JP3656312B2 - Suspension spring unit for refrigerator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compressor of a Stirling refrigerator used as a cryocooler, a reciprocating piston incorporated in an expander, and a suspension spring unit for guiding and supporting a displacer in the reciprocating direction.
[0002]
[Prior art]
In the Stirling refrigerator described above, a configuration in which a reciprocating piston incorporated in a compressor and an expander and a displacer are guided and supported by a suspension spring is disclosed in, for example, Japanese Patent Laid-Open No. 5-288419. ing.
FIG. 3 is a configuration diagram of a Stirling refrigerator that uses such a suspension spring to support a piston of a compressor and a displacer of an expander. In the figure, reference numeral 1 denotes a horizontal axis type compressor incorporating a reciprocating piston 1a, 2 denotes a horizontal axis type expander including a reciprocating displacer 2b equipped with a regenerator 2a, 3 denotes a compressor 1 This is a connecting pipe that is piped between the compression space and the displacer 2 a of the expander 2. The piston 1a of the compressor 1 is driven to reciprocate in the axial direction by an electromagnetic actuator 1b incorporated in the machine, and two places of the piston rod 1c connected to the piston 1a are guided in the reciprocating direction by the suspension spring 4. I support it. Reference numeral 1d denotes a piston position detector.
[0003]
On the other hand, in the expander 2, the displacer 2b is reciprocally driven in the axial direction by an electromagnetic actuator 2c incorporated in the apparatus, and the two parts of the rod 2d connected to the displacer 2b are connected in the same manner as the piston 1a of the compressor 1. The suspension spring 4 guides and supports it in the reciprocating direction. In addition, 2e is a position detector of the displacer 2b, 2f is an active balancer attached to the expander 2, and suppresses generation | occurrence | production of the vibration of a cold-heat generation end surface. The operation principle of the Stirling refrigerator having such a configuration is well known, and is described in detail in Japanese Patent Laid-Open No. 5-288419.
[0004]
Next, the conventional structure of the suspension spring unit 4 will be described with reference to FIGS. That is, as shown in FIG. 5, the suspension spring unit 4 includes a plurality of (three in the illustrated example) leaf springs 4a arranged in parallel and an outer peripheral spacer 4b interposed between each leaf spring 4a. , The inner circumferential spacer 4c, the outer circumferential retaining plate 4d, and the inner circumferential retaining plate 4e are stacked and integrated with a fastening bolt. The inner circumferential end of the spring unit 4 is the piston rod 1c of the compressor 1, the expansion The outer end of the displacer rod 2d of the machine 2 is coupled to a fixed member in the machine, for example, a yoke of an electromagnetic actuator.
[0005]
Further, the plate spring 4a has a ring-shaped plate made of a highly elastic thin metal plate as a base, and a plurality of spiral slits 4f are formed on the plate surface as shown in FIG. 4, and between the slits 4f. It has a structure in which an arm portion 4g that can be bent in a direction perpendicular to the plate surface is formed.
When the suspension spring unit 4 having such a structure is used to support the piston 1a of the compressor 1 and the displacer 2b of the expander 2, the pistons 1a and 2b are reciprocated in the axial direction by driving the electromagnetic actuators 1b and 2c. Then, following the stroke operation, the arm portion 4g of the leaf spring 4a bends in the left-right direction around the neutral position (position where no bending is considered).
[0006]
[Problems to be solved by the invention]
By the way, if the above-described suspension spring unit 4 is employed to support the piston and the displacer of the horizontal shaft type compressor 1 and the expander 2 shown in FIG. 3, the following problems arise in terms of operation.
That is, in the leaf spring 4a having a structure in which a flexible arm portion is formed by inserting a spiral slit in the plate surface, the relationship between the stroke position of the piston and the displacer and the spring constant in the radial direction of the leaf spring 4a is shown in FIG. It has the characteristics expressed by A characteristic line A in the figure is a spring characteristic per leaf spring, and a characteristic line B is a combined spring characteristic in which three leaf springs are overlapped. As can be seen from this characteristic diagram, the spring constant is the maximum at the neutral position where the stroke position is “0”, that is, the leaf spring 4a is maintained in its original state and the arm portion 4g is not bent. When the arm portion is bent in the reciprocating direction, the spring constant rapidly decreases, and the spring constant is minimized at the stroke end positions of the piston and the displacer. In addition, in the spring unit in which a plurality of leaf springs are stacked, as indicated by the composite characteristic line B, the difference in spring constant between the neutral position and the stroke end position (forward / return dead point) is further increased. For this reason, the linearity of the suspension spring is reduced, and during operation of the refrigerator, a large excitation force is generated in the radial direction due to the dead weight of the movable part including the piston and the displacer, and the vibration and amplitude increase. In particular, when the amplitude in the radial direction increases, mechanical interference may occur between the fixed portion and the piston and the displacer when the piston and the displacer reciprocate, thereby causing a failure.
[0007]
The present invention has been considered in view of the above points, and for a Stirling refrigerator, a suspension spring unit for supporting a reciprocating piston and a displacer incorporated in a horizontal shaft type compressor and an expander. A suspension for a refrigerator that solves the problem and averages the spring constant in the radial direction of the spring unit with respect to the stroke position of the piston and the displacer, and improves the linearity of the spring unit to suppress the occurrence of vibrations in the refrigerator. An object is to provide a spring unit.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a plurality of flat plate ring-shaped plate springs each having a spiral slit formed on a plate surface, and each plate spring includes an inner peripheral end portion and an outer peripheral end portion. In order to shift the neutral position of each leaf spring relative to the reciprocating stroke position of the piston and the displacer with respect to the suspension spring unit that is an assembly in which a spacer is interposed between the two, Assume that an offset is set between each leaf spring and assembled.
[0009]
And as an offset provision means in the said structure, with respect to the spacer inserted in the inner and outer periphery between leaf | plate springs, the plate | board thickness of an outer periphery spacer is set thicker than the plate | board thickness of an inner periphery spacer. Alternatively, the thickness of the inner peripheral pacer is set to be larger than the thickness of the outer peripheral spacer.
As described above, by setting the offset of the plurality of leaf springs constituting the suspension spring unit so as to shift the neutral position of each leaf spring relative to the stroke position of the piston and the displacer, the spring with respect to the stroke position is set. The spring constant of the unit is averaged, and the linearity as a suspension spring unit is improved. Therefore, by appropriately designing the number of leaf springs of the suspension spring unit and the amount of offset according to the weight of the movable part including the piston and displacer, and the stroke range of the reciprocating motion, the radial excitation force is reduced during operation. The vibration and amplitude of the refrigerator can be kept small.
[0010]
Moreover, by changing the thicknesses of the outer peripheral spacer and the inner peripheral spacer as described above, an offset can be easily set between the leaf springs.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. First, the operation principle of the present invention will be described with reference to FIG. In the figure, characteristic lines A1, A2, and A3 are the spring characteristics of the three stacked leaf springs incorporated in the suspension spring unit (basically the same as the conventional structure shown in FIG. 5). The leaf springs A2, A3 arranged in the center of the spring unit indicate the spring characteristics corresponding to the leaf springs arranged on the left and right sides, and the neutral position of the spring is relative to the stroke position between each leaf spring. An offset is set so as to deviate. In other words, among the three stacked leaf springs, the leaf springs lined up in the center (characteristic line A1) align the neutral position of the spring (the original position with no deflection) with the stroke position “0” of the piston and the displacer, and are arranged on the left and right. The spring (characteristic line A2, A3) is constructed by assembling a suspension spring unit so that the neutral position thereof is matched with, for example, the stroke positions “+1” and “−1”. A specific assembly structure will be described in the section of each embodiment described later.
[0012]
Thus, by setting an offset between the plurality of leaf springs, the combined spring characteristic C has a substantially constant spring constant in the range of stroke positions “+1” to “−1” as shown in the figure. In addition, the peak value of the spring constant is smaller by Δk than the conventional composite spring characteristic B shown in FIG. 6B, and therefore, the stroke position “0” and the positions “+5” and “−5” corresponding to the stroke end are The spring constant difference between the two is reduced as compared with the conventional characteristic B. This improves the linearity of the suspension spring unit, and the radial excitation force applied to the piston 1a of the compressor 1 and the displacer 2b of the expander 2 during operation of the horizontal shaft type Stirling refrigerator shown in FIG. Reduced to reduce vibration and amplitude.
[0013]
Next, a specific suspension spring unit assembly structure for providing the above-described offset will be described in the following embodiments. In addition, in the figure of each Example, the same code | symbol is attached | subjected to the same member corresponding to FIG.
[Example 1]
FIG. 1 is an assembly structure diagram of an embodiment corresponding to claim 2 of the present invention. A suspension spring unit 4 basically includes three leaf springs 4a arranged in parallel and each plate, similarly to the structure of FIG. The outer peripheral spacer 4b and the inner peripheral spacer 4c inserted one by one between the springs 4a, the outer peripheral presser plate 4d, and the inner peripheral presser plate 4e are overlapped to be integrated by a fastening bolt, and the suspension spring The inner peripheral end of the unit 4 is connected to the piston rod 1c of the compressor 1 and the displacer rod 2d of the expander 2 shown in FIG. 3, and the outer peripheral end is connected to a fixing member in the apparatus, for example, a yoke of an electromagnetic actuator.
[0014]
Here, regarding the outer peripheral spacer 4b and the inner peripheral spacer 4c, the thickness of the inner peripheral spacer 4c is set to d0, and the thickness of the outer peripheral spacer 4b is set to d1 (d1> d0). Among the three leaf springs 4a arranged with the inner and outer peripheral spacers therebetween, an offset corresponding to the spacer thickness difference (d1 -d0) between the leaf springs arranged in the center and the leaf springs arranged on both sides thereof (FIG. 6 ( b)) is given.
[0015]
That is, in the state of FIG. 1 corresponding to the stroke position “0” in FIG. 6B, the leaf springs arranged in the center are in the neutral position and are not bent, but the leaf springs arranged on both sides are mutually It is bent in the opposite direction. Then, as the Stirling refrigerator is operated from this state, when the piston of the compressor and the displacer of the expander reciprocate and the stroke position is displaced, the bending allowance of each leaf spring changes depending on the direction, and the spring unit 4 is The composite spring constant in the radial direction is averaged by transitioning as shown by the composite characteristic line C in FIG. 6B, and the linearity of the suspension spring unit is improved.
[0016]
[Example 2]
FIG. 2 shows an embodiment corresponding to claim 3 of the present invention. In this embodiment, the inner and outer spacers 4b and 4c are different from those of the first embodiment in that the inner peripheral spacer 4c. The thickness d2 is determined to be greater than the thickness d0 of the outer peripheral spacer 4c, and the offset described in FIG. 6B is set between the leaf springs 4a.
[0017]
【The invention's effect】
As described above, for example, for a Stirling refrigerator, a horizontal spring compressor, a reciprocating piston incorporated in an expander, and a suspension spring unit that supports a displacer form a spiral slit on the plate surface A plurality of flat plate ring-shaped leaf springs, and each leaf spring is integrally assembled by interposing a spacer between the inner peripheral end portion and the outer peripheral end portion. In the case where the inner peripheral end is coupled to the piston or the rod of the displacer and the outer peripheral end is attached to a fixed member in the machine, according to the present invention, the neutral position of each leaf spring is set to the reciprocating stroke of the piston and the displacer. Stroke position of piston and displacer by assembling with offset between each leaf spring so as to shift relative to position Radial direction of the resultant spring constant against are averaged, to improve the linearity of the suspension spring unit.
[0018]
Therefore, by appropriately designing the number of leaf springs of the suspension spring unit and the amount of offset according to the weight of the movable part including the piston and displacer, and the stroke range of the reciprocating motion, the radial excitation force is reduced during operation. The vibration and amplitude of the refrigerator can be kept small.
[Brief description of the drawings]
FIG. 1 is a structural cross-sectional view showing an assembly structure of a suspension spring unit corresponding to a first embodiment of the present invention. FIG. 2 is a structural cross-sectional view showing an assembly structure of a suspension spring unit corresponding to a second embodiment of the present invention. FIG. 4 is a plan view of a leaf spring incorporated in a suspension spring unit in the refrigerator shown in FIG. 3. FIG. 5 is a suspension employing the leaf spring shown in FIG. FIG. 6 shows a conventional assembly structure of a spring unit, where (a) is a longitudinal sectional view and (b) is a cross-sectional plan view. FIG. 6 is a spring characteristic diagram showing the relationship between the stroke position of the suspension spring unit and the radial spring constant. 5A is a spring characteristic diagram corresponding to the conventional structure in FIG. 5, and FIG. 5B is a spring characteristic diagram corresponding to the embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Compressor 1a Piston 1c Piston rod 2 Expander 2b Displacer 2d Displacer rod 4 Suspension spring unit 4a Leaf spring 4b Outer spacer 4c Inner spacer 4f Swirl slit 4g Arm part

Claims (3)

A suspension spring unit that supports a compressor of a Stirling refrigerator, a reciprocating piston incorporated in an expander, and a displacer. Each of the leaf springs, and an inner peripheral end portion of the spring unit. Each piston spring is connected to the rod of the displacer and the outer peripheral end is attached to a fixed member in the machine, so that the neutral position of each leaf spring is shifted relative to the reciprocating stroke position of the piston or displacer. A suspension spring unit for a refrigerator, which is assembled by setting an offset between leaf springs. 2. The spring unit according to claim 1, wherein the thickness of the outer peripheral spacer is set to be larger than the thickness of the inner peripheral spacer with respect to the spacer interposed between the inner and outer peripheries between the leaf springs as the offset applying means. Suspension spring unit for refrigerator. 2. The spring unit according to claim 1, wherein the thickness of the inner peripheral pacer is set to be larger than the thickness of the outer peripheral spacer with respect to the spacer interposed between the inner and outer periphery between the leaf springs as the offset applying means. Suspension spring unit for refrigerator.

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