JP2002174173A - Pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration of a pump furnished with a reciprocating piston. SOLUTION: Both of the pistons 13, 14 are arranged at symmetrical positions against a rotational center (a) of a rotation axis 52 and are made to symmetrically reciprocate around the rotational center (a) as their axis. Consequently, inertial force of the both pistons 13, 14 is cancelled, and vibration of the pump by the inertial force can be reduced. Additionally, phases of an intake process and a discharge process of the first piston 13 are made antiphases against phases of an intake process and a discharge process of the second piston 14. Consequently, the second piston 14 comes to be in the discharge process when the first piston 13 is in the intake process, it is possible to halve discharge of the pump at the time of the discharge process in comparison with the pump with which the discharge processes of the both pistons 13, 14 are simultaneously carried out, it is possible to reduce pulsation and it is possible to reduce noise due to discharging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump for sucking and discharging a fluid as a piston reciprocates.
Particularly, it is suitable for a vacuum pump for sucking and discharging gas.

[0002]

2. Description of the Related Art In a conventional vacuum pump, one piston is reciprocated by a connecting rod connected to a crankshaft so that gas is sucked and discharged to the outside (for example, Japanese Utility Model Publication No. 61-34923). Reference).

[0003]

However, the above conventional pump has a problem that the pump vibrates due to the inertial force of the piston as the piston reciprocates.

[0004] The present invention has been made in view of the above points, and an object of the present invention is to reduce the vibration of a pump having a reciprocating piston.

[0005]

Means for Solving the Problems In order to achieve the above object, the present inventors have made the following studies. In other words, a plurality of pistons reciprocated vertically with respect to the rotation center of the drive shaft are provided with the rotation of the drive shaft which is coaxially coupled to and rotates with the rotation shaft of the motor. The pumps which are arranged at equal intervals in the direction of rotation and reciprocate symmetrically about the center of rotation were studied. According to this pump, the inertial forces of the plurality of pistons act in directions canceling each other and are cancelled, and the vibration of the pump due to the inertial force of the pistons can be reduced.

Here, in the above-discussed pump, if the phases of the suction step and the discharge step of each piston are all set to the same phase so that the discharge steps of a plurality of pistons are all performed at the same time, noise due to discharge is generated. It turned out to be a problem.

Therefore, according to the first aspect of the present invention, a driving means (50) having a rotating shaft (52) and a driving shaft (40) coaxially coupled to the rotating shaft (52) and rotating.
And a piston (13, 14) reciprocated in a direction perpendicular to a rotation center (a) of the drive shaft (40) with rotation of the drive shaft (40), The piston (13, 14) is connected to the drive shaft (4).
A plurality of pistons (13, 14) are reciprocated symmetrically about the rotation center (a), and a plurality of the pistons (13, 14) are arranged at equal intervals in the rotation direction of 0). Among the plurality of pistons (13, 14), the phases of the suction step and the discharge step due to the reciprocating motion of at least one piston (13) are the phases of the suction step and the discharging step due to the reciprocating motion of the other pistons (14). Is characterized by being in antiphase with respect to.

According to this, since the phase of the suction step and the discharge step of at least one piston (13) is made opposite to the phase of the suction step and the discharge step of the other piston (14), one phase is set. When one of the pistons (13) is in the suction step, the other piston (14) is in the discharge step, so that the discharge of the pump in the discharge step is smaller than that of the pump in which the discharge steps of the plurality of pistons (13, 14) are performed simultaneously. The volume can be reduced, and noise due to emissions can be reduced.

Further, similarly to the pump discussed above, the inertial forces of the plurality of pistons (13, 14) are canceled by acting in directions canceling each other.
The vibration of the pump due to the inertial force of 4) can be reduced.

Further, according to the present invention, a driving means (50) having a rotating shaft (52) and the driving shaft (5) are provided.
2) a drive shaft (40) coaxially coupled to and rotating, and the drive shaft (40) with the rotation of the drive shaft (40).
First reciprocatingly reciprocating with respect to the rotation center (a) of
A first pump chamber (P1) having a built-in piston (13) and a second piston (14) and the first and second pistons (13, 14), in which fluid is sucked and discharged by the first piston (13). ) And a housing (10) forming a second pump chamber (P2) through which fluid is sucked and discharged by the second piston (14). The first pump chamber (P1) is provided with ), The second pump chamber (P2) is disposed on the rotation center (a) side with respect to the second piston (14). The first and second pistons (13, 14) are arranged symmetrically about the rotation center (a) so as to reciprocate symmetrically.

According to this, the first pump chamber (P1) is arranged on the side opposite to the rotation center (a) with respect to the first piston (13), and the second pump chamber (P2) is connected to the second piston (14). )
When the first piston (13) is in the suction process, the second piston (14) is in the discharge process when the two pistons (13, 14) reciprocate symmetrically. When the first piston (13) is in the discharging step, the second piston (14) is in the suction step. Therefore, the discharge amount of the pump in the discharge step can be reduced as compared with the pump in which the discharge strokes of both pistons (13, 14) are performed simultaneously, and the noise due to discharge can be reduced.

Further, similarly to the pumps discussed above, the inertial forces of the plurality of pistons (13, 14) are canceled by acting in directions canceling each other, and the pistons (13, 1) are canceled.
The vibration of the pump due to the inertial force of 4) can be reduced.

The reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS. FIGS. 1 to 4 are sectional views of the pump. In FIGS. 1 and 2, the piston is located at the bottom dead center, and in FIGS. 3 and 4, the piston is located at the top dead center. In addition,
FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 4 is a sectional view taken along line BB of FIG.

This pump is used, for example, as a vacuum pump for supplying a negative pressure to a vacuum booster (not shown) of a vehicle braking system.

In FIG. 1, a cylindrical housing 10 is formed with a crank chamber 11 having a columnar hole shape extending in the vertical direction. At both ends of the housing 10, a thin cylindrical member made of stainless steel in which a piston described later slides is formed. Are mounted.

The outer surface on the right side of the housing 10 is formed as a flat surface, and an electric motor (drive means) 50 is attached to the flat surface by screws or the like (not shown). The inside of the motor 50 communicates with the crankcase 11, and the air in the crankcase 11 is discharged into the atmosphere from the drain pipe 51 through the inside of the motor 50.

One end of a rotating shaft 52 of the motor 50 extends to the crank chamber 11, and a crankshaft (drive shaft) 40 is coaxially connected to one end of the rotating shaft 52. This crankshaft 40
Are two eccentric shafts 41 eccentrically arranged with respect to the rotation center (axis) a of the crankshaft 40 and the rotation shaft 52.
(See FIGS. 2 to 4), and a bearing 42 mounted on the outer peripheral side of the eccentric shaft 41. As shown in FIGS. 2 and 4, these eccentric shafts 41 are located at symmetrical positions equidistant from the rotation center a, in other words, in the rotation direction b of the crankshaft 40 and the rotation shaft 52 (FIG. 2). ) Are arranged at regular intervals (180 ° intervals).

In the housing 10, first and second pistons 13, 14 which are reciprocated vertically with respect to the rotation shaft 52 and the rotation center a of the crank shaft 40 with the rotation of the crank shaft 40 are arranged. Have been. These pistons 1
3, 14 are symmetrical with respect to the center of rotation a, in other words, at equal intervals (180 ° intervals) in the rotation direction b (see FIG. 2).
Are located in

The rotation shafts 5 of the pistons 13 and 14
A first rod 15 and a second rod 1 each having a cylindrical shape are provided on two sides.
6 are connected. A first rod plate 15a and a second rod plate 16a each having a rectangular plate shape are connected to the rotating shaft 52 side of both rods 15, 16.

The pistons 13 and 14 are reciprocated symmetrically about the rotation center a.
That is, when the first piston 13 moves from bottom dead center to top dead center, the second piston 14 also moves from bottom dead center to top dead center, and the first piston 13 moves from top dead center to bottom dead center. When moving to the point, the second piston 14 also moves from the top dead center to the bottom dead center.

Also, at both end openings of the housing 10,
First and second end plates 17 and 18 are mounted so as to close the opening. Also, housing 1
A first support plate 19 and a second support plate 20 for slidably supporting the first and second rods 15 and 16 are mounted in 0.

The first pump chamber P is formed by the first end plate 17, the housing 10, and the first piston 13.
1 is formed, and the second support plate 20 and the housing 10 are formed.
A second pump chamber P2 (see FIGS. 3 and 4) is formed by the second piston 14 and the second piston 14. Therefore, the first pump chamber P1 is arranged on the opposite side of the rotation center a with respect to the first piston 13, and the second pump chamber P2 is
4 is disposed on the rotation center a side.

A first cover 21 having a first pipe portion 21a is mounted on the upper end of the housing 10, and a first space 22 is formed between the first cover 21 and the first end plate 17. ing. A second space 23 is formed by the second end plate 18, the housing 10, and the second piston 14. The second end plate 18 is formed with a communication hole 18a for communicating the inside and outside of the housing 10, and the pressure in the second space 23 is reduced to the second pressure.
Regardless of the position of the piston 14, the pressure is always equal to the pressure (atmospheric pressure) outside the pump.

A piston ring 24 made of four-hooker ethylene (PTFE) having a low coefficient of friction is mounted on the outer periphery of the first and second pistons 13 and 14.
During the reciprocating movement of the pistons 3 and 14, the piston ring 24 slides on the inner peripheral surface of the cylinder liner 12 while maintaining airtightness.

The first pump chamber P in the first piston 13
A ring-shaped first discharge check valve 25 made of rubber having high heat resistance and a first valve plate 26 are mounted on one side. The first piston 13 and the first valve plate 26 are formed with communication holes 13a and 26a for communicating the first pump chamber P1 with the crank chamber 11. Then, the communication hole 26a of the first valve plate 26 is opened and closed by the first discharge check valve 25, and the first discharge check valve 25 is
The valve is opened when the pressure in the first pump chamber P1 becomes higher than the pressure in the crank chamber 11 (during a discharge step described later).

The first end plate 17 has the first
Communication hole 17a for communicating the pump chamber P1 with the first space 22
On the first pump chamber P1 side of the first end plate 17, a mushroom-shaped first suction check valve 27 for opening and closing the communication hole 17a is mounted. The first suction check valve 27 is made of heat-resistant rubber and has a first pump chamber P
When the pressure of No. 1 becomes lower than the pressure of the first space 22 (during a suction process described later), the umbrella portion is deformed and the valve is opened.

The second support plate 20 has a ring-shaped second heat-resistant rubber on the crank chamber 11 side.
A discharge check valve 28 is mounted. On the other hand, on the second pump chamber P2 side, a ring-shaped second ring made of rubber having high heat resistance is provided.
A suction check valve 29 is mounted. In a portion corresponding to the second support plate 20, the housing 1
0 is provided with a second pipe portion 10a on the outer surface thereof.
A communication hole 20a communicating the pump chamber P2 and a communication hole 20b communicating the second pump chamber P2 and the crank chamber 11 are formed.

The communication hole 20a is connected to the second suction check valve 2
The second pump chamber P2 is opened and closed when the pressure in the second pump chamber P2 becomes lower than the pressure in the second pipe portion 10a (during a suction step described later). On the other hand, the communication hole 20b is opened and closed by the second discharge check valve 28, and is opened when the pressure in the second pump chamber P2 becomes higher than the pressure in the crank chamber 11 (during a discharge step described later).

In the crank chamber 11, between the first rod plate 15a and the first support plate 19 and between the second rod plate 16a and the second support plate 20, the pistons 13 and 14 are connected to the crankshaft. A first spring 30 and a second
A spring 31 is inserted and arranged on each of the rods 15,16. The springs 30 and 31 allow the first rod plate 15a and the second rod plate 16a to always contact the bearing 42.

The housing 10, pistons 13, 1
4, rods 15, 16 and rod plates 15a, 16
a, end plates 17 and 18, support plates 19 and 2,
The cover 0, the cover 21, and the valve plate 26 are made of heat-resistant polybutylene terephthalate (PBT).

The first pipe portion 21a and the second pipe portion 10a are connected to a pressure chamber in a vacuum booster of a vehicle braking device (not shown).

Next, the operation of the pump having the above configuration will be described with reference to FIGS.

When the pressure of the pressure chamber in the vacuum booster becomes negative pressure (negative pressure close to the atmospheric pressure side) or atmospheric pressure lower than the set negative pressure, the pump is energized and the motor 50 starts operating. . When the motor 50 is energized, the crankshaft 40 rotates. 2 and FIG. 4 indicates the locus of the center point of the eccentric shaft 41.

First, while the crankshaft 40 rotates 90 degrees from the position shown in FIGS. 1 and 2 to the position shown in FIGS. 3 and 4, both pistons 13 and 14 are pushed by the eccentric shaft 41 and the bearing 42. Both move from bottom dead center to top dead center. Here, the first pump chamber P1 is arranged on the side opposite to the rotation center a with respect to the first piston 13, and the second pump chamber P2 is arranged on the rotation center a side with respect to the second piston 14. Therefore, when the pistons 13 and 14 move from the bottom dead center to the top dead center as described above, a discharge step is performed in the first pump chamber P1, and the second pump chamber P
At 2, an inhalation step is performed.

The discharge step in the first pump chamber P1 and the suction step in the second pump chamber P2 will now be described in detail.
When the piston 13 moves from the bottom dead center to the top dead center (discharge stroke), the volume of the first pump chamber P1 is reduced, the pressure of the first pump chamber P1 is increased, and the first pump chamber P1 is moved.
When the pressure becomes higher than the pressure in the crank chamber 11, the first discharge check valve 25 opens. Then, the air in the first pump chamber P1 flows through the communication hole 26 of the first valve plate 26.
a through the communication hole 13a of the first piston 13 into the crank chamber 11.

On the other hand, when the second piston 14 moves from the bottom dead center toward the top dead center (suction stroke), the volume of the second pump chamber P2 increases and the pressure of the second pump chamber P2 decreases. Then, when the pressure in the second pump chamber P2 becomes lower than the pressure in the communication hole 20a of the second support plate 20, the second suction check valve 29 opens. Then, the air in the pressure chamber of the vacuum booster passes through the second pipe section 10a and the communication hole 20a of the second support plate 20 to the second pump chamber P2.
Inhaled.

Next, while the crankshaft 40 rotates 90 degrees from the position shown in FIGS. 3 and 4 to the position shown in FIGS.
Both are moved from top dead center to bottom dead center by being urged to 1. During this movement, a suction step is performed in the first pump chamber P1, and a discharge step is performed in the second pump chamber P2.
That is, the phases of the suction process and the discharge process by the reciprocating motion of the first piston 13 are opposite to the phases of the suction process and the discharging process by the reciprocating motion of the second piston 14.

Here, the suction step in the first pump chamber P1 and the discharge step in the second pump chamber P2 will be described in detail.
When the piston 13 moves from the top dead center to the bottom dead center (suction stroke), the volume of the first pump chamber P1 increases, the pressure of the first pump chamber P1 decreases, and the first pump chamber P1 When the pressure of the first space 22 becomes lower than the pressure of the first space 22, the first
The suction check valve 27 opens. Then, the air in the pressure chamber of the vacuum booster is supplied to the first pipe portion 21a and the first space 2.
2, and is sucked into the first pump chamber P1 through the communication hole 17a of the first end plate 17.

On the other hand, when the second piston 14 moves from the top dead center to the bottom dead center (discharge stroke), the volume of the second pump chamber P2 is reduced and the pressure of the second pump chamber P2 rises. Then, when the pressure in the second pump chamber P2 becomes higher than the pressure in the crank chamber 11, the second discharge check valve 28 opens. Then, the air in the second pump chamber P2 is discharged to the crank chamber 11 through the communication hole 20b of the second support plate 20.

With the above operation, when the pressure in the pressure chamber of the vacuum booster becomes a negative pressure larger than the set negative pressure (negative pressure close to the vacuum side), the power supply to the motor 50 is stopped and the pump is stopped.

The spring constant K1 of the first spring 30
Is set so as to exert a force required to move the first piston 13 from the top dead center to the bottom dead center. The spring constant K2 of the second spring 31 It is set to exert the necessary force to move to the bottom dead center. Here, when the first piston 13 moves from the top dead center to the bottom dead center, a suction process is performed,
When the second piston 14 moves from the top dead center to the bottom dead center, a discharging process is performed. Since the force required to move the first piston 13 in the suction step is greater than the force required to move the second piston 14 in the discharge step, the spring constant K1 of the first spring 30 is:
The second spring 31 is set to be larger than the spring constant K2.

In this embodiment, both pistons 13, 14
Are arranged symmetrically with respect to the rotation center a of the crankshaft 40 and the rotation shaft 52 (that is, at equal intervals in the rotation direction b of the crankshaft 40 and the rotation shaft 52), and the pistons 13 and 14 are rotated. Since the pistons 13 and 14 are reciprocated symmetrically about the center a, the two pistons 13 and 14 move in the opposite directions symmetrically with respect to the axis of the crankshaft 40 and the rotating shaft 52, and the inertial force of the two pistons 13 and 14 is canceled. . Therefore, it is possible to reduce the vibration of the pump due to the inertial force of the pistons 13 and 14.

Further, since the phases of the suction step and the discharge step of the first piston 13 are made opposite to the phases of the suction step and the discharge step of the second piston 14, the first piston 13 is in the suction step when the first piston 13 is in the suction step. Since the two pistons 14 are in the discharge step, the discharge amount of the pumps in the discharge step can be reduced by half compared to a pump in which the discharge steps of both pistons 13 and 14 are performed at the same time, and noise due to discharge can be reduced.

In the pump in which the two pistons 13 and 14 are simultaneously discharged, air is intermittently discharged. In contrast, the pump of the present embodiment discharges air continuously. Pulsation can be reduced, and noise due to discharge can be reduced. The air discharged into the crank chamber 11 during the discharge stroke of the pistons 13 and 14 is discharged into the atmosphere from the drain pipe 51 through the inside of the motor 50.
Then, the volume of a portion into which the air enters when the discharged air flows into the motor 50 from the crank chamber 11 becomes large, and the throttling function works when the air is discharged, so that the sound can be reduced.
Further, the inside of the motor 50 can be cooled by the discharged air.

(Other Embodiments) In the above embodiment, two eccentric shafts 41 are provided on the crankshaft 40.
Alternatively, a cam may be provided.

In the above embodiment, an example in which two pistons are provided has been described. However, the present invention is applicable to a pump having a plurality of pistons (two or more). In this case, for example, in a pump having a plurality of pistons, the crankshaft 40
In addition, a plurality of pistons are arranged at regular intervals in the rotation direction b of the rotating shaft 52 (for example, 120 ° intervals in the case of three pieces), and at equal intervals (for example, 120 ° intervals in the case of three pieces). ) And the same number of eccentric shafts as the number of pistons are arranged at the same distance from the rotation center a. Then, the phases of the suction step and the discharge step due to the reciprocation of at least one piston are made opposite to the phases of the suction step and the discharge step due to the reciprocation of the other pistons.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pump according to an embodiment of the present invention at a piston bottom dead center position.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view of the pump of FIG. 1 at a piston top dead center position.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

[Description of Signs] 10 ... housing, 13 ... first piston, 14 ... second piston, 40 ... crankshaft, 50 ... electric motor, 52 ...
Rotation axis, a: rotation center, P1: first pump chamber, P2: second pump chamber.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Moruji Sakai 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Co., Ltd. 3H076 AA03 AA21 BB01 BB02 CC07 CC24 CC28 CC31

Claims (2)

[Claims] A driving means (5) having a rotating shaft (52).
0), a drive shaft (40) coaxially coupled to the rotation shaft (52) and rotating, and the drive shaft (4) with the rotation of the drive shaft (40).
0) a piston (13, 14) reciprocated in a direction perpendicular to a rotation center (a) of the drive shaft (40), wherein the piston (13, 14) rotates in a rotational direction of the drive shaft (40). A plurality of pistons (13, 14) are reciprocated symmetrically about the rotation center (a), and the plurality of pistons (13, 14) are arranged at equal intervals. 13 and 14), the phases of the suction step and the discharge step due to the reciprocation of at least one piston (13) are opposite to the phases of the suction step and the discharge step due to the reciprocation of the other piston (14). A pump characterized in that: 2. A driving means (5) having a rotating shaft (52).
0), a drive shaft (40) coaxially coupled to the rotation shaft (52) and rotating, and the drive shaft (4) with the rotation of the drive shaft (40).
0) a first piston (13) and a second piston (14) reciprocated in the vertical direction with respect to the rotation center (a); and the first and second pistons (13, 14). A first pump chamber (P1) in which fluid is sucked and discharged by the first piston (13) and the second piston (1);
The second pump chamber (P2) where the fluid is sucked and discharged by 4)
And a housing (10) forming the first piston (1).
3) is disposed on the opposite side to the rotation center (a), and the second pump chamber (P2) is provided with the second piston (1).
4) is disposed on the rotation center (a) side, and the first and second pistons (13, 14) are disposed symmetrically about the rotation center (a) and reciprocate symmetrically. A pump characterized by being operated.