CN111852873A

CN111852873A - Mechanical vacuum pump

Info

Publication number: CN111852873A
Application number: CN202010731111.5A
Authority: CN
Inventors: 辜庆伟; 杨金才; 张尧; 李祥; 彭海; 胡刚; 傅云峰; 焦璐
Original assignee: Chongqing Changan Automobile Co Ltd
Current assignee: Chongqing Changan Automobile Co Ltd
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2020-10-30
Anticipated expiration: 2040-07-27
Also published as: CN111852873B

Abstract

The invention discloses a mechanical vacuum pump, which comprises a pump body, an exhaust valve plate and a baffle plate, wherein the pump body is provided with an exhaust cavity, an exhaust valve seat is arranged in the exhaust cavity, the exhaust valve plate and the baffle plate are arranged on the exhaust valve seat through fixing screws, the mechanical vacuum pump also comprises a pressure maintaining cavity arranged at the back of the exhaust valve plate, and an exhaust hole is formed in the pressure maintaining cavity; when the vacuum pump exhausts, gas firstly enters the pressure maintaining cavity and then enters the cylinder cover through the exhaust hole on the pressure maintaining cavity. The invention reduces the force of the exhaust valve plate knocking the baffle and the pump body, thereby reducing knocking noise.

Description

Mechanical vacuum pump

Technical Field

The invention belongs to the technical field of vacuum pumps, and particularly relates to a mechanical vacuum pump.

Background

Mechanical vacuum pumps are widely used in automotive engines to provide vacuum for brake systems, and often generate a rattling sound when an exhaust valve plate is opened/closed under the condition of meeting performance requirements, thereby affecting the sound quality of the engine.

Currently, when many engines are idling, high-pressure fuel systems, mechanical vacuum pumps and valves are seated, and the engine sound is relatively noisy and poor in sound quality due to difference of sound frequencies, so that the problem of knocking sound of the mechanical vacuum pumps is inevitable. However, the mechanical vacuum pump has the characteristics of performance requirements, internal rotation, small structure and the like, the conventional method for solving the problem of noise of the mechanical vacuum pump starts from the molded line, but the performance of the vacuum pump is influenced by optimizing the molded line, redesign and matching are needed, the required time period is long, the development progress of an engine is influenced, the situation is not allowed, a plurality of mechanical vacuum pumps bring the problem to the market, and the noise quality of the engine is poor. As shown in fig. 1 and 2, when the vacuum pump is operated, the eccentric rotor 5 with the slide block 4 rotates counterclockwise, the slide block 4 slides against the inner wall of the pump body 1 under the action of self centrifugal force, the air suction working chamber is continuously enlarged, the sucked body opens the check valve (the check valve is arranged in the pump and plays a pressure maintaining role for the system) through the air suction pipe and enters the air suction working chamber, and when the slide block 4 rotates to a certain position, the air suction is finished. At the moment, the sucked gas is isolated, the eccentric rotor 5 continues to rotate, the isolated gas is gradually compressed, namely the pressure is increased, when the pressure is increased to be larger than the sum of the opening force of the exhaust valve plate and the back pressure of the exhaust valve plate, the exhaust valve plate 2 is opened, the gas is exhausted, and at the moment, the exhaust valve plate 2 knocks the baffle 3 to generate a first knocking sound; when the eccentric rotor 5 continuously rotates, gas in the vacuum pump is reduced, the pressure is reduced, and the sum of the back pressure of the exhaust valve plate 2 and the resilience force of the exhaust valve plate 2 is larger than the pressure in the pump body 1, the exhaust valve plate 2 is seated to knock the pump body 1, and a second sound knocking sound is generated. As shown in fig. 3, the main frequency of the knocking sound spectrum of the mechanical vacuum pump at idle speed is 1650-. As shown in FIG. 4, the average noise level is 15.23dB (A) and the process capability Ppk is-1.33, which are the sound pressure level process capability of the corresponding frequency of the knocking feature and do not meet the requirement.

Therefore, it is necessary to develop a new mechanical vacuum pump.

Disclosure of Invention

The invention aims to provide a mechanical vacuum pump which can reduce the force of an exhaust valve plate knocking a baffle and a pump body so as to reduce knocking noise.

The invention relates to a mechanical vacuum pump, which comprises a pump body, an exhaust valve plate and a baffle plate, wherein the pump body is provided with an exhaust cavity, an exhaust valve seat is arranged in the exhaust cavity, the exhaust valve plate and the baffle plate are installed on the exhaust valve seat through fixing screws, the mechanical vacuum pump also comprises a pressure maintaining cavity arranged at the back of the exhaust valve plate, and an exhaust hole is formed in the pressure maintaining cavity; when the vacuum pump exhausts, gas firstly enters the pressure maintaining cavity and then enters the cylinder cover through the exhaust hole on the pressure maintaining cavity.

Further, a first pressure-holding cavity connecting end face is arranged at the opening of the pressure-holding cavity, and a plurality of first bolt holes are formed in the first pressure-holding cavity connecting end face; the pump body is provided with a second pressure maintaining cavity connecting end surface at the periphery close to the exhaust cavity, and a plurality of second bolt holes are arranged at intervals at the periphery of the second pressure maintaining cavity connecting end surface; the plurality of second bolt holes and the plurality of first bolt holes correspond to each other one by one and are fixedly connected together through bolts.

Further, the exhaust hole is formed in the bottom of the pressure keeping cavity.

The invention has the following advantages: under the condition of meeting the performance and the flow rate, the pressure difference between the front and the back of the exhaust valve plate is reduced, and the force of the exhaust valve plate for knocking the baffle and the pump body is reduced, so that the knocking noise is reduced. The invention successfully controls the knocking sound of the mechanical vacuum pump on the premise of not influencing the structure and the performance of the vacuum pump, and improves the sound quality of the engine.

Drawings

FIG. 1 is a schematic diagram of an external structure of a conventional mechanical vacuum pump;

FIG. 2 is a schematic diagram of an internal structure of a conventional mechanical vacuum pump;

FIG. 3 is a schematic diagram of the knocking sound spectrum of a conventional mechanical vacuum pump;

FIG. 4 is a prior art mechanical vacuum pump rapping frequency sound pressure level process capability;

FIG. 5 is a schematic structural diagram of a mechanical vacuum pump according to the present embodiment;

FIG. 6 is a schematic structural view of the connection end surface of the pressure-maintaining cavity and the first pressure-maintaining cavity in this embodiment;

FIG. 7 is a schematic diagram of the power consumption process capability after adding a voltage holding cavity;

FIG. 8 is a graphical illustration of a statistical plot of the sound pressure level process for the frequency of tapping after increasing the holding pressure chamber;

wherein: the pump comprises a pump body 1, an exhaust valve plate 2, a baffle plate 3, a slide block 4, an eccentric rotor 5, a fixing screw 6, an exhaust cavity 7, an exhaust valve seat 8, a pressure maintaining cavity 9, an exhaust hole 10, a first pressure maintaining cavity connecting end face 11, a first bolt hole 12, a second pressure maintaining cavity connecting end face 13 and a second bolt hole 14.

Detailed Description

The invention will be further explained with reference to the drawings.

As shown in fig. 5 and 6, in this embodiment, a mechanical vacuum pump includes a pump body 1, an exhaust valve plate 2, a baffle plate 3, wherein the pump body 1 has an exhaust cavity 7, an exhaust valve seat 8 is disposed in the exhaust cavity 7, the exhaust valve plate 2 and the baffle plate 3 are mounted on the exhaust valve seat 8 through a fixing screw 6, and the mechanical vacuum pump further includes a pressure maintaining cavity 9 disposed at the back of the exhaust valve plate 2, and an exhaust hole 10 is disposed on the pressure maintaining cavity 9; when the vacuum pump exhausts, gas firstly enters the pressure maintaining cavity 9 and then enters the cylinder head cover through the exhaust hole 10 on the pressure maintaining cavity 9. In the exhaust process, the pressure in the pressure maintaining cavity 9 can be continuously greater than the pressure in the cylinder head cover, so that the back pressure of the exhaust valve plate 2 is not reduced rapidly, the pressure difference between the front surface and the back surface of the exhaust valve plate 2 is smaller than the original state, the resultant force acting on the exhaust valve plate 2 is reduced, and the knocking noise is reduced.

As shown in fig. 5, the discharge valve sheet 2 and the flapper 3 are mounted on the discharge valve seat 8 by fixing bolts 10.

As shown in fig. 5 and 6, in the present embodiment, a first pressure holding cavity connecting end surface 11 is provided at the mouth of the pressure holding cavity 9, and a plurality of first bolt holes 12 are provided on the first pressure holding cavity connecting end surface 11; a second pressure maintaining cavity connecting end surface 13 is arranged on the periphery of the pump body 1 close to the exhaust cavity 7, and a plurality of second bolt holes 14 are arranged on the periphery of the second pressure maintaining cavity connecting end surface 13 of the pump body 1 at intervals; the plurality of second bolt holes 14 and the plurality of first bolt holes 12 correspond one to one and are fixedly connected together by bolts.

As shown in fig. 5 and 6, the pressure-holding cavity 9 covers the back of the air release valve plate 2, and plays a role in blocking the knocking sound while adjusting the pressure, thereby further reducing the knocking sound of the air release valve plate 2.

In the present embodiment, as shown in fig. 5, the exhaust hole 10 is opened on the bottom of the pressure holding chamber 9. The size of the exhaust hole 10 needs to ensure that the performance of the vacuum pump can reach the standard after the pressure maintaining cavity 9 is added, and other problems can not be caused. Fig. 7 shows a power consumption process capability analysis chart after the pressure holding chamber 9 is added. As shown in FIG. 8, after the pressure maintaining cavity 9 is added, the average value of the frequency noise corresponding to knocking of the exhaust valve plate 2 is 8.74dB (A), Ppk is 2.08, and the subjective evaluation is more than 8 minutes, so that the requirement is met. It follows that the present embodiment effectively controls the slapping sound of the mechanical vacuum pump.

Claims

1. The utility model provides a mechanical vacuum pump, includes the pump body (1), exhaust valve block (2) and baffle (3), the pump body (1) has exhaust chamber (7), be equipped with exhaust valve seat (8) in exhaust chamber (7), install on exhaust valve seat (8) through set screw (6) exhaust valve block (2) and baffle (3), its characterized in that: the pressure maintaining device also comprises a pressure maintaining cavity (9) arranged at the back of the exhaust valve plate (2), and an exhaust hole (10) is formed in the pressure maintaining cavity (9); when the vacuum pump exhausts, gas firstly enters the pressure maintaining cavity (9) and then enters the cylinder cover through the exhaust hole (10) on the pressure maintaining cavity (9).

2. A mechanical vacuum pump according to claim 1, wherein: a first pressure-holding cavity connecting end surface (11) is arranged at the opening part of the pressure-holding cavity (9), and a plurality of first bolt holes (12) are formed in the first pressure-holding cavity connecting end surface (11); a second pressure maintaining cavity connecting end surface (13) is arranged on the periphery of the pump body (1) close to the exhaust cavity (7), and a plurality of second bolt holes (14) are arranged on the periphery of the second pressure maintaining cavity connecting end surface (13) of the pump body (1) at intervals; the plurality of second bolt holes (14) and the plurality of first bolt holes (12) correspond to each other one by one and are fixedly connected together by bolts.

3. A mechanical vacuum pump according to claim 1 or 2, wherein: the exhaust hole (10) is formed in the bottom of the pressure keeping cavity (9).