Gear pump and fluid discharge device

Abstract

To provide a gear pump that enables a drive gear and a driven gear to be made thinner without making a housing thinner, and that can suitably transfer a fluid at a small flow rate.SOLUTION: A gear pump 1 includes a drive gear 10 that is rotationally driven about an axis L1, a driven gear 20 that meshes with the drive gear 10 and is driven to rotate about an axis L2, and a housing 30 that accommodates the drive gear 10 and the driven gear 20. The housing 30 is configured by combining a housing body 31 having a gear accommodation chamber α1 for accommodating the drive gear 10 and the driven gear 20, a front plate 32 disposed on a front surface side of the housing body 31, and a rear plate 33 disposed on a rear surface side of the housing body 31. The gear pump is provided with a spacer 30 that is fitted between the front plate 32 or the rear plate 33 and side surfaces of the drive gear 10 and the driven gear 20 in the gear accommodation chamber α1, and that reduces a front-rear width of the gear accommodation chamber α1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gear pump for transporting a fluid and a fluid discharge device using the same. [Background technology]

[0002] Fluid discharge devices that discharge a fluid from a nozzle are used in various applications. For example, when assembling an interior part (such as an interior panel) to an automobile body (such as a door panel), a process of applying an adhesive along the peripheral edge of the door panel (a hemming process) is performed. This hemming process is generally performed by discharging an adhesive (fluid) from the nozzle of the fluid discharge device onto the door panel (workpiece) while moving the nozzle two-dimensionally or three-dimensionally.

[0003] As an example of a fluid discharge device, as shown in FIG. 1 of Patent Document 1, an industrial robot 10 (articulated robot arm) is used to move a coating gun 20 (nozzle). The adhesive (fluid) is stored in a container 50 (fluid storage tank), and by driving a gear pump 33, the adhesive (fluid) is transferred from the container 50 (fluid storage tank) to the coating gun 20 (nozzle). Patent Document 1 describes that by using a gear pump instead of an air pump as a means for transferring the fluid, pulsation of the adhesive (fluid) discharged from the coating gun 20 (nozzle) can be suppressed.

[0004] Various gear pumps are known for such applications. For example, FIG. 3 of Patent Document 2 shows a gear pump 1 including a pair of gears 3 (drive gear and driven gear) that mesh with each other and a housing 2 that rotatably supports the pair of gears 3 (drive gear and driven gear). The housing 2 is composed of a housing main body 22, a first plate 23 (front plate) that covers the front side of the housing main body 22, and a second plate 24 (rear plate) that covers the rear side of the housing main body 22. As shown in FIG. 6 of the same document, the housing main body 2 is provided with a gear housing opening 223 (gear housing chamber) that houses the pair of gears 3 (drive gear and driven gear), a supply port 225 (fluid inlet) that introduces a fluid into the gear housing opening 223 (gear housing chamber), and a discharge space 212 (fluid outlet) that discharges the fluid from the gear housing opening 223 (gear housing chamber).

[0005] In the gear pump 1 of Patent Document 1, when the drive shaft 41 is driven to rotate, the gear 3 (drive gear) fixed to the outer periphery of the drive shaft 41 also rotates, and another gear (driven gear) meshing with the gear 3 (drive gear) rotates around the driven shaft 42. As a result, fluid introduced from the supply port 225 (fluid inlet) into the gear housing opening 223 (gear housing chamber) is held in the tooth grooves on the outer periphery of each gear 3 (drive gear and driven gear). As the gears 3 (drive gear and driven gear) rotate, the fluid moves along the inner wall surface of the gear housing opening 223 (gear housing chamber) and is transferred to the discharge space 212 (fluid delivery section). The fluid delivered to the discharge space 212 (fluid delivery section) is discharged to the outside of the gear pump 1 through an outlet hole 234 provided in the first plate 23 (front plate). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 07-116590 [Patent Document 2] Japanese Patent Publication No. 2023-104243 Summary of the Invention [Problem to be solved by the invention]

[0007] In a fluid ejection device that uses a gear pump to transport fluid, as described above, when the flow rate of the fluid ejected from the nozzle is low, the drive gear can be rotated at a low speed. However, rotating the drive gear at a low speed reduces responsiveness when adjusting the rotational speed of the drive gear. That is, it takes longer for the drive gear to reach the commanded rotational speed after a command to change the rotational speed is given to the drive means (e.g., motor) that rotates the drive gear. Furthermore, it becomes difficult to adjust the rotational speed of the drive gear with high precision (fine resolution). This makes it difficult not only to quickly change the flow rate of the fluid ejected from the nozzle, but also to adjust the flow rate with high precision.

[0008] For example, when performing a hemming process using a fluid discharge device as described above, if the flow rate of the adhesive (fluid) discharged from the nozzle cannot be quickly and finely adjusted when transitioning from a linear application of the adhesive (fluid) to a curved application, problems such as uneven width of the applied adhesive (fluid) (liquid pools forming at the application site) are likely to occur. The workpiece to which the adhesive (fluid) is to be applied is not necessarily flat but can also be curved. Even when applying adhesive (fluid) to a curved workpiece, the above problems are likely to occur unless the flow rate of the adhesive (fluid) discharged from the nozzle can be quickly and precisely adjusted in accordance with the undulations of the workpiece's surface. For this reason, it is not recommended to rotate the gear pump's drive gear at a low speed during the hemming process.

[0009] In this regard, if the drive gear and driven gear are made thinner (reducing their width in the front-to-rear direction), the amount of adhesive (fluid) transferred per one rotation of the drive gear and driven gear is reduced, and the flow rate of the fluid discharged from the nozzle can be kept low even if the drive gear is not rotated in a low-speed range (even if the drive gear is rotated in a constrained range). Furthermore, this improves responsiveness when adjusting the rotational speed of the drive gear, and makes it possible to adjust the rotational speed of the drive gear with fine resolution. This reduces the occurrence of problems in the hemming application process.

[0010] However, in conventional gear pumps, reducing the thickness of the drive gear and driven gear requires that the housing that houses them also be made thinner (reducing its width in the front-to-rear direction). This is because gaps known as "side clearances" are formed between the side surfaces of the drive gear and driven gear and the rear surface of the front plate, and between the side surfaces of the drive gear and driven gear and the front surface of the rear plate. If the housing thickness (width in the front-to-rear direction) remains the same and only the drive gear and driven gear are thinned, this side clearance increases, causing the adhesive (fluid) to short-path through this side clearance from the fluid inlet to the fluid outlet. However, thinning the housing also creates other problems. For example, the housing often includes a fluid inlet for introducing adhesive (fluid) into the gear accommodating chamber, and other mechanisms for connecting the gear pump to other components. However, thinning the housing makes it difficult to incorporate these mechanisms in the housing.

[0011] The present invention has been made to solve the above problems, and provides a gear pump that can thin the drive gear and driven gear without thinning the housing, and can suitably transfer fluid at a low flow rate. In particular, it is an object of the present invention to provide a gear pump that can easily adjust the flow rate of the transferred fluid with good responsiveness and high precision. Another object of the present invention is to provide a fluid discharge device that can be suitably used in a hemming application process. [Means for solving the problem]

[0012] The above issues are: a drive gear that is driven to rotate around an axis in the front-rear direction; a driven gear that meshes with the drive gear and rotates around an axis extending in the front-rear direction; a housing for accommodating a drive gear and a driven gear; Equipped with The housing is a housing body having a gear accommodating chamber for accommodating a drive gear and a driven gear; a front plate disposed on the front side of the housing body; A rear plate disposed on the rear side of the housing body; A gear pump configured by combining A spacer is provided in the gear accommodating chamber, which is fitted between the front plate or rear plate and the side surfaces of the driving gear and driven gear, thereby reducing the front-to-rear width of the gear accommodating chamber. A gear pump characterized by This is solved by providing

[0013] By fitting the spacer into the gear accommodating chamber in this way, it is possible to make the drive gear and the driven gear thinner without making the housing thinner. This makes the gear pump suitable for transferring fluids at low flow rates. Specifically, the gear pump can improve its responsiveness when changing the fluid flow rate. In addition, the gear pump can precisely control the fluid flow rate.

[0014] In the gear pump of the present invention, only one spacer may be used, but it is preferable to use multiple spacers. As a spacer, a front spacer fitted between the front plate and the side surfaces of the drive gear and the driven gear in the gear accommodating chamber; a rear spacer fitted between the rear plate and the side surfaces of the drive gear and the driven gear in the gear accommodating chamber; It is preferable to use

[0015] This is because the housing body is provided with a fluid inlet for introducing fluid into the gear accommodating chamber and a fluid outlet for discharging fluid from the gear accommodating chamber. Therefore, thinning the drive gear and driven gear requires a change in the design of the housing body (requiring a change in the location of the fluid inlet and fluid outlet). In particular, the fluid inlet is often located in the middle of the housing body in the longitudinal direction. In this case, if the drive gear and driven gear are thinned and a spacer is placed on only one side of the gear accommodating chamber (one side in the longitudinal direction from the drive gear and driven gear), the longitudinal positions of the fluid inlet and the drive gear and driven gear will be misaligned. This necessitates a change in the design of the housing body. However, by sandwiching the drive gear and driven gear between a front spacer and a rear spacer as described above, the longitudinal positions of the fluid inlet and the drive gear and driven gear can be aligned without changing the design of the housing body. Therefore, even if the drive gear and driven gear are thinned, the existing housing body can be reused.

[0016] In the gear pump of the present invention, the thickness of the spacer (thickness in the front-rear direction; the same applies hereinafter) varies depending on the application of the gear pump, and is not particularly limited. However, if the spacer is too thin, the width by which the drive gear and driven gear can be thinned becomes small, thereby reducing the significance of adopting the configuration of the present invention. For this reason, it is preferable that the ratio T / W of the spacer's thickness in the front-rear direction (referred to as T) to the gear accommodating chamber's front-rear width (referred to as W) be 0.2 or more, and the ratio T2 / W of the drive gear and driven gear's thickness in the front-rear direction (referred to as T2) to the gear accommodating chamber's front-rear width W be 0.8 or less. Here, when multiple spacers are used (when the spacer is composed of a front spacer and a rear spacer as described above), the spacer's thickness in the front-rear direction T refers to the total thickness of the multiple spacers.

[0017] In addition, the above problem is The above gear pump (the gear pump of the present invention); a fluid supply means for supplying fluid to the gear pump; a nozzle for discharging the fluid transferred from the gear pump; an articulated robot arm having a nozzle fixed to its end; a control means for controlling the gear pump and the articulated robot arm; Equipped with The control means changes the rotation speed of the drive gear of the gear pump in response to the movement of the articulated robot arm. A fluid ejection device characterized by This can also be solved by providing

[0018] The gear pump of the present invention exhibits excellent responsiveness and precision. Therefore, by incorporating the gear pump into the fluid discharge device described above and coordinating the operation of the articulated robot arm of the fluid discharge device with the rotational speed of the gear pump's drive gear, it becomes possible to discharge a fluid onto a workpiece in a uniform streak. For example, when performing a hemming process to apply adhesive (fluid) to a workpiece, the width of the applied adhesive can be made uniform even in areas where the adhesive (fluid) is applied in a corner shape. Furthermore, the width of the applied adhesive can be made uniform even when applying adhesive (fluid) to a workpiece with a complex curved surface. [Effects of the Invention]

[0019] As described above, the present invention provides a gear pump that can appropriately transport fluid at low flow rates by making the drive gear and driven gear thinner without reducing the thickness of the housing. In particular, it also provides a gear pump that can easily adjust the flow rate of the transported fluid with good responsiveness and high precision. It also provides a fluid discharge device that can be suitably used in a hemming application process. [Brief explanation of the drawings]

[0020] [Figure 1] 10 is a diagram showing a state in which an adhesive is discharged and applied to a workpiece using a fluid discharge device. FIG. [Figure 2]2 is an enlarged plan view showing the periphery of a nozzle in the fluid ejection device of FIG. 1. FIG. [Figure 3] 2 is an exploded perspective view of a gear pump used in the fluid discharge device of FIG. 1. FIG. [Figure 4] 2 is a cross-sectional view showing a state in which the gear pump used in the fluid ejection device of FIG. 1 is cut along a plane parallel to the yz plane. [Figure 5] 2 is a cross-sectional view showing a state in which the gear pump used in the fluid ejection device of FIG. 1 is cut along a plane parallel to the xz plane. DETAILED DESCRIPTION OF THE INVENTION

[0021] The gear pump of the present invention will be described with reference to the drawings. However, the configuration described below is merely a preferred embodiment, and the technical scope of the gear pump of the present invention is not limited to the configuration described below. The gear pump of the present invention can be modified as appropriate within the scope of the spirit of the invention. For example, the following description will be given using an example in which the gear pump of the present invention is used in a fluid discharge device, but the use of the gear pump is not limited thereto and the gear pump can be used in various applications such as transporting fluids.

[0022] 1. Fluid Discharge Device First, the fluid discharge device will be described. FIG. 1 is a diagram showing how an adhesive (fluid F) is discharged and applied to a workpiece W using the fluid discharge device. FIG. 2 is an enlarged plan view showing the periphery of a nozzle 3 in the fluid discharge device of FIG. 1. The fluid discharge device shown in FIG. 1 is used to discharge and apply fluid F to a workpiece W. In this embodiment, the workpiece W is positioned by a jig (not shown). This fluid discharge device includes a gear pump 1, a fluid supply means 2, a nozzle 3, an articulated robot arm 4, and a control means 5.

[0023] The fluid supply means 2 supplies the fluid F to the gear pump 1, which will be described later. A vane pump may be used as the fluid supply means 2, but in this embodiment, a cylinder pump (piston pump) is used. There are no particular limitations on the location where the fluid supply means 2 is provided, but providing the fluid supply means 2 near the gear pump 1 shortens the length of the transfer path of the fluid F and makes it less likely that the properties of the fluid F will change during transfer (reducing the thermal history of the fluid F). For this reason, in this embodiment, the fluid supply means 2 is provided next to the gear pump 1.

[0024] The gear pump 1 transfers the fluid F supplied from the fluid supply means 2 to the nozzle 3 by the rotation of a drive gear 10 and a driven gear 20 (see FIG. 3 , described below). The fluid F entering the gear pump 1 is transferred by the fluid supply means 2 (cylinder pump), and therefore pulsation occurs in the fluid F entering the gear pump 1. However, the gear pump 1 absorbs the pulsation and transfers the fluid F to the nozzle 3 at a stable pressure. The location of the gear pump 1 is not particularly limited, but locating the gear pump 1 near the nozzle 3 shortens the transfer path length of the fluid F and makes it less likely that the properties of the fluid F will change during transfer (reducing the thermal history of the fluid F). For this reason, in this embodiment, the gear pump 1 is located near the nozzle 3.

[0025] The nozzle 3 is used to discharge the fluid F transferred from the gear pump 1. The shape of the nozzle 3 varies depending on the discharge mode of the fluid F. In this embodiment, the nozzle 3 is formed by a single straight tube, and the fluid F is discharged from the nozzle 3 in the form of a single line. The nozzle 3 is fixed to the tip end (terminal end) of the articulated robot arm 4.

[0026] The articulated robot arm 4 includes an arm having multiple joints. By bending or rotating this arm at the joints, the position and orientation of the tip (terminal end) of the arm can be changed three-dimensionally. A servo motor is provided at each joint of the arm. The servo motor performs rotational motion according to the rotation amount and rotation speed input thereto. By combining the rotational motions of multiple servo motors, the arm of the articulated robot arm 4 can perform complex movements like a human arm. In this embodiment, a nozzle 3 is provided at the tip (terminal end) of the arm of the articulated robot arm 4, and therefore the position and orientation of the discharge of the fluid F can be changed by controlling the articulated robot arm 4.

[0027] The control means 5 controls the gear pump 1, the fluid supply means 2, and the articulated robot arm 4. The gear pump 1 and the fluid supply means 2 change the transfer speed (flow rate) of the fluid F according to signals from the control means 5. The articulated robot arm 4 is also driven three-dimensionally according to signals from the control means 5 so that the tip (terminal end) of the arm traces a predetermined trajectory relative to the workpiece W. The control means 5 is a computer equipped with a central processing unit (CPU) and a storage device. The control means 5 is electrically connected to the gear pump 1 etc. by wire or wirelessly.

[0028] As described above, the control means 5 controls the flow rate of the fluid F and the operation of the articulated robot arm 4. In this embodiment, the flow rate of the fluid F discharged from the nozzle 3 is adjusted according to the movement of the nozzle 3. For example, when the nozzle 3 is moved slowly relative to the workpiece W, the flow rate of the fluid F discharged from the nozzle 3 is reduced. When the nozzle 3 is moved quickly relative to the workpiece W, the flow rate of the fluid F discharged from the nozzle 3 is increased. When the nozzle 3 is moved along a linear trajectory, the flow rate of the fluid F discharged from the nozzle 3 is increased. When the nozzle 3 is moved along a curved trajectory, the flow rate of the fluid F discharged from the nozzle 3 is decreased. By continuously and precisely adjusting the flow rate in this manner, the width of the fluid F applied to the workpiece W can be made constant regardless of the location. This allows the above-mentioned hemming process and other steps to be performed with high precision.

[0029] The fluid F discharged from the nozzle 3 can be adjusted by changing the rotational speed of the drive gear 10 in the gear pump 1. Furthermore, the control means 5 itself is able to grasp the movement mode of the nozzle 3 relative to the workpiece W. This is because the control signal that drives the articulated robot arm 4 (the control signal that governs the movement mode of the nozzle 3) is nothing other than what is generated by the control means 5 based on the program stored in the control means 5.

[0030] The movement of the nozzle 3 relative to the workpiece W can also be determined from the output of each servo motor (a rotary encoder that measures the amount of rotation of the servo motor provided at each joint of the arm) in the articulated robot arm. However, if the flow rate of the fluid F discharged from the nozzle 3 is adjusted based on the output from the servo motor in the articulated robot arm 4, the flow rate of the fluid F will be adjusted by tracking the movement of the articulated robot arm 4. Therefore, when the movement of the articulated robot arm 4 changes, the change is reflected in the flow rate of the fluid F with a delay, which makes it more likely that the fluid F applied to the workpiece W will be disturbed. Therefore, it is preferable that the control means 5 controls the gear pump 1 in accordance with a control signal generated by itself (a control signal output to the articulated robot arm 4).

[0031] 2. Gear pumps Next, the gear pump 1 used in the fluid discharge device of FIG. 1 will be described. FIGS. 3 to 5 show the gear pump 1 used in the fluid discharge device of FIG. 1. FIG. 3 is an exploded perspective view of the gear pump 1, FIG. 4 is a cross-sectional view of the gear pump 1 taken along a plane parallel to the yz plane, and FIG. 5 is a cross-sectional view of the gear pump 1 taken along a plane parallel to the xz plane. FIGS. 3 to 5 and FIG. 2 show a Cartesian coordinate system consisting of the x, y, and z axes. The orientations of the x, y, and z axes are consistent across different drawings. Hereinafter, the positive x-axis direction will be referred to as the "right" side, the negative x-axis direction will be referred to as the "left" side, the positive y-axis direction will be referred to as the "rear" side, the negative y-axis direction will be referred to as the "front" side, the positive z-axis direction will be referred to as the "upper" side, and the negative x-axis direction will be referred to as the "lower" side. However, these directions are used merely for convenience of explanation and do not limit the direction in which the gear pump 1 is used.

[0032] As shown in FIG. 3, the gear pump 1 includes a drive gear 10, a driven gear 20, a housing 30, a drive shaft 40, and a spacer 50.

[0033] 3, the housing 30 is configured by combining a housing main body 31, a front plate 32, and a rear plate 33. In this embodiment, the housing main body 31, the front plate 32, and the rear plate 33 are integrated by inserting bolts 60 and dowels 70 into through holes provided in the housing main body 31, the front plate 32, and the rear plate 33 so as to pass through predetermined locations in the front-rear direction.

[0034] The housing body 31 has a thick plate-like (block-like) shape. A gear accommodating chamber α1 having an oval cross section is provided through the housing body 31 in the front-rear direction. The gear accommodating chamber α1 accommodates the drive gear 10 and the driven gear 20. A protrusion 31a protruding to the right (positive side in the x-axis direction) is provided on the outer periphery of the housing body 31.

[0035] As shown in FIG. 5, the protruding portion 31a of the housing main body 31 is provided with a fluid inlet α2 and a fluid inlet passage α3. The fluid supply means 2 (FIG. 2) is connected to the fluid inlet α2. The fluid F supplied from the fluid supply means 2 is taken into the gear pump 1 through the fluid inlet α2 and introduced into the gear accommodating chamber α1 through the fluid inlet passage α3. The fluid inlet α2 is provided at three locations on the top surface (the surface on the positive side in the z-axis direction), bottom surface (the surface on the negative side in the z-axis direction), and right surface (the surface on the positive side in the x-axis direction) of the protruding portion 31a. Two of the fluid inlet α2 are blocked with plugs 31b, leaving only the remaining fluid inlet α3 open to the fluid inlet passage α3. By providing the fluid inlet α2 at multiple locations in this way, the degree of freedom in connecting the fluid supply source 2 to the gear pump 1 can be increased.

[0036] A fluid delivery passage α4 is connected to the left side of the gear accommodating chamber α1 (the side opposite to the side connected to the fluid introduction passage α3). As shown in FIG. 4, this fluid delivery passage α4 penetrates the front plate 32 in the front-rear direction (y-axis direction) and leads to a fluid delivery port α5 provided on the front side (the surface on the negative side in the y-axis direction) of the front plate 32. The fluid F in the gear accommodating chamber α1 is delivered to the outside of the gear pump 1 through this fluid delivery passage α4 and the fluid delivery port α5. The rear end (the end on the positive side in the y-axis direction) of the nozzle 3 (FIG. 2) is connected to the fluid delivery port α5.

[0037] 3, the front plate 32 is disposed on the front surface (the surface on the negative side in the y-axis direction) of the housing main body 31. The rear plate 33 is disposed on the rear surface (the surface on the positive side in the y-axis direction) of the housing main body 31. In other words, the housing main body 31 is sandwiched between the front plate 32 and the rear plate 33 in the front-to-rear direction (y-axis direction). The outer peripheral shapes of the front plate 32 and the rear plate 33 substantially match the outer peripheral shapes of the housing main body 31 excluding the protruding portion 31a.

[0038] The front plate 32 is a slightly thick plate. The front plate 32 is provided with the fluid delivery path α4 (FIG. 4) and the fluid delivery port α5 described above. The rear plate 33 is a thinner plate than the front plate 32. The rear plate 33 is provided with a through-hole extending in the front-rear direction, through which the drive shaft 40 (described later) is inserted.

[0039] As already described, the drive gear 10 and the driven gear 20 are accommodated in the gear accommodating chamber α1 in the housing main body 31. The drive gear 10 and the driven gear 20 have a plurality of teeth on their outer peripheries. The drive gear 10 and the driven gear 20 have substantially the same shape. In this embodiment, spur gears (gears with a plurality of parallel teeth on the outer periphery of a cylindrical member) are used as the drive gear 10 and the driven gear 20, but helical gears (gears with a twisted spur gear shape) can also be used. The drive gear 10 and the driven gear 20 are arranged in a state of circumferential contact with each other so that their teeth mesh with each other. The gear accommodating chamber α1 has an oval cross section (a shape formed by connecting a pair of arc segments with a pair of straight lines), and the outer diameters of the drive gear 10 and the driven gear 20 are set slightly smaller than the diameters of the arc segments in the gear accommodating chamber α1.

[0040] Of the drive gear 10 and driven gear 20, the drive gear 10 is fixed integrally to the outer periphery of the drive shaft 40. In this embodiment, a key 42 is fitted into a recess 41 provided on the outer periphery of the drive shaft 40, and the key 42 is engaged with a recess 11 provided in a through hole (through which the drive shaft 40 is inserted) of the drive gear 10. The drive shaft 40 is journaled in the housing 30 so as to be rotatable about an axis L1. A rotary drive means 6 (FIG. 2) such as an electric motor is connected to the drive shaft 40. In this way, the drive gear 10 is integrated with the drive shaft 40 by the key 42. Therefore, when the drive shaft 40 rotates about the axis L1, the drive gear 10 also rotates integrally with the drive shaft 40.

[0041] On the other hand, the driven gear 20 is journaled on a shaft 52a in a state in which it can rotate about an axis L2. The shaft 52a is fixed integrally to a rear plate 52, which will be described later. Therefore, when the rotation drive means 6 (FIG. 2) is driven and the drive shaft 40 and the drive gear 10 rotate about the axis L1 (see arrow A1 in FIG. 5), the driven gear 20 rotates about the axis L2 (see arrow A2 in FIG. 5) in response to the rotation of the drive gear 10. The rotation direction A1 of the drive gear 10 and the rotation direction A2 of the driven gear 20 are opposite to each other.

[0042] When the drive gear 10 and the driven gear 20 rotate in the directions of arrows A1 and A2 (FIG. 5), respectively, the fluid F (fluid F introduced into the gear accommodating chamber α1 from the fluid inlet passage α3) on one side (positive side in the x-axis direction) of the gear accommodating chamber α1 is held in the tooth grooves of the drive gear 10 and the tooth grooves of the driven gear 20, passes between the inner circumferential surface of the gear accommodating chamber α1 and the outer circumferential surfaces of the drive gear 10 and the driven gear 20, and is transferred to the other side (negative side in the x-axis direction) of the gear accommodating chamber α1. The fluid F that reaches the other side of the gear accommodating chamber α1 flows through the fluid delivery passage α4 and is delivered to the outside of the gear pump 1 from the fluid delivery port α5 (FIG. 4) of the front plate 32.

[0043] The base end of the nozzle 3 (Fig. 2) is connected to this fluid outlet α5, so the fluid F delivered from the gear pump 1 is discharged from the tip of the nozzle 3, as shown in Fig. 1. When the rotation speed of the drive gear 10 is increased, the flow rate of the fluid F discharged from the nozzle 3 increases, and when the rotation speed of the drive gear 10 is decreased, the flow rate of the fluid F discharged from the nozzle 3 decreases.

[0044] The spacer 50 is fitted into the gear accommodating chamber α1 to reduce the front-to-rear width (width in the y-axis direction) of the gear accommodating chamber α1. As already mentioned, the gear accommodating chamber α1 is provided by penetrating the housing main body 1 in the front-to-rear direction (y-axis direction), and therefore the front-to-rear width of the gear accommodating chamber α1 is equal to the front-to-rear thickness (thickness in the y-axis direction) of the housing main body 1. However, by fitting the spacer 50 into the gear accommodating chamber α1, the front-to-rear width of the gear accommodating chamber α1 can be made smaller than the front-to-rear thickness of the housing main body 1. The outer peripheral shape of the spacer 50 is made to roughly match the inner peripheral shape of the gear accommodating chamber α1 so that it fits snugly into the gear accommodating chamber α1.

[0045] By using this spacer 50 to effectively reduce the front-to-rear width of the gear accommodating chamber α1, the drive gear 10 and the driven gear 20 can be made thinner (reduced front-to-rear thickness). This makes it possible to make the gear pump 1 suitable for transferring a small flow rate of the fluid F. Specifically, the gear pump 1 can improve responsiveness when changing the flow rate of the fluid F. In addition, the gear pump 1 can also precisely control the flow rate of the fluid F.

[0046] Incidentally, even without using the spacer 50, the drive gear 10 and the driven gear 20 can be made thinner by reducing the front-to-rear thickness of the housing body 31. However, reducing the front-to-rear thickness of the housing body 31 makes it difficult to provide the fluid inlet port α2 and the like with the specified dimensions in the housing body 31. This makes it difficult to connect piping (piping connecting the fluid supply means 2 and the gear pump 1) to the housing body 31. In this regard, by using the spacer 50, the drive gear 10 and the driven gear 20 can be made thinner without reducing the front-to-rear thickness of the housing body 1.

[0047] Although only one spacer 50 may be used, two spacers 50 are used in this embodiment. Specifically, as shown in FIG. 3 , a front spacer 51 and a rear spacer 52 are used as the spacers 50. The front spacer 51 is disposed in front of the drive gear 10 and the driven gear 20 (negative side in the y-axis direction), and the rear spacer 52 is disposed in rear of the drive gear 10 and the driven gear 20 (positive side in the y-axis direction). That is, as shown in FIG. 4 , the front spacer 51 is fitted between the rear surface (surface facing the positive side in the y-axis direction) of the front plate 32 and the front side surfaces (surfaces facing the negative side in the y-axis direction) of the drive gear 10 and the driven gear 20 in the gear accommodating chamber α1. On the other hand, the rear spacer 52 is fitted between the front surface (surface facing the negative side in the y-axis direction) of the rear plate 33 and the rear side surfaces (surfaces facing the positive side in the y-axis direction) of the drive gear 10 and the driven gear 20 in the gear accommodating chamber α1.

[0048] The front and rear thicknesses of the front spacer 51 and the rear spacer 52 are made equal. In conventional gear pumps 1, the fluid inlet port α2 (FIG. 3) and the fluid inlet passage α3 (FIG. 5) are often provided in the middle of the housing body 31 in the front-to-rear direction (y-axis direction). However, by using two spacers 50 (the front spacer 51 and the rear spacer 52) with the same front-to-rear thickness, it is possible to position the drive gear 10 and the driven gear 20 in the middle of the gear accommodating chamber α1 in the front-to-rear direction (y-axis direction). This makes it possible to reuse the housing body 31 that was used in the conventional gear pump 1.

[0049] The front-to-rear thickness of the spacer 50 varies depending on the application of the gear pump 1, and is not particularly limited. However, if the front-to-rear thickness of the spacer 50 is too small, the width by which the drive gear 10 and the driven gear 20 can be thinned becomes small, and the significance of using the spacer 50 is reduced. For this reason, the ratio T / W (= (T1 + T2) / W) of the front-to-rear thickness T of the spacer 50 (the sum T1 + T2 of the front-to-rear thickness T1 of the front spacer 51 and the front-to-rear thickness T2 of the rear spacer 52 in FIG. 4) to the front-to-rear width W of the gear accommodating chamber α1 (FIG. 4) is preferably 0.2 or greater. The ratio T / W is more preferably 0.3 or greater, and even more preferably 0.4 or greater. The ratio T / W can also be even greater, at 0.5 or greater. In this embodiment, the front-to-rear width W of the gear accommodating chamber α1 is approximately 34 mm, the front-to-rear thicknesses T1 and T2 of the front spacer 31 and rear spacer 32 are each 10 mm, and the ratio T / W (= (T1 + T2) / W) is approximately 0.58.

[0050] Furthermore, in the gear pump 1, the gaps formed on the sides of the drive gear 10 and the driven gear 20 are called "side clearances." If this side clearance C1 (FIG. 4) is large, the fluid F is more likely to short-pass through the side clearance C1 from the fluid inlet path α3 to the fluid outlet path α4. If the fluid F short-passes, it becomes difficult for the gear pump 1 to precisely control the flow rate of the fluid F discharged from the nozzle 3. In this regard, by using the spacer 50, it is possible to keep the side clearance C1 small even if the drive gear 10 and the driven gear 20 are made thin. It is preferable to keep this side clearance C1 to 30 μm or less. It is even more preferable to keep the side clearance C1 to 20 μm or less, 10 μm or less, or even 5 μm.

[0051] Furthermore, in the gear pump 1, the gap formed on the outer periphery of the drive gear 10 and the driven gear 20 is called the "top clearance." If this top clearance C2 (FIG. 4) is wide, the fluid F in the gear accommodating chamber α1 will be unable to be retained in the tooth grooves of the drive gear 10 and the driven gear 20 and will be more likely to flow through this top clearance C2 from the fluid inlet passage α3 to the fluid outlet passage α4. In this case, too, it becomes difficult to precisely control the flow rate of the fluid F discharged from the nozzle 3 using the gear pump 1. For this reason, it is preferable to keep this top clearance C2 to 30 μm or less. It is even more preferable to reduce the top clearance C2 to 20 μm or less, 10 μm or less, or even 5 μm.

[0052] The capacity of the gear pump 1 varies depending on the application of the fluid discharge device, but as already mentioned, the gear pump 1 of this embodiment is suitable for transporting a small flow rate of the fluid F. For this reason, the capacity of the gear pump 1 is preferably 10 cc / rev or less, more preferably 5 cc / rev or less, and even more preferably 1 cc / rev or less. The capacity of the gear pump 1 can also be reduced to 0.5 cc / rev or less, or 0.1 cc / rev or less.

[0053] 3.Other The type of fluid F discharged by the fluid discharge device of this embodiment is not particularly limited. Examples of the fluid F include adhesives and paints. The fluid F may be low-viscosity (viscosity of 100 mPa·sec or less), high-viscosity (viscosity of 10 Pa·sec or more), or any of the fluids with intermediate viscosities therebetween. [Explanation of symbols]

[0054] 1 gear pump 2 Fluid supply means 3 nozzles 4 Articulated robot arm 5. Control measures 6 Rotation drive means 10 Drive gear 11 Recess 20 Driven gear 30 Housing 31 Housing body 31a Protrusion 31b Stopper 32 Front plate 33 Rear plate 40 Drive shaft 41 Recess 42 keys 50 spacer 51 Front spacer 52 Rear spacer 52a shaft 60 volts 70 Dowel F fluid double work α1 gear housing α2 fluid inlet α3 fluid introduction path α4 fluid delivery path α5 fluid outlet

Claims

1. a drive gear that is driven to rotate around an axis in the front-rear direction; a driven gear that meshes with the drive gear and rotates around an axis extending in the front-rear direction; a housing for accommodating a drive gear and a driven gear; Equipped with The housing is a housing body having a gear accommodating chamber for accommodating a drive gear and a driven gear; a front plate disposed on the front side of the housing body; A rear plate disposed on the rear side of the housing body; A gear pump configured by combining A spacer is provided in the gear accommodating chamber, which is fitted between the front plate or rear plate and the side surfaces of the driving gear and driven gear, thereby reducing the front-to-rear width of the gear accommodating chamber. A gear pump characterized by:

2. As a spacer, a front spacer fitted between the front plate and the side surfaces of the drive gear and the driven gear in the gear accommodating chamber; a rear spacer fitted between the rear plate and the side surfaces of the drive gear and the driven gear in the gear accommodating chamber; 2. The gear pump according to claim 1, further comprising:

3. The ratio T / W of the thickness (referred to as T) of the spacer in the front-to-rear direction to the front-to-rear width (referred to as W) of the gear accommodating chamber is 0.2 or more, The thickness (T) of the drive gear and the driven gear in the front-to-rear direction relative to the front-to-rear width W of the gear accommodating chamber ２ The ratio T ２ / W is set to 0.8 or less 2. The gear pump according to claim 1.

4. A gear pump according to any one of claims 1 to 3; a fluid supply means for supplying fluid to the gear pump; a nozzle for discharging fluid from the gear pump; an articulated robot arm having a nozzle fixed to its end; a control means for controlling the gear pump and the articulated robot arm; Equipped with The control means changes the rotation speed of the drive gear of the gear pump in response to the movement of the articulated robot arm. A fluid ejection device comprising:

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