JP5341671B2 - External gear pump and brake device having the same - Google Patents

Description

  The present invention relates to an external gear pump that performs pumping action by rotation of a pair of gears, and a brake device including the external gear pump.

  In Patent Document 1, a groove is formed in a closed region of the gear pump, thereby suppressing vibration and noise caused by cavitation during high rotation.

JP 2003-113781 A

  However, the above prior art cannot obtain a sufficient volumetric efficiency, resulting in a decrease in pump performance.

  An object of the present invention is to provide an external gear pump that can achieve high pump efficiency while suppressing vibration and noise.

  In order to achieve the above object, in the external gear pump of the present invention, the first communication groove that communicates the low pressure chamber and the first confinement region during the expansion stroke, the high pressure chamber and the first confinement region during the compression process, A second communication groove that communicates with the first and second communication grooves, so that the minimum value of the predetermined volume is within the first confinement region and within the blocking section where the communication with the first and second communication grooves is blocked. I made it.

  Therefore, in the present invention, high pump efficiency can be obtained while suppressing vibration and noise.

It is a side view of the gear pump housed in the housing of the first embodiment. It is a top view of the gear pump part of Example 1. It is a disassembled perspective view of the gear pump of Example 1. FIG. It is a characteristic view showing the relationship between a meshing part volume and a gear rotation angle. It is a figure showing the state of engagement of each gear at the time of the start of closing, the time of the minimum closing, and the end of closing. It is a characteristic view showing the relationship between the position of a communicating groove and the reduction margin of volumetric efficiency. It is a front view of the side plate showing the discharge side communication groove and the suction side communication groove of Example 1. It is a figure showing the meshing state of each gear and the positional relationship of each groove | channel at the time of the closing start of Example 1, the time of the minimum closing, and the end of closing. It is a front view of the side plate showing a discharge side communication groove and a suction side communication groove. 6 is a front view of a side plate showing a discharge side communication groove and a suction side communication groove of Example 2. FIG.

A first embodiment of the present invention will be described with reference to the drawings. The external gear pump 60 of the first embodiment is a pump that is applied to a brake system of an automobile, and is mounted on a known antilock brake control, vehicle behavior control, automatic brake control, or brake-by-wire system. The description is omitted because it is not particularly affected by the hydraulic circuit configuration and the control system.
(About gear pump)
1 is a side view of the gear pump 60 housed in the housing 30, FIG. 2 is a top view of the gear pump portion, and FIG. 3 is an exploded perspective view of the gear pump. As shown in FIGS. 1 to 3, the gear pump 60 is housed in a pump housing hole 37 formed in the housing 30. The gear pump 60 is provided on both sides in the axial direction of the drive gear 61 provided on the drive shaft 61A connected to a motor or the like (not shown), the driven gear 62 provided on the driven shaft 62A, and the drive shaft 61A and the driven shaft 62A. A pair of side plates 63 and 64 and a seal block 65 are formed. The drive shaft of the motor is connected to the drive shaft 61A. The side plate 63 provided with the support holes 63A and 63B and the side plate 64 provided with the support holes 64A and 64B are inserted into the drive shaft 61A and the driven shaft 62A from both axial sides. As a result, the drive gear 61 and the driven gear 62 are pivotally supported so as to mesh with each other and rotate. Further, there is a sliding surface that rotates and slides between the side plate 64 and the side surfaces of the drive gear 61 and the driven gear 62. The sliding surface seals the low pressure chamber connected to the suction passage and the high pressure chamber formed on the outer periphery of the gear pump 60 in a liquid-tight manner. The side plates 63 and 64 are made of a material having high hardness. Details regarding the shape of the side surface portion of the side plate 64 will be described later.
The side plates 63 and 64 are provided with arc-shaped notches 63C and 64C on the contact surface side with the seal block 65, respectively. The notch 63C is formed between the support holes 63A and 63B, and the notch 64C is formed between the support holes 64A and 64B. The notches 63C and 64C are formed over the entire width of the side plates 63 and 64 in the axial direction and constitute a part of the low-pressure chamber. Seal rings 66 are provided between the side plate 63 and the housing 30 and between the side plate 64 and the housing 30, respectively. The seal ring 66 is configured to liquid-tightly seal between the low pressure chamber formed in the side plates 63 and 64 and the seal block 65 and the housing 30.
The seal block 65 is provided with concave curved surfaces 65A and 65B cut out in a concave curved shape along the tooth tips of the drive gear 61 and the driven gear 62 on the contact surface side with the side plates 63 and 64. . Further, an arcuate arc groove 65C is provided across the entire width of the seal block 65 at a position between the concave curved surfaces 65A and 65B and in contact with the notches 63C and 64C, and the notches 63C and 64C and the arcs. A low pressure chamber is formed by the groove 65C.
It is designed so that a discharge side confinement region (second confinement region) is always formed between the concave curved surfaces 65A and 65B and the gears 61 and 62 regardless of the rotation angle of the gear ( (See FIG. 7). On the other hand, it is designed such that a suction side confining region (first confining region) is always formed in the meshing portion of each gear 61 and 62. Further, the volume of the brake fluid confined in the discharge side confinement region is formed to be larger than the volume of the brake fluid confined in the suction side confinement region. That is, when the gear pump 60 is driven to rotate, the flow rate of the working fluid once confined in the suction side confinement region flows out from the low pressure chamber via the discharge confinement region more than the flow rate of flow into the low pressure chamber. means. Thereby, the pressure rise by the gear pump 60 is achieved. Hereinafter, in the suction side confinement region, the mode in which the brake fluid is confined from the state opened to the high pressure chamber is referred to as a compression stroke, and the mode in which the confined fluid flows into the low pressure chamber is referred to as the stroke in which the confinement region is changed from compression to expansion. It describes.
The seal block 65 is detachably wound around the side plates 63 and 64 by the metal coil spring 67 to constitute a pump assembly, whereby the low pressure chamber communicated with the suction passage is formed by the notches 63C and 64C and the arc groove 65C. It is formed. The seal block 65 is made of an aluminum material having a hardness lower than that of the side plates 63 and 64, but may be made of a resin or the like. Moreover, although the seal block and the side plate are made of separate members, they may be made of an integral member. In this case, it goes without saying that a metal coil spring or the like is unnecessary.

(Regarding the confinement area)
As described above, the suction side confinement region is formed in the meshing portion of the gears 61 and 62. The volume of this space (hereinafter referred to as the meshing portion volume) has a characteristic of a quadratic curve that starts to decrease from the start of confinement, has an inflection point, and starts to increase as the gear rotates. FIG. 4 is a characteristic diagram showing the relationship between the meshing portion volume and the gear rotation angle, and FIG. 5 is a diagram showing the meshing state of each gear at the start of closing, at the time of minimum closing, and at the end of closing. The positions (rotation angles) at the start and end of closing of each gear 61 and 62 are determined by the meshing point of the gear according to the basic design shape. Hereinafter, the confined region in FIG. 5 is divided into A, the high pressure region located at a rotation angle before the confined region is divided into B, and the low pressure region located at a rotation angle past the confined region is divided into C. explain. “At the start of closing” means the moment when region B and region A are further defined by meshing after region C and region A are defined by meshing. When the gear rotation angle advances from this closing start angle, the area A becomes smaller than the meshing portion volume at the start of closing while the areas A, B, and C are defined, and the minimum closing is the minimum volume. It ’s an angle. Next, when the rotation angle advances from this minimum closing angle, the region A increases and the meshing portion volume increases, reaching a closing end angle that is substantially the same volume as the closing start angle. At this time, the engagement point between the region A and the region C is separated while the region B and the region A are defined, and the region A and the region C communicate with each other.
As described above, when the confinement region A is formed, the meshing portion volume in the region A is repeatedly compressed and expanded in accordance with the rotation, which may cause vibration and noise. In particular, when applied to automobile brake oil, this brake oil has a low compression rate, and a very large pressure fluctuation occurs, which may cause oil hammering and deteriorate durability. Further, when the side plate is lifted by the oil hammer, the sealing performance between the side surface of the gear and the side plate cannot be obtained, and the high pressure chamber and the low pressure chamber communicate with each other, which may cause a decrease in discharge performance. Furthermore, in the low-pressure chamber immediately after the end of the closing, the volume of the low-pressure chamber increases at a stroke by the meshing portion volume and changes to negative pressure. When the volume fluctuation amount of the low-pressure chamber is large as described above, bubbles are precipitated in the working fluid, and there is a possibility that abnormal noise is generated as the deposited bubbles disappear.

From the above viewpoint, conventionally, grooves are formed on the sliding surface of the side plate so as to have the positional relationship shown in FIG. This groove extends from the region B side and communicates with the inside of the enclosed region A, and extends from the region C side and communicates with the inside of the enclosed region A. Hereinafter, a groove that communicates the region B and the region A is referred to as a discharge-side communication groove M1, and a groove that communicates the region C and the region A is referred to as a suction-side communication groove M2. In the conventional example, from the viewpoint of preventing cavitation, the discharge side communication groove M1 extends from the inflection point to the latter half of the closing section, and after the blocking section start position passes the minimum closing angle (ie, the inflection point). It forms so that it becomes. Then, the working fluid once confined is formed so as to increase in volume in a blocking section, which is a section in which the working fluid is confined, and then communicate with the suction side communication groove M2. As a result, the volume at which the confinement is started is set to be relatively large, and after being slightly expanded in the shut-off section and communicating with the low pressure side, the volume fluctuation in the low pressure chamber is suppressed, and the cavitation is suppressed. Yes.
However, since volume fluctuation occurs in the cut-off section, there is still concern about the occurrence of cavitation. In addition, from the viewpoint of volumetric efficiency of the gear pump 60, such a design is very inefficient. FIG. 6 is a characteristic diagram showing the relationship between the position of the communication groove and the reduction in volumetric efficiency. Here, volumetric efficiency represents the relationship between the volume of the discharge side confinement region and the volume of the suction side confinement region. The larger the volume difference between the two, the smaller the decrease in volumetric efficiency. The smaller the volume, the greater the reduction in volumetric efficiency. When the communication grooves M1 and M2 are arranged at the positions as in the conventional example, a sufficient difference cannot be provided between the volume of the discharge side confinement region (see FIG. 7) and the volume of the suction side confinement region. The volumetric efficiency is greatly reduced.

  Therefore, in the first embodiment, the position of each groove is adjusted so that the volume fluctuation in the shut-off section is small and the volumetric efficiency is high, and the inflection point is provided between the closing start and the closing end. It was. FIG. 7 is a front view of the side plate showing the discharge side communication groove M1 and the suction side communication groove M2 of the first embodiment. The side surface of the side plate 63 includes a base portion 631 that does not slide contact with the side surface of each gear, and a seal portion 632 that protrudes from the base portion 631 toward the gear side and contacts the side surface of each gear. The seal portion 632 includes an annular portion 632a formed so as to surround the outer periphery of each shaft, a suction side confinement portion 632b that forms a suction side confinement region with the left and right annular portions 632a as a ground, and a seal A discharge side confinement portion 632c that forms a discharge side confinement region with the block 65; A discharge side communication groove M1 is formed on the suction side confining portion 632b on the high pressure chamber side and near the driven shaft 62A. A suction side communication groove M2 is formed on the suction side confining portion 632b on the low pressure chamber side and near the drive shaft 62A. Each of the grooves M1 and M2 has a triangular cross section and is formed so that its cross-sectional area increases toward the high pressure chamber side or the low pressure chamber side. The cross-sectional shape is not limited to a triangle, and may be a square or a curved surface. Further, the example in which the drive shaft 62A is on the left side in FIG. 7 is shown, but as shown in FIG. 9, when the drive shaft 62A is on the right side, the positional relationship between the grooves M1 and M2 may be reversed. .

FIG. 8 is a diagram showing the meshing state of each gear and the positional relationship of each groove at the start of closing, at the minimum closing time and at the end of closing, and FIG. 4 is a diagram showing the relationship between the gear rotation angle and the communication by each groove. It is. Since the discharge side communication groove M1 communicates the region B and the region A at the starting rotation angle of the suction side confinement region, the fluid is not actually confined yet. When the gear rotation angle reaches the predetermined angle θ1, the communication between the region B and the region A by the discharge side communication groove M1 is cut off, and the cut-off zone is entered. The volume of the trapped fluid when entering the shut-off zone is almost the same as or slightly larger than the minimum confinement amount. In this state, when the gear rotation angle is further increased by θ0, the minimum closing angle is reached. At this time, since the volume of the confined working fluid is originally small, the hydraulic pressure fluctuation is small even when the minimum confinement angle is reached. Further, when the gear rotation angle is increased by θ0, the blocking section is ended, and the region A and the region C are communicated by the suction side communication groove M2. At the time of this communication, since the volume confined in the shut-off section is very small, the fluctuation due to the volume increase in the low pressure chamber is also reduced, and the occurrence of vibration and cavitation can be suppressed. In addition, since the flow passage cross-sectional areas of the discharge side communication groove M1 and the suction side communication groove M2 are configured to gradually change, it is possible to suppress the occurrence of vibration and noise.
FIG. 6 is a characteristic diagram showing the relationship between the position of the communication groove and the reduction in volumetric efficiency. When the discharge side communication groove M1 and the suction side communication groove M2 are arranged at the position shown in the first embodiment, the difference between the volume of the discharge side confining region and the volume of the suction side confining region can be increased. A decrease in efficiency can be suppressed. If the decrease in volumetric efficiency can be suppressed within 5%, extremely high efficiency can be obtained as compared with the prior art. Therefore, it is desirable to define the positions of the discharge side communication groove M1 and the suction side communication groove M2 in a positional relationship that achieves a reduction in volumetric efficiency within 5%.
As described above, the following operational effects can be obtained in the first embodiment.
(1) A discharge-side communication groove M1 (first communication groove) that communicates the low-pressure chamber and the suction side confinement region (first confinement region) during the expansion stroke, and the high-pressure chamber and the suction side confinement during the compression process. An inhalation section provided with a suction side communication groove M2 (second communication groove) that communicates with the region, and within the suction side confinement region, in which the communication between the discharge side and the suction side communication grooves M1, M2 is interrupted The rotation angle has a minimum value of the predetermined volume inside, in other words, the engagement portion volume is minimum. Therefore, high volumetric efficiency can be obtained while suppressing vibration and abnormal noise.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 10 is a front view of the side plate showing the discharge side communication grooves M1a and M1b and the suction side communication grooves M2a and M2b according to the second embodiment. As shown in FIG. 10, two grooves may be formed in advance. This is because the other groove is sealed by the side surface of the gear. Thus, when applied to a seal block of a small external tandem gear pump used in a hydraulic circuit of an automobile brake system, the system can be assembled without worrying about the relationship between the drive gear and the driven gear for each system. As a result, erroneous assembly can be prevented, and the manufacturing cost can be reduced because the same parts need only be manufactured.

(Other examples)
The present invention has been described based on the embodiments. However, the specific configuration of the present invention is not limited to the configurations shown in the embodiments, and there are design changes and the like that do not depart from the gist of the invention. Are also included in the present invention. In the embodiment, the pump used in the brake system of the automobile has been described. However, a pump used in another system may be used. Further, the present invention is not limited to the configuration provided with the seal block, and can be applied without problems even to a pump that secures a discharge side confinement region between housings and the like. If the decrease in volumetric efficiency can be suppressed within 5%, extremely high efficiency can be obtained as compared with the prior art. Therefore, it is desirable to define the positions of the discharge side communication groove M1 and the suction side communication groove M2 in a positional relationship that achieves a reduction in volumetric efficiency within 5%. Specifically, by designing so as not to have an area where the volumetric efficiency reduction margin is 5% or more within the gear rotation angle range sandwiched between the gear rotation angles θ1 and θ2, the section where the volume is necessarily minimized Even if it is not provided, the same effect can be obtained.

30 Housing 37 Pump receiving hole 60 Gear pump 61 Drive gear 62 Driven gear 63 Side plate 64 Side plate 65 Seal block M1 Discharge side communication groove M1a, M1b Discharge side communication groove M2 Suction side communication groove M2a, M2b Suction side communication groove

Claims (6)

A drive gear driven by a drive source;
A driven gear that rotates by meshing with the drive gear;
A side plate having a sliding surface on which the side surfaces of both gears slide;
A first confinement region for confining brake fluid in a predetermined volume formed by the meshing of each gear, and a second confinement for confining a brake fluid amount larger than the predetermined volume formed by a tooth groove of each gear. An external gear pump that pumps brake fluid from the low pressure chamber to the high pressure chamber,
The side plate, a second communicating with the first communication groove, and the high pressure chamber during compression line extent and said first closed narrowing region which communicates with said first closed narrowing region and the low-pressure chamber during the expansion stroke With a communication groove,
The first communication groove is formed so as to face only the side surface of one gear of the gears, and the second communication groove is formed so as to face only the side surface of the other gear of the gears,
It is configured to have a minimum value of the predetermined volume within the first confinement region and within a blocking section where communication with the first and second communication grooves is blocked. External gear pump. A drive gear driven by a drive source ;
A driven gear that rotates by meshing with the drive gear;
Side plates disposed on the side surfaces of the two gears;
A closed region formed by meshing of both gears provided in the meshing region of each gear by rotation of each gear;
A brake device that includes an external gear pump that pumps brake fluid from a low-pressure chamber to a high-pressure chamber by expanding and compressing the confinement region, and generates a braking force by the pumped brake fluid.
The side plate has a first groove formed to face only the side surface of one of the gears, and a second groove formed to face only the side surface of the other gear of the gears. And
A first section communicating with the low-pressure chamber through the first groove in the first rotation angle range of the two gears; and a second section in the second rotation angle range through the second groove. A second section that communicates with the high-pressure chamber; a third section that is formed between the range in which the first section is formed and the second section and is not in communication with the low-pressure chamber and the high-pressure chamber; A brake device characterized in that the section has a rotation angle at which the engagement portion volume is minimized. A drive gear driven by a drive source;
A driven gear that rotates by meshing with the drive gear;
Side plates disposed on the side surfaces of the two gears;
A first confinement region for confining brake fluid in a predetermined volume formed by the meshing of each gear, and a second confinement for confining a brake fluid amount larger than the predetermined volume formed by a tooth groove of each gear. An external gear pump that pumps brake fluid from the low pressure chamber to the high pressure chamber,
A first communication groove that communicates the low pressure chamber and the first confinement region during the expansion stroke and a second communication channel that communicates the high pressure chamber and the first confinement region during the compression process. A communication groove,
The first communication groove is formed so as to face between a tooth tip circle and a tooth bottom circle of one of the gears, and the second communication groove is a tooth tip of the other gear of the gears. Formed to face between the circle and the root circle,
An external gear pump characterized in that the first communication groove and the second communication groove are set in a range in which a decrease in volumetric efficiency is within 5%.   The external gear pump according to claim 1,
  The external gear pump, wherein the first and second communication grooves are formed so as to face only the side surfaces of the one and the other gears in the blocking section.   The brake device according to claim 2,
  The brake device according to claim 1, wherein the first and second grooves are formed so as to face only the side surfaces of the one and the other gears in the third section.   The external gear pump according to claim 3,
  The first communication groove is formed to face between the tooth tip circle and the tooth bottom circle of the one gear at the end of closing of the first closing region,
  The second communication groove is formed so as to face between a tip circle and a root circle of the other gear at the start of closing of the first closing region. External gear pump.

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