Linear displacement device with high power density

Abstract

The invention discloses a linear displacement device with high power density. The linear displacement device comprises a shell, a motor, a planetary gear speed reduction unit, a cylindrical gear speed reduction unit, a reverse planetary roller lead screw and a grating ruler. Rotation input by the motor is firstly decelerated by the planetary gear deceleration unit and then decelerated by the cylindrical gear deceleration unit to drive a nut roller of the reverse rotation type planetary roller screw to rotate, rotation of the main screw rod is limited by the frame, and therefore the main screw rod is driven to linearly move to be final output. The ruler of the grating ruler and the total screw perform linear displacement together, and the reading head of the grating ruler reads the displacement, so that the linear displacement distance of the total screw is determined. The speed reduction unit has the advantages of being small in size, large in speed reduction ratio and adjustable in speed reduction ratio, the reverse-rotation type planetary roller serves as a linear transmission device, and compared with a standard planetary roller lead screw, the reverse-rotation type planetary roller lead screw has the advantages of being high in bearing capacity, high in speed performance, resistant to abrasion and high in rigidity. Therefore, the characteristics of small size, high load, high precision and high power density are realized.

Description

Technical Field

[0001] The invention relates to a linear displacement device, in particular to a linear displacement device with high power density. Background Art

[0002] A linear displacement device is a device that drives the corresponding components to move in a straight line. Common linear position devices include lead screw modules, electric cylinders, etc. Some use scenarios with small space, high precision, and high power density, such as joint actuators of humanoid robots, finger drives of manipulators, medical equipment, electronic patch equipment, machine tool grinding, coating heads of new energy lithium battery coating machines, etc. In such use scenarios, there are relatively high requirements for the load-bearing capacity, displacement speed, displacement accuracy, etc. of the linear displacement device, as well as the appearance and volume of the linear displacement device itself. Summary of the invention

[0003] The present application provides a high-power density linear displacement device, which aims to have a compact structure and a small size while also taking into account better load-bearing capacity, displacement speed, and displacement accuracy, and is more in line with the requirements of small space, high precision, and high power density usage scenarios.

[0004] In the present application, a high power density linear displacement device is provided, comprising: The housing is in a rectangular parallelepiped shape; it is provided with: an input chamber, an output chamber and a second deceleration chamber; the input chamber and the output chamber are arranged in parallel; the input chamber is divided into: a first deceleration chamber on the first side and a mounting chamber on the second side; a through hole is provided on the second side wall of the output chamber; the second deceleration chamber connects the first side of the input chamber and the first side of the output chamber; The motor is installed in the mounting cavity to provide an initial rotation input; The planetary gear reduction unit is installed in the first reduction chamber; the ring gear is fixed, and the sun gear is connected to the output shaft of the motor. A cylindrical gear reduction unit is arranged in the second reduction chamber; an input gear is connected to a planet carrier of the planetary gear reduction unit; A reversing planetary roller screw is installed in the output cavity; the nut roller is connected to the output gear of the cylindrical gear reduction unit; the main screw is restricted from rotating, and its second side portion is the final displacement output, which passes through the outlet; The grating ruler is installed on the main screw, and the reading head is installed on the housing.

[0005] In some embodiments, the housing includes: a main frame, a front cover, a planetary reduction housing, and a tailstock; The motor is mounted between the second side of the main frame and the first side of the front cover; The planetary gear reduction unit is installed between the first side of the main frame and the second side of the planetary reduction housing; The other gears of the cylindrical gear reduction unit except the output gear are installed between the first side of the planetary reduction housing and the second side of the tailstock; The inverted planetary roller screw and the output gear of the cylindrical gear reduction unit form a set of components, which are installed between the first side of the main frame and the second side of the tailstock.

[0006] In some embodiments, a linear displacement frame is fixedly connected to a middle portion of the main screw near the second side portion; the main screw is restricted from rotating by the linear displacement frame; and the installation position of the ruler is the linear displacement frame.

[0007] In some embodiments, the housing further includes: a grating scale housing; a reversing planetary roller screw between the motor and the reading head; the grating scale housing covers the reading head and leaves a cavity on the first side of the reading head; the main frame is also provided with a threading groove connecting the mounting cavity and the cavity.

[0008] In some embodiments, the housing further comprises: a rear cover; the rear cover is fixedly connected to the first side of the tailstock; and a fourth bearing for connecting the output gear is installed between the first side of the tailstock and the second side of the rear cover.

[0009] In some embodiments, the middle portion of the main screw is detachably fixedly connected to the second side portion, and the linear displacement frame is fixedly connected in a manner of being fixed between the two.

[0010] In some embodiments, the cylindrical gear reduction unit has a reduction ratio of 2.5 to 3.5 and includes a small gear as an input gear, a large gear as an output gear, and a middle gear meshing therebetween.

[0011] In some embodiments, the planetary gear reduction unit has one stage, two stages or three stages.

[0012] In summary, in the present application, a high power density linear displacement device includes: a housing, a motor, a planetary gear reduction unit, a cylindrical gear reduction unit, a reversing planetary roller screw and a grating ruler. The rotation of the motor input is first decelerated by the planetary gear reduction unit, and then decelerated by the cylindrical gear reduction unit, driving the nut roller of the reversing planetary roller screw to rotate, and the total screw is restricted from rotating by the frame, thereby driving the total screw to linearly displace as the final output. The scale of the grating ruler and the total screw are linearly displaced together, and the displacement read by the reading head of the grating ruler is used to determine the linear displacement distance of the total screw.

[0013] The beneficial effects are as follows: 1. The reduction unit adopts the method of planetary gear reduction plus small gear meshing with middle gear, and middle gear meshing with large gear to drive the nut roller to rotate, which has the advantages of small volume and large reduction ratio, and the number of planetary gear reduction can be increased according to different usage conditions, thereby expanding the reduction ratio. 2. Compared with the standard planetary roller screw, the radial load on the nut roller is partially offset due to the reverse arrangement direction of the reverse planetary roller, thereby improving the load-bearing capacity of the linear displacement device; since the number of planetary rollers can be reduced, their rotational inertia is small, which is conducive to increasing the rotation speed of the nut roller and the displacement speed of the linear displacement device; since the contact angle between the planetary roller and the nut roller and the center screw is smaller, the wear resistance is better; since the contact points between the planetary roller and the nut roller and the center screw are more dispersed in the axial direction, the stiffness of the reverse roller screw is higher; in summary, the linear displacement device adopts the reverse planetary roller as a linear transmission device, which has the advantages of high load-bearing capacity, high-speed performance, wear resistance and high stiffness compared with the standard planetary roller screw. 3. The grating scale displacement distance measurement unit cleverly fixes the grating scale on the linear displacement frame, which can limit the rotation of the center screw and convert it into the linear displacement of the total screw. The grating scale reader can also accurately measure the displacement distance of the total screw in real time.

[0014] The planetary gear deceleration plus cylindrical gear deceleration of the deceleration unit of the present invention has the advantages of small size, large reduction ratio and adjustable reduction ratio; the linear displacement device adopts the reverse planetary roller as the linear transmission device, which has the advantages of high load capacity, high speed performance, wear resistance and high rigidity compared with the standard planetary roller screw. Thus, the device has the characteristics of small size, high load, high precision and high power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0016] Figure 1 A schematic diagram of this application; Figure 2 Schematic diagram of the distribution of various cavities in the shell; Figure 3 This is a schematic diagram of the present application after the shell is cut open; Figure 4 is a schematic diagram of a planetary gear reduction unit; Figure 5 The installation diagram of the reversing planetary roller screw and the linear cage is shown in FIG. Figure 6 It is a schematic diagram of the setting of the reverse planetary roller screw; Figure 7 This is a schematic diagram of the grating ruler settings; Figure 8 The schematic diagram of the housing includes a main frame, a front cover, a planetary reduction housing and a tailstock; Fig. 9 A schematic diagram of the main frame; Fig.10 It is a schematic diagram of the setting of the grating scale housing and the third mounting surface; Fig.11 Schematic diagram of the main frame and grating scale housing after being cut open along the linear groove.

[0017] In the figure, 1. Shell; 1-1. Main frame; 1a. Input cavity; 1a-1. First deceleration cavity; 1a-2. Mounting cavity; 1b. Output cavity; 1e. First abutting surface; 1f. Second mounting surface; 1g. Second abutting surface; 1h. First mounting surface; 1i. Third mounting surface; 1j. Connecting groove; 1k. Mounting part; 1L. Wire groove; 1-2. Front cover; 1d. Through-port; 1-3. Planetary deceleration housing; 1-4. Tail stock; 1c. Second deceleration cavity; 1-5. Back cover; 1-6. Grating ruler housing; 1m. Cavity; 2. Motor; 3. Planetary gear reduction unit; 3-1. Ring gear; 3-2. Sun gear; 3-3. Planet carrier; 3-4. Planet gear; 4. Cylindrical gear reduction unit; 4-1. Small gear; 4-2. Middle gear; 4-3. Large gear; 5. Reversing planetary roller screw; 5-1. Nut roller; 5-2. Main screw; 5a. Center screw; 5b. Middle section of screw; 5c. Upper section of screw; 5-3. Roller cage; 5-4. Planetary roller; 6. Grating ruler; 6-1. Scale ruler; 6-2. Reading head; 7. Linear displacement frame; 8. Sliding sleeve; 9. First bearing; 10. Second bearing; 11. The third bearing; 12. Fourth bearing. DETAILED DESCRIPTION

[0018] The following is further described in conjunction with the accompanying drawings, which are only used as examples and are not strictly drawn to scale. Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Including" or "including" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. In the absence of conflict, the embodiments in the present application can be combined with each other.

[0019] See also Figure 1 and Figure 3 A linear displacement device for measuring displacement by a grating ruler comprises: a housing 1, a motor 2, a planetary gear reduction unit 3, a cylindrical gear reduction unit 4, a reversing planetary roller screw 5 and a grating ruler 6.

[0020] See also Figure 2 The outer shell 1 is in the shape of a rectangular parallelepiped and is provided with an input chamber 1a, an output chamber 1b and a second deceleration chamber 1c.

[0021] The input chamber 1a and the output chamber 1b are parallel, that is, the first side of the input chamber 1a and the first side of the output chamber 1b face the same side, and the second side of the input chamber 1a and the second side of the output chamber 1b face the other opposite side. The input chamber 1a is divided into: a first deceleration chamber 1a-1 and an installation chamber 1a-2, wherein the first deceleration chamber 1a-1 is on the first side, and the installation chamber 1a-2 is on the second side. A through hole 1d is provided on the second side wall of the output chamber 1b. The second deceleration chamber 1c connects the first side of the input chamber 1a and the first side of the output chamber 1b, that is, the first deceleration chamber 1a-1 and the output chamber 1b are connected on the first side.

[0022] See also Figure 3 The motor 2 is installed in the installation cavity 1a-2 and is used to provide initial rotation input for the linear displacement device.

[0023] The planetary gear reduction unit 3 is installed in the first reduction chamber 1a-1. The number of stages of the planetary gear reduction unit 3 is one, two or three, and the reduction ratio is 3 to 5.

[0024] See also Figure 3 and Figure 4Taking the first stage as an example, the planetary gear reduction unit 3 may include: a ring gear 3-1, a sun gear 3-2, a planet carrier 3-3 and a plurality of planetary gears 3-4. The ring gear 3-1 is fixed to the first reduction chamber 1a-1, and the sun gear 3-2 is used as the input of the planetary gear reduction unit 3, connected to the output shaft of the motor 2, and driven to rotate by the output shaft of the motor 2. Correspondingly, the planet carrier 3-3 is used as the output of the planetary gear reduction unit 3. If two or three stages are used, the sun gear 3-2 of the first stage is used as the input of the planetary gear reduction unit 3, the planet carrier 3-3 is connected to the sun gear 3-2 of the adjacent first stage, and the planet carrier 3-3 of the last stage is used as the output of the planetary gear reduction unit 3.

[0025] See also Figure 3 The cylindrical gear reduction unit 4 is arranged in the second reduction chamber 1c. The input gear is connected to the planet carrier 3-3 of the planetary gear reduction unit 3. In addition, the reduction ratio and the number of cylindrical gears used in the cylindrical gear reduction unit 4 directly determine the length and width of the second reduction chamber 1c.

[0026] In some embodiments, the reduction ratio of the cylindrical gear reduction unit 4 is 2.5 to 3.5. The cylindrical gear reduction unit 4 has three cylindrical gears, including a small gear 4-1 as an input gear, a large gear 4-3 as an output gear, and a middle gear 4-2 meshing therebetween.

[0027] By using the above-mentioned reduction ratio and number of cylindrical gears, the second reduction chamber 1c can have appropriate length and width dimensions.

[0028] See also Figure 3 and Figure 6 The inverted planetary roller screw 5 is installed in the output cavity 1b. More specifically, the inverted planetary roller screw 5 may include: a nut roller 5-1, a main screw 5-2, two roller cages 5-3 and a plurality of planetary rollers 5-4.

[0029] The nut roller 5 - 1 serves as the input of the reverse planetary roller screw 5 , is connected to the output gear of the cylindrical gear reduction unit 4 , and is driven to rotate by the output gear.

[0030] The main screw 5-2 serves as the output of the reverse planetary roller screw 5, and its rotation needs to be restricted.

[0031] The first side portion of the total screw 5-2 is a central screw 5a with a thread and a gear ring 3-1, which is inserted into the nut roller 5-1. The middle portion of the total screw 5-2 is the screw middle section 5b, which passes through the end cover of the nut roller 5-1. The second side portion of the total screw 5-2 is the screw upper section 5c, which serves as the final displacement output of the linear displacement device and passes through the through-port 1d. A sliding sleeve 8 can also be installed at the position of the through-port 1d to make the screw upper section 5c pass more smoothly, reduce the matching clearance between the sliding sleeve 8 and the screw upper section 5c, and improve the displacement accuracy.

[0032] Two roller retainers 5-3 are rotatably connected to the main screw 5-2, respectively at the two ends of the center screw 5a. More specifically, the second end of the center screw 5a is detachably fixedly connected to the first end of the screw middle section 5b, and the connection between the two forms an annular groove for installing one roller retainer 5-3. The first end of the center screw 5a is provided with a first protrusion for inserting another roller retainer 5-3, and a screw can be installed on the first protrusion. By rotating the screw, the retainer 5-3 on the first side of the planetary roller 5-4 is squeezed to adjust the preload force of the meshing between the planetary roller 5-4 and the center screw 5a, thereby achieving precision adjustment.

[0033] Both ends of the plurality of planetary rollers 5-4 are rotatably connected to the two roller retainers 5-3, respectively, and each planetary roller 5-4 is meshed around the central screw 5a and the nut roller 5-1.

[0034] The scale 6-1 of the grating ruler 6 is installed on the main screw 5-2, and the reading head 6-2 is installed on the housing 1. The scale 6-1 is read by the reading head 6-2 to obtain the linear displacement value of the main screw 5-2.

[0035] The way in which the main screw 5-2 is restricted from rotating is as follows: In some embodiments, the cross section of the upper section 5c of the screw corresponds to the shape of the through-port 1d and can be designed to be non-circular.

[0036] See also Figure 3 , Figure 6 and Figure 7 In some embodiments, a linear displacement frame 7 is fixedly connected to a position of the middle section 5b of the screw near the upper section 5c of the screw, and the rotation of the main screw 5-2 is limited by the linear displacement frame 7. More specifically, the linear displacement frame 7 is provided with two opposite fitting surfaces, and the two fitting surfaces are parallel to the axis of the main screw 5-2, and respectively fit the two opposite cavity walls of the output cavity 1b. The linear displacement frame 7 is also used as the installation position of the scale 6-1. More specifically, the linear displacement frame 7 can be L-shaped, with one section perpendicular to the axis of the main screw 5-2, used for fixed connection with the main screw 5-2, and the other section parallel to the axis of the main screw 5-2, extending toward the first side, for installation of the scale 6-1.

[0037] Compared with the non-circular cross-section of the upper section 5c of the screw and the shape of the through-port 1d, it is more convenient to use the linear displacement frame 7, which can provide an installation position for the scale 6-1.

[0038] See also Figure 5In some embodiments, the middle section 5b of the screw rod is detachably fixedly connected to the upper section 5c of the screw rod, and the linear displacement frame 7 is fixedly connected between the two. More specifically, the middle section 5b of the screw rod is provided with a second protrusion, and the linear displacement frame 7 is provided with a hole for inserting the second protrusion, and both are non-circular to limit relative rotation; after the upper section 5c of the screw rod is fixedly connected to the middle section 5b of the screw rod, the linear displacement frame 7 is blocked to limit relative movement.

[0039] For the housing 1 , the assembly of the motor 2 , the planetary gear reduction unit 3 , the cylindrical gear reduction unit 4 , and the counter-rotating planetary roller screw 5 is considered.

[0040] In some embodiments, the housing 1 may be composed of two identical housings, that is, the input chamber 1a, the output chamber 1b, and the second deceleration chamber 1c are divided into two parts and respectively distributed on the two housings. The motor 2, the planetary gear reduction unit 3, the cylindrical gear reduction unit 4, the reversing planetary roller screw 5, and the grating ruler 6 are first installed in one of the housings, and then the other housing is installed.

[0041] See also Figure 8 and Fig. 9 In some embodiments, the housing 1 may include: a main frame 1-1, a front cover 1-2, a planetary reduction housing 1-3 and a tailstock 1-4.

[0042] The motor 2 is installed between the second side of the main frame 1-1 and the first side of the front cover 1-2. More specifically, the installation cavity 1a-2 can be entirely or partially provided in the main frame 1-1, the motor 2 enters the main frame 1-1 from the second side, and a first abutting surface 1e is provided in the main frame 1-1 for the motor 2 to abut against; the second side of the main frame 1-1 is a second installation surface 1f for the front cover 1-2 to be installed, and the motor 2 is installed in the installation cavity 1a-2 by fitting the front cover 1-2 to the first abutting surface 1e.

[0043] The planetary gear reduction unit 3 is installed between the first side of the main frame 1-1 and the second side of the planetary reduction housing 1-3. More specifically, the first reduction chamber 1a-1 can be entirely or partially arranged in the main frame 1-1, the planetary gear reduction unit 3 enters the main frame 1-1 from the first side, and the main frame 1-1 is provided with a second abutting surface 1g for the gear ring 3-1 to abut against; the first side of the main frame 1-1 is two staggered first mounting surfaces 1h, wherein the first mounting surface 1h closer to the second mounting surface 1f is provided for the planetary reduction housing 1-3 to be installed, and the planetary gear reduction unit 3 is installed in the first reduction chamber 1a-1 by fitting the planetary reduction housing 1-3 to the second abutting surface 1g.

[0044] The other gears of the cylindrical gear reduction unit 4 except the output gear are installed between the first side of the planetary reduction housing 1-3 and the second side of the tailstock 1-4. More specifically, the size of the tailstock 1-4 is larger than the size of the planetary reduction housing 1-3, and the overlapping area of ​​the two forms a part of the second reduction chamber 1c for the installation of these other gears, that is, the first side and the second side of each gear are connected to the first bearing 9, and the two first bearings 9 are respectively connected to the tailstock 1-4 and the planetary reduction housing 1-3.

[0045] The reversing planetary roller screw 5 and the output gear of the cylindrical gear reduction unit 4 form a set of components. That is, the first side of the nut drum 5-1 and the second side of the output gear are not connected to the bearing, and the two are directly plugged together.

[0046] The formed assembly is installed between the first side of the main frame 1-1 and the second side of the tailstock 1-4. More specifically, the input chamber 1a can be set in the main frame 1-1, and the reversing planetary roller screw 5 enters the main frame 1-1 from the first side. A second bearing 10 is provided in the main frame 1-1, and the second bearing 10 is connected to the end cover of the nut roller 5-1; the tailstock 1-4 is provided with a third bearing 11 on the part beyond the planetary reduction housing 1-3, and the third bearing 11 is connected to the first side of the output gear; the first installation plane farther from the second installation plane is provided for the installation of the excess part of the tailstock 1-4, forming the remaining part of the second reduction chamber 1c (this part of the second reduction chamber 1c is connected to the output chamber 1b), and this group of components is installed in the second reduction chamber 1c of the output chamber 1b. Correspondingly, the reading head 6-2 is also installed on the main frame 1-1, and the through-port 1d is also provided on the front cover 1-2.

[0047] In addition, during linear displacement, the main screw 5-2 will be subjected to a large axial pressure or thrust, which will be transmitted to the nut roller 5-1. The second bearing 10 and the third bearing 11 both use thrust bearings, and the two thrust bearings limit the axial displacement of the nut roller 5-1.

[0048] Compared with the housing 1, which can be composed of two shells, the design of the main frame 1-1, the front cover 1-2, the planetary reduction housing 1-3 and the tailstock 1-4 can more conveniently assemble the motor 2, the planetary gear reduction unit 3, the cylindrical gear reduction unit 4, and the reversing planetary roller screw 5, and it is also more convenient to remove one of them separately for maintenance. More specifically, the motor 2 can be taken out separately by removing the front cover 1-2; the cylindrical gear reduction unit 4 can be taken out separately by removing the tailstock 1-4; the planetary reduction housing 1-3 and the tailstock 1-4 are removed, and the removed two are kept together, and the planetary gear reduction unit 3 and the reversing planetary roller screw 5 can be taken out separately.

[0049] See also Figure 8In some embodiments, the housing 1 may further include a rear cover 1-5. The rear cover 1-5 is fixedly connected to the first side of the tailstock 1-4. A fourth bearing 12 for connecting the output gear is also provided between the first side of the tailstock 1-4 and the second side of the rear cover 1-5.

[0050] On the one hand, the sealing is improved by the rear cover 1-5, and on the other hand, the fourth bearing 12 is added to make the output gear and the reversing planetary roller screw 5 rotate more stably.

[0051] See also Fig. 9 and Fig.10 In some embodiments, the housing 1 may further include: a grating scale housing 1-6.

[0052] The installation position of the reading head 6-2 on the main frame 1-1 is set so that the reversing planetary roller screw 5 is between the motor 2 and the reading head 6-2. More specifically, a connecting groove 1j connected to the output cavity 1b and two protruding mounting parts 1k are provided on the third mounting surface 1i corresponding to the main frame 1-1. The reading head 6-2 is mounted on these two mounting parts 1k. If the main screw 5-2 is used in a linear moving frame in a manner that the rotation is restricted, then a section of the linear moving frame for mounting the scale 6-1 slides in the connecting groove 1j.

[0053] See also Fig.10 and Fig.11 , the grating scale housing 1-6 covers the reading head 6-2, and a cavity 1m is left on the first side of the reading head 6-2. More specifically, the first side of the grating scale housing 1-6 can be fixedly connected to the tailstock 1-4, and the second side can be fixedly connected to the main frame 1-1. The main frame 1-1 is also provided with a wire groove 1L connecting the installation cavity 1a-2 and the cavity 1m. More specifically, the wire groove 1L can be two locations, respectively located on both sides of the connecting groove 1j.

[0054] The control module for the motor 2 and the grating ruler 6 can be arranged in the cavity 1m, that is, the motor 2 is connected to the control module through two wire slots 1L. The grating ruler housing 1-6 protects the reading head 6-2 and the control module.

Claims

1. A high power density linear displacement device, characterized in that: include: The housing (1) is in the shape of a rectangular parallelepiped; it is provided with an input chamber (1a), an output chamber (1b) and a second deceleration chamber (1c); the input chamber (1a) and the output chamber (1b) are arranged in parallel; the input chamber (1a) is divided into a first deceleration chamber (1a-1) on the first side and a mounting chamber (1a-2) on the second side; a through hole (1d) is provided on the second side wall of the output chamber (1b); the second deceleration chamber (1c) connects the first side of the input chamber (1a) and the first side of the output chamber (1b); A motor (2) is installed in the installation cavity (1a-2) to provide an initial rotation input; The planetary gear reduction unit (3) is installed in the first reduction chamber (1a-1); the ring gear (3-1) is fixed, and the sun gear (3-2) is connected to the output shaft of the motor (2). A cylindrical gear reduction unit (4) is arranged in the second reduction chamber (1c); the input gear is connected to the planet carrier (3-3) of the planetary gear reduction unit (3); A reversing planetary roller screw (5) is installed in the output cavity (1b); a nut roller (5-1) is connected to the output gear of the cylindrical gear reduction unit (4); the main screw (5-2) is restricted from rotating, and its second side portion is the final displacement output, which passes through the outlet (1d); The grating ruler (6) and the scale ruler (6-1) are installed on the main screw (5-2), and the reading head (6-2) is installed on the housing (1).

2. A high power density linear displacement device according to claim 1, characterized in that: The housing (1) comprises: a main frame (1-1), a front cover (1-2), a planetary reduction housing (1-3) and a tailstock (1-4); The motor (2) is installed between the second side of the main frame (1-1) and the first side of the front cover (1-2); The planetary gear reduction unit (3) is installed between a first side of the main frame (1-1) and a second side of the planetary reduction housing (1-3); The other gears of the cylindrical gear reduction unit (4) except the output gear are installed between the first side of the planetary reduction housing (1-3) and the second side of the tailstock (1-4); The inverted planetary roller screw (5) and the output gear of the cylindrical gear reduction unit (4) form a set of components, which are installed between the first side of the main frame (1-1) and the second side of the tailstock (1-4).

3. A high power density linear displacement device according to claim 1, characterized in that: A linear displacement frame (7) is fixedly connected to a middle portion of the main screw rod (5-2) near the second side portion; the main screw rod (5-2) is restricted from rotating by the linear displacement frame (7); and the installation position of the scale (6-1) is the linear displacement frame (7).

4. A high power density linear displacement device according to claim 2, characterized in that: The housing (1) further comprises: a grating scale housing (1-6); a reversing planetary roller screw (5) between the motor (2) and the reading head (6-2); the grating scale housing (1-6) covers the reading head (6-2), and a cavity (1m) is left on a first side of the reading head (6-2); and the main frame (1-1) is further provided with a threading groove (1L) connecting the installation cavity (1a-2) and the cavity (1m).

5. A high power density linear displacement device according to claim 2, characterized in that: The housing (1) further comprises: a rear cover (1-5); the rear cover (1-5) is fixedly connected to a first side of a tailstock (1-4); and a fourth bearing (12) for connecting an output gear is installed between the first side of the tailstock (1-4) and the second side of the rear cover (1-5).

6. A high power density linear displacement device according to claim 3, characterized in that: The middle part of the main screw rod (5-2) is detachably fixedly connected to the second side part, and the linear displacement frame (7) is fixedly connected in a manner of being fixed between the two.

7. A high power density linear displacement device according to claim 1, characterized in that: The cylindrical gear reduction unit (4) has a reduction ratio of 2.5 to 3.5 and comprises a small gear (4-1) as an input gear, a large gear (4-3) as an output gear, and a middle gear (4-2) meshing therebetween.

8. The high power density linear displacement device according to claim 1, characterized in that: The planetary gear reduction unit (3) is one-stage, two-stage or three-stage.

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