TWI406990B - Sewing machine of the oil pump - Google Patents

Abstract

The invention aims to solve the problem that suction behaviour is lowered since air invades a suction inlet of an upper pump in an oil pump device comprising two layers which are the upper pump and a lower pump. The invention provides an oil pump device (1) of a sewing machine, comprising a rotating pump (2) and a rotating pump (3) forming two up and down layers, which are disposed on a rotor shaft 6 rotating by linking to the main shaft of the sewing machine and have an upper rotor and a lower rotor which are respectively disposed in the rotor chambers of an upper casing (21) and a lower casing (31). Lubricant oil is sucked in through each suction inlet, and discharged to each portion of the sewing machine through a discharge aperture at the same time. A discharging groove (211) with two open ends is formed correspondingly to the discharging aperture of the upper pump (3) above the lower casing (31) connected with the lower surface of the upper casing (31). An oil feeding path (2x) communicating the pump chamber with the rotor chamber of upper casing (21) is formed through a rotor at the downstream of the suction inlet of the lower casing (21). Therefore, part of the lubricant oil sucked into the lower pump and discharged is fed to the rotor chamber of the upper casing through the oil feeding path.

Description

Sewing machine oil pump device

The present invention relates to an oil pump device for sewing a sewing machine that supplies lubricating oil to various parts inside the sewing machine frame in an industrial sewing machine such as an overlock sewing machine or a flat chain stitch sewing machine.

In the past, the industrial sewing machine lubricates the movable parts such as the needle, the ring top, and the push cloth in order to meet the high speed of the sewing speed. This oil lubrication is performed by driving of an oil pump device that is disposed at the lower inner side of the sewing machine frame and that rotates the main shaft to rotate. In other words, the oil passages connected to the discharge port of the oil pump device are respectively extended to the respective movable portions dispersed in the sewing machine frame, and the oil return passage connected to the suction port of the oil pump device is connected to each movable portion. The lubricating oil recovery port that is installed is driven by the oil pump device to discharge the lubricating oil in the oil delivery path, and discharges the respective movable portions from the fuel injection ports formed at the intermediate portions and the end portions of the oil passages corresponding to the respective movable portions. At the same time, the lubricating oil after the lubrication is completed is recovered from the recovery port through the return path through the suction port of the oil pump device, and is again sucked into the oil pump device. (For example, refer to Patent Document 1 and Patent Document 2).

Specifically, the oil pump device 1 is composed of a pump connected to the lower pump 2 and the upper pump 3, which are connected to the upper and lower pumps, as shown in Figs. 5 and 6, and each of the pumps 2 and 3 is configured as A conventional cycloidal pump in which the outer rotor 4 and the inner rotor 5 are housed in the lower case 21 and the upper case 31 which are joined to each other.

In other words, in each of the pumps 2 and 3, the outer rotor 4 is a ring-shaped member that is rotatably fitted in a rotor chamber provided in a circular cross section of each of the casings 21 and 31, and the inner peripheral surface thereof is distributed with a plurality of In the figure, there are five concave portions. Further, the inner rotor 5 is located inside the outer rotor 4 provided in each of the casings 21 and 31, and is rotatably disposed by the eccentric rotor shafts 6, and the outer peripheral surface thereof is distributed with the outer rotor 4 and the outer rotor 4 The shape corresponding to each of the convex portions is one less than the number of the concave portions (four in the figure), and one of the convex portions is formed in the eccentric direction to engage the concave portion of the outer rotor 4. one.

The rotor shaft 6 protrudes above the upper casing 31 of the upper pump 3, and its projecting end portion engages with a worm wheel 7 as a driven gear. The engagement position of the worm wheel 7 is set to a substantially right angle crossing the middle portion of the main shaft S in a state where the oil pump device 1 is mounted inside the sewing machine frame F, and the worm wheel 7 is engaged with the corresponding position of the main shaft S at the intermediate portion. Worm (drive gear) 8.

Further, the main shaft S is protruded outside the sewing machine frame F, and its protruding end is fitted to the pulley 9. Next, the pulley 9 provided on the main shaft S and the pulley provided on the output shaft of the sewing machine motor (not shown) are wound around the belt 10, and the main shaft S is rotationally driven by a belt drive from the sewing machine motor (see Fig. 8).

Therefore, the rotor shaft 6 is rotationally driven in accordance with the rotation of the main shaft S transmitted through the worm 8 and the worm wheel 7, and the inner rotor 5 provided inside the upper and lower casings 31 and 21 is rotated by the rotation. The rotation of the inner rotor 5 is transmitted to the outer rotor 4 via a concave portion that is engaged with the convex portion of the outer surface of the inner rotor 5, and the outer rotor 4 also rotates together with the inner rotor 5.

Here, since the concave portion of the outer rotor 4 is one more than the convex portion of the inner rotor 5, the rotation of the inner rotor 5, as shown in Fig. 6, is gradually changed by its abutment in one rotation. The cross-sectional area (volume) of the pump chamber P sandwiched between the convex portions of the boundary portion of the outer rotor 4.

Each of the casings 21 and 31 has intake rakes 2a and 3a formed in a half portion on the side where the volume of the pump chamber P is increased, and similarly, discharge rakes 2b and 3b are formed in the half portions on the side where the cross-sectional area of the pump chamber P is reduced. The pump chamber P whose volume is changed according to the rotation of the inner rotor 5 and the outer rotor 4 is a pumping action, that is, sucking oil while being in a rotational position formed integrally with the suction jaws 2a and 3a, and discharging the oil into the maximum volume and discharging it. To spit out 2b, 3b.

The suction port 2a of the lower pump 2 is a lower suction port that communicates with the lower casing 21 through the filter, and the discharge port 2b communicates with the discharge port 21b that is open to the outside of the lower casing 21 (see Fig. 5).

Further, the suction port 3a of the upper pump 3 is connected to the suction port 31a (see FIG. 5) which is open to the outside of the upper casing 31, and the discharge port 3b is opened. As shown in FIG. 7, the two ends are opened to the outside to form the lower case. 21 above the discharge groove 211.

In the above-described oil pump device 1, as shown in Fig. 8, the discharge port 21b of the lower pump 2 is connected to one end of the oil feed pipe P1 so as to be extendable to the uppermost portion of the sewing machine frame F, and the other end of the oil feed pipe P is It is connected to the inlet side of the oil filter f fixedly supported at this position. The outlet side of the oil filter f is connected to the oil supply path 2P which is disposed above and below the sewing machine frame F, and the oil supply path P2 which is branched below is connected to the sliding bearing j for supporting the middle portion of the main shaft S. Further, the oil delivery path P2 which is branched above is connected to the injection nozzle N which is opened in the space on the sewing machine frame F, and is connected to the oil delivery pipe P3 which is extended to the lower portion of the sewing machine frame F. The oil pipe P3 is bent at the lower end portion and extended to the lower end side of the sewing machine frame F, and communicates with the arrangement position of the unillustrated sliding bearing for supporting the front end portion of the main shaft S, and is connected to the spindle S axis. An oil passage (not shown) in the heart.

Further, one end of the oil return pipe P5 is connected to the suction port 31a of the upper pump 3, and is bent upward to extend to the upper end side of the sewing machine frame F, and communicates with the vicinity of the needle bar (not shown).

Further, the discharge groove 211 which serves as the discharge port of the upper pump 3 is formed as an opening so that the lubricating oil can be ejected from the open end thereof.

Next, the operation of the oil pump device 1 configured as described above will be described.

First, the rotation of the main shaft S due to the belt drive of the sewing machine motor is transmitted to the movable portion such as the needle, the ringer, and the push cloth via a conventional transmission means (not shown), and the movement of the movable parts is performed by the movable parts. Sewing.

At this time, the rotation of the main shaft S is transmitted to the rotor shaft of the oil pump device 1 via the worm 8 and the worm wheel 7, and the rotary motion of the rotor shaft 6 is used for each of the lower pump 2 and the upper pump 3 for configuring the oil pump device 1. In the rotor chambers of the casings 21 and 31, the pumping action by the rotation of the rotor formed by the inner rotor 5 and the outer rotor 4 causes the lubricating oil to be discharged to the oil feed pipe P1 connected to the discharge port 21b of the lower pump 2, and is transmitted through the upper pump 3 The discharge port, that is, the discharge groove 211, allows the lubricating oil to be sprayed around, so that the lubricating oil remains in the bottom of the sewing machine frame F having the oil pan function.

The lubricating oil discharged into the oil pipe P1 is cleaned by the oil filter f, and then introduced into the oil delivery path P2 and then distributed to the upper and lower sides, and the lower distribution oil is guided to the arrangement position of the intermediate support sliding bearing j of the main shaft S, and the oil is supplied. The sliding surface of the sliding bearing j and the main shaft S is lubricated to the sliding surface.

In addition, most of the upper distribution oil is sent to the lower end side of the sewing machine frame F via the oil delivery pipe P3, and is not shown in detail, but is guided to the arrangement position of the sliding bearing for the front end of the main shaft S, and the oil is supplied. To the sliding surface of the sliding bearing and the main shaft S, the sliding surface is lubricated, and is guided to the respective portions in the axial length direction via the oil passage provided in the axial portion of the main shaft S, and the needle, the ring top, the push cloth, and the like Lubrication by the moving part. Further, the remaining portion of the upper distribution oil is ejected from the ejection nozzle N into the upper space of the sewing machine frame F, and the movable portion such as the needle disposed in the space is lubricated.

The lubricating oil for lubricating the respective parts as described above is recovered in the bottom of the sewing machine frame F having the oil pan function, and is sucked into the lower portion of the lower pump 2 by the pump action of the pump 2 immersed in the recovered lubricating oil. It is again subjected to boosting for recycling.

On the other hand, the lubricating oil supplied to the upper space is recovered to the suction port 31a of the upper pump 3 through the oil return pipe P5, and is again discharged from the discharge port, that is, the discharge groove 211 of the lower casing 2, to the surroundings.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-166737

[Patent Document 2] Japanese Real Fair No. 3-31272

However, the above-described oil pump device is composed of two layers of a lower pump and an upper pump, and the discharge port of the upper pump is constituted by a discharge groove formed at both ends and formed on the lower case. On the other hand, between the rotor chamber of the upper casing and the outer rotor and the inner rotor that rotates in the rotor chamber, a slight gap is secured to allow rotation. In this way, when the suction of the upper pump cannot recover sufficient lubricating oil, the air may pass through the discharge port of the upper pump, that is, the discharge groove formed on the lower casing at both ends, the rotor chamber and the outer rotor of the upper casing, and A small gap between the inner rotors invades the suction port of the upper pump. When air intrudes into the suction port, the suction performance of the upper pump is lowered, and the recovery of the lubricating oil supplied to the upper space of the sewing machine frame is further reduced, resulting in a lower suction performance.

The present invention has been made in view of the above problems, and an object of the invention is to provide a sewing machine device comprising two layers of a lower pump and an upper pump, and a sewing machine capable of reliably preventing air from entering the suction port of the upper pump and causing a decrease in suction performance. Oil pump unit.

In the oil pump device of the sewing machine of the present invention, the rotor shaft is rotated by the rotation of the main shaft of the sewing machine, and the lower rotor and the upper rotor provided on the rotor shaft are respectively rotated above and below the rotor chamber of the lower casing and the rotor chamber of the upper casing. The pump of the layer is configured to suck the lubricating oil through the respective suction ports of the upper and lower pumps, and simultaneously discharge the dust to the respective parts of the sewing machine by the discharge port, and is characterized in that the upper surface of the case is joined to the lower surface of the upper case. a discharge groove having at least one opening, the discharge groove being formed corresponding to the discharge port of the upper pump, and the lower case being formed with a pump chamber formed by a rotor that can be sucked into the downstream side of the crucible and a rotor chamber of the upper case The communication passage is connected so that a part of the lubricating oil discharged into the discharge port by the suction port of the lower pump is supplied to the rotor chamber of the upper casing through the oil supply passage.

According to the present invention, when the rotation of the main shaft is rotated to rotate the rotor shaft, the lower and lower pumps connected to the upper and lower pumps and the upper and lower rotors are respectively rotated in the rotor chambers of the upper and lower casings, so that the lubricating oil passes through the respective suction ports. At the same time as the inhalation, it is discharged to the parts of the sewing machine by the discharge. That is, the lubricating oil is enclosed in the pump chamber formed by the rotating rotor, thereby increasing its pressure so as to be discharged toward the discharge port. Here, in the lower pump, when the pump chamber formed by the rotating rotor reaches a position close to the oil supply path, a part of the lubricating oil is supplied to the rotor chamber of the upper casing of the upper pump through the oil supply path. Next, the lubricating oil supplied to the upper casing rotor chamber of the upper pump is a gap formed between the rotor chamber through which the pressure enters the upper casing and the upper rotor which is rotatably accommodated in the rotor chamber, while being filled in the suction port.

As a result, even if the air passes through the discharge port of the upper pump, that is, the discharge groove formed at least one end opening on the lower case intrudes into the suction port from the rotor chamber of the upper case, the gap formed between the rotor chamber and the upper rotor of the upper case has been Since the filled lubricating oil is sealed, it is possible to prevent the air from entering the suction port through the gap, and it is possible to surely prevent the lowering of the suction performance of the upper pump.

Further, in the oil pump device of the sewing machine of the present invention, the rotor shaft is rotated by the rotation of the main shaft of the sewing machine, and the lower rotor and the upper rotor provided in the rotor shaft are respectively rotated in the rotor chamber of the lower casing and the rotor chamber of the upper casing. The upper and lower layers of the pump are configured to suck the lubricating oil through the respective suction ports of the upper and lower pumps, and are discharged to the respective parts of the sewing machine by the discharge port, and are characterized in that the upper surface of the case is joined under the upper case. a discharge groove having at least one end opening is formed, and the discharge groove is formed corresponding to the discharge port of the upper pump, and the upper case is formed with a communication path penetrating from the rotor chamber on the downstream side of the suction port to the upper surface. Thereby, a part of the lubricating oil discharged from each part of the sewing machine is supplied to the rotor chamber of the upper casing through the communication path.

According to the present invention, when the rotation of the main shaft is rotated to rotate the rotor shaft, the lower and lower pumps connected to the upper and lower pumps and the upper and lower rotors are respectively rotated in the rotor chambers of the upper and lower casings, so that the lubricating oil is separately sucked through the respective suction ports. At the same time, spit it out to the parts of the sewing machine. That is, the lubricating oil is enclosed in the pump chamber formed by the rotating rotor so that the pressure is increased so that it is discharged toward the discharge port. At this time, a part of the lubricating oil supplied to each part of the sewing machine is lowered to the oil pumping device to enter the communication path which has been formed in the upper casing of the upper pump. Then, the lubricating oil that has entered the communication path enters the gap formed between the rotor chamber of the upper casing and the upper rotor that is rotatably accommodated in the rotor chamber by its own weight, while being filled in the suction port.

As a result, even if the air passes through the discharge port of the upper pump, that is, the discharge groove formed at least one end opening on the lower case enters the suction port from the rotor chamber of the upper case, the gap formed between the upper case and the upper rotor is formed. Since the filled lubricating oil is sealed, it is possible to prevent the air from entering the suction port through the gap, and it is possible to surely prevent the suction performance of the upper pump from being lowered.

According to the present invention, the oil pump device including the lower pump and the upper pump can reliably prevent the inhalation of air into the upper pump and cause a decrease in the suction performance.

[Best Embodiment of the Invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 and Fig. 2 are views showing an embodiment of the oil pump device 1 of the sewing machine of the present invention.

The lower pump 2 and the upper pump 3 for the oil pump device 1 have substantially the same structure as the lower pump 2 and the upper pump 3 described above, and the same members are denoted by the same reference numerals, and detailed description thereof will be omitted. Only explain the differences.

The lower casing 21 of the pump 2 is configured to be a downstream side rotor chamber of the suction port 2a, and a pump chamber P and an upper pump 3 formed by the inner rotor 5 and the outer rotor 4 that can rotate are formed. The downstream side rotor chamber of the suction port 3a serves as the oil supply passage 2x that communicates. The oil supply passage 2x has a smaller diameter at the tip end portion of the opening of the upper casing 31 of the upper pump 3 than the base end portion of the opening of the rotor chamber of the lower casing 21.

Therefore, when the main shaft s is rotated by the belt drive through the sewing machine motor not shown, the rotation of the worm 8 and the worm wheel 7 causes the rotor shaft 6 to rotate, so that the inner rotors 5 are respectively on the rotor chamber of the lower casing 21 of the lower pump 2 and The rotor chamber of the upper casing 31 of the pump 3 rotates, and the rotation of the inner rotor 5 causes the outer rotor 4 to rotate, and the lubricating oil is sucked in by the negative pressure generated by the suction jaws 2a, 3a while the sucked lubricating oil is sealed. The pump chamber P formed by the inner rotor 5 and the outer rotor 4 is discharged toward the discharge ports 2b and 3b on the downstream side in the rotation direction of the rotor shaft 6. At this time, when the pump chamber P formed by the rotating inner rotor 5 and the outer rotor 4 reaches a position close to the oil supply path 2x, a part of the lubricating oil which is closed in the pump chamber P so as to increase the pressure is in the oil supply path. The 2x small-diameter front end portion is pressed to make the pressure more pressurized, and then supplied to the rotor chamber of the upper casing 31 of the upper pump 3 through the oil supply passage 2x. Next, the lubricating oil supplied to the rotor chamber of the upper casing 31 of the upper pump 3 is a gap formed between the rotor chamber 5 and the outer rotor 4 which are accommodated in the rotor chamber by the rotor chamber which is pressurized into the upper casing 31 by the pressure thereof. At the same time filled with inhalation 埠 3a. In this way, even if the air passes through the discharge port of the upper pump 3, that is, the discharge groove 211 formed at the both ends of the lower casing 21 and enters the suction port 3a from the gap of the rotor chamber of the upper casing 31, the rotor chamber of the upper casing 31 and The gap formed between the rotor 5 and the outer rotor 4 housed in the rotor chamber is sealed by the filled lubricating oil, so that the air can be prevented from entering the suction port 3a through the gap.

As a result, it is possible to surely prevent a decrease in the suction performance caused by the intrusion of air into the suction port 3a of the upper pump 3, and it is possible to constantly suck and collect the set amount of the lubricating oil, and to discharge the lubricating oil around the discharge groove 211.

Further, in the lower pump 2, most of the lubricating oil enclosed in the pump chamber P so as to increase the pressure is discharged through the discharge port 21b in the oil delivery pipe P1, and supplied to the sewing machine parts to lubricate the movable portion, and then recovered. The bottom of the sewing machine frame F is used for recirculation.

Next, another embodiment of the oil pump device 1 of the sewing machine of the present invention will be described with reference to Figs. 3 and 4 .

The lower pump 2 and the upper pump 3 for the oil pump device 1 of the embodiment are similarly designed, and the same components as those of the lower pump 2 and the upper pump 3 described above are denoted by the same reference numerals, and are omitted here. The detailed description will only explain the differences.

The oil pump device 1 constitutes the upper casing 31 of the upper pump 3, and is formed with a communication passage 3x through which the rotor chamber on the downstream side of the suction port 3a penetrates. The communication passage 3x has an upper end opening which is open on the upper surface of the upper casing 31 so as to be larger than a lower end opening in the opening of the rotor chamber.

Therefore, when the main shaft S is rotated by the belt drive through the sewing machine motor not shown, the rotor shaft 6 is rotated by the worm 8 and the worm wheel 7, so that the inner rotor 5 is respectively in the rotor chamber of the lower casing 21 of the lower pump 2 and the upper pump 3 The rotor chamber of the upper casing 31 rotates, and the rotation of the inner rotor 5 causes the outer rotor 4 to rotate, and the lubricating oil is sucked in by the negative pressure generated by the suction ports 2a, 3a. The pump chamber P formed by the fifth and outer rotors 4 is discharged toward the downstream side in the rotation direction of the rotor shaft 6. Then, in the lower pump 2, the lubricating oil which is closed in the pump chamber P so as to increase the pressure is discharged to the oil delivery pipe P1 through the discharge port 21b, and is supplied to the lubrication movable portion of each part of the sewing machine, and is recovered at the bottom of the sewing machine frame F as Recycled again. Similarly, in the upper pump 3, the lubricating oil is sucked and collected by the suction port 31a through the oil return pipe P5, and then ejected from both ends of the discharge port 211 of the lower casing 21 from the discharge port.

As described above, a part of the lubricating oil discharged from the nozzle N in the upper portion of the sewing machine frame F or a part of the lubricating oil discharged from the discharge groove 211 of the lower casing 21 is discharged through the oil pipe P1. The oil pump device 1 is lowered to enter the communication passage 3x formed in the upper casing 31 of the upper pump 3, and temporarily remains at the lower end portion which becomes the small diameter. Then, the lubricating oil remaining in the upper casing 31 communication passage 3x of the upper pump 3 is a gap formed between the inner rotor 5 and the outer rotor 4 which are accommodated in the rotor chamber by the rotor chamber which enters the upper casing 31 by its own weight. , filled with inhalation 埠 3a. In this way, even if the air passes through the discharge port of the upper pump 3, that is, the discharge groove 211 formed at the both ends of the lower casing 21 and enters the suction port 3a from the rotor chamber of the upper casing 31, the rotor chamber of the upper casing 31 is housed in Since the gap formed between the inner rotor 5 and the outer rotor 4 of the rotor chamber is sealed by the filled lubricating oil, it is possible to prevent air from entering the suction port 3a through the gap.

As a result, it is possible to surely prevent the air from entering the suction port 3a of the upper pump 3, thereby causing a decrease in the suction performance, and it is possible to constantly suck and collect the set amount of the lubricating oil, and to discharge the lubricating oil around the discharge groove 211.

Further, in the above-described embodiment, the above-described lower casing of the lower pump is formed, and the discharge groove formed corresponding to the upper pump discharge port is opened at both ends. However, the discharge groove may be formed to have only one end opening.

1. . . Oil pump device

2. . . Down pump

2x. . . Oil supply road

twenty one. . . Lower case

211. . . Spit out

3. . . Upper pump

3x. . . Connected road

31. . . Upper shell

4. . . Outer rotor

5. . . Inner rotor

6. . . Rotor shaft

7. . . Worm gear

8. . . Worm

F. . . frame

S. . . Spindle

Fig. 1 is a partially cutaway half cross-sectional view showing an embodiment of an oil pump device of a sewing machine according to the present invention.

Fig. 2 is a bottom view of the lower pump of the oil pump device of Fig. 1.

Fig. 3 is a partially omitted half cross-sectional view showing another embodiment of the oil pump device of the sewing machine of the present invention.

Fig. 4 is a top pump diagram showing the oil pump device of Fig. 3, wherein (a) is a plan view and (b) is a bottom view.

Figure 5 is a perspective view for explaining the oil pump device of the sewing machine.

Fig. 6 is a bottom view showing the operation of the oil pump device of Fig. 5.

Fig. 7 is a partially omitted plan view showing the lower case of the lower pump in the oil pump device of Fig. 5.

Fig. 8 is a schematic view showing a schematic configuration of a main part of a sewing machine provided with the oil pump device of Fig. 5.

1. . . Oil pump device

2. . . Down pump

2x. . . Oil supply road

twenty one. . . Lower case

211. . . Spit out

3. . . Upper pump

4. . . Outer rotor

5. . . Inner rotor

6. . . Rotor shaft

7. . . Worm gear

Claims (2)

The oil pump device of the sewing machine rotates the rotor shaft by the rotation of the main shaft of the sewing machine, so that the lower rotor and the upper rotor of the rotor shaft are respectively rotated on the second floor of the rotor chamber of the lower casing and the rotor chamber of the upper casing The lower pump is configured to allow the lubricating oil to be sucked through the respective suction ports of the upper and lower pumps, and is discharged to the respective parts of the sewing machine by the discharge port, and is characterized in that the upper surface of the case is formed under the lower surface of the upper case. a discharge groove having at least one opening, the discharge groove being formed corresponding to the discharge port of the upper pump, and the lower case being formed with a pump chamber formed by a rotor that can be sucked into the downstream side of the crucible and a rotor chamber of the upper case The communication passage is connected so that a part of the lubricating oil discharged into the discharge port by the suction port of the lower pump is supplied to the rotor chamber of the upper casing through the oil supply passage. The oil pump device of the sewing machine rotates the rotor shaft by the rotation of the main shaft of the sewing machine, so that the lower rotor and the upper rotor of the rotor shaft are respectively rotated on the second floor of the rotor chamber of the lower casing and the rotor chamber of the upper casing The lower pump is configured to allow the lubricating oil to be sucked through the respective suction ports of the upper and lower pumps, and is discharged to the respective parts of the sewing machine by the discharge port, and is characterized in that the upper surface of the case is joined by the surface below the upper case a discharge groove having at least one opening, the discharge groove being formed corresponding to the discharge port of the upper pump, and the upper case being formed with a communication passage penetrating from the rotor chamber on the downstream side of the suction port to the upper surface of the upper case. Thereby, a part of the lubricating oil discharged from each part of the sewing machine is supplied to the rotor chamber of the upper casing through the communication path.