CN113757106B

CN113757106B - Multi-gear hydraulic pump

Info

Publication number: CN113757106B
Application number: CN202111084538.1A
Authority: CN
Inventors: 张青军
Original assignee: Hebei Hengsheng Pumps Co ltd
Current assignee: Hebei Hengsheng Pumps Co ltd
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2023-05-12
Anticipated expiration: 2041-09-16
Also published as: CN113757106A

Abstract

The invention provides a multi-gear hydraulic pump, which relates to the technical field of hydraulic pumps and aims to solve the problems that when the existing multi-gear hydraulic pump is used, a protection structure is not perfect enough, the internal structure is easy to damage when the existing multi-gear hydraulic pump is impacted, and oil leakage is easy to occur after long-time use; the main body is a multi-gear hydraulic pump body, and the side edge of the main body is of a rectangular structure; the auxiliary grooves are formed in the two ends of the protection piece. The guard piece is used for installing in the main part outside for the guard piece can protect the main part all-round, when making this device meet the impact, can be through the guard piece atress, and then reduce the local impact force that receives of main part, and the main part appears the oil leak in the time of the back of using for a long time, makes oil can with the inside contact of guard piece, if leak oil in a large number, the inside that oil can enter into the collecting vat, also can not discharge outwards in a large number.

Description

Multi-gear hydraulic pump

Technical Field

The invention belongs to the technical field of hydraulic pumps, and particularly relates to a multi-gear hydraulic pump.

Background

The multi-gear hydraulic pump is a multi-gear pump, and refers to a gear pump with the same transmission shaft for driving two or more than two independent working gears. The pumps are often housed together in a single housing. Compact structure, small size, and convenient overall arrangement of the host. The method is widely applied to construction engineering machinery.

For example, application number: CN201710801977.7 relates to a multiple heavy-duty gear pump with a lightweight structural design, comprising a front cover, more than one middle pump body and a rear pump body which are sequentially connected from front to back; the gear pump comprises a gear pump body, a driving gear, a driven gear, a first main shaft mounting hole, a second main shaft mounting hole, a first driven shaft mounting hole and a second driven shaft mounting hole, wherein the first main shaft mounting hole, the second main shaft mounting hole, the first driven shaft mounting hole and the second driven shaft mounting hole are formed in the rear of the driving gear and the driven gear in the middle pump body, and a first connecting cavity for communicating the first main shaft mounting hole, the second main shaft mounting hole, the first driven shaft mounting hole and the second driven shaft mounting hole is formed in the middle pump body.

Based on prior art discovery, current multi-gear hydraulic pump is when using, and protective structure is not perfect enough, when meetting the striking, damages inner structure easily, and the phenomenon of oil leak appears easily after long-time use, and current multi-gear hydraulic pump is in the use, can't convenient fixed mounting protective structure, and protective structure appears not hard up easily after long-time use.

Disclosure of Invention

In order to solve the technical problems, the invention provides a multi-gear hydraulic pump, which aims to solve the problems that the existing multi-gear hydraulic pump is not perfect in protection structure, is easy to damage the internal structure when in collision and is easy to leak oil after long-time use, and the existing multi-gear hydraulic pump cannot be used for conveniently and fixedly installing the protection structure, and the protection structure is easy to loosen after long-time use.

The invention discloses a multi-gear hydraulic pump, which is characterized by comprising the following specific technical means:

a multi-gear hydraulic pump comprises a main body, a protective piece, an auxiliary groove, a connecting piece, a bottom piece, a mounting piece and a supporting piece; the main body is a multi-gear hydraulic pump body, and the side edge of the main body is of a rectangular structure; the auxiliary grooves are arranged at two ends of the protective piece, and sealing strips outside the auxiliary grooves are in contact with the main body; the bottom piece is positioned at two sides of the bottom of the protection piece, and two ends of the bottom piece are embedded into the fixing groove at the bottom; the bottom of the plugboard is inserted into the slot of the bottom piece, and fixing blocks are inserted into the limit slots on two sides of the slot; the installation parts are sleeved on the outer sides of the protection parts, and the reflecting plates on the side edges of the installation parts are distributed in a staggered manner; the supporting piece is arranged at the bottom of the mounting piece, and the top end of the connecting rod of the supporting piece is inserted into the bottom groove;

the protection piece comprises a fixing groove, a collecting groove and a clamping groove, the protection piece is of a T-shaped structure, and the inner side of the protection piece is of an arc-shaped structure; the inner sides of the two ends of the protective piece are provided with fixing grooves which are of T-shaped structures; the inside of the protective piece is provided with uniformly arranged collecting grooves which are of L-shaped structures, and the included angle of the inside of the collecting grooves is of an inclined structure; the guard is mounted on both sides of the main body;

the connecting piece comprises a plugboard, a stress groove and a fixed block, the connecting piece is of an I-shaped structure, and the plugboard is arranged at the bottom of the connecting piece; the inserting plate is of a rectangular plate-shaped structure, and stress grooves which are uniformly arranged are formed in two sides of the bottom of the inserting plate; the stress groove is of a T-shaped structure, and a spring is arranged in the stress groove; the connecting piece is installed at the side of guard piece, and the both ends embedding of connecting piece is in the inside of fixed slot.

Further, the main body comprises a connecting plate and a clamping block, the top end of the main body is provided with the connecting plate, and the connecting plate is of a plate-shaped structure; the side of main part is equipped with two symmetrical structure's fixture block, and the fixture block is wedge structure.

Further, the protection piece further comprises clamping grooves, the clamping grooves are of wedge-shaped structures, the clamping grooves are formed in two sides of the inside of the protection piece, and clamping blocks are embedded in the clamping grooves.

Further, the auxiliary groove comprises a sealing strip, and the sealing strip is arranged on the lateral side of the outer end of the auxiliary groove; the sealing strip is of a wedge-shaped structure, and is made of rubber.

Further, the connecting piece further comprises a fixing block, wherein the fixing block is of a T-shaped structure, and the outer end of the fixing block is of a wedge-shaped structure; the inner end of the fixed block is embedded into the stress groove, and the inner end of the fixed block is contacted with the spring.

Further, the bottom piece comprises a slot and a limiting groove, the bottom piece is of an I-shaped structure, the slot is arranged in the middle of the bottom piece, and two sides of the top end of the slot are of inclined structures; limiting grooves which are uniformly arranged are formed in two sides of the bottom of the slot, and the limiting grooves are of rectangular structures.

Further, the mounting piece comprises a reflecting plate and a bottom groove, the mounting piece is of two U-shaped plate structures, and the reflecting plates are mounted on the inner sides of two ends of the mounting piece through connecting ropes; the reflecting plate is of a rectangular plate-shaped structure, and the inner side of the reflecting plate is of an arc-shaped structure; the bottom corner position of installed part is equipped with the kerve, and the kerve is circular structure.

Further, the supporting piece comprises a connecting rod, the supporting piece is of a rectangular structure, two sides of the supporting piece are of an inclined structure, and the middle position of the supporting piece is of a rectangular structure; four connecting rods are arranged at the corner positions of the top end of the supporting piece, and the connecting rods are of cylindrical structures.

Compared with the prior art, the invention has the following beneficial effects:

1. in the device, the protecting piece is arranged on the outer side of the main body, so that the protecting piece can protect the main body in all directions, when the device encounters impact, the protecting piece can bear force, the local impact force borne by the main body is reduced, oil can contact with the inside of the protecting piece when the main body leaks oil after long-time use, if a large amount of oil leaks, the oil can enter the inside of the collecting tank, and cannot be discharged outwards, the fixing groove is used for embedding the connecting piece and the bottom piece, so that the two protecting pieces can be effectively pulled and fixed and then are tightly connected together, loosening does not occur after the device is used for a long time, the collecting tank is used for the oil due to the leakage, and the clamping groove is used for being arranged inside the protecting piece, so that the clamping block can be inserted into the inside of the clamping groove after the protecting piece is installed, and further the fixing is assisted and strengthened;

2. in this device, the connecting piece has been set up, the connecting piece is used for embedding its both ends at the fixed slot inside, and then make the connecting piece can link together the guard shield, and then strengthen fixedly, make the concatenation that the guard shield can stabilize together, and then strengthen fixedly, avoid appearing becoming flexible after long-time use, the connecting piece is I shape structure, in order to insert the fixed slot inside of both sides guard shield simultaneously, and the picture peg is then used for inserting inside the slot, make the connecting piece can be in the same place fixedly with the firm connection of bottom part, the atress groove is used for installing the fixed block through the spring, make the fixed block can receive the outside removal of spring power, the fixed block has played the effect of inserting spacing inslot, make the picture peg insert after, can be more firm, be difficult for extracting more.

Drawings

Fig. 1 is a schematic perspective view of the present invention.

Fig. 2 is a schematic bottom view of the present invention.

Fig. 3 is a schematic view of an exploded structure of the present invention.

Fig. 4 is a schematic view of the main body exploded structure of the present invention.

Fig. 5 is an exploded and partially sectioned schematic view of the connector of the present invention.

Fig. 6 is a partially enlarged schematic view of the portion a of the present invention drawn from fig. 5.

Fig. 7 is an exploded bottom view of the mount of the present invention.

In the figure, the correspondence between the component names and the drawing numbers is:

1. a main body; 101. a connecting plate; 102. a clamping block; 2. a guard; 201. a fixing groove; 202. a collection tank; 203. a clamping groove; 3. an auxiliary groove; 301. a sealing strip; 4. a connecting piece; 401. inserting plate; 402. a stress groove; 403. a fixed block; 5. a base member; 501. a slot; 502. a limit groove; 6. a mounting member; 601. a reflection plate; 602. a bottom groove; 7. a support; 701. and (5) connecting a rod.

Detailed Description

Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit the scope of the invention.

In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," "tail," and the like are used as an orientation or positional relationship based on that shown in the drawings, merely to facilitate description of the invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "connected," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

Examples:

as shown in fig. 1 to 7:

the invention provides a multi-gear hydraulic pump, which comprises a main body 1, a protection piece 2, an auxiliary groove 3, a connecting piece 4, a bottom piece 5, a mounting piece 6 and a supporting piece 7; the main body 1 is a multi-gear hydraulic pump body, and the side edge of the main body 1 is of a rectangular structure; the auxiliary grooves 3 are arranged at the two ends of the protective piece 2, and the sealing strips 301 outside the auxiliary grooves 3 are contacted with the main body 1; the bottom piece 5 is positioned at two sides of the bottom of the protection piece 2, and two ends of the bottom piece 5 are embedded into the fixed groove 201 at the bottom; the bottom of the plugboard 401 is inserted into the slot 501 of the bottom piece 5, and the fixing blocks 403 are inserted into the limit grooves 502 on two sides of the slot 501; the mounting pieces 6 are sleeved on the outer sides of the protection pieces 2, and the reflecting plates 601 on the side edges of the mounting pieces 6 are distributed in a staggered mode; the supporting member 7 is installed at the bottom of the installation member 6, and the top end of the connecting rod 701 of the supporting member 7 is inserted into the inside of the bottom groove 602;

the protection piece 2 comprises a fixed groove 201, a collecting groove 202 and a clamping groove 203, wherein the protection piece 2 is of a T-shaped structure, and the inner side of the protection piece 2 is of an arc-shaped structure; the inner sides of the two ends of the protection piece 2 are provided with fixing grooves 201, and the fixing grooves 201 are of T-shaped structures; the inside of the protection piece 2 is provided with uniformly arranged collecting grooves 202, the collecting grooves 202 are of L-shaped structures, and the included angles inside the collecting grooves 202 are of inclined structures; the protection pieces 2 are arranged on two sides of the main body 1, the protection pieces 2 are arranged on the outer side of the main body 1, so that the protection pieces 2 can protect the main body 1 in all directions, when the device encounters impact, the protection pieces 2 can bear force, the local impact force of the main body 1 can be reduced, and when oil leakage occurs after the main body 1 is used for a long time, oil can contact with the inside of the protection pieces 2, if a large amount of oil leakage occurs, the oil can enter the inside of the collecting tank 202 and cannot be discharged outwards, the fixing tank 201 is used for embedding the mounting connecting pieces 4 and the bottom piece 5, so that the two protection pieces 2 can be effectively pulled and fixed, and then are tightly connected together, and after the device is used for a long time, the loosening does not occur, and the collecting tank 202 is used for the oil due to the leakage;

the connecting piece 4 comprises an inserting plate 401, a stress groove 402, a fixing block 403 and an I-shaped structure, wherein the inserting plate 401 is arranged at the bottom of the connecting piece 4; the plugboard 401 is of a rectangular plate-shaped structure, and stress grooves 402 which are uniformly arranged are formed in two sides of the bottom of the plugboard 401; the stress groove 402 is of a T-shaped structure, and a spring is arranged in the stress groove 402; the connecting piece 4 is installed at the side of guard piece 2, and the both ends embedding of connecting piece 4 is in the inside of fixed slot 201, connecting piece 4 is used for embedding its both ends in the inside of fixed slot 201, and then make connecting piece 4 can link together guard piece 2, and then strengthen fixedly, make guard piece 2 splice together that can be firm, and then strengthen fixedly, avoid appearing becoming flexible after long-time use, connecting piece 4 is I-shaped structure, in order to insert the fixed slot 201 inside of both sides guard piece 2 simultaneously, and picture peg 401 is used for inserting inside slot 501, make connecting piece 4 can be in the same place fixedly with the firm connection of bottom part 5, stress groove 402 is used for through spring installation fixed block 403, make fixed block 403 can receive spring power outwards to remove.

The main body 1 comprises a connecting plate 101 and a clamping block 102, the connecting plate 101 is arranged at the top end of the main body 1, and the connecting plate 101 is of a plate-shaped structure; the side of main part 1 is equipped with two symmetrical structure's fixture block 102, and the fixture block 102 is wedge structure, and connecting plate 101 is used for establishing on main part 1 top for main part 1 can firm installation use, and fixture block 102 is used for establishing at main part 1 side, makes after protector 2 installs, and fixture block 102 can insert the inside fixed of draw-in groove 203, and then supplementary fixed protector 2.

Wherein, the protection piece 2 further comprises a clamping groove 203, the clamping groove 203 is of a wedge-shaped structure, the clamping groove 203 is arranged on two sides of the inside of the protection piece 2, the clamping block 102 is embedded in the clamping groove 203, and the clamping groove 203 is arranged inside the protection piece 2, so that after the protection piece 2 is installed, the clamping block 102 can be inserted into the clamping groove 203, and further the fixing is assisted and strengthened.

Wherein, the auxiliary groove 3 comprises a sealing strip 301, and the sealing strip 301 is arranged at the side edge of the outer end of the auxiliary groove 3; the sealing strip 301 is of a wedge-shaped structure, the sealing strip 301 is made of rubber, the auxiliary groove 3 is arranged on the side edge of the protection piece 2, so that the installation structure can pass through, and the sealing strip 301 is in contact with the side edge of the main body 1, so that sealing is assisted.

The connecting piece 4 further comprises a fixing block 403, wherein the fixing block 403 is of a T-shaped structure, and the outer end of the fixing block 403 is of a wedge-shaped structure; the inner of fixed block 403 is embedded in the inside of atress groove 402, and the inner and the spring of fixed block 403 contact, and fixed block 403 has played the inside effect of inserting spacing groove 502 for after picture peg 401 inserts, can be more firm, be difficult for extracting more.

The bottom piece 5 comprises a slot 501 and a limiting slot 502, the bottom piece 5 is of an I-shaped structure, the slot 501 is arranged in the middle of the bottom piece 5, and two sides of the top end of the slot 501 are of an inclined structure; the bottom both sides of slot 501 are equipped with evenly arranged spacing groove 502, and spacing groove 502 is rectangular structure, and bottom piece 5 is used for installing in the fixed slot 201 inside of bottom for guard piece 2 can be firmly pulled fixedly, and slot 501 is then used for inserting picture peg 401, makes can fix together between connecting piece 4 and the bottom piece 5, and spacing groove 502 is used for inserting installation fixed block 403, makes picture peg 401 unable convenient pull out, and then firm fixed.

Wherein, the mounting piece 6 comprises a reflecting plate 601 and a bottom groove 602, the mounting piece 6 is of two U-shaped plate structures, and the reflecting plate 601 is arranged on the inner sides of two ends of the mounting piece 6 through connecting ropes; the reflecting plate 601 has a rectangular plate structure, and the inner side of the reflecting plate 601 has an arc structure; the bottom corner position of the installation piece 6 is provided with a bottom groove 602, the bottom groove 602 is of a circular structure, the installation piece 6 is used for driving the reflecting plate 601 to be installed on the outer sides of the main body 1 and the protection piece 2, when the main body 1 transmits sound, the sound can be rebounded by the inner side of the reflecting plate 601, and further the sound transmission is reduced, and the bottom groove 602 is used for installing the connecting rod 701.

The supporting piece 7 comprises a connecting rod 701, the supporting piece 7 is of a rectangular structure, two sides of the supporting piece 7 are of an inclined structure, and the middle position of the supporting piece 7 is of a rectangular structure; the top corner position of support piece 7 is equipped with four connecting rods 701, and connecting rod 701 is cylindrical structure, and support piece 7 has played this device when using, and support piece 7 can be installed according to the demand for connecting rod 701 can insert in the inside of kerve 602, and then is fixed with the firm support of main part 1.

When in use, the utility model is characterized in that: when needs use this device, can be earlier through the outside of manpower control guard 2 installation in main part 1, make guard 2 can protect main part 1, make the fixture block 102 of main part 1 can go into and go out to the inside of draw-in groove 203, and then make guard 2 can be by supplementary fixed mounting, make guard 2 can protect main part 1, avoid main part 1 directly to receive the impact, if main part 1 appears the oil leak in time, fluid can directly enter into the inside of collecting vat 202, make fluid can not spill, then install through manpower control bottom piece 5, the both ends of first control bottom piece 5 insert the fixed slot 201 inside of bottom, then the connecting piece 4 installation at control top, make picture peg 401 at connecting piece 4 bottom can aim at slot 501, then control connecting piece 4 insert the fixed slot 201 inside at top, then push down connecting piece 4, make connecting piece 4 can be embedded into the fixed slot 201 inside, picture peg 401 inserts the inside of slot 501 simultaneously, and fixed block 403 then receives the internal compression automatically force, and then compress the spring, after connecting piece 4 embeds, make the inside of connecting piece 403 can be followed by the fixed plate 601 make the sound and make the inside of sound-absorbing plate 2 make the sound-emitting at the bottom piece 2, can make the inside of the sound-emitting device with the fixed plate 601 when the fixed plate is installed to the fixed bottom piece is contacted with the fixed plate 2.

The embodiments of the invention have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A multi-gear hydraulic pump, characterized by: comprises a main body (1), a protective piece (2), an auxiliary groove (3), a connecting piece (4), a bottom piece (5), a mounting piece (6) and a supporting piece (7); the main body (1) is a multi-gear hydraulic pump body, and the side edge of the main body (1) is of a rectangular structure; the auxiliary grooves (3) are arranged at two ends of the protective piece (2), and sealing strips (301) at the outer sides of the auxiliary grooves (3) are contacted with the main body (1); the bottom piece (5) is positioned at two sides of the bottom of the protection piece (2), and two ends of the bottom piece (5) are embedded into the fixed groove (201) at the bottom; the bottom of the plugboard (401) is inserted into the slot (501) of the bottom piece (5), and the fixing blocks (403) are inserted into the limit grooves (502) on two sides of the slot (501);

the mounting piece (6) comprises a reflecting plate (601) and a bottom groove (602), the mounting piece (6) is of two U-shaped plate structures, and the reflecting plate (601) is mounted on the inner sides of two ends of the mounting piece (6) through connecting ropes; the reflecting plate (601) is of a rectangular plate-shaped structure, and the inner side of the reflecting plate (601) is of an arc-shaped structure; a bottom groove (602) is formed in the bottom corner position of the mounting piece (6), and the bottom groove (602) is of a circular structure;

the mounting pieces (6) are sleeved on the outer sides of the protection pieces (2), and reflecting plates (601) on the side edges of the mounting pieces (6) are distributed in a staggered mode; the supporting piece (7) is arranged at the bottom of the mounting piece (6), and the top end of the connecting rod (701) of the supporting piece (7) is inserted into the bottom groove (602);

the protection piece (2) comprises a fixing groove (201), a collecting groove (202) and a clamping groove (203), the protection piece (2) is of a T-shaped structure, and the inner side of the protection piece (2) is of an arc-shaped structure; the inner sides of the two ends of the protective piece (2) are provided with fixing grooves (201), and the fixing grooves (201) are of T-shaped structures; the inside of the protection piece (2) is provided with uniformly arranged collecting grooves (202), the collecting grooves (202) are of L-shaped structures, and the included angles inside the collecting grooves (202) are of inclined structures; the protection pieces (2) are arranged on two sides of the main body (1);

the connecting piece (4) comprises an inserting plate (401), a stress groove (402) and a fixing block (403), the connecting piece (4) is of an I-shaped structure, and the inserting plate (401) is arranged at the bottom of the connecting piece (4); the inserting plate (401) is of a rectangular plate-shaped structure, and stress grooves (402) which are uniformly arranged are formed in two sides of the bottom of the inserting plate (401); the stress groove (402) is of a T-shaped structure, and a spring is arranged in the stress groove (402); the connecting piece (4) is arranged on the side edge of the protection piece (2), and two ends of the connecting piece (4) are embedded into the fixing groove (201).

2. The multi-gear hydraulic pump of claim 1, wherein: the main body (1) comprises a connecting plate (101) and a clamping block (102), the connecting plate (101) is arranged at the top end of the main body (1), and the connecting plate (101) is of a plate-shaped structure; two clamping blocks (102) with symmetrical structures are arranged on the side edge of the main body (1), and the clamping blocks (102) are of wedge-shaped structures.

3. The multi-gear hydraulic pump of claim 1, wherein: the protection piece (2) further comprises clamping grooves (203), the clamping grooves (203) are of wedge-shaped structures, the clamping grooves (203) are formed in two sides of the inside of the protection piece (2), and clamping blocks (102) are embedded in the clamping grooves (203).

4. The multi-gear hydraulic pump of claim 1, wherein: the auxiliary groove (3) comprises a sealing strip (301), and the sealing strip (301) is arranged on the lateral side of the outer end of the auxiliary groove (3); the sealing strip (301) is of a wedge-shaped structure, and the sealing strip (301) is made of rubber.

5. The multi-gear hydraulic pump of claim 1, wherein: the connecting piece (4) further comprises a fixing block (403), the fixing block (403) is of a T-shaped structure, and the outer end of the fixing block (403) is of a wedge-shaped structure; the inner end of the fixed block (403) is embedded in the stress groove (402), and the inner end of the fixed block (403) is contacted with the spring.

6. The multi-gear hydraulic pump of claim 1, wherein: the bottom piece (5) comprises a slot (501) and a limiting groove (502), the bottom piece (5) is of an I-shaped structure, the slot (501) is arranged in the middle of the bottom piece (5), and two sides of the top end of the slot (501) are of an inclined structure; limiting grooves (502) which are uniformly arranged are formed in two sides of the bottom of the slot (501), and the limiting grooves (502) are of rectangular structures.

7. The multi-gear hydraulic pump of claim 1, wherein: the support piece (7) comprises a connecting rod (701), the support piece (7) is of a rectangular structure, two sides of the support piece (7) are of an inclined structure, and the middle position of the support piece (7) is of a rectangular structure; four connecting rods (701) are arranged at the top end corners of the supporting piece (7), and the connecting rods (701) are of a cylindrical structure.