Hydraulic module, in particular for generating pressure and / or controlling pressure in a slip-controllable braking system of a motor vehicle, and mounting method for a hydraulic module

Abstract

The invention relates, in one aspect, to a hydraulic module (10), in particular for generating pressure and / or controlling pressure in a slip-controllable braking system of a motor vehicle, and also relates to a mounting method for a hydraulic module (10). Hydraulic modules (10) comprise, inter alia, a piston pressure generator (14) having a piston (18) which is slidably accommodated in a cylinder bore (20) in a housing block (12) and can be driven to perform an axial movement A. The piston (18) delimits a working chamber (22), the volume of which changes depending on the movement direction of the piston (18). A guide gap (38) between a periphery of the piston (18) and the cylinder bore (20) is sealed against the working chamber (22) by means of a seal assembly (40a). According to the invention, a guide element (46) is provided on a side of the seal assembly (40a) which is remote from the working chamber (22), against which guide element the periphery of the piston (18) can be radially supported, with this guide element (46) being accommodated in a receiving groove (44) in the housing block (12) in such a way that it radially projects in part into the guide gap (38). The guide element (46) prevents contact between the piston (18) and the wall of the cylinder bore (20) and prevents wear. In another aspect, the invention relates to a mounting method for the hydraulic module according to the invention.

Description

[0001] Disclosure of the invention

[0002] title and / or and

[0003] State of the art

[0004] The invention relates to a hydraulic module, in particular for pressure generation and / or pressure control in a slip-controllable braking system of a motor vehicle according to the features of the preamble of claim 1, as well as to an assembly method for a hydraulic module according to the features of the preamble of claim 8.

[0005] A hydraulic module according to the invention is understood below to mean an assembly consisting of a housing block, a piston pressure generator arranged on the housing block and a gear for driving this piston pressure generator.

[0006] The piston pressure generator comprises a piston that is slidably mounted in a cylinder bore of the housing block and that defines a working chamber. This piston can be driven by the gearbox to perform an axial movement in a pressure build-up or pressure release direction. The volume of the working chamber decreases when the piston moves in the pressure build-up direction or increases when the piston is actuated in the opposite direction in the pressure release direction. The piston is driven by an electrically controlled electric motor with a motor shaft, the rotary motion of which is converted by the gearbox into an axial movement of the piston. Pressure fluid displaced from the working chamber is displaced into a brake circuit connected to the hydraulic module, thereby increasing the pressure level prevailing there.In the opposite case, the pressure level drops when the piston is actuated in the opposite direction and the volume flows from the brake circuit back to the working chamber.

[0007] Such hydraulic modules are primarily used in electronically controlled vehicle brake systems to generate and / or regulate brake pressure. They allow, among other things, rapid and reliable adjustment of the brake pressure of the wheel brakes to the slip conditions of the associated vehicle wheels, or enable brake pressure buildup when the vehicle enters an unstable driving condition or when the traffic situation in the vicinity of the vehicle requires it to avoid an accident.

[0008] The piston pressure generator is controlled by an electronic control unit and can be activated regardless of whether the driver of the vehicle indicates a braking request. Because the driver is not directly involved in the buildup of brake pressure, such braking systems are referred to as power braking systems, unlike conventional muscle-powered braking systems.

[0009] As explained, the piston of the piston pressure generator is slidably mounted in a cylinder bore of the housing block. An existing guide gap between the circumference of the piston and the wall of the cylinder bore is sealed from the working chamber by a sealing arrangement.

[0010] State of the art

[0011] A hydraulic module according to these designs is already known, for example, from the document DE 10 2019 208397A1.

[0012] In the known hydraulic module, a guide gap between the cylinder bore and the piston circumference is designed to be relatively narrow, which has the advantage that this guide gap and thus the working chamber can be well sealed and that the risk of the sealing arrangement being extruded into this guide gap due to the piston movement and thus being damaged is extremely low.

[0013] A disadvantage, however, is that from a manufacturing perspective, the production of narrow guide gaps is understandably more complex and therefore more expensive than the production of wider guide gaps. Furthermore, tolerance-related dimensional deviations in the manufacture of the piston, cylinder bore, and / or transmission components can lead to concentricity errors of the longitudinal axes of these components, angular errors, and / or a wobbling movement of the driven piston. In conjunction with narrow guide gaps, these errors can collectively lead to the piston contacting the cylinder bore wall, thereby subjecting it to effective radial forces and causing wear.

[0014] While such wear can be counteracted, for example, by a suitable coating of the cylinder bore, such a coating entails additional effort, which negatively impacts the manufacturing costs of a hydraulic module. Furthermore, these constraints influence the structural design, the manufacturing process, and the material selection for the piston.

[0015] Advantages of the invention

[0016] A hydraulic module according to the features of claim 1 has the advantage that it can be manufactured more cost-effectively than a conventional hydraulic module while maintaining unchanged quality with regard to the piston guidance and the sealing of the working chamber or the guide gap for the piston. The cost savings are based, on the one hand, on a guide gap that can now be made radially wider between the circumference of the piston and the wall of the cylinder bore, and, on the other hand, on the possible elimination of the need for a complex coating of the wall of the cylinder bore and / or the piston circumference to prevent potentially occurring wear. Furthermore, an expanded range of options regarding the selection of materials for the piston is possible. For example, a piston made of steel can be used in the future, which can also be produced more cost-effectively through forming.The components of the transmission can now also be manufactured using deep drawing technology in sufficient quality.

[0017] The aforementioned advantages are based on the use of a guide element for the piston, which is arranged in a housing-side receiving groove on a side of the sealing arrangement facing away from the working chamber. This receiving groove is formed along the inner circumference of the cylinder bore and accommodates the guide element in such a way that this guide element protrudes in sections into the guide gap between the piston circumference and the cylinder bore.

[0018] Further advantages or advantageous developments of the invention emerge from the subclaims or from the following description.

[0019] If a dimensionally elastic, diagonally slotted ring with two free and opposing ends is used as the guide element, this guide element can be easily radially preloaded and its outer diameter reduced during assembly. Using a mounting sleeve and a punch, the guide element can then be inserted into the cylinder bore and positioned in the designated receiving groove without fear of damage. Once the guide element has snapped into the designated receiving groove, it is held or trapped in place after the piston has been installed in the cylinder bore.

[0020] Due to its reasonable costs, good friction properties and resistance to brake fluids, a guide element made of PTFE is particularly suitable.

[0021] The guide element is mounted in the receiving groove for axial and radial movement. Due to its slotted design and its elasticity, it is able to compensate for tolerance-related wobbling movements of the piston, angular errors, or axial misalignment between the components of the piston drive. Contact between the piston and the cylinder bore wall is largely eliminated.

[0022] The guide element's receiving groove is stepped from the outside to the inside, forming contact shoulders against which the guide element can be radially supported. These contact shoulders limit the maximum possible expansion of the guide element and thus protect the component from excessive loads or breakage. The relative position of the contact shoulders to the longitudinal axis L limits the maximum deformation of the guide element to such an extent that no contact occurs between the piston circumference and the bore wall over the entire operating time of the hydraulic module, or that the radial forces occurring in the event of contact do not cause any significant wear to the bore wall or piston.

[0023] A section of the receiving groove with a smaller cross-section is located between the contact shoulders and a groove base of this receiving groove. This section is hydraulically connected to a pressure-medium-carrying area of ​​the housing, so that pressure medium flows to a rear side of the guide element facing away from the piston and penetrates to the piston circumference. To prevent pressure medium from penetrating the interior of the gearbox, the guide element is arranged between two sealing assemblies in an advantageous development of the invention. The sealing assemblies have pressurizable sealing lips which are brought into contact with the groove flank, the groove base or the housing block and the piston circumference by the effective pressure of the pressure medium. The sealing lips of the sealing assemblies are lubricated by the existing pressure medium and are thus protected against premature wear.In addition, the lubricated sealing arrangements ensure particularly effective sealing of the working chamber with minimal frictional forces that inhibit piston movement.

[0024] drawing

[0025] An embodiment of the invention is illustrated in the drawing and explained in detail in the following description. The drawing comprises several figures, of which

[0026] Fig.l shows a hydraulic module according to the invention in longitudinal section, while in the

[0027] Fig. 2 shows a detail X according to Fig.l in an enlargement.

[0028] This detail shows the arrangement of a guide element in the housing block of the hydraulic module on which the invention is based.

[0029] Fig.3 and

[0030] Fig.4 illustrates the assembly process of a guide element according to the invention in a receiving groove of the housing of the hydraulic module, wherein in Fig.3 a housing block, a mounting sleeve and a guide element are shown in an exploded view in 3-dimensional form, while in Fig.4 a section of the housing block with the mounting sleeve inserted into the cylinder bore and the guide element inserted therein is shown in longitudinal section.

[0031] Corresponding components are provided with uniform reference symbols in the individual figures.

[0032] Description of an embodiment

[0033] The hydraulic module (10) shown in Fig. 1 comprises a housing block (12) with a piston pressure generator (14) arranged thereon, as well as a gear (16) for driving a piston (18) of this piston pressure generator (14). A cylinder bore (20) is formed on the housing block (12), in which the piston (18) is received and movably guided for a reciprocating axial movement, as indicated by the double arrow A. This piston (18) is designed as a hollow piston and, with its closed end or

[0034] Piston head a working chamber (22) filled with hydraulic pressure medium.

[0035] The components of the gear mechanism (16) that actuates the piston (18) are located inside the hollow piston. These comprise a spindle (24) and a spindle nut (26) surrounding this spindle (24). The spindle (24) is connected to the piston (18) at its end located in the hollow interior of the piston (18) in a rotationally fixed manner. A spindle pin engages in a blind-hole-like pin receptacle on the inside of the piston crown, thus establishing a frictional connection between the components.

[0036] On the outer circumference of the spindle (24) and the inner circumference of the spindle nut (26), mutually associated and spirally circulating raceway sections of a recirculating ball track are formed. Recirculating balls, which are accommodated in this recirculating ball track, establish a mechanical engagement between the spindle (24) and the spindle nut (26).

[0037] The spindle nut (26) is rotatably mounted inside the cylinder bore (20) by a bearing (28). The bearing is designed, for example, as a rolling bearing and is housed in a bearing seat of a bearing plate (30) which is anchored circumferentially in the cylinder bore (20) of the housing block (12). The bearing plate (30) has a central recess in which a drive device (32) is arranged, which is supported on the inner ring of the rolling bearing and is coupled in a rotationally fixed manner to the spindle nut (26). This drive device (32) projects to the left of the hydraulic module (10) as shown in Fig. 1 and serves to transmit a rotational movement, for example from a motor / gearbox unit (not shown), to the spindle nut (26).

[0038] At its open end, opposing support elements (34) are formed on the piston (18). These project radially outward from the piston (18) in a wing-like manner and engage in associated guide grooves (36) on the housing block side, which extend in the direction of a longitudinal axis L of the cylinder bore (20) in the housing block (12). The support elements (34) are supported in the circumferential direction on the flanks of the guide grooves (36), so that the piston (18) and the spindle (24) coupled to it cannot follow the rotary movement of the spindle nut (26). As a result, the spindle drive or gear (16) described above converts a rotary movement of the spindle nut (26) into an axial movement of the piston (18).

[0039] Depending on the direction of rotation, the piston (18) is driven in a pressure build-up direction or in an opposite pressure release direction. In the pressure build-up direction, the piston (18) moves into the working chamber (22) and displaces the pressure fluid contained therein into a connected brake circuit (not visible). If the piston (18) moves in the opposite direction, i.e., in the pressure release direction, the volume of the working chamber (22) increases and pressure fluid flows back from the brake circuit into this working chamber (22), correspondingly reducing the pressure level in the connected brake circuit.

[0040] As explained, the piston (18) is guided directly in the housing block (12). For this purpose, a circumferential guide gap (38) is provided between a circumference of the piston (18) and a wall of the cylinder bore (20). The latter is sealed off from the working chamber (22) in order to enable pressure changes in the working chamber (22) due to the described axial movement of the piston (18). The measures taken according to the invention for guiding the piston (18) in the cylinder bore (20) and for sealing the guide gap (38) between the piston (18) and the cylinder bore (20) are shown in detail X and are explained below with reference to a detailed description of Fig. 2, which shows this detail X in an enlarged view.

[0041] In the exemplary embodiment, the aforementioned guide gap (38) is sealed from the working chamber (22) by two sealing assemblies (40a; 40b). Both are each accommodated in an associated annular groove (42a, 42b) formed at an axial distance from one another on the inner wall of the cylinder bore (20). The first sealing assembly (40a) or high-pressure seal facing the working chamber (20) is designed as a multi-chamber sealing ring, the individual chambers of which are open towards the working chamber (22). Pressurized fluid from this working chamber (22) can thus penetrate into the chambers and apply or press the sealing assembly (40a) against the flanks of the surrounding annular groove (42a) or against the piston circumference.

[0042] The second sealing arrangement (40b) is arranged on the side of the first sealing arrangement (40a) facing away from the working chamber (22) and is designed as a lip seal with two sealing lips. A first sealing lip rests against the base of the annular groove (42b), and a second sealing lip also rests against the piston circumference. The closed side of the second sealing arrangement (40b) is axially supported on the flank of the annular groove (42b) facing away from the working chamber.

[0043] Between the two annular grooves (42a, 42b) for the sealing arrangements (40a, b), a likewise annular receiving groove (44) for receiving a guide element (46) for the piston (18) is arranged on the wall of the cylinder bore (20). This receiving groove (44) is stepped once at a right angle in its cross-section in its radial direction of extension, i.e. starting from its side open towards the piston (18) inwards, and is thus divided into two merging groove sections of different axial extent or width. A transition between the groove sections forms contact shoulders (48) on which the guide element (46) received in the wider groove section of the receiving groove (44) is supported at the edges, while covering the narrower groove section of the receiving groove (44) with a central region.

[0044] The guide element (46) has, for example, a rectangular cross-section and protrudes radially from the receiving groove (44) in sections into the guide gap (38) between the piston (18) and the cylinder bore (20). The groove section of the receiving groove (44) in which the guide element (46) lies is wider, viewed in the direction of the longitudinal axis L of the hydraulic module (10), than the section of the guide element (46) projecting into this receiving groove (44), so that the latter is accommodated in the receiving groove (44) with lateral and axial play in both spatial directions.

[0045] The narrower groove section of the receiving groove (44) is located on the side of the contact shoulders (48) facing away from the piston (18) and extends radially between these contact shoulders (48) and a base of the receiving groove (44). This groove section is in contact, not visible in the drawing, with cavities in the housing block (12) in which pressure medium at atmospheric pressure is located. These cavities, for example channels or chambers, are preferably connected to a pressure medium reservoir. Pressure medium at atmospheric pressure thus passes through the narrower groove section of the receiving groove (44) to a rear side of the guide element (46) facing away from the piston (18).

[0046] This guide element (46) is made of a brake fluid-resistant material with good sliding properties, such as PTFE. It is designed as a single-slit ring whose free ends are opposite one another. A slot S through the guide element (46) runs diagonally to the longitudinal axis L. The end faces of the free ends of the slot S are radially beveled in the same direction, i.e., from outside to inside, so that even with slight radial pressure on the circumference of the guide element (46), the two ends slide over each other, consequently reducing the outer diameter of the guide element (46) and simultaneously increasing its radial preload.Conversely, the slot S traversing the guide element (46) also allows for radial expansion of the guide element (46), for example, if the piston (18) resting against it exerts radial forces on the inner circumference during its actuation due to manufacturing tolerances of the components of the transmission (16). In the installed state, the maximum possible expansion of the guide element (46) is, as mentioned, limited by the contact shoulders (48) of the receiving groove (44), thereby effectively protecting the guide element (46) against overload or damage.

[0047] In order to prevent the piston (18) from coming into contact with the wall of the cylinder bore (20) of the housing block (12), the dimensions of the guide element (46) and the position of the contact shoulders (48) of the receiving groove (44) are coordinated with one another in such a way that the guide element (46) projects radially in sections into the guide gap (38) between the piston (18) and the wall of the cylinder bore (20) when it rests against these contact shoulders (48) with its rear side facing away from the piston.

[0048] Through the slot S, pressure medium enters the interior of the guide ring (46) facing the piston (18). Furthermore, the pressure medium flows along the outside or side of the guide element (46) to the piston circumference and spreads from there toward the two sealing assemblies (40a, b). The sealing lips of these sealing assemblies (40a, b) resting on the piston circumference, as well as the guide ring (46), are thereby lubricated, cause little frictional resistance on the piston (18), and are subject to minimal wear.

[0049] The sealing groove (42a) divides the cylinder bore (20) into a bore section facing the working chamber (22) and a bore section facing away from the working chamber (22). The bore section facing the working chamber can be designed with a slightly larger inner diameter than the bore section of the cylinder bore (20) facing away from the working chamber, so that the guide gap (38) between the piston (18) and the wall of the cylinder bore (20) is somewhat larger on the side facing the working chamber and allows the piston (18) to assume a certain inclination relative to the longitudinal axis L during actuation without the piston circumference coming into contact with the wall of the cylinder bore (20). The maximum inclination of the piston (18) and thus the enlargement of the inner diameter of the cylinder bore (20) in the bore section facing the working chamber is determined by the structural design of the guide ring (46) and its associated receiving groove (44).

[0050] Fig. 3 and Fig. 4 illustrate the assembly process for the guide element. Fig. 3 shows, in a three-dimensional exploded view, the previously explained housing block (12) with a cylinder bore (20) formed thereon for the piston (18) of a piston pressure generator (14), a mounting sleeve (50) with a stepped outer diameter that is provided so that it can be inserted into this cylinder bore (20), and finally the guide element (46) with the continuous slot S, which is to be placed in the receiving groove (44) formed on the inner circumference of the cylinder bore (20) with the aid of the mounting sleeve (50). The guide element (46) is in the relaxed state in the illustration; the two free ends of the guide element (46) are spaced apart from one another, and the slot S, which is aligned diagonally to the longitudinal axis L, is thus open.

[0051] Fig. 4 shows, in an enlarged detail, the section of the housing block (12) with the cylinder bore (20) in longitudinal section. This cylinder bore (20) penetrates the housing block (12) from a first flat or upper side (52) to a plane-parallel, opposite, second flat or lower side (54) of this housing block (12). After the cylinder bore (20) has been produced, a total of three annular grooves (42a, 42b, 44) are formed along the inner wall of the cylinder bore (20) using a suitable tool. These three grooves (42a, 42b, 44) are arranged in a region of the cylinder bore (20) close to the underside, each at a mutual distance, viewed in the direction of the longitudinal axis L of the cylinder bore (20).The two outer grooves (42a, 42b) have a rectangular cross-section with continuous lateral flanks and are intended to receive the sealing arrangements (40a, 40b) disclosed in connection with the description of Figure 2.

[0052] The third annular or receiving groove (44), located between the two outer annular grooves (42a, 42b), penetrates radially less deeply into the housing block (12) than the two outer annular grooves (42a, 42b). In cross-section, starting from the inner wall of the cylinder bore (20), it is offset radially outwards at a right angle and is therefore divided into a first groove section, which is wider when viewed in the direction of the longitudinal axis of the cylinder bore, and a second groove section, which is narrower in comparison and forms the groove base. Both groove sections merge into one another, with the transition being designed at a right angle, as explained, and thus having circumferential bearing shoulders (48) concentric with the inner wall of the cylinder bore (20) (Fig. 2).

[0053] The mounting sleeve (50) is inserted into the cylinder bore (20) prepared in this way. It is made, for example, of a plastic material and has a radially projecting flange (50a) at one end, with which it lies flush against the upper side (52) of the housing block (12). A shaft (50b) of the mounting sleeve (50), which adjoins the flange (50a), extends into the cylinder bore (20) and lies flush against its wall. The extension of the shaft (50b) is dimensioned such that the mounting sleeve (50), in the installed state, ends behind the first annular groove (42b) for the first sealing arrangement (40b) and immediately in front of the receiving groove (44) for the guide element (46), as seen in the direction of insertion.

[0054] An insertion bevel (50c) is formed in the flange area of ​​the mounting sleeve (50), the inner diameter of which decreases continuously from the outside to the inside of the mounting sleeve (50). At the opening to the outside, the insertion bevel (50c) has an inner diameter that is slightly larger than the outer diameter of a radially non-preloaded guide element (46). In this non-preloaded state, the free ends of the guide element are located opposite each other at a small distance, and the slot S through the guide element (46) is open.

[0055] If a force directed along the longitudinal axis L of the cylinder bore (20) is applied to this guide element (46) from the outside, using a punch or the like, this guide element (46) slides along the insertion bevel, and the aforementioned slot S begins to close. Because the end faces of the guide element (46) are radially beveled in the same direction, they slide over one another as soon as they come into contact, so that the outer dimension of the guide element (46) gradually decreases until it corresponds to the inner diameter of the mounting sleeve (50) in the region of its shaft (50b). At the same time, the guide element (46) is radially preloaded.

[0056] The guide element (46), thus preloaded, is advanced further along the shaft (50b) into the interior of the cylinder bore (20) and finally beyond the opposite end of this shaft (50b). As soon as the guide element (46) completely emerges from the mounting sleeve (50), the preload is released, and the guide element (46) snaps into the provided receiving groove (44), which is formed directly at the end of the shaft (50b) of the mounting sleeve (50) on the wall of the cylinder bore (20).

[0057] With a remaining radial preload, the guide element (46) is supported circumferentially on the contact shoulders (48) of the receiving groove (44) and protrudes in sections beyond the opening of this receiving groove (44) into the interior of the cylinder bore (20), as shown in Fig.2.

[0058] The plunger and mounting sleeve (50) are no longer required and can be removed from the housing block (12) or the cylinder bore (20). The piston (18) is then inserted into the

[0059] Cylinder bore (20). A transition from the piston crown to the piston skirt is provided with a radius or a phase, whereby the piston (18) slightly widens the guide element (46) and thus further preloads it as soon as it engages with it. In a final assembly position, the guide element (46) is fixedly positioned in the receiving groove (44). It encloses the piston (18) circumferentially and supports this piston (18) radially in the cylinder bore (20) when it is moved back and forth in the cylinder bore (20) driven by the gear (16).

[0060] Of course, changes or additions to the described embodiment are conceivable without departing from the scope of protection limited by the following claims.

Claims

Claims:

1. Hydraulic module (10), in particular for generating and / or controlling brake pressure in a slip-controlled vehicle brake system, comprising a housing block (12) in which a cylinder bore (20) is formed, a piston (18) of a piston pressure generator (14) received in the cylinder bore (20), which delimits a working chamber (22), and a transmission (16) by which the piston (18) can be driven to an axial movement A in a pressure build-up direction or in an opposite pressure reduction direction, wherein a volume of the working chamber (22) decreases when the piston (18) moves in the pressure build-up direction or increases when the piston (18) is driven in the pressure reduction direction, and wherein a circumferential guide gap (38) is provided between a circumference of the piston (18) and a wall of the cylinder bore (20), which is sealed to the working chamber (22) by a sealing arrangement (40a), characterized in thatthat a guide element (46) is provided on one side of the sealing arrangement (40a) facing away from the working chamber (22), with which the piston (18) can be supported radially around its circumference in the cylinder bore (20), wherein the guide element (46) is received in a receiving groove (44) on the wall of the cylinder bore (20) such that the guide element (46) projects radially into the guide gap (38) in sections. Hydraulic module according to claim 1, characterized in that the guide element (46) is a form-elastic, once-slotted ring element with two free and opposite ends. Hydraulic module according to claim 1 or 2, characterized in that the guide element is made of PTFE or a brake fluid-resistant plastic. Hydraulic unit according to any one of claims 1 to 3, characterized in that the receiving groove (44) of the guide element (46) is located between the first working chamber (22), which faces directly towards the working chamber. A sealing arrangement (40a) and a second sealing arrangement (40b) located remote from the working chamber (22). Hydraulic module according to one of claims 1 to 4, characterized in that the receiving groove (44) has a stepped cross-section from the outside to the inside and forms internal contact shoulders (48) on which the guide element (46) can be radially supported. Hydraulic module according to claim 5, characterized in that that a groove section of the receiving groove (44), which is formed between the mounting shoulder (48) and a groove base, is in contact with a pressure medium-carrying cavity on the housing block (12).

7. Hydraulic module according to one of claims 1 to 6, characterized in that the guide element (46) is axially The game is recorded in the recording space (44).

8. Assembly procedure for a hydraulic module according to one of the Claims 1 to 7, characterized by: Providing a housing block (12) with a cylindrical bore (20) formed thereon and a receiving groove (44) for a guide element (46) inside this cylindrical bore (20), Inserting a mounting sleeve (50) into the cylinder bore (20), inserting a guide element (46) into the mounting sleeve (50) and applying a thrust force to the guide element (46) in the direction of a longitudinal direction L of the cylinder bore (20) until the guide element (46) exits the mounting sleeve (50) at the opposite end and snaps into the associated receiving groove (44).

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