Patent Description:
A manual gas pump and an electric gas pump are two forms of pumps for providing a high-pressure gas source. During use of the manual gas pump, an operator needs to continuously operate the manual gas pump. In order to provide a sufficiently powerful gas pressure source, the operator needs to contribute heavy labor, and this greatly affects operation efficiency. Compared with the manual gas pump, the electric gas pump does not require heavy labor from the operator. However, a conventional electric gas pump is generally large in size and heavy, and the conventional electric gas pump is generally difficult to transport to an operation site. In addition, in a field that generally desires small and medium gas flows and high pressure, the conventional electric gas pump consumes a relatively large amount of energy, and has poor start-up performance. <CIT> discloses a piston compressor having a dynamic mass compensation in the region of the crank mechanism. <CIT> discloses a piston vacuum pump having pistons mounted on, and coupled to, a crankshaft so that approximately complete balancing of oscillating inertial forces is achieved. <CIT> discloses a multi-stage reciprocating compressor whose power is distributed on both sides of a crankshaft.

Therefore, it is desired to provide an automated, small-sized, and highly integrated electric gas pump so as to satisfy preferences of a specific field.

In various aspects, the present disclosure provides a multi-stage electric gas pump that is generally small in size, high in integration degree, fast in startup, and low in energy consumption relative to conventional electrical gas pumps as discussed above. Such a multi-stage electric gas pump may be integrated in, for example, a portable high pressure calibration device so as to provide a designated high-pressure gas source.

In at least one aspect, the present disclosure provides a multi-stage electric gas pump, comprising an eccentric shaft comprising a main body having a longitudinal axis, a first eccentric portion, and a
second eccentric portion. The first eccentric portion and the second eccentric portion are fixed on the main body. The eccentric shaft is driven by the driving mechanism to produce a first circular movement of the first eccentric portion performed around the longitudinal axis and a second circular movement of the second eccentric portion performed around the longitudinal axis,
wherein the second circular movement is synchronized with the first circular movement. A first cylinder is comprised of a first chamber and a first piston rod. The first piston rod is connected to the first eccentric portion and is configured to reciprocate in response to the first circular movement of the first eccentric portion of the eccentric shaft so as to periodically pressurize gas drawn into the first chamber from an external environment of the multi-stage electric gas pump and then discharge first pressurized gas out of the first chamber. A second cylinder is in fluid communication with the first cylinder. The second cylinder is comprised of a second chamber and a second piston rod. The second piston rod is connected to the first eccentric portion of the eccentric shaft and is configured to reciprocate in response to the first circular movement of the first eccentric portion so as to periodically pressurize the first pressurized gas drawn into the second chamber from the first chamber of the first cylinder and then discharge second pressurized gas out of the second chamber. A third cylinder is in fluid communication with the second cylinder. The third cylinder is comprised of a third chamber and a third piston rod. The third piston rod is connected to the second eccentric portion of the eccentric shaft and is configured to reciprocate in response to the second circular movement of the second eccentric portion so as to periodically pressurize the second pressurized gas drawn into the third chamber from the second chamber of the second cylinder and then discharge third pressurized gas out of the third chamber.

In another aspect, the present disclosure provides a multi-stage electric gas pump, comprising an eccentric shaft comprising a main body having a longitudinal axis and at least one eccentric portion connected to the main body. The eccentric shaft is driven by the driving mechanism so that the at least one eccentric portion performs circular movement around the longitudinal axis; a first cylinder comprising a first chamber and a first piston rod, and the first piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize gas drawn into the first chamber from an external environment of the multi-stage electric gas pump and then discharge first pressurized gas out of the first chamber; a second cylinder being in fluid communication with the first cylinder, the second cylinder comprising a second chamber and a second piston rod, and the second piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize the first pressurized gas drawn into the second chamber from the first chamber of the first cylinder and then discharge second pressurized gas out of the second chamber; and a third cylinder being in fluid communication with the second cylinder, the third cylinder comprising a third chamber and a third piston rod, and the third piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize the second pressurized gas drawn into the third chamber from the second chamber of the second cylinder and then discharge third pressurized gas out of the third chamber, wherein the connections between the first piston rod, the second piston rod, the third piston rod and the eccentric portion are configured so that the second cylinder discharges gas while the first cylinder and the third cylinder draw in gas and that the second cylinder draws in gas while the first cylinder and the third cylinder discharge gas.

In another aspect, the present disclosure provides a high pressure calibration device comprising an embodiment of the multi-stage electric gas pump described herein so as to provide a high-pressure gas source.

The foregoing is a summary of the present disclosure where simplification, generalization, and omitted details may exist. Therefore, it should be appreciated by those skilled in the art that this summary section is for exemplary illustration only.

The aforementioned features and other features of the present disclosure will be more fully and clearly understood through the specification below and the appended claims with reference to the accompanying drawings. It can be understood that these accompanying drawings illustrate only a few embodiments of the present disclosure. The content of the present disclosure will be described more explicitly and in more detail with the accompanying drawings.

Before any embodiment of the present disclosure is explained in detail, it should be understood that applications of the present disclosure are not limited to the details of construction and the arrangement of components set forth in the following description or shown in the following accompanying drawings. The present disclosure may have other embodiments, and may be practiced or implemented in various ways. In addition, it should be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

The following detailed description is made with reference to the accompanying drawings constituting a part of the description. Unless otherwise specified in the context, similar reference numerals usually represent similar components in the accompanying drawings. Embodiments can be adopted and other modifications can be made. It can be understood that the various aspects of the present disclosure generally described herein and graphically presented in the accompanying drawings may be arranged, replaced, combined, and designed in many different configurations, and these configurations all explicitly constitute a part of the present disclosure.

<FIG> shows a perspective view of a multi-stage electric gas pump <NUM> according to an embodiment of the present disclosure. As shown in <FIG>, the gas pump <NUM> includes a frame <NUM> and a mounting plate <NUM> mounted on the frame <NUM>. A motor <NUM> is mounted on the mounting plate <NUM> to provide a driving force when the motor <NUM> is under operation. When the motor <NUM> is operating, a driving wheel <NUM> (shown in <FIG>) connected to the motor <NUM> drives an endless belt <NUM>, and the endless belt <NUM> drives a driven wheel <NUM> to rotate. The endless belt <NUM> may be referred to as a belt, a motor belt, or the like, that readily drives the driven wheel <NUM>. Other details of the driving mechanism will be described in detail below in conjunction with other accompanying drawings. In an embodiment, the motor <NUM> may be a brushless direct-current motor or another common motor or driving mechanism.

Continuing to refer to <FIG>, the gas pump <NUM> includes a gas inlet <NUM> and a gas outlet <NUM>. When the motor <NUM> is operating, gas in an environment outside the gas pump <NUM> can enter the gas pump <NUM> through the gas inlet <NUM>, be pressurized by the gas pump <NUM>, and then be discharged out of the gas pump <NUM> through the gas outlet <NUM>. More specifically, the gas pump <NUM> includes a first cylinder <NUM>, a second cylinder <NUM>, and a third cylinder <NUM>. The first cylinder <NUM> is operably in communication with the environment through the gas inlet <NUM>, and is in fluid communication with the second cylinder <NUM> located downstream thereof. The second cylinder <NUM> is further in fluid communication with the third cylinder <NUM> located downstream thereof. The third cylinder <NUM> is operably in communication with the environment through the gas outlet <NUM>, which is downstream from the third cylinder <NUM>.

<FIG> shows a cross-sectional view of the multi-stage electric gas pump <NUM> as shown in <FIG>, and further shows an internal structure of the gas pump <NUM>. As shown in <FIG>, the first cylinder <NUM> includes a first piston bush <NUM> defining a first chamber <NUM> and a first cylinder cover <NUM> sealingly connected to the first piston bush <NUM>. The first cylinder cover <NUM> and the first piston bush <NUM> may at least partially delimit the first chamber <NUM>. The first cylinder cover <NUM> includes a first inlet <NUM> and a first outlet <NUM>. The first inlet <NUM> is in fluid communication with the gas inlet <NUM>, and the first outlet <NUM> is in fluid communication with the second cylinder <NUM>. In an embodiment, the first inlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows gas to enter the first chamber <NUM> only from the environment outside the gas pump <NUM>. In addition, the first outlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows gas to be discharged downstream only from the first chamber <NUM>. In an embodiment, the first cylinder <NUM> further includes a first piston rod <NUM>. The first piston rod <NUM> includes a first piston cup <NUM> matching the first piston bush <NUM>. The first piston cup <NUM> may be made of a rubber material, and, therefore, may be referred to herein as a first piston rubber cup. The first piston rubber cup <NUM> is configured to seal the first piston bush <NUM> together with the first cylinder cover <NUM>. The first piston rod <NUM> can drive the first piston rubber cup <NUM> to reciprocate in the first chamber <NUM> to periodically change the volume of the first chamber <NUM> so as to continuously draw in gas from the environment through the first inlet <NUM> (during at least part of a time period when the first piston rod <NUM> moves in a left direction as shown in <FIG>, the check valve <NUM> at the first inlet <NUM> is opened, and the check valve <NUM> at the first outlet <NUM> is closed) and discharge the pressurized gas through the first outlet <NUM> (during at least part of a time period when the first piston rod <NUM> moves in a right direction as shown in <FIG>, the check valve <NUM> at the first inlet <NUM> is closed, and the check valve <NUM> at the first outlet <NUM> is opened). In other words, the first piston rod <NUM> may move in a leftward direction and a rightward direction, respectively, based on the orientation shown in <FIG>, resulting in the first piston rubber cup <NUM> moving toward and away from the first cylinder cover <NUM>, respectively.

Continuing to refer to <FIG>, similar to the first cylinder <NUM>, the second cylinder <NUM> includes a second piston bush <NUM> defining a second chamber <NUM> (shown in <FIG>) and a second cylinder cover <NUM> sealingly connected to the second piston bush <NUM>. The second cylinder cover <NUM> includes a second inlet <NUM> and a second outlet <NUM>. The second piston bush <NUM> and the second cylinder cover <NUM> at least partially delimit the second chamber <NUM>. The second inlet <NUM> is in fluid communication with the first outlet <NUM>, and the second outlet <NUM> is in fluid communication with the third cylinder <NUM>. For example, a fluid pipeline may be provided between the second inlet <NUM> and the first outlet <NUM>, and/or a fluid pipeline may be provided between the second outlet <NUM> and the third cylinder <NUM>. In an embodiment, the second inlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows pressurized gas provided through the second inlet <NUM> to move upstream to enter the second chamber <NUM> only. In addition, the second outlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows gas to be discharged only through the second outlet <NUM> downstream from the second chamber <NUM>. In an embodiment, the second cylinder <NUM> further includes a second piston rod <NUM>. The second piston rod <NUM> includes a second piston cup <NUM> matching the second piston bush <NUM>. The second piston cup <NUM> may be made of a rubber material, and therefore, may be referred to herein to as a second piston rubber cup. The second piston rubber cup <NUM> is configured to seal the second piston bush <NUM> together with the second cylinder cover <NUM>. The second piston rod <NUM> can drive the second piston rubber cup <NUM> to reciprocate in the second chamber <NUM> so as to continuously draw the pressurized gas from the first chamber <NUM> through the second inlet <NUM> and discharge the pressurized gas through the second outlet <NUM>. In an embodiment, the second piston rod <NUM> and the first piston rod <NUM> are fixedly connected to each other, and the orientations of the second piston rod <NUM> and the first piston rod <NUM> (in <FIG>, the first piston rod <NUM> is directed towards the right, and the second piston rod <NUM> is directed towards the left) are opposite, so that when the first piston rod <NUM> draws gas into the first chamber <NUM> through the first inlet <NUM>, the second piston rod <NUM> discharges gas out of the second chamber <NUM> through the second outlet <NUM> (in a state as shown in <FIG>). When the first piston rod <NUM> discharges pressurized gas out of the first chamber <NUM> through the first outlet <NUM>, the second piston rod <NUM> draws, through the second inlet <NUM>, the pressurized gas discharged out of the first chamber <NUM> into the second chamber <NUM>. In this manner, the gas can be pressurized stage by stage by means of the first cylinder <NUM> and the second cylinder <NUM>. In other words, the second piston rod <NUM> may move in a leftward direction and a rightward direction, respectively, based on the orientation shown in <FIG>, resulting in the second piston rubber cup <NUM> moving toward and away from the second cylinder cover <NUM>, respectively.

<FIG> shows a cut view of the multi-stage electric gas pump <NUM> rotated by an angle, and shows a fluid passage between the first cylinder <NUM> and the second cylinder <NUM>. As shown in <FIG>, after being discharged out of the first chamber <NUM> through the first outlet <NUM>, the pressurized gas enters, through a passage <NUM> located in the first cylinder cover <NUM>, a passage <NUM> located in the frame <NUM>, and further enters the second chamber <NUM> through a passage <NUM> located in the second cylinder cover <NUM> and the second inlet <NUM>.

As shown in <FIG>, the third cylinder <NUM> includes a third piston bush <NUM> defining a third chamber <NUM> and a third cylinder cover <NUM> sealingly connected to the third piston bush <NUM>. The third cylinder cover <NUM> and the third piston bush <NUM> may at least partially delimit the third chamber <NUM>. The third cylinder cover <NUM> includes a third inlet <NUM> (shown in <FIG>) and a third outlet <NUM>, and the third outlet <NUM> is in fluid communication with the gas outlet <NUM> through a passage <NUM> located in the third cylinder cover <NUM>. In an embodiment, the third outlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows gas to be discharged only from the third chamber <NUM>. In an embodiment, the third cylinder <NUM> further includes a third piston rod <NUM>. The third piston rod <NUM> includes a third piston cup <NUM> matching the third piston bush <NUM>. The third piston cup <NUM> may be made of a rubber material, and therefore, may be referred to herein as a third piston rubber cup. The third piston rubber cup <NUM> is configured to seal the third piston bush <NUM> together with the third cylinder cover <NUM>. The third piston rod <NUM> can drive the third piston rubber cup <NUM> to reciprocate in the third chamber <NUM> so as to continuously draw in gas from the second chamber <NUM> through the third inlet <NUM> and discharge pressurized gas through the third outlet <NUM>. In other words, the third piston rod <NUM> may move in a leftward direction and a rightward direction, respectively, based on the orientation shown in <FIG> resulting in the third piston rubber cup <NUM> moving toward and away from the third cylinder cover <NUM>, respectively.

In some embodiments, the third cylinder <NUM>, the second cylinder <NUM>, and the first cylinder <NUM> are configured to have substantially the same structure, and gradually pressurize inflowing gas in a similar manner until a desired pressure is reached. It can be understood that in some other embodiments, these cylinders may also be configured to have different structures or have different maximum volumes, or cylinders in more stages may be provided for stage-by-stage pressurization. In some embodiments, respective maximum volumes of the first chamber <NUM>, the second chamber <NUM>, and the third chamber <NUM> of the first cylinder <NUM>, the second cylinder <NUM>, and the third cylinder <NUM> respectively, are decreasing, so that after entering the second chamber <NUM>, the gas discharged out of the first chamber <NUM> is further compressed due to a difference between the maximum volumes of the first chamber <NUM> and the second chamber <NUM>, and that after entering the third chamber <NUM>, the gas discharged out of the second chamber <NUM> is further compressed due to a difference between the maximum volumes of the second chamber <NUM> and the third chamber <NUM>. In some embodiments, the maximum volume of the first chamber <NUM> may be approximately four times the maximum volume of the second chamber <NUM>, and the maximum volume of the second chamber <NUM> may be approximately twice the maximum volume of the third chamber <NUM>. Those skilled in the art can configure other maximum volume ratios, and this is not limited in the present disclosure.

In an embodiment, the third piston rod <NUM> is parallel to the first piston rod <NUM> and the second piston rod <NUM>, and an orientation of the third piston rod <NUM> is the same as the orientation of the second piston rod <NUM>. However, the directions of driving forces received by the second piston rod <NUM> and the third piston rod <NUM> may be opposite, so that opening and closing timings of the second cylinder <NUM> and the third cylinder <NUM> match each other. Therefore, the second cylinder <NUM> may discharge gas while the third cylinder <NUM> draws in gas so as to cause the pressurized gas to flow unidirectionally between the two respective cylinders. It can be understood that in some other embodiments, respective positions of these cylinders and orientations of the piston rods may be adjusted according to preferences as long as stage-by-stage flowing of the gas in these cylinders is not affected.

In an embodiment, when the third piston rod <NUM> draws gas into the third chamber <NUM> through the third inlet <NUM>, the second piston rod <NUM> discharges gas out of the second chamber <NUM> through the second outlet <NUM> (in a state as shown in <FIG>), and when the third piston rod <NUM> discharges pressurized gas out of the third chamber <NUM> through the third outlet <NUM>, the second piston rod <NUM> draws, through the second inlet <NUM>, the pressurized gas discharged out of the first chamber <NUM> into the second chamber <NUM>. It can be learned that the first cylinder <NUM>, the second cylinder <NUM>, and the third cylinder <NUM> pressurize the gas from the environment stage by stage by way of cooperation between gas drawing and gas discharging of the first piston rod <NUM>, the second piston rod <NUM>, and the third piston rod <NUM>. Specifically, when the first cylinder <NUM> draws in gas, the second cylinder <NUM> discharges gas, and the third cylinder <NUM> draws in gas, and when the first cylinder <NUM> discharges gas, the second cylinder <NUM> draws in gas, and the third cylinder <NUM> discharges gas.

In the embodiment of <FIG>, the multi-stage electric gas pump <NUM> uses a single eccentric shaft <NUM> to transmit to a plurality of piston rods a driving force provided by the motor. The plurality of piston rods may include the first, second, and third piston rods <NUM>, <NUM>, <NUM>, respectively. The following will further describe the cooperation between gas drawing and gas discharging of the first piston rod <NUM>, the second piston rod <NUM>, and the third piston rod <NUM> in conjunction with features of the multi-stage electric gas pump <NUM> related to the eccentric shaft <NUM>.

<FIG> shows a cut view of the multi-stage electric gas pump <NUM> rotated by another angle, and shows the fluid passage after the gas of the second cylinder <NUM> is discharged from the second outlet <NUM>. As shown in <FIG>, after being discharged out of the second chamber <NUM> through the second outlet <NUM>, the pressurized gas enters, through a passage <NUM> located in the second cylinder cover <NUM>, a passage <NUM> located in the frame <NUM>.

<FIG> shows a cut view of the multi-stage electric gas pump <NUM> rotated by another angle, and shows the fluid passage before the gas enters the third cylinder <NUM>. As shown in <FIG>, the pressurized gas enters, through the passage <NUM> located in the frame <NUM>, a passage <NUM> located in the third cylinder cover <NUM>, and enters the third chamber <NUM> through the third inlet <NUM>. In an embodiment, the third inlet <NUM> is provided with a check valve <NUM>, and the check valve <NUM> allows the pressurized gas to enter the third chamber <NUM> only. On the basis of a combination of <FIG>, it can be learned that the gas entering the gas pump <NUM> through the gas inlet <NUM> is sequentially pressurized by the first cylinder <NUM>, the second cylinder <NUM>, and the third cylinder <NUM> in fluid communication with each other and is then discharged from the gas outlet <NUM>.

Further, referring to <FIG> and <FIG>, the multi-stage electric gas pump further includes a linear bearing <NUM> fixed on the frame <NUM>. The third piston rod <NUM> is slidably connected to the linear bearing <NUM> so as to reciprocate under cooperation of the linear bearing <NUM>. Specifically, one end of the third piston rod <NUM> is connected to the third piston bush <NUM>, and the other end thereof is connected to the linear bearing <NUM>. These respective ends of the third piston rod <NUM> may be opposite to each other. Those skilled in the art can understand that this configuration enables the third piston rod <NUM> to achieve a stable linear reciprocation under driving force of a second eccentric portion <NUM> of the eccentric shaft <NUM>.

Returning to <FIG>, the multi-stage electric gas pump <NUM> further includes the eccentric shaft <NUM>, and the eccentric shaft <NUM> is fixed to the frame <NUM> by way of bearings 201a and 201b. The eccentric shaft <NUM> includes an elongated main body <NUM> and a first eccentric portion <NUM> and a second eccentric portion <NUM> fixed to two ends of the main body <NUM>. The first and second eccentric portions <NUM>, <NUM> may be offset from an axis of the main body <NUM>. The main body <NUM> of the eccentric shaft <NUM> is fixed to the driven wheel <NUM> so as to rotate together with the driven wheel <NUM>, and when the main body <NUM> rotates around a main body axis <NUM>, the first eccentric portion <NUM> and the second eccentric portion <NUM> also rotate in synchronization with the main body <NUM>.

<FIG> shows a partially exploded view of the multi-stage electric gas pump <NUM>, and includes a perspective view of the eccentric shaft <NUM> in <FIG>. As shown in <FIG>, the main body <NUM> of the eccentric shaft <NUM> includes a main body axis <NUM>. Driven by the driven wheel <NUM>, the main body <NUM> can rotate around the main body axis <NUM>. The first eccentric portion <NUM> of the eccentric shaft <NUM> includes a first eccentric axis <NUM>, and the second eccentric portion <NUM> of the eccentric shaft <NUM> includes a second eccentric axis <NUM>. In an embodiment, the main body axis <NUM>, the first eccentric axis <NUM>, and the second eccentric axis <NUM> are parallel to each other, and the first eccentric axis <NUM> and the second eccentric axis <NUM> are offset from the main body axis <NUM>. In other words, when the main body <NUM> rotates around the main body axis <NUM>, both the first eccentric portion <NUM> and the second eccentric portion <NUM> perform circular movement around the main body axis <NUM>. In an embodiment, the first eccentric axis <NUM> and the second eccentric axis <NUM> are located on two sides of the main body axis <NUM>, and the first eccentric axis <NUM>, the second eccentric axis <NUM>, and the main body axis <NUM> are on the same plane. In other words, when the main body <NUM> rotates around the main body axis <NUM>, respective circular movement trajectories of the first eccentric portion <NUM> and the second eccentric portion <NUM> differ in phase by <NUM> degrees.

Continuing to refer to <FIG> and <FIG>, the first eccentric portion <NUM> is in mechanical cooperation with the first and second piston rods <NUM>, <NUM>, respectively. For example, in an embodiment, the first eccentric portion <NUM> of the eccentric shaft <NUM> is directly connected to the first piston rod <NUM> by way of a first crank <NUM>. Those skilled in the art can understand that although the embodiment in <FIG> shows that the first eccentric portion <NUM> is directly connected to the first piston rod <NUM>, when the first piston rod <NUM> and the second piston rod <NUM> have other structures, the first eccentric portion <NUM> may also be directly connected to the second piston rod <NUM>.

Further, the first crank <NUM> has a first circular trough <NUM> located at one end thereof and a second circular trough <NUM> located at the other end thereof. The first circular trough can accommodate a bearing <NUM>, and the first eccentric portion <NUM> is fixed to the bearing <NUM> by way of a nut <NUM>, so that the first crank <NUM> can rotate around the first eccentric axis <NUM>. The second circular trough <NUM> can accommodate one end of a first cam bearing <NUM>, so that the first crank <NUM> can rotate around an axis <NUM> of the first cam bearing <NUM>. The other end of the first cam bearing <NUM> is fixed to the first piston rod <NUM>. Those skilled in the art can understand that rotational movement of the first eccentric portion <NUM> performed around the main body axis <NUM> can drive the first crank <NUM> to perform a revolution movement and the revolution movement of the first crank <NUM> can drive the first piston rod <NUM> and the second piston rod <NUM> to reciprocate.

Similarly, referring to <FIG>, the second eccentric portion <NUM> is in mechanical cooperation with the third piston rod <NUM>. For example, in an embodiment, the second eccentric portion <NUM> is connected to the third piston rod <NUM> by means of a second crank <NUM>. Since the structure of the second crank <NUM> is similar to the structure of the first crank <NUM>, and since a connection relationship between the second eccentric portion <NUM> and the third piston rod <NUM> is similar to a connection relationship between the first eccentric portion <NUM> and the first piston rod <NUM>, it is not repeatedly described herein. Particularly, those skilled in the art can also understand that rotational movement of the second eccentric portion <NUM> around the main body axis <NUM> can drive the second crank <NUM> to perform a revolution movement and the revolution movement of the second crank <NUM> can drive the third piston rod <NUM> to reciprocate. In addition, it can be learned that respective directions of the reciprocations of the first piston rod <NUM>, the second piston rod <NUM>, and the third piston rod <NUM> are all transverse to the main body axis <NUM>. For example, in an embodiment, the first, second, and third piston rods <NUM>, <NUM>, <NUM>, respectively, are all perpendicular to the main body axis <NUM>.

Those skilled in the art can understand that since the first eccentric portion <NUM> and the second eccentric portion <NUM> differ in phase by <NUM> degrees when rotating around the main body axis <NUM>, and the orientation of the third piston rod <NUM> is the same as the orientation of the second piston rod <NUM> and is opposite to the orientation of the first piston rod <NUM>, gas drawing and gas discharging operations of the third piston rod <NUM> may be contrary to gas drawing and gas discharging operations of the second piston rod <NUM> and be the same as gas drawing and gas discharging operations of the first piston rod <NUM>. Those skilled in the art can understand that by adjusting a phase difference existing when the first eccentric portion <NUM> and the second eccentric portion <NUM> rotate around the main body axis <NUM> and by accordingly adjusting an orientation of the third piston rod <NUM> relative to the second piston rod <NUM>, cooperation between the three cylinders can also be achieved so as to achieve three-stage pressurization of gas. For example, it may be configured that the phase difference existing when the first eccentric portion <NUM> and the second eccentric portion <NUM> rotate around the main body axis <NUM> is <NUM> degrees, and the orientation of the third piston rod <NUM> is opposite to that of the second piston rod <NUM> and is the same as the orientation of the first piston rod <NUM>. On the basis of such configurations, only respective positions of the third cylinder <NUM>, the motor <NUM>, the fluid passage in the frame <NUM>, and the like need to be adjusted, and a three-stage pressurization function can be implemented.

<FIG> shows a portable high pressure calibration device <NUM> according to an embodiment of the present disclosure, the portable high pressure calibration device <NUM> including the multi-stage electric gas pump <NUM> according to an embodiment of the present disclosure. In an operation state, the multi-stage electric gas pump <NUM> can provide a high-pressure gas source for the high pressure calibration device <NUM> so as to implement a calibration function of the calibration device <NUM>.

<FIG> shows a rear view of the high pressure calibration device <NUM> in <FIG>, wherein a rear cover of the high pressure calibration device is removed. As shown in <FIG>, the multi-stage electric gas pump <NUM> is fixed to the high pressure calibration device <NUM> by means of a housing <NUM>, and provides pressurized gas through the gas outlet <NUM>.

The portable high pressure calibration device <NUM> may be a handheld device that may be operated by a user with a single hand. For example, the user may be able to actuate buttons on the front of the portable high pressure calibration device <NUM> with ease when performing a calibration of a device under test (DUT). The user may be able to lift and move the handheld device between DUTs being calibrated utilizing the portable high pressure calibration device <NUM>. The handheld nature of the portable high pressure calibration device <NUM> provides a user ease of use along with ease of moving the portable high pressure calibration device <NUM> relative to other pressure calibration devices that may operate by the user manually actuating a pump. The handheld nature of the portable high pressure calibration device <NUM> may allow for a user to easily transport the portable high pressure calibration device <NUM> between different sites that may be at different locations to test and calibrate different types of DUTs, for example, pressure measurement devices or instruments.

In various aspects, a multi-stage electric gas pump may thus be summarized as including an eccentric shaft including a main body having a longitudinal axis, a first eccentric portion, and a second eccentric portion, wherein the first eccentric portion and the second eccentric portion are fixed on the main body; the eccentric shaft is driven by the driving mechanism to produce a first circular movement of the first eccentric portion performed around the longitudinal axis and a second circular movement of the second eccentric portion performed around the longitudinal axis, wherein the second circular movement is synchronized with the first circular movement; a first cylinder including a first chamber and a first piston rod, and the first piston rod being connected to the first eccentric portion and being configured to reciprocate in response to the first circular movement of the first eccentric portion so as to periodically pressurize gas drawn into the first chamber from an external environment of the multi-stage electric gas pump and then discharge first pressurized gas out of the first chamber; a second cylinder being in fluid communication with the first cylinder, the second cylinder including a second chamber and a second piston rod, and the second piston rod being connected to the first eccentric portion and being configured to reciprocate in response to the first circular movement of the first eccentric portion so as to periodically pressurize the first pressurized gas drawn into the second chamber from the first chamber of the first cylinder and then discharge second pressurized gas out of the second chamber; and a third cylinder being in fluid communication with the second cylinder, the third cylinder including a third chamber and a third piston rod, and the third piston rod being connected to the second eccentric portion and being configured to reciprocate in response to the second circular movement of the second eccentric portion so as to periodically pressurize the second pressurized gas drawn into the third chamber from the second chamber of the second cylinder and then discharge third pressurized gas out of the third chamber.

The second circular movement may be offset by <NUM> degrees in phase relative to the first circular movement.

The first piston rod and the second piston rod may be connected to each other, and an orientation of the first piston rod may be opposite to an orientation of the second piston rod.

The third piston rod may be parallel to the first piston rod and the second piston rod, and an orientation of the third piston rod may be the same as the orientation of the second piston rod.

The multi-stage electric gas pump may further include a first crank having a first end and a second end, wherein the first end of the first crank may be connected to the first eccentric portion of the eccentric shaft, and the second end of the first crank may be connected to one of the first piston rod and the second piston rod by way of a first cam bearing.

The multi-stage electric gas pump may further include a second crank having a first end and a second end, wherein the first end of the second crank may be connected to the second eccentric portion of the eccentric shaft, and the second end of the second crank may be connected to the third piston rod by way of a second cam bearing.

The first chamber may include a first piston bush and a first cylinder cover; the first cylinder cover may have a first inlet for sucking gas from the external environment and a first outlet for discharging the first pressurized gas; the first piston rod may include a first piston rubber cup; and the first piston rubber cup may be configured to seal the first piston bush together with the first cylinder cover.

The second chamber may include a second piston bush and a second cylinder cover; the second cylinder cover may have a second inlet for sucking the first pressurized gas and a second outlet for discharging the second pressurized gas; the second piston rod may include a second piston rubber cup; and the second piston rubber cup may be configured to seal the second piston bush together with the second cylinder cover.

The third chamber may include a third piston bush and a third cylinder cover; the third cylinder cover may have a third inlet for sucking the second pressurized gas and a third outlet for discharging the third pressurized gas; the third piston rod may include a third piston rubber cup; and the third piston rubber cup may be configured to seal the third piston bush together with the third cylinder cover.

The first inlet, the first outlet, the second inlet, the second outlet, the third inlet, and the third outlet each may include a check valve.

The driving mechanism may be a motor; the multi-stage electric gas pump may further include a driving wheel and a driven wheel; the driving wheel may be connected to the motor, and may be driven by the motor; the driven wheel may be connected to the main body of the eccentric shaft, and may be configured to rotate the main body of the eccentric shaft around the longitudinal axis; connected to the motor, and configured to rotate the main body of the eccentric shaft around the longitudinal axis; the driven wheel may be connected to the driving wheel by means of a belt, and may be driven by the driving wheel.

The motor may be a brushless direct-current motor.

The main body of the eccentric shaft may be elongated, and the first eccentric portion and the second eccentric portion may be respectively located at two ends of the main body of the eccentric shaft.

The longitudinal axis of the main body may be perpendicular to the first piston rod, the second piston rod, and the third piston rod.

A maximum volume of the first chamber may be greater than a maximum volume of the second chamber, and the maximum volume of the second chamber may be greater than a maximum volume of the third chamber.

The third piston connecting rod may be slidably connected to a linear bearing so as to reciprocate under cooperation of the linear bearing.

In various aspects, a multi-stage electric gas pump may be summarized as including an eccentric shaft, the eccentric shaft including a main body having a longitudinal axis and at least one eccentric portion connected to the main body, and the eccentric shaft being driven by the driving mechanism so that the eccentric portion performs circular movement around the longitudinal axis; a first cylinder including a first chamber and a first piston rod, and the first piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize gas drawn into the first chamber from an external environment of the multi-stage electric gas pump and then discharge first pressurized gas out of the first chamber; a second cylinder being in fluid communication with the first cylinder, the second cylinder including a second chamber and a second piston rod, and the second piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize the first pressurized gas drawn into the second chamber from the first chamber of the first cylinder and then discharge second pressurized gas out of the second chamber; and a third cylinder being in fluid communication with the second cylinder, the third cylinder including a third chamber and a third piston rod, and the third piston rod being connected to the eccentric portion and being configured to reciprocate in response to the circular movement of the eccentric portion so as to periodically pressurize the second pressurized gas drawn into the third chamber from the second chamber of the second cylinder and then discharge third pressurized gas out of the third chamber, wherein the connections between the first piston rod, the second piston rod, the third piston rod and the eccentric portion are configured so that the second cylinder discharges gas while the first cylinder and the third cylinder draw in gas and that the second cylinder draws in gas while the first cylinder and the third cylinder discharge gas.

Additionally a portable high pressure calibration device may be summarized as including the multi-stage electric gas pump described herein.

Those of ordinary skill in the art can understand and implement other variations of the disclosed embodiments by studying the specification, the disclosure, the accompanying drawings and the claims. In the claims, the word "comprise" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality of elements or steps. In practical applications of the present disclosure, one component may perform functions of multiple technical features recited in the description and claims.

Claim 1:
A multi-stage electric gas pump (<NUM>), comprising:
an eccentric shaft (<NUM>) including a main body (<NUM>) having a longitudinal axis, a first eccentric portion (<NUM>), and a second eccentric portion, wherein the first eccentric portion (<NUM>) and the second eccentric portion (<NUM>) are fixed on the main body (<NUM>), the eccentric shaft (<NUM>) is driven by a driving mechanism to produce a first circular movement of the first eccentric portion (<NUM>) around the longitudinal axis and a second circular movement of the second eccentric portion (<NUM>) around the longitudinal axis, and the second circular movement is synchronized with the first circular movement;
a first cylinder (<NUM>) including a first chamber (<NUM>) and a first piston rod (<NUM>), the first piston rod (<NUM>) being connected to the first eccentric portion (<NUM>);
a second cylinder (<NUM>) in fluid communication with the first cylinder (<NUM>), the second cylinder (<NUM>) including a second chamber (<NUM>) and a second piston rod (<NUM>), the second piston rod (<NUM>) being connected to the first eccentric portion (<NUM>); and
a third cylinder (<NUM>) in fluid communication with the second cylinder (<NUM>), the third cylinder (<NUM>) including a third piston rod (<NUM>) and a third chamber (<NUM>), the third piston rod (<NUM>) being connected to the second eccentric portion (<NUM>), characterised in that:
the first piston rod (<NUM>) and the second piston rod (<NUM>) are connected to each other, such that an orientation of the first piston rod (<NUM>) is always opposite to an orientation of the second piston rod (<NUM>); and
the third piston rod (<NUM>) is parallel to the first piston rod (<NUM>) and the second piston rod (<NUM>), and an orientation of the third piston rod (<NUM>) and the orientation of the second piston rod (<NUM>) are always the same.