned by the piston to the other And the braking force is imparted to the rotary body by the passage resistance flowing through the orifice through the viscous fluid to the one chamber or to the one chamber from the other chamber.

Conventional dampers typically mold a piston with a synthetic resin and also form an orifice at the time of piston molding.

When the orifice is formed at the time of piston molding, there is a limit to the sectional area of the orifice hole due to the shape of the pin forming the orifice hole and the strength of the pin.

Therefore, when the orifice is formed at the time of piston molding, there is an inconvenience that the damper is enlarged to obtain a large braking force.

An object of the present invention is to provide a damper capable of achieving a large braking force by reducing an area of an orifice hole even when an orifice is formed at the time of molding a piston or an obstruction member.

In the present invention, when a rotary body rotatably disposed on one end of a housing is rotated, a piston accommodated in the housing so as to be movable in the axial direction is moved, and the piston moves from one chamber on the side of the rotary body partitioned by the piston to the other chamber Or a damper for imparting a braking force to the rotary body by a passage resistance through which the viscous fluid flows into the one chamber from the other chamber through the orifice, the damper comprising: an opening in the piston; a closing member for closing the opening in the piston; And at least one of the circumference of the opening or the circumference of the closing member is provided with a groove to be an orifice.

It is preferable that the closing member is made to be urged from the one chamber to the other chamber with the opening being circular, the closing member having the shape of the truncated cone portion, and closing the opening with the truncated cone portion Do.

1 is an exploded perspective view showing components of a damper according to an embodiment of the present invention,

Fig. 2 is an enlarged side view of the housing body shown in Fig. 1 as seen from the open end side,

3 is a sectional view taken along the line A-A in Fig. 2,

FIG. 4A is an enlarged side view of the piston cam body shown in FIG. 1, FIG. 4B is an enlarged view of the piston cam body viewed from the cam portion side, and FIG. 4C is a cross- (D) is a sectional view taken along the line BB in Fig. 4 (c), Fig. 4

5 (a), 5 (b), 5 (c) and 5 (d) are explanatory diagrams showing the shapes of the cam portions,

Fig. 6 is an explanatory view of a part of Fig. 1 taken along the line C-C in Fig.

7 is an explanatory diagram of a state in which the lid and the toilet seat (toilet seat)

8 is an explanatory view showing a damper on the way to turn the toilet seat downwardly in a state in which the toilet seat is rotated up to its maximum;

Fig. 9 is an explanatory view showing a damper after the toilet seat is turned downward to contact the toilet bowl;

10 is an explanatory view showing the relationship between the flat plate portion of the piston cam body and the closing member when the toilet seat is forcibly pivoted downward;

11 is a perspective view showing another example of a groove to be an orifice,

Figs. 12 (a) and 12 (b) are explanatory views showing another example of the cam surface of the piston cam body.

DESCRIPTION OF THE REFERENCE NUMERALS

D ... damper, 1 ... housing,

2 ... housing body, 3a ... stepped portion,

3b ... guide groove, 3c ... concave portion,

3d ... Bypass home,

4 ... annular positioning stones,

5: a mounting part, 6: a locking claw,

7 ... cap, 8 ... opening,

9: engagement hole, 11: piston cam body,

12 ... plate portion, 13a ... opening,

13b ... groove, 14 ... cam portion,

15 ... cam surface, 15a ... first cam surface,

15b ... second cam surface, 15c ... third cam surface,

15d ... stopper surface, 15e ... third cam surface,

15f ... third cam face, 16 ... locking hole,

17 ... engaging projection, 18 ... annular ridge,

19 ... circumferential groove, 20 ... circumferential rib,

21 ... dust removing net, 31 ... closing member,

32 ... a truncated cone portion, 32a ... a groove,

33 ... shaft portion, 34 ... coil spring,

35: an attachment cap, 36: an elastic engagement claw (elastic engagement claw)

37 ... opening, 41 ... coil spring,

42 ... O-ring, 51 ... rotation cam body,

52a ... end portion, 52 ... flat plate portion,

53 ... rotation cam portion, 54 ... shaft portion,

61 ... O-ring, 71 ... viscous fluid,

a, b ... chamber, B ... toilet,

S ... toilet seat (toilet seat), C ... cover,

W ... aquarium.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is an exploded perspective view showing components of a damper according to an embodiment of the present invention. Fig. 2 is an enlarged side view of the housing main body shown in Fig. 1, 4 is an enlarged side view of the piston cam body shown in Fig. 1, an enlarged view of the piston cam body viewed from the cam portion side, and an enlarged view of the piston cam body seen from the annular ridge side. Figs. 4A, 4B, (A), (b), (c) and (d) are explanatory diagrams showing the shapes and engaging relationships of both cam portions, Fig. 6 is a cross- Fig. 2 is an explanatory view in which a part is broken by the CC line of Fig. 2 in a state where each component shown in Fig. 2 is assembled.

In these figures, D represents a damper and includes a housing 1, a piston cam body 11, a dust removing net 21, a closing member 31, coil springs 34 and 41, a mounting cap 35, the O-rings 42, 61, the rotating cam body 51, and the viscous fluid 71. [

The housing 1 is composed of a housing main body 2 made of synthetic resin and one end opened and the other end closed and a cap 7 made of a synthetic resin to be attached to the open end side of the housing main body 2 .

An inner circumferential portion of the housing main body 2 is provided with an end portion stepped in a depth direction that is continuous with the open end and rotatably accommodates the flat plate portion 52 of the rotating cam body 51 3a of the piston cam body 11 and a fitting protrusion 17 of the piston cam body 11 extending inwardly by a predetermined length inwardly from the inside of the end portion 3a (toward the closed end of the housing main body 2) Two concave portions 3c extending inwardly from the inside of the end portion 3a in parallel to the axis by a predetermined length and two guide grooves 3b guiding the inside of the concave portion 3c And a bypass groove 3d having a predetermined depth and narrower width than the concave portion 3c is provided.

The guide groove 3b, the concave portion 3c and the bypass groove 3d are provided symmetrically with respect to the axis of the housing main body 2, respectively.

An annular positioning projection 4 for positioning one end of the coil spring 41 is provided inside the bottom of the housing main body 2 at a predetermined radius.

A mounting portion 5 for mounting the mounting member on the outer circumference of the housing main body 2 and a plurality of mounting tanks 6 for mounting the cap 7 are provided have.

The cap 7 is provided with a circular opening 8 through which the shaft portion 54 of the rotating cam body 51 is rotatably inserted and a plurality of engaging portions 8 corresponding to the engaging tanks 6 of the housing main body 2, A hole 9 is provided.

The piston cam body 11 made of synthetic resin has a circular flat plate portion 12 and two cam portions 14 provided symmetrically with respect to the axis on one surface of the flat plate portion 12, An engaging projection 17 provided on the outer periphery of the opposite side of the flat plate portion 12 of the two cam portions 14 to engage with the guide groove 3b and an opening 13a formed on the other side of the flat plate portion 12, As shown in Fig.

A circular opening 13a having a tapered surface which contracts and closes from one surface side to the other surface side is provided at the center of the flat plate portion 12. A groove 13b serving as an orifice is formed in a part of the periphery of the opening 13a, Is installed.

The cam portion 14 is provided with a first cam surface 15a, a second cam surface 15b, a third cam surface 15c, and a stopper surface 15d, to which the pivot cam portion 53 of the pivotal cam body 51 engages , And an engaging hole 16 are provided.

The cam portion 14, the facets 15a to 15d, the engaging holes 16 and the engaging projections 17 are provided symmetrically with respect to the axis of the flat plate portion 12, respectively.

Reference numeral 19 denotes a circumferential groove, which is provided on the outer periphery of the flat plate portion 12 side of the piston cam body 11 and accommodates the O-ring 42 therein.

4, the O-ring 42 is provided at the edge of the circumferential groove 19 on the side of the cam portion 14 side and the radius is formed in the circumferential groove 20, as shown in Fig. 4 (d) Ring 42 so as not to come out of the O-ring 42, and the thickness thereof is minimized in consideration of the holding strength of the O-ring 42 and the like.

The dust removing net 21 made of synthetic resin has an edge smaller than that of the groove 13b and is welded to the annular ridge 18.

The closure member 31 made of synthetic resin is provided with a truncated cone portion 32 for opening and closing the opening 13a of the piston cam body 11 and a shaft portion 32 provided in the center of the bottom surface of the truncated cone portion 32 in the axial direction And a shaft portion 33 as shown in Fig.

The coil spring 34 urges the closing member 31 so that the truncated cone portion 32 closes the opening 13a of the piston cam body 11.

The synthetic resin attaching cap 35 is provided with an elastic engaging jaw 36 which is inserted between the cam portions 14 of the piston cam body 11 to engage with the engaging holes 16, And an opening 36 for securing it is provided.

The coil spring 41 to be loaded in the housing main body 2 is to bias the piston cam body 11 toward the open end side of the housing main body 2.

The O-ring 42 is accommodated in the peripheral groove 19 of the piston cam body 11 to seal between the housing body 2 and the piston cam body 11.

The rotating cam body 51 made of synthetic resin has a flat plate portion 52 having a circular shape rotatable at the end portion 3a of the housing main body 2 and provided with a round end portion 52a around one surface, A rotation cam portion 53 provided symmetrically with the shaft on the other surface of the piston 52 to engage with the two cam portions 14 of the piston cam body 11 and a cam 7 projecting from the opening 8 of the shaft 7.

In addition, the O-ring 61 seals between the housing main body 2 and the turning cam body 51.

Next, an example of assembly will be described.

It is assumed that the dust removing net 21 is welded to the annular ridge 18.

The one end side of the coil spring 34 is inserted into the mounting cap 35 with the open end side facing upward and the shaft portion 33 of the closing member 31 is inserted into the upper side of the coil spring 34, (32) is placed on the coil spring (34).

An elastic engaging jaw 36 is associated with the engaging hole 16 between the cam portion 14 of the piston cam body 11 with the annular ridge 18 and the dust removing net 21 as the upper side, The mounting cap 35 on which the closing member 31 is placed is press-fitted from below.

When the mounting cap 35 is pressed downward between the cam portions 14 as described above, the elastic engaging jaw 36 is pushed by the cam portion 14 and bent inward, so that the mounting cap 35 is inserted between the cam portions 14 The truncated cone portion 32 engages with the opening 13a to close the opening 13a. As a result, the portion of the groove 13b becomes an orifice hole through which the viscous fluid 71 flows.

When the mounting cap 35 is pressed to reduce the coil spring 34, the elastic engaging jaw 36 reaches the position of the engaging hole 16 and opens wide by the elastic force of the self engaging jaw 36, The closure member 31 and the coil spring 34 can be attached to the piston cam body 11 with the mounting cap 35. [

Thus, when the mounting cap 35 is attached to the piston cam body 11, the mounting cap 35 is separated from the flat plate portion 12. [

Then, the O-ring 42 is loaded in the peripheral groove 19.

Next, a coil spring 41 is loaded into the housing main body 2 with the opening end side facing upward, one end of the coil spring 41 is positioned outside the annular positioning projection 4, A predetermined amount of viscous fluid 71 such as oil is injected into the housing main body 2.

The pivotal cam portion 53 is positioned between the cam portions 14 of the piston cam body 11 with the annular ridge 18 and the dust removing net 21 side downward so that the pivotal cam body 51 The O-ring 61 is placed on the end portion 52a of the flat plate portion 52 and the shaft portion 54 is inserted into the opening 8 with the opening end side downward, The cap 7 is placed on top of the cap.

The engaging projection 17 is made to correspond to the guide groove 3b and the engaging hole 9 is made to correspond to the interlocking tier 6 so that the annular ridge 18 is formed inside the other end of the coil spring 41, The fitting protrusion 17 is guided to the guide groove 3b while the coil spring 41 is being shrunk so that the piston cam body 11, The rotation cam portion 53 and the flat plate portion 52 enter the housing main body 2 and the cap 7 descends on the outer side of the housing main body 2 and the engaging jaw 6 enters into the engaging hole 9, The piston cam body 11 to which the dust removing net 21, the closing member 31, the coil spring 34 and the mounting cap 35 are attached, the coil spring 41, the O-rings 42 and 61, A part of the rotating cam body 51 and the viscous fluid 71 can be received in the housing 1. [

When the piston cam body 11 is thus inserted into the housing main body 2, the viscous fluid 71 is guided by the guide groove 3b, the concave portion 3c or the bypass groove 3d outside the O-ring 42, The chamber a of the housing main body 2 and the flat portion 12 of the housing main body 2 are separated by the plate portion 12 and the bottom portion of the housing main body 2, 12, and 52 are filled with the viscous fluid 71, so that the chamber b can be assembled as shown in FIG.

Fig. 8 is an explanatory view showing a damper on the way to turn the toilet seat downwardly in a state in which the toilet seat is rotated upward to the maximum. Fig. 9 is an explanatory view showing the state in which the toilet seat is rotated downward Fig. 10 is an explanatory view showing the relationship between the flat plate portion of the piston cam body and the closing member when the toilet seat is forcibly pivoted downward. Fig.

In these drawings, B denotes a toilet bowl and S denotes a toilet seat. The toilet seat S is partially engaged with the shaft portion 54 of the damper D, which is mounted at a predetermined position of the toilet seat B by the mounting portion 5 And rotates together with the shaft portion 54.

C denotes a lid and is mounted so as to rotate around the shaft portion 54 of the damper D so that it can freely rotate.

W represents a water tank.

Next, the operation of the damper, that is, the turning operation of the toilet seat will be described.

First, as shown in Fig. 7, the toilet seat S is turned up to the maximum (the horizontal state is 0 degrees and 115 degrees) so that the toilet seat S is raised with the lid C interposed between the water tray W and the toilet seat , The damper D becomes the state shown in Fig.

As shown by the solid line in FIG. 5 (a), the cam portions 14 and 53 are configured such that the rotation cam portion 53 abuts on the stopper surface 15d and is separated from the first cam surface 15a by a distance d, (D) is in the state shown in Fig.

In this state, when the toilet seat S is rotated downward and the rotating cam body 51 is rotated, the rotation cam portion 53 rotates by a distance d and falls from the stopper surface 15d. In Fig. 5 (a) As shown by the chain line, abuts on the first cam face 15a whose inclination angle is gentle.

When the toilet seat S is further rotated downward so that the rotation cam portion 53 is in the depressed state shown in Fig. 5 (b), the toilet seat S is moved to the one-dot chain line As shown in Fig.

When the toilet seat S is rotated downward, the rotation cam portion 53 is separated from the second cam face 15b to release the lock. Thereafter, the rotation cam body 51 is rotated by its own weight of the toilet seat S 5 (c), and when the pivoting cam portion 53 is finally put in the pressing state shown in Fig. 5 (d), the toilet seat S is also rotated 7 to the toilet bowl B in a horizontal state as shown by the two-dot chain line.

When the cam faces 15a to 15c are pressed by the pivotal cam portions 53 as described above, the fitting protrusions 17 are guided to the guide grooves 3b so that the piston cam body 11 contracts the coil springs 41, When the turning cam body 53 pushes from the first cam face 15a of Fig. 5 (a) to the start of the third cam face 15c of Fig. 5 (c) Since the viscous fluid 71 flows from the chamber a to the chamber b through the bypass groove 3d because the chambers a and b are communicated by the bypass groove 3d, The braking force can not be imparted to the rotation of the vehicle body S.

However, when the pivot cam portion 53 starts to press the third cam face 15c in the direction of Fig. 5 (d) in Fig. 5 (c), the O-ring 42, Since the viscous fluid 71 flows through the orifice hole from the chamber a to the chamber b since the viscous fluid 71 passes through the bypass groove 3d, have.

Then, the piston cam body 11 finally moves to the state shown in Fig.

When the toilet seat S is forcibly rotated when the toilet seat S is lowered as described above so that the pressure of the viscous fluid 71 in the chamber a rises more than necessary, The viscous fluid 71 is supplied from the chamber a to the chamber b through the opening 13a so that the coil spring 34 is moved to reduce the coil spring 34 as shown in Fig. 10 And the groove 13b.

Therefore, the damper D and the toilet seat S can be protected from being damaged even if an unreasonable load is applied at the same time.

As described above, when the piston cam body 11 is moved so as to reduce the chamber a, the viscous fluid 71 is supplied to the groove 13b after the dust covering the groove 13 is removed from the dust removing net 21 The groove 13b is not blocked when the braking force is applied through the passage.

As shown in Fig. 7, when the toilet seat S in the horizontal state is turned upwardly and leaned against the water tray W, the rotation cam portion 53 pivots in the direction separating from the cam surface 15, The cam body 11 is pushed toward the pivotal cam body 51 by the urging force of the coil spring 41 so that the respective cam faces 15c to 15a follow the pivotal cam portion 53 and eventually the state shown in Fig. do.

The turning cam body 51 is separated from the piston cam body 11 and the braking force is not applied to the turning cam body 51 so that the toilet seat S can be smoothly moved upward It is possible to rotate well.

As described above, according to the embodiment of the present invention, the concave portion 3c is provided on the inner periphery of the housing body 2 on the chamber b side other than the braking stroke in which the O-ring 42 slides, The shear resistance caused by the viscous fluid 71 between the housing main body 2 and the pivotal cam body 51 can be increased by a large clearance between the piston main body 2 and the piston cam body 11 and the pivotal cam body 51 The outer circumferential diameter of the piston cam body 11 other than the necessary portion can be reduced and at the same time the locking hole 16 (16) is formed in the piston cam body 11, The shear resistance caused by the viscous fluid 71 between the housing main body 2 and the piston cam body 11 is reduced so that the piston cam body 11 is urged by the biasing force of the coil spring 41 It is possible to improve the following ability to follow the rotation of the rotation cam portion 53 .

A bypass groove 3d for communicating the chamber a and the chamber b from the locked state by the cam portion 14 to the unlocked state is provided on the inner periphery of the housing main body 2 The initial braking force for rotating the rotation cam portion 53 in the direction for imparting the braking force is extremely reduced. Therefore, a large load is not applied when the rotation cam portion 53 is unlocked, 53, and at the same time, it is possible to smoothly rotate the turning cam portion 53 smoothly in the turning range in which the braking force is not required, and the operability can be improved.

The lock state is a state in which the load in the rotating direction of the toilet seat S from the toilet seat S to the turning cam body 51 does not exceed the inclination of the cam through the resistance of the coil spring 41. [

Since the orifice is formed by the groove 13b by closing the opening 13a of the piston cam body 11 with the conical portion 32 of the closing member 31, (Accuracy) can be improved when the piston cam body 11 is formed, and a large braking force can be given to the orifice having a small cross-sectional area.

Since the opening 13a of the piston cam body 11 is closed by the truncated cone portion 32 by abutting the closing member 31 with the coil spring 34, the viscous fluid 71 The viscous fluid 71 flows from the chamber a to the chamber b by opening the opening 13a by reducing the coil spring 34. As a result, (13a) and the groove (13b).

Therefore, even if an unreasonable load is applied at the same time, the damper D and the toilet seat S serving as the braking member can be protected from being damaged.

The gap between the second cam face 15b for locking the rotation cam portion 53 and the stopper face 15d is made larger than the width of the rotation cam portion 53 to have a width at the position for locking the rotation cam portion 53 Therefore, when the rotation of the toilet seat S in the descending direction is braked, the toilet seat S can be raised against the lid C leaned against the water tray W so that the toilet seat S is separated from the lid C So that the appearance when the toilet seat S stands up is improved.

The first cam surface 15a (see FIG. 1), which contacts the second cam surface 15b before the rotation cam portion 53 is rotated in the unlocking direction within the lock range and abuts on the second cam surface 15b, It is possible to improve the operability at the initial stage of rotation in the lock release direction within the lock range of the rotation cam portion 53 in which the load of the toilet seat S is small.

The circumferential rib 20 is provided at the edge of the peripheral groove 19 to hold the O-ring 42 and reduce the outer diameter of the cam portion 14 of the piston cam body 11, The shear resistance caused by the viscous fluid 71 between the housing main body 2 and the piston cam body 11 is reduced because the clearance between the piston cam body 11 and the piston cam body 11 is increased. It is possible to improve the following ability to follow the rotation of the rotation cam portion 53 and return.

Since the dust removing net 21 is provided, when the braking force is applied, the viscous fluid 71 is removed from the groove 13b after the dust covering the groove 13, which becomes the orifice, is removed by the dust removing net 21 , The groove 13b is not blocked, and the braking action can be surely obtained.

11 is a perspective view of an occluding member showing another example of a groove to be an orifice.

In Fig. 11, reference numeral 32a denotes a groove to be an orifice, and is provided from one end to the other end on the main surface of the truncated cone portion 32.

In this case, the groove 13b is not provided in the opening 13a provided in the piston cam body 11. [

When the groove 32a serving as an orifice is provided on the main surface of the truncated cone portion 32 of the closure member 31 and the groove 13b is provided in the opening 13a provided in the piston cam body 11 Can be obtained.

Figs. 12 (a) and 12 (b) are explanatory views showing another example of the cam surface of the piston cam body.

In Fig. 12, reference numerals 15e and 15f denote third cam faces arranged side by side on the second cam face 15b.

12 (a), when the cam surface 15 is formed, the third cam surface 15e is formed as a protruding circular arc surface, so that the downward movement of the toilet seat S is transmitted to the slow start / quick end can do.

12 (b), when the cam surface 15 is formed, since the third cam surface 15f is formed as a stepped shape, the movement of the toilet seat S descending is made quick in the slow start , And a slow end.

5, when the cam surface 15 is formed, since the third cam surface 15c is formed into a slightly rounded arc surface, it is possible to make the movement of the toilet seat S descending as a quick start / slow end have.

Therefore, by changing the shape of the third cam surface constituting the cam surface 15, the stroke of the piston cam body 11 can be changed, and at the same time, the movement of the toilet seat S can be changed.

In the above-described embodiment, the opening 13a provided in the piston cam body 11 is formed as the circumferential surface of the truncated cone portion, but needless to say, it may be a circular opening.

When the groove 13b serving as the orifice is provided in the opening 13a of the piston cam body 11 and the groove 32a serving as the orifice is provided on the circumferential surface of the truncated cone portion 32 of the closing member 31 The same effect can be obtained when both grooves 13b and 32a are provided.

The opening 13a provided in the piston cam body 11 is closed by the truncated cone portion 32 of the closing member 31 urged by the coil spring 34 while leaving the groove 13b, May be left on the piston cam body 11 for closing the opening 13a or a groove may be formed in the closing body to be an orifice.

As described above, according to the present invention, since the piston is provided with the opening, the piston is provided with the closing member for closing the opening, and the groove which becomes the orifice is provided on at least one of the circumference of the opening or the circumference of the closing member. It is possible to form the groove to be an orifice of the piston or the closing member with a good degree and also to provide a large braking force with the orifice having a small cross sectional area.

Therefore, a small and large braking force can be obtained.

Since the opening is made circular, the closing member is formed to have the shape of a truncated cone, and the occluding member is biased from the chamber side to the other chamber side by the occluding member for blocking member so as to close the opening with the truncated cone, When the pressure of the viscous fluid in the other chamber rises more than necessary, the closing member shrinks the biasing member for the closing member to open the opening , The viscous fluid flows through the openings and grooves from one chamber to the other chamber.

Therefore, even if a large load is applied at the time of braking, the damper and the braking member can be protected from being damaged.

Claims (2)

When the rotary body rotatably disposed on one end of the housing is rotated, a piston accommodated in the housing so as to be movable in an axial direction moves, and the piston moves from one chamber on the rotary body side to the other chamber Or a damper that applies a braking force to the rotary body by a passage resistance through which the viscous fluid flows from the other chamber to the one chamber through the orifice, An opening is provided in the piston, An obstruction member for closing the opening is provided in the piston, And a groove to be the orifice is provided on at least one of the periphery of the opening or the periphery of the closing member, . The method according to claim 1, The opening is circular, Wherein the closing member has a shape having a truncated cone portion, And the closing member is biased toward the other chamber side from the one chamber side by the biasing member for the closing member so as to close the opening with the conical large- .