A diaphragm composite sealing device suitable for claw-type dry pumps

Abstract

The present invention relates to the field of claw-type dry pump seals and discloses a diaphragm-type composite seal suitable for claw-type dry pumps. The seal comprises a pump chamber, a transmission case, a front housing, and a rotating shaft. A one-way diaphragm is provided on the inside of the front housing. The rotating shaft passes through the front housing and the one-way diaphragm, with the pump chamber and the transmission case at either end of the rotating shaft. A retainer is provided on the side of the one-way diaphragm near the transmission case. The retainer is sleeved and fixed to the rotating shaft. The side of the one-way diaphragm near the pump chamber, the front housing, and the rotating shaft enclose a pressure chamber. The pressure chamber transmits air pressure within the pump chamber to the one-way diaphragm, forcing the side of the one-way diaphragm into close contact with the retainer, thereby improving the sealing performance of the claw-type dry pump.

Description

Technical Field

[0001] The present invention relates to the field of claw-type dry pump seals, and in particular to a diaphragm-type composite sealing device suitable for claw-type dry pumps. Background Art

[0002] As the power component of the hydrogen circulation system, the claw-type dry pump requires a comprehensive consideration of both pump efficiency and the need for oil-free recycling. Therefore, oil-tight sealing and sealing the gap between the pump casing and the rotor present technical challenges. Furthermore, proper lubrication of the transmission gears and bearings is essential for reliable transmission. Key issues include sealing the lubricating oil and sealing the hydrogen between the pump chamber and the transmission case. Lubricating oil must not enter the pump chamber, and hydrogen in the pump chamber must not leak through the transmission case. The former would contaminate the hydrogen and even damage the fuel cell stack, while the latter would cause hydrogen leakage, raising safety concerns.

[0003] Because claw-type dry pumps operate through the meshing of two claws, both claws are active during operation, requiring a reliable gear transmission system to transmit the power required for their operation. In the transmission system, the driven gear receives power through its meshing relationship with the driving gear. Since the driven gear and the driving gear are in contact with each other, lubrication is essential. Furthermore, the bearings supporting the gears also require lubrication to ensure proper operation. Gears and bearings in transmission systems are typically lubricated using splash lubrication. The transmission case typically contains a sufficient amount of specialized lubricant, typically enough to soak the teeth of the lower gears. Where necessary, a specially designed "splash plate" is incorporated into the structure to ensure adequate lubrication of bearings and gears (in multi-stage transmissions) located high in the case.

[0004] The traditional claw type dry pump sealing device is Figure 1 As shown, the rotating shaft 6 is supported on the bearing 5, the left end of the rotating shaft 6 is in the transmission box 7, and the right end of the rotating shaft 6 is provided with a rotor 2 (claw), which is located in the pump chamber 1. The Y-shaped sealing ring 4 is used between the pump chamber 1 and the transmission box 7 to block the lubricating oil of the transmission box 7 from flowing into the pump chamber 1 to ensure that the hydrogen is not contaminated. However, since the sealing "lip" of the Y-shaped sealing ring 4 is always subject to wear, it will inevitably lead to seal failure after a certain period of use. The lubricating oil will flow along the rotating shaft 6 to the pump chamber 1, thereby causing oil corrosion and pollution to the hydrogen. The above situation will cause the performance of the battery stack to decline, and in severe cases, it will cause the battery stack to fail or be directly scrapped. Therefore, as a hydrogen circulation pump, it must be ensured that under no circumstances can the lubricating oil of the transmission box 7 be allowed to escape into the pump chamber 1. The lubricating oil sealing problem here has become one of the technical difficulties of this dry pump. Summary of the Invention

[0005] The present invention aims to provide a diaphragm type composite sealing device suitable for a claw type dry pump, so as to improve the sealing performance of the claw type dry pump.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a diaphragm-type composite sealing device suitable for a claw-type dry pump, comprising a pump chamber, a transmission box, a front housing and a rotating shaft, a one-way membrane is provided on the inner side of the front housing, the rotating shaft passes through the front housing and the one-way membrane, the two ends of the rotating shaft are respectively at the pump chamber and the transmission box, a retaining frame is provided on the side of the one-way membrane close to the transmission box, the retaining frame is sleeved and fixed on the rotating shaft, the one-way membrane close to the pump chamber side and the front housing and the rotating shaft enclose a pressure chamber, the pressure chamber transmits the air pressure in the pump chamber to the one-way membrane, so that the side of the one-way membrane is close to the retaining frame.

[0007] The beneficial effects of this program are:

[0008] 1. During the operation of a dry pump, the rotating shaft drives the retaining frame to rotate together, thereby transferring kinetic energy to the pump chamber. To prevent lubricating oil from entering the pump chamber through the gap between the retaining frame and the front housing, this solution provides a one-way diaphragm with a one-way valve function. Specifically, since the hydrogen pressure in the pump chamber is usually about 40kPa, the pressure in the pressure chamber can also reach the same value, thereby generating a thrust in the length direction of the rotating shaft on the one-way diaphragm, so that the side of the one-way diaphragm is pressed against the retaining frame, closing the gap between the one-way diaphragm and the retaining frame, thereby preventing lubricating oil from entering the pump chamber.

[0009] 2. Compared with the existing technology, the sealing effect will fail after the lip position where the Y-shaped sealing ring and the rotating shaft contact is worn to a certain extent; in this solution, the side of the one-way membrane is close to the retaining frame, and the side of the one-way membrane is involved in the wear. After the one-way membrane is worn, under the action of air pressure, the one-way membrane will still be close to the retaining frame. Its wear resistance is related to the thickness of the one-way membrane. Therefore, this solution has better wear resistance. After long-term use, the sealing effect is better than the existing technology.

[0010] 3. The faster the pump runs, the faster the shaft rotates, and the easier it is for lubricant to enter the pump chamber. However, at the same time, the greater the pressure in the pump chamber, the tighter the one-way diaphragm and retainer become, the better the sealing effect, and the greater the wear of the one-way diaphragm. Therefore, the sealing effect of the one-way diaphragm can vary according to the shaft speed, thereby improving the sealing when lubricant can easily enter the pump chamber and reducing wear when lubricant is difficult to enter the pump chamber.

[0011] 4. To achieve the above effect, it is necessary to increase the contact surface between the one-way membrane and the gas to ensure that the gas generates sufficient pressure on the one-way membrane. Therefore, this solution sets a pressure chamber on the side of the one-way membrane close to the pump chamber instead of setting other solids to press against the one-way membrane.

[0012] Preferably, as an improvement, the device further includes a diaphragm seat and a countersunk bolt, which passes through the diaphragm seat, the one-way diaphragm, and the front housing, and is then threadedly connected. With this arrangement, the countersunk bolt secures the one-way diaphragm to the front housing, and the diaphragm seat and the chimera clamp the one-way diaphragm, preventing the one-way diaphragm from shaking, thereby preventing the one-way diaphragm from wrinkling and losing contact with the retaining frame, thereby ensuring the sealing effect of the one-way diaphragm. This also facilitates assembly and disassembly, increasing the maintainability of the device.

[0013] Preferably, as an improvement, the diaphragm seat is located between the one-way diaphragm and the retainer. The space between the diaphragm seat and the retainer sequentially forms a number of lubrication cavities, which are connected by fine slits and decrease in volume from the outside to the inside. With this arrangement, the side closest to the rotating shaft is the inner side. By arranging the diaphragm seat and the retainer, the gap between them is controlled. The larger the lubrication cavity, the more liquid there is, the greater the hydraulic pressure, and the easier it is for liquid to enter the pump chamber through the gap. Therefore, the closer to the rotating shaft, the smaller the lubrication cavity; the farther away from the rotating shaft, the greater the linear velocity of the retainer, and thus the larger the lubrication cavity, providing sufficient lubrication for the friction of the retainer.

[0014] Preferably, as an improvement, a front felt ring is provided in the outermost lubrication cavity, and grease is provided in the remaining lubrication cavities. This arrangement prevents impurities and lubricating oil from entering between the retainer and the fixed seat through the front felt ring, thereby improving the sealing effect. Compared with lubricating oil, grease has lower fluidity and is less likely to flow into the pump cavity.

[0015] Preferably, as an improvement, the portion of the retainer closest to the shaft protrudes near the pump chamber to form a pressing portion, which is in close contact with the one-way membrane. In this way, the closer to the shaft, the slower the linear speed, and the less wear there is on the pressing portion and the one-way membrane.

[0016] Preferably, as an improvement, a small felt ring is provided in the adjustment cavity formed by the pressing part, the rotating shaft and the one-way membrane. Such an arrangement has the following effects:

[0017] 1. A small felt ring is set to form a multi-layer seal to further prevent liquid from entering the pump cavity;

[0018] 2. After long-term wear, the contact area between the one-way membrane and the pressing part becomes thinner due to wear. The farther the position is from the rotating shaft, the greater the linear speed and the faster the wear rate of the one-way membrane. After the position farthest from the rotating shaft is damaged, the one-way membrane will fail. In this solution, the position where the one-way membrane is pressed against the pressing part is the first fitting part, the side wall of the adjustment cavity is formed below the first fitting part, and the step below the adjustment part is pressed against the second fitting part. After the thickness of the first fitting part begins to decrease, it is easier to deform. Under the action of air pressure, the adjustment part squeezes the small felt circle and arches toward the inside of the adjustment cavity, thereby pushing the first fitting part out in the opposite direction away from the pressing part, thereby reducing the wear of the first fitting part. At this time, due to the arching of the adjustment part, the upper end of the adjustment part contacts the inner side of the pressing part, thereby moving the wear position, making the wear more uniform, and extending the service life of the one-way membrane.

[0019] 3. After the one-way film is pressed against the step and the pressing part at the same time, most of the air pressure acts on the adjusting part, causing the adjusting part to arch more, thereby making the wear more uniform; and the arching of the adjusting part causes the lower end of the second fitting part to move upward, but due to the setting of the step, the lower end of the second fitting part is always in contact with the rotating shaft.

[0020] Preferably, as an improvement, an annular step is provided on the rotating shaft, the step and the abutment being aligned on the side closest to the pump chamber, with the one-way membrane simultaneously abutting the step and the abutment. With this arrangement, for ease of installation, the retainer is typically fitted with an interference fit on the rotating shaft. To further enhance sealing, the one-way membrane is abutted against both the step and the abutment, thereby preventing lubricant from leaking from the contact area between the rotating shaft and the retainer.

[0021] Preferably, as an improvement, a rear felt ring is provided on the side of the pressure chamber near the pump chamber, and is disposed between the front housing and the rotating shaft. This arrangement forms a multi-layer seal, further preventing liquid from entering the pump chamber. Furthermore, the rear felt ring does not block the passage of gas, nor does it affect the connection between the pump chamber and the pressure chamber, thereby preventing the one-way membrane from adhering tightly to the abutment portion under the action of gas pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a cross-sectional view of the prior art;

[0023] Figure 2 is a cross-sectional view of an embodiment;

[0024] Figure 3 for Figure 2 A magnified view of point A;

[0025] Figure 4 for Figure 3 Enlarged view of point B. DETAILED DESCRIPTION

[0026] The following is further described in detail through specific implementation methods:

[0027] The figure marks in the drawings of the specification include: pump chamber 1, rotor 2, front housing 3, Y-type sealing ring 4, retaining frame 410, protrusion 411, tightening portion 412, one-way membrane 421, diaphragm seat 422, countersunk bolt 423, front felt ring 431, grease 432, small felt ring 433, pressure chamber 434, rear felt ring 435, bearing 5, rotating shaft 6, step 610, transmission box 7.

[0028] Example

[0029] The embodiment is basically as follows Figure 2-Figure 4 Shown: A diaphragm composite sealing device suitable for claw-type dry pumps, and Figure 1 The difference between the prior art and the prior art is that the Y-shaped sealing ring 4 is eliminated, and the similarities are that both include a pump chamber 1, a transmission box 7 and a rotating shaft 6, such as Figure 2 As shown, the part between the pump chamber 1 on the right and the transmission box 7 on the left is the front housing 3, the rotating shaft 6 passes through the front housing 3 and is rotatably connected to the front housing 3, and a rotor 2 is provided at the right end of the rotating shaft 6. The rotor 2 is located in the pump chamber 1. In this embodiment, the side close to the rotating shaft 6 is the inner side.

[0030] like Figure 3 As shown, a sealing system is provided between the front housing 3 and the rotating shaft 6. The sealing system includes, from left to right, a bearing 5, a retaining frame 410, a one-way membrane 421 and a rear felt ring 435. The bearing 5 and the front housing 3 are bolted together. The one-way membrane 421 is made of polyimide material. An annular step 610 is provided on the rotating shaft 6.

[0031] like Figure 4 As shown, the retaining frame 410 is fitted over the rotating shaft 6, and three rightward protrusions 411 are provided on the right side of the retaining frame 410, among which the protrusion 411 closest to the rotating shaft 6 is the tightening portion 412, and the step 610 is aligned with the right side of the tightening portion 412, on the inner side of the one-way membrane 421; the sealing system also includes a diaphragm seat 422 and a countersunk bolt 423, the countersunk bolt 423 passes horizontally through the diaphragm seat 422, the outer side of the one-way membrane 421 and the front shell 3 and is threadedly connected, and a sealant is used to seal between the bolt and the diaphragm seat 422, and the diaphragm seat 422 and the front shell 3 cooperate to clamp the one-way membrane 421. The diaphragm seat 422 is located between the one-way diaphragm 421 and the retaining frame 410. The space enclosed by the adjacent protrusions 411 of the retaining frame 410 and the diaphragm seat 422 forms three lubrication chambers in sequence. The lubrication chambers are connected by fine gaps. The volume of the lubrication chamber decreases from the outside to the inside. A front felt ring 431 is provided in the outermost lubrication chamber for interference fit, and grease 432 is provided in the remaining lubrication chambers for interference fit; a small felt ring 433 is provided in the adjustment chamber for interference fit, formed by the tightening portion 412, the rotating shaft 6 and the one-way diaphragm 421.

[0032] The right side of the one-way membrane 421 and the front shell 3 and the rotating shaft 6 form a pressure chamber 434, which transmits the air pressure in the pump chamber 1 to the one-way membrane 421, so that the inner left side of the one-way membrane 421 is in contact with the step 610 and the pressing part 412 at the same time.

[0033] The specific implementation steps are as follows:

[0034] During the operation of the dry pump, the rotating shaft 6 drives the retaining frame 410 to rotate together, thereby transmitting kinetic energy to the pump chamber 1; since the hydrogen pressure in the pump chamber 1 is usually about 40kPa, the pressure in the pressure chamber 434 can also reach the same value, thereby generating a thrust in the length direction of the rotating shaft 6 on the one-way membrane 421, so that the side of the one-way membrane 421 is close to the step 610 and the pressing part 412, forming a one-way valve structure, and using the air pressure during the operation of the device to close the gap, thereby effectively sealing the hydrogen, thereby preventing the lubricating oil in the transmission box 7 from entering the pump chamber 1.

[0035] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A diaphragm composite sealing device suitable for a claw-type dry pump, characterized by: It includes a pump chamber, a transmission box, a front shell and a rotating shaft. A one-way membrane is provided on the inner side of the front shell. The rotating shaft passes through the front shell and the one-way membrane. The two ends of the rotating shaft are respectively the pump chamber and the transmission box. A retaining frame is provided on the side of the one-way membrane close to the transmission box. The retaining frame is sleeved and fixed on the rotating shaft. The one-way membrane close to the pump chamber side and the front shell and the rotating shaft form a pressure chamber. The pressure chamber transmits the air pressure in the pump chamber to the one-way membrane, so that the side of the one-way membrane is close to the retaining frame.

2. A diaphragm composite sealing device suitable for a claw-type dry pump according to claim 1, characterized in that: It also includes a diaphragm seat and a countersunk bolt, which passes through the diaphragm seat, the rear of the one-way diaphragm and the front shell for threaded connection.

3. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 2, characterized in that: The diaphragm seat is located between the one-way diaphragm and the retainer. The space between the diaphragm seat and the retainer forms a plurality of lubrication chambers in sequence. The lubrication chambers are connected by fine gaps, and the volume of the lubrication chambers decreases from the outside to the inside.

4. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 3, characterized in that: A front felt ring is arranged in the outermost lubrication cavity, and lubricating grease is arranged in the remaining lubrication cavities.

5. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 1, characterized in that: The part of the retainer closest to the rotating shaft is protruded close to one side of the pump chamber to form a pressing portion, and the pressing portion is in close contact with the one-way membrane.

6. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 5, characterized in that: The adjusting cavity is formed by the pressing part, the rotating shaft and the one-way membrane, and a small felt ring is arranged in the adjusting cavity.

7. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 6, characterized in that: An annular step is provided on the rotating shaft, the step and the abutting portion are aligned with one side close to the pump chamber, and the one-way membrane is pressed against the step and the abutting portion at the same time.

8. The diaphragm composite sealing device suitable for a claw-type dry pump according to claim 7, characterized in that: A rear felt ring is provided on one side of the pressure chamber close to the pump chamber, and the rear felt ring is arranged between the front shell body and the rotating shaft.

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