JP7802880B2 - Two-stage reciprocating compressor - Google Patents

Description

The present invention relates to a two-stage reciprocating compressor.

Two-stage reciprocating compressors are known that compress air in two stages to obtain high-pressure compressed air. Two-stage reciprocating compressors have a low-pressure cylinder and a high-pressure cylinder. In a two-stage reciprocating compressor, air compressed in the low-pressure cylinder is sent to the high-pressure cylinder, where it is further compressed. The compressed air compressed in the high-pressure cylinder is supplied to pneumatic machinery via a discharge port. When a two-stage reciprocating compressor is installed in a commercial vehicle, the compressed air discharged from the high-pressure cylinder head is supplied to, for example, brakes or air suspension. A conventional two-stage reciprocating compressor is disclosed in Japanese Patent Application Laid-Open No. 2013-040586.

Compression heat is generated during the air compression process, causing the temperature of the cylinder and piston to rise during operation of the reciprocating compressor. Furthermore, because the electric motor is driven by an applied current, this current generates Joule heat, which also increases the temperature of the electric motor. For this reason, conventional reciprocating compressors are often equipped with cooling fans. Two-stage reciprocating compressors equipped with cooling fans are disclosed in Japanese Patent Application Laid-Open Nos. 9-264253 and 2016-070233.

JP 2013-040586 A Japanese Patent Application Publication No. 9-264253 JP 2016-070233 A

Further improvements in cooling efficiency are required in two-stage reciprocating compressors equipped with cooling fans.

One object of the present disclosure is to improve the cooling effect in a two-stage reciprocating compressor. Other objects of the present disclosure can be understood by reference to the entire description of the present specification.

A two-stage reciprocating compressor according to one aspect of the present invention comprises a rotary drive source housed in a case, an output shaft extending in the axial direction that outputs rotation from the rotary drive source and has one end protruding from an end face of the case, a low-pressure compression element that compresses air using the rotational drive force from the output shaft as a power source, an intercooler that cools the compressed air discharged from the low-pressure compression element, a high-pressure compression element that further compresses the compressed air cooled by the intercooler using the rotational drive force from the motor output shaft as a power source, and a blower fan connected to the output shaft and positioned axially between the end face of the housing and the intercooler.

In one aspect of the present invention, the case has a plurality of ribs extending in the axial direction on its outer surface.

In one aspect of the present invention, the case has a plurality of other ribs extending perpendicular to the axial direction.

A two-stage reciprocating compressor according to one aspect of the present invention further includes a silencer that supplies the air to the low-pressure compression element.

A two-stage reciprocating compressor according to one aspect of the present invention further includes covers for at least a portion of the case, the low-pressure compression element, the intercooler, the high-pressure compression element, and the blower fan.

One aspect of the present invention relates to a vehicle. The vehicle is equipped with the above-described two-stage reciprocating compressor.

Embodiments of the present invention can improve the cooling effect in a two-stage reciprocating compressor.

FIG. 1 is a perspective view schematically illustrating a two-stage reciprocating compressor according to an embodiment. FIG. 2 is a schematic side view of the two-stage reciprocating compressor of FIG. 1 . FIG. 3 is a cross-sectional view schematically showing a cross section of the two-stage reciprocating compressor of FIG. 2 taken along line AA. FIG. 10 is a perspective view schematically showing a two-stage reciprocating compressor according to another embodiment. FIG. 2 is a schematic cross-sectional view of a two-stage reciprocating compressor according to another embodiment.

A two-stage reciprocating compressor 1 according to various embodiments of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a perspective view schematically illustrating a two-stage reciprocating compressor 1 according to one embodiment of the present invention. Figure 2 is a schematic side view of the two-stage reciprocating compressor 1 of Figure 1. Figure 3 is a schematic cross-sectional view of the two-stage reciprocating compressor 1 taken along line A-A in Figure 2. When referring to the up-down direction in this specification, the up-down direction shown in Figure 1 is used as the reference unless otherwise specified by the context. When referring to the front-rear direction in this specification, the front-rear direction shown in Figure 2 is used as the reference unless otherwise specified by the context. Figure 2 shows an axis C that coincides with the central axis of a crankshaft (described below). Axis C extends in the front-rear direction. In this specification, the direction along axis C is sometimes referred to as the axial direction, and the direction extending perpendicular to axis C is sometimes referred to as the radial direction.

As shown in FIG. 1, the two-stage reciprocating compressor 1 includes a housing 10. The housing 10 has a motor case 11, a crankcase 12, a first cylinder 13a, and a second cylinder 13b. The first cylinder 13a and the second cylinder 13b are each provided above the crankcase 12. Four legs are attached to the underside of the housing 10 via supports 19. The two-stage reciprocating compressor 1 is installed in a desired installation location via the legs 18.

The outer surface of the motor case 11 is provided with a plurality of first ribs 11a extending axially and second ribs 11b extending vertically. The upper ends of the second ribs 11b are connected to the rear ends of the corresponding first ribs 11a. Some of the multiple first ribs 11a extend from the rear end to the front end of the motor case 11, while the remaining portions extend forward from the rear end of the motor case 11, connecting to the second ribs 11b midway.

The motor case 11 has an internal space that penetrates its interior along the axis C. The motor case 11 has a generally hollow cylindrical shape. A motor 22 is disposed in the internal space of the motor case 11. The motor 22 has a stator coil 22a attached to the inner wall of the motor case 11, a rotor 22b mounted radially inside the stator coil 22a, and a motor shaft 22c that rotates with the rotor 22b. The motor 22 may also be equipped with a rotation detection sensor that detects the rotational position of the rotor 22b. The through-hole in the motor case 11 is closed at its rear end by a rear cap 23. As a result, the rear surface of the rear cap 23 forms the rear end surface 11c of the motor case 11. A through-hole is provided in the radial center of the rear cap 23, connecting the internal space of the motor case 11 with the external space. The motor shaft 22c extends through the through-hole in the rear cap 23 to the outside of the housing 10. The motor rotating shaft 22c is rotatably supported relative to the motor case 11 via bearings.

A blower fan 24 is attached to the rear end of the motor shaft 22c, which protrudes rearward from the motor case 11. The blower fan 24 rotates together with the motor shaft 22c around the central axis C. The rotation of the blower fan 24 generates an airflow fi that flows axially from the rear of the blower fan 24 toward the fan, and an airflow fo that flows axially from the front of the blower fan 24 along the outer surface of the housing 10.

The crankcase 12 has an internal space that penetrates its interior along the axis C. The internal space of the crankcase 12 and the internal space of the motor case 11 are separated by a partition wall 20. The through-hole provided in the crankcase 12 is closed at its front end by a front cap 21. The front cap 21 has a substantially disk-shaped cap body 21a and a dome 21b that protrudes forward from the radial center of the cap body 21a.

A crank mechanism is disposed within the interior space of the crankcase 12. This crank mechanism has a crankshaft 15. The crankshaft 15 extends along the central axis C within the crankcase 12 and motor case 11. The crankshaft 15 is supported at its front end by the front cap 21. The crankshaft 15 enters the motor case 11 through a through-hole provided in the partition wall 20 and is supported within the motor case 11 on the inner circumferential surface of the hollow motor shaft 22c. The crankshaft 15 is attached to the motor shaft 22c so as to rotate together with the motor shaft 22c around the central axis C. As a result, the rotational driving force from the motor 22 is transmitted to the crankshaft 15 via the motor shaft 22c.

The crankshaft 15 has a first eccentric portion 15a and a second eccentric portion 15b located axially rearward of the first eccentric portion 15a. The first eccentric portion 15a and the second eccentric portion 15b have a circular shape in a cross section perpendicular to the axis C. The center of the eccentric portion 15a is eccentric from the axis C. A first piston 16a is connected to the first eccentric portion 15a via a first connecting rod 14a. Similarly, a second piston 16b is connected to the second eccentric portion 15b via a second connecting rod 14b. The rotational motion of the crankshaft 15 is converted into reciprocating motion of the first piston 16a by the first connecting rod 14a, and into reciprocating motion of the second piston 16b by the second connecting rod 14b. In this way, the first piston 16a reciprocates inside the first cylinder 13a, and the second piston 16b reciprocates inside the second cylinder 13a.

The first eccentric portion 15a and the second eccentric portion 15b have different phases. For example, the phase of the first eccentric portion 15a and the phase of the second eccentric portion 15b are shifted by 180° from each other. Due to this phase shift, when the first piston 16a is driven in a direction that compresses the cylinder chamber of the first cylinder 13a, the second piston 16b is driven in a direction that expands the cylinder chamber of the second cylinder 13b. On the other hand, when the second piston 16b is driven in a direction that compresses the cylinder chamber of the second cylinder 13b, the first piston 16a is driven in a direction that expands the cylinder chamber of the first cylinder 13a.

A first cylinder head 17a is provided at the end of the first cylinder 13a, and a second cylinder head 17b is provided at the end of the second cylinder 13b. The first cylinder head 17a has an intake port 27a for drawing air into its internal space and an exhaust port 27b for discharging compressed air. The internal space of the first cylinder head 17a is divided into an intake chamber and a discharge chamber by a partition. Air that flows into the intake chamber from outside the first cylinder head 17a via the intake port 27a is drawn into the first cylinder 13a, compressed by the first piston 16a reciprocating within the cylinder 13a, and then discharged into the discharge chamber. This compressed air is introduced from the exhaust port 27b of the first cylinder head 17a through piping 26a to the intercooler 25, cooled by the intercooler 25, and then introduced into the second cylinder head 17b through piping 26b. The second cylinder head 17b has an intake port 28a for drawing compressed air from the pipe 26b and an exhaust port (not shown) for discharging compressed air that has undergone second-stage compression in the second cylinder 13b. Air flowing into the second cylinder head 17b through the intake port 28a is drawn into the second cylinder 13b, undergoes second-stage compression by the first piston 16b reciprocating within the cylinder 13b, and is then discharged to the outside of the second cylinder head 17b through the exhaust port. The compressed air that has undergone second-stage compression in the second cylinder 13b can be supplied to various pneumatic machines (not shown). Pneumatic machines include various devices that operate using compressed air. When the two-stage reciprocating compressor 1 is installed in a commercial vehicle, the compressed air from the second cylinder 13b can be supplied to, for example, air brakes, air suspension, and various other pneumatic machines installed in the commercial vehicle.

In this way, in the two-stage reciprocating compressor 1, air introduced from the outside undergoes a first stage of compression in the first cylinder 13a, and a second stage of compression in the second cylinder 13b. Thus, the first cylinder 13a is a low-pressure cylinder, and the second cylinder 13b is a high-pressure cylinder. In this specification, the first cylinder 13a may be referred to as the low-pressure compression element, and the second cylinder 13b may be referred to as the high-pressure compression element. The low-pressure compression element may include the first piston 16a and the first cylinder head 17a. The high-pressure compression element may include the second piston 16b and the second cylinder head 17b.

As shown in FIG. 3, the intercooler 25 is located axially rearward of the blower fan 24. In other words, the blower fan 24 is located between the intercooler 25 and the rear end face of the motor case 11. The intercooler 25 is attached to the motor case 11, for example, by bolts (not shown).

The intercooler 25 is connected to the exhaust port 27b of the first cylinder head 17a via piping 26a and to the intake port 28a of the second cylinder head 17b via piping 26b. The intercooler 25 has a serpentine piping connecting piping 26a and piping 26b, and numerous fins attached to this piping. High-temperature compressed air compressed in the first cylinder 13a is supplied to the piping of the intercooler 25 from piping 26a. As described above, an airflow fi flows as the blower fan 24 rotates, and this airflow passes through the intercooler 25. Because this airflow fi flows along the outer surfaces of the piping and fins of the intercooler 25, the compressed air passing through the intercooler 25 is cooled.

Next, the operation of the two-stage reciprocating compressor 1 will be described. When current is applied to the stator coil 22a, the rotor 22b rotates relative to the stator coil 22a. At this time, the rotation of the rotor 22b is transmitted to the crankshaft 15 and the blower fan 24 via the motor rotating shaft 22c. The rotational motion of the crankshaft 15 is converted into reciprocating motion of the first piston 16a by the first connecting rod 14a, and then converted into reciprocating motion of the second piston 16b by the second connecting rod 14b. Due to this reciprocating motion of the first piston 16a and the second piston 16b, air introduced from the outside undergoes a first stage of compression in the first cylinder 13a and a second stage of compression in the second cylinder 13b. The air compressed in the first cylinder 13a is cooled by the intercooler 25 before being introduced into the second cylinder 13b. Cooling air is supplied to the intercooler 25 from the blower fan 24, which rotates due to the rotational driving force from the motor 22.

Figure 4 is a perspective view showing a two-stage reciprocating compressor 1 according to another embodiment of the present invention. The two-stage reciprocating compressor 1 of Figure 4 differs from the two-stage reciprocating compressor 1 shown in Figure 1 in that it includes a cover 40. The cover 40 is a soundproof cover. The cover 40 may cover the entire periphery of the two-stage reciprocating compressor 1. In the illustrated embodiment, for ease of installation on a vehicle body, the legs 18 of the two-stage reciprocating compressor 1 are exposed from the cover 40. A through-hole connecting the inside and outside of the cover 40 may be provided in a portion of the cover 40. The cover 40 is made of a material with soundproofing properties. Examples of materials for the cover 40 include felt, polyvinyl chloride, or other soundproof materials. The cover 40 can prevent sound generated by the two-stage reciprocating compressor 1 from leaking to the outside.

Figure 5 is a perspective view showing a two-stage reciprocating compressor 1 according to another embodiment of the present invention. The two-stage reciprocating compressor 1 of Figure 5 differs from the two-stage reciprocating compressor 1 shown in Figure 1 in that it includes a silencer 50. The silencer 50 is attached to the dome 21b of the front cover 21. The silencer 50 has, for example, a hollow cylindrical shape. The internal space of the silencer 50 is defined into a first chamber that takes in outside air through the intake port 50a and a silencing chamber connected to the first chamber and taking in air from the first chamber. The intake port 50a may be located anywhere on the silencer 50. The silencer 50 may have a partitioned space other than the internal space, the first chamber, and the silencing chamber. The silencing chamber is connected to the intake port 27a of the first cylinder head 17a. When the motor 22 is driven, the suction chamber of the first cylinder head 17a becomes negative pressure, and air is drawn into the first chamber from outside the silencer 50. This air enters the sound-absorbing chamber from the first chamber. The air expands in the sound-absorbing chamber, thereby reducing the intake noise generated when outside air is drawn in.

The above-described two-stage reciprocating compressor 1 can be mounted, for example, on a commercial vehicle. One aspect of the present invention is a vehicle equipped with the two-stage reciprocating compressor 1.

The effects of the above embodiment are described below. In one embodiment of the present invention, the blower fan 24 is disposed axially between the rear end face 11c of the motor case 11 and the intercooler 25. This allows the cooling air generated by the blower fan 24 to pass through the intercooler 25 more easily, improving the cooling effect of the compressed air in the intercooler 25. In conventional two-stage reciprocating compressors, the intercooler is disposed axially between the rear end face of the motor case and the blower fan. In this arrangement in conventional two-stage reciprocating compressors, the cooling air sent from the blower fan to the intercooler collides with the rear end face of the motor case, disrupting the airflow, and the cooling air from the blower fan does not sufficiently contribute to cooling the intercooler. In an embodiment of the present invention, the cooling effect is improved by changing the axial arrangement of the blower fan and the intercooler.

In the above embodiment, a plurality of first ribs 11a extending in the axial direction and a plurality of second ribs 11b extending in the up-down direction are provided on the outer surface of the motor case 11. When the two-stage reciprocating compressor 1 is in operation, Joule heat is generated by an electric current applied to the stator coil 22a, and the heat generated in the stator coil 22a is transferred to the motor case 11. Because the first ribs 11a and the second ribs 11b increase the surface area of the outer surface of the motor case 11, the heat generated in the stator coil 22a can be efficiently dissipated into the atmosphere.
Furthermore, the first ribs 11a guide the cooling air from the blower fan 24 in the axial direction along the outer surface of the motor case 11. Therefore, the cooling air from the blower fan 24 flows between adjacent first ribs 11a, which further improves the heat dissipation efficiency.

The dimensions, materials, and arrangement of each component described in this specification are not limited to those explicitly described in the embodiments, and each component can be modified to have any dimensions, materials, and arrangement that fall within the scope of the present invention. Furthermore, components not explicitly described in this specification can be added to the described embodiments, and some of the components described in each embodiment can be omitted.

Some of the modified examples are shown below. The motor case 11 and crankcase 12 may have an integrated one-piece structure. The motor case 11 and crankcase 12 may be configured as separate members. The two-stage reciprocating compressor 1 may be provided with a control circuit for controlling the motor 22.

The inventions described in the claims of the original application of this application are as follows:
[1]
a rotary drive source housed in a case;
an output shaft extending in the axial direction, the output shaft outputting rotation from the rotary drive source and having one end protruding from an end face of the case;
a low-pressure compression element that compresses air using the rotational driving force from the output shaft as a power source;
an intercooler that cools the compressed air discharged from the low-pressure compression element;
a high-pressure compression element that further compresses the compressed air cooled by the intercooler using the rotational driving force from the output shaft as a power source;
a blower fan connected to the output shaft and disposed between the end surface of the case and the intercooler in the axial direction;
A two-stage reciprocating compressor comprising:
[2]
The case has a plurality of ribs extending in the axial direction on its outer surface.
[1] The two-stage reciprocating compressor according to [1].
[3]
The case has a plurality of other ribs extending in a direction perpendicular to the axial direction.
[2] The two-stage reciprocating compressor according to [2].
[4]
a silencer for supplying the air to the low-pressure compression element;
[4] The two-stage reciprocating compressor according to any one of [1] to [3].
[5]
a cover that covers at least a portion of the case, the low-pressure compression element, the intercooler, the high-pressure compression element, and the blower fan;
[1] to [4]. A two-stage reciprocating compressor according to any one of [1] to [4].
[6]
[1] to [5]. A motor vehicle equipped with the two-stage reciprocating compressor according to any one of [1] to [5].

1 Two-stage reciprocating compressor 10 Housing 11 Motor case 12 Crankcase 13a First cylinder (low-pressure side cylinder)
13b Second cylinder (high pressure side cylinder)
14a First connecting rod 14b Second connecting rod 15 Crankshaft 15a First eccentric portion 15b Second eccentric portion 16a First piston 16b Second piston 17a First cylinder head 17b Second cylinder head 18 Leg portion 19 Support portion 21 Front cap 22 Motor 22a Stator coil 22b Rotor 22c Motor rotating shaft 23 Rear cap 24 Blower fan 25 Intercooler

Claims (4)

a rotary drive source housed in a case;
an output shaft extending in the axial direction, the output shaft outputting rotation from the rotary drive source and having one end protruding from an end face of the case;
a low-pressure compression element that compresses air using the rotational driving force from the output shaft as a power source;
an intercooler that cools the compressed air discharged from the low-pressure compression element;
a high-pressure compression element that further compresses the compressed air cooled by the intercooler using the rotational driving force from the output shaft as a power source;
a blower fan connected to the output shaft and disposed between the end surface of the case and the intercooler in the axial direction;
Equipped with
a plurality of first ribs extending in the axial direction and a plurality of second ribs extending in the up-down direction are provided on an outer surface of the case,
the plurality of first ribs include a long rib extending from a rear end of the case to a front end of the case along the axial direction,
the first ribs include a plurality of short ribs extending from a rear end of the case along the axial direction to a position just forward of a front end of the case,
the plurality of short ribs are connected to upper ends of corresponding second ribs among the plurality of second ribs,
the plurality of second ribs include a distal second rib disposed distally with respect to the blower fan, and a proximal second rib disposed closer to the blower fan than the distal second rib,
the distal second rib is longer than the proximal second rib in the vertical direction;
Each of the plurality of short ribs and the plurality of second ribs is configured such that a distal end thereof distal to the outer surface of the case exists on an imaginary reference plane that passes through a position spaced apart from the output shaft and extends along the up-down direction and the front-rear direction parallel to the axial direction.
Two-stage reciprocating compressor. The two-stage reciprocating compressor of claim 1, further comprising a silencer that supplies the air to the low-pressure compression element. The two-stage reciprocating compressor according to claim 1 or 2, further comprising a cover that covers at least a portion of the case, the low-pressure compression element, the intercooler, the high-pressure compression element, and the blower fan. A motor vehicle equipped with the two-stage reciprocating compressor described in any one of claims 1 to 3.