Retrofittable smart door lock

Abstract

A retrofittable intelligent door lock for converting an existing mechanical door lock, characterized in that it comprises: a lock cylinder configured to replace a lock cylinder of the existing mechanical door lock, and having in its center a standard mounting bore for mounting and fastening to an existing lock body via a laterally inserted bolt, wherein an end of the lock cylinder located near the inside of a door body is provided with a first guide section; a release mechanism comprising a housing, a drive source, a gear assembly, and a rotary element; wherein the drive source drives the rotary element to rotate via the gear assembly, and the rotary element is configured to penetrate the lock cylinder to drive its actuation;wherein the housing is provided on a side facing the door body with a second guide section, wherein the second guide section and the first guide section interact with each other in such a way that they are axially slidable and limited in the circumferential direction, so that the unlocking mechanism can axially approach or move away from the locking cylinder; and a locking element which serves to fix the second guide section and the first guide section relative to each other, so that the unlocking mechanism lies tightly against the surface of the door body.

Description

TECHNICAL AREA The present utility model relates to the technical field of intelligent door locks, in particular a retrofittable intelligent door lock for converting an existing mechanical door lock. STATE OF THE ART With the rise of smart homes, more and more users want to upgrade their traditional mechanical door locks to smart locks. Currently, there are two main methods for achieving this upgrade: The first method is to completely replace the entire door lock, including the lock body, cylinder, and inner and outer plates. This method is complex to install and can irreversibly damage the existing door structure. The second method is to use a retrofit smart device that fits over an existing knob or key to operate it. However, existing retrofit smart door locks still have the following drawbacks in practical application: First, their adaptability to different installation styles is poor.Due to significant variations in door thickness, the overhang of the existing lock cylinder varies. Existing retrofittable systems often struggle to meet the requirements for flush mounting across different door thicknesses, resulting in insufficient stability after installation. Secondly, the installation process is relatively complex. Although some retrofittable products promise non-destructive installation, actual mounting still requires the use of adhesive or drilling holes in the existing door panel. This is not only cumbersome but also leaves traces after removal. Thirdly, the manual unlocking experience is poor. Many retrofittable drive mechanisms remain constantly engaged with a reduction assembly of an electric motor.If the user has to manually turn the knob to open the lock, they must overcome the enormous reverse resistance of the electric motor and reduction gear set, resulting in strenuous operation and high mechanical wear. Furthermore, ensuring priority for emergency unlocking is difficult. In some products, if the electronic system fails or the electric motor jams, interference with the internal transmission mechanism prevents the external mechanical key from disengaging the clutch mechanism normally, thus rendering the mechanical key ineffective in an emergency. Therefore, it is an urgent technical problem that experts in this field need to solve: to provide a retrofittable smart door lock that is easy and quick to install, can automatically adapt to different door thicknesses, and does not affect either the manual unlocking experience or the priority of the mechanical key. CONTENTS OF THE PRESENT USE SAMPLE The present utility model aims to solve the problems of existing retrofittable intelligent door locks, namely poor installation adaptability, cumbersome installation, high resistance to manual unlocking and the difficulty in ensuring the priority of the mechanical key, by providing a retrofittable intelligent door lock characterized by easy installation, strong adaptability and a mechanical priority function.According to the present utility model, the problem is solved by the following technical solution: a retrofittable intelligent door lock for converting an existing mechanical door lock, comprising: a lock cylinder configured to replace a lock cylinder of the existing mechanical door lock, and having in its center a standard mounting bore for mounting and fastening to an existing lock body via a laterally inserted bolt, wherein an end of the lock cylinder located near the inside of a door body is provided with a first guide section; a release mechanism comprising a housing, a drive source, a gear assembly, and a rotary element; wherein the drive source, via the gear assembly, drives the rotary element to rotate, and the rotary element is configured to penetrate the lock cylinder to drive its actuation;wherein the housing is provided on a side facing the door body with a second guide section, wherein the second guide section and the first guide section interact with each other in such a way that they are axially slidable and limited in the circumferential direction, so that the unlocking mechanism can axially approach or move away from the locking cylinder; and a locking element which serves to fix the second guide section and the first guide section relative to each other, so that the unlocking mechanism lies tightly against the surface of the door body. In a preferred solution, the first guide section is a cylindrical section extending from the locking cylinder towards the unlocking mechanism, while the second guide section is a sliding bore formed in the housing; wherein the locking element comprises a bolt that is inserted into the housing from a side face in a locking manner to bear against the first guide section; wherein, alternatively, the locking element comprises an elastic pin that is inserted into and mounted in the housing from a side region, and a handle rotatably attached to the housing for actuating the elastic pin; wherein a mounting groove for receiving the elastic pin is provided in the housing;wherein the elastic pin is configured to be guided radially through the second guide section and to bear against the first guide section; wherein a rotating section of the handle has a cam contour and is configured to depress the elastic pin according to the lever principle to effect a locking action. In a preferred solution, the sliding bore is configured to adapt to a vertical or horizontal installation position of the housing relative to the locking cylinder. In a preferred solution, an end of the locking cylinder located near the outside of the door body is provided with an extension assembly to adapt to the thickness of the door body; wherein the extension assembly comprises a mounting block which is secured to an end region of the locking cylinder by means of a bolt, and a pivot column which is precisely and rotatably mounted in the mounting block and axially limited by it; wherein the mounting block has a first thickness in the axial direction and its outer contour corresponds to the cut outer contour of the locking cylinder, while the pivot column has an axial bore corresponding to a keyhole of the locking cylinder. In a preferred solution, a large gear is provided in the housing, which coaxially drives the rotating element to rotate, wherein the housing has an external rotary knob which can coaxially drive the large gear to rotate, and wherein a connecting section between the large gear and the rotary knob is mounted on the housing via a bearing. In a preferred solution, the gear assembly comprises a reduction gear set, at the end of which a first gear is provided; a pivot arm is rotatably mounted on a shaft of the first gear, and a second gear is provided at the free end of the pivot arm, which engages with the first gear; under the drive from the power source, the second gear is moved so that it pivots towards the large gear and engages with it; after the power source is stopped by driving the large gear by means of the rotary knob or by driving the first gear in the opposite direction by means of the power source, the second gear can be disengaged from the large gear. In a preferred solution, the lock cylinder comprises the following: a lock housing with a standard mounting bore; a locking block with a radially projecting annular shoulder on its inner wall, the annular shoulder being provided with an axially extending first keyway; an inner connecting piece and an outer connecting piece, both slidably mounted in the locking block and each provided on their outer wall with a key that can be aligned with the first keyway; and a first sleeve and a second sleeve that are fitted externally over the respective connecting piece, fixed axially, and rotatably attached to the two ends of the locking block; the inner walls of the first sleeve and the second sleeve each being provided with a second keyway into which the key can slide. In a preferred solution, a T-shaped element is provided in the outer connecting piece, with one end of the T-shaped element being fixed to the inner connecting piece; a first spring is provided between the T-shaped element and the outer connecting piece, and a second spring is provided between the inner connecting piece and a radial column in the first sleeve, the spring force of the second spring being greater than that of the first spring. In a preferred solution, it is provided that in the normal state without an inserted key, the key of the inner connecting piece engages in the first keyway under the influence of the second spring; wherein, in the state with an inserted external key, this key, via the T-shaped element and overcoming the compressive force of the second spring, pushes the inner connecting piece so that it is moved axially and leaves the first keyway, while at the same time the key of the outer connecting piece enters the first keyway. In a preferred solution, it is further provided that it includes a control board provided in the housing, in which a wireless communication module is integrated, which is configured to establish a wireless connection with an external mobile device via a Bluetooth module in order to realize remote unlocking. Advantageous effects of the present utility model: 1. The sliding fit between the unlocking mechanism and the locking cylinder allows for stepless adjustment to different door thicknesses, enabling a flush fit on the door surface without additional drilling. Installation adaptability is excellent, and the installation process is very simple. No professional is required for on-site installation, reducing installation costs. 2. The clutch mechanism ensures that the reduction gear set automatically disengages when the rotary knob is turned manually, eliminating the reverse resistance of the electric motor. This improves the feel of manual operation and ensures smooth manual unlocking. 3.By utilizing the varying spring forces and the physical drive provided by the T-shaped element, it is ensured that the external mechanical key can always forcibly unlock the door, thus increasing security. 4. The extension assembly allows the outer end face of the lock cylinder to be essentially flush with the outer surface of the door body. BRIEF DESCRIPTION OF THE DRAWINGS The present utility model will be discussed in more detail below with reference to the accompanying drawings and specific exemplary embodiments. Figure 1 shows a schematic representation of the overall structure of the intelligent door lock according to a first embodiment; Figure 2 shows a schematic structural sectional view of the intelligent door lock according to the first embodiment; Figure 3 shows a schematic structural view of the assembly of the inner area of ​​the housing according to the first embodiment; Figure 4 shows a schematic structural view of the assembly of the second guide section and the locking cylinder according to the first embodiment; Figure 5 shows a schematic structural view of the assembly of two extension assemblies with different thicknesses according to the first embodiment; Figure 6 shows a schematic structural view of the fit of the large gear with the first gear and the second gear according to the first embodiment; Figure 7 shows the assembly of the second gear with the first gear and the second gear according to the first embodiment.Fig. 7 a schematic structural sectional view of the locking cylinder according to the first embodiment; Fig. 8 a schematic exploded view of the construction of the locking cylinder according to the first embodiment; Fig. 9 a schematic structural sectional view of the locking element according to a second embodiment; Fig. 10 a schematic structural sectional view of the intelligent door lock according to a third embodiment. DETAILED DESCRIPTION The present utility model will be discussed in more detail below with reference to the accompanying drawings. First example: Reference is made to Figs. 1, 2, 3, 4, 5, 6, 7 to 8. A retrofittable intelligent door lock for converting an existing mechanical door lock according to the present embodiment comprises: a locking cylinder 1 configured to replace a locking cylinder of the existing mechanical door lock and mounted via a lateral mounting bolt of an existing lock body, wherein the locking cylinder 1 specifically has a standard mounting bore 100 in its center, which serves for mounting and fastening to the existing lock body via a bolt inserted laterally from a door body, wherein an end of the locking cylinder 1 located near the inside of the door is provided with a first guide section 1a; a release mechanism 2 comprising a housing 21, a drive source 22, a gear assembly 23 and a rotary element 24;wherein the drive source 22 drives the rotary element 24 to rotate via the gear assembly 23 and the rotary element 24 is configured to engage the locking cylinder 1 to drive its actuation; wherein the housing 21 is provided on a side facing the door body with a second guide section 2a, wherein the second guide section 2a and the first guide section 1a interact with each other in such a way that they are axially slidable and circumferentially limited, so that the unlocking mechanism 2 can axially approach or move away from the locking cylinder 1; wherein the first guide section 1a is a cylindrical section extending from the locking cylinder 1 in the direction of the unlocking mechanism 2, while the second guide section 2a is a sliding bore formed in the housing 21. The retrofittable intelligent door lock also includes a locking element 3, which serves to fix the second guide section 2a and the first guide section 1a relative to each other, so that the unlocking mechanism 2 lies close to the surface of the door body. In the present embodiment, the installation of the retrofittable intelligent door lock begins with the replacement of the existing mechanical lock cylinder. After the user removes the existing mechanical lock cylinder, they replace it with the special lock cylinder 1 according to the present embodiment. This lock cylinder 1 is positioned and secured by inserting a bolt through a mounting bolt hole on a side face of the existing lock body into the standard mounting hole 100, thus ensuring the stability of the lock cylinder 1 on the door body. At this point, the exposed first guide section 1a at an end of the lock cylinder 1 located near the inside of the door serves as a mounting base for the unlocking mechanism 2.During the assembly of the unlocking mechanism 2, the second guide section 2a on the rear of the housing 21 is aligned with the first guide section 1a of the locking cylinder 1, causing both guide sections to interact in such a way that they slide axially. Since the thickness of different door bodies varies, the length by which the first guide section 1a of the locking cylinder 1 protrudes from the door body also varies. The user can slide the housing 21 axially until it sits flush against the surface of the door body. Once the housing 21 is flush against the door body, it is then secured by means of the locking element 3. The installation process is very simple, and no professional is required for on-site installation, which reduces installation costs. The locking element 3 comprises a bolt that is inserted into the housing 21 from a side surface, engaging with the first guide section 1a. Specifically, a projection is provided on the inside of a wall of the housing 21 located near the door body. This projection has a threaded through-hole extending laterally from the housing 21 to the second guide section 2a, into which the bolt is screwed. When the housing 21 is firmly seated against the door body, the fastening bolt is tightened so that the end of the bolt penetrates the second guide section 2a and rests firmly against the outer circumference of the first guide section 1a of the locking cylinder 1. The frictional and compressive force between the bolt end and the first guide section 1a positions the housing 21 axially and prevents it from loosening.The combination of the locking element 3 with the sliding fit allows stepless adjustment to different door body thicknesses without the need to drill additional holes in the door body. The second guide section 2a includes a sliding bore formed in the housing 21, the sliding bore being configured to allow adjustment to a vertical or horizontal installation position of the housing 21 relative to the locking cylinder 1. If the unlocking mechanism 2 and the position of an existing door handle interfere with each other, the installation direction of the unlocking mechanism 2 can be adjusted. An end of the locking cylinder 1 located near the outer surface of the door body is provided with an extension assembly 19 to accommodate the thickness of the door body. The extension assembly 19 comprises a mounting block 192, which is secured to an end region of the locking cylinder 1 by means of a bolt 191, and a pivot column 193, which is precisely and rotatably mounted in the mounting block 192 and axially limited by the mounting block 192. The mounting block 192 has a first thickness in the axial direction, and its outer contour corresponds to the cut outer contour of the locking cylinder 1, while the pivot column 192 has an axial bore 194 corresponding to a keyhole of the locking cylinder 1. Several extension assemblies 19 with different thicknesses can be provided.Depending on the required requirements for different door body thicknesses, one or more extension assemblies 19 can be added to an end face of the locking cylinder, so that the outer end face of the locking cylinder 1 is essentially flush with the outer surface of the door body. The housing 21 contains a large gear 4 that coaxially drives the rotating element 24. The housing 21 has an external rotary knob 41 that coaxially drives the large gear 4. A connecting section between the large gear 4 and the rotary knob 41 is mounted to the housing 21 via a bearing 42. The gear assembly 23 comprises a reduction gear set, at the end of which a first gear 231 is provided. A pivot arm 232 is rotatably mounted on a shaft of the first gear 231, and a second gear 233 is provided at the free end of this pivot arm. This second gear 233 meshes with the first gear 231. Under drive from the power source 22, the second gear 233 is moved so that it pivots towards the large gear 4 and engages with it. After the power source 22 is stopped, the second gear can be disengaged from the large gear 4 by driving the large gear 4 using the rotary knob 41 or by driving the first gear 231 in the opposite direction using the power source 22. The drive source 22 transmits the driving force via the reduction gear set to the first gear 231 located at its end. Since the pivot arm 232, which carries the second gear 233, is rotatably mounted on the shaft of the first gear 231, the rotation of the first gear 231, either clockwise or counterclockwise, generates a tangential force that causes the pivot arm 232 to pivot towards the centrally located large gear 4. As the pivot arm 232 pivots, the second gear 233 engages with the large gear 4. The driving force is then transmitted to the large gear 4 and the rotating element 24, which is fixed coaxially with it, causing the rotating element 24 to rotate in order to unlock the gear. After completion of the unlocking process and the stopping of the power output of the drive source 22, the thrust force of the first gear 231 acting on the second gear 233 disappears.By driving the large gear 4 using the rotary knob 41, or by adjusting the drive source 22 so that, after completion of the unlocking process, it reverses the rotation of the first gear 231, the second gear 233 can be disengaged from the large gear 4. Since the large gear 4 is already disengaged from the reduction gear assembly 23 at this point, the user only needs to overcome the very low friction of the rotating element 24 and the bearing 42 to enable easy rotation without having to move the drive source 22 (electric motor) and the complex reduction gear assembly 23. This significantly improves ease of manual operation. The lock cylinder 1 comprises: a lock housing 18, which is formed in one piece and whose outer contour is adapted to a mounting bore of a standard mechanical door lock, wherein the standard mounting bore 100 is provided on the lock housing 18; a locking block 11, which is arranged on a recess of the lock housing 18 and on whose inner wall a radially projecting annular shoulder 111 is provided, wherein the annular shoulder 111 is provided with an axially extending first keyway 112; an inner connecting piece 12a and an outer connecting piece 12b, both of which are slidably installed in the locking block 11 and each of which is provided on their outer wall with a key (12c, 12d) which is tunable to the first keyway 112;as well as a first sleeve 13 and a second sleeve 14, which are fitted externally over the respective connecting piece, fixed in the axial direction and rotatably attached to the two ends of the locking block 11; wherein the inner walls of the first sleeve 13 and the second sleeve 14 are each provided with a second keyway (13a or 14a) into which the key (12c or 12d) can slide. Furthermore, a T-shaped element 15 is inserted into the outer connecting piece 12b, with one end of the T-shaped element 15 being fixed to the inner connecting piece 12a. A first spring 16 is provided between the T-shaped element 15 and the outer connecting piece 12b, and a second spring 17 is provided between the inner connecting piece 12a and a radial column 131 in the first sleeve 13. The spring force of the second spring 17 is greater than that of the first spring 16. In a further embodiment, it is provided that, in the normal state without an inserted key, the key 12d of the inner connecting piece 12a engages in the first keyway 112 under the influence of the second spring 17. When an external key is inserted, this key, via the T-shaped element 15 and overcoming the compressive force of the second spring 17, pushes the inner connecting piece 12a such that it is moved axially and leaves the first keyway 112, while simultaneously the key 12c of the outer connecting piece 12b enters the first keyway 112. In its normal state, the spring force of the second spring 17 between the inner connecting piece 12a and the first sleeve 13 is relatively strong and greater than the spring force of the first spring 16 on the outer connecting piece 12b. Therefore, the inner connecting piece 12a is pushed towards the center of the lock cylinder 1, so that the key 12d on its outer wall engages in the first keyway 112 on the inner wall of the locking block 11. At this point, the rotating element 24 on the inside of the door, via the first sleeve 13 and the inner connecting piece 12a, rotates the locking block 11, thus achieving electronic unlocking. When an external user inserts a mechanical key, the end of the key presses against the T-shaped element 15 that penetrates the outer connecting piece 12b. The T-shaped element 15 moves inwards with the insertion of the key.Since one end of the T-shaped element 15 is fixed to the inner connecting piece 12a, it directly pulls or pushes the inner connecting piece 12a to move it, overcoming the compressive force of the second spring 17, causing the key 12d of the inner connecting piece 12a to disengage from the first keyway 112. Simultaneously, the outer connecting piece 12b moves inward under the influence of the key pressure or a follow-up mechanism, so that its own key 12c engages in the first keyway 112 of the locking block 11. At this point, control of the locking block 11 is forcibly switched from the inside to the outside. The user can then directly rotate the locking block 11 by turning the key.This structure ensures that the external mechanical key always has the highest physical priority, regardless of the state of the electronic actuator (including motor blockage or power failure), thus guaranteeing escape and access in emergency situations. In a preferred solution, the unlocking mechanism 2 according to the present embodiment further comprises a control board 5 arranged in the housing 21. A wireless communication module is integrated into the control board 5, which is configured to establish a wireless connection via Bluetooth with an external mobile device to enable remote unlocking. After successful identity verification via Bluetooth or the wireless communication module, the control board 5 drives the drive source 22 to rotate. Second embodiment Reference is made to Fig. 9. The difference between the present embodiment and the first embodiment lies in the design of the locking element 3. In the present embodiment, the locking element 3 comprises an elastic pin 31, which is inserted into and mounted in the housing 21 from a side region, and a handle 32 rotatably attached to the housing 21, which serves to actuate the elastic pin 31. A mounting groove 200 is provided on the housing 21 for receiving the elastic pin 31. The elastic pin 31 is configured to be guided radially through the second guide section 2a and to bear against the first guide section 1a. A rotating section of the handle 32 has a cam contour 321 and is configured to depress the elastic pin 31 according to the lever principle in order to achieve a locking action.Specifically, a projection is present on the inside of a wall of the housing 21 located near the door body, forming the vertically extending mounting groove 200. The elastic pin 31 is pre-assembled in this mounting groove 200 and provided with a return spring 311, which holds the elastic pin in its retracted position under normal conditions. The handle 32 is rotatably attached to the opening of the mounting groove 200 via a clevis pin. When the handle 32 is depressed, the cam contour 321 located at its base presses against the elastic pin 31, forcing it to overcome the spring force and extend radially to engage in the first guide section 1a of the locking cylinder 1 or to press firmly against it. Furthermore, a recess 211 is provided on the side wall of the housing 21 to receive the handle 32.The handle 32 is fully housed in the recess 211 on the side of the housing 21, which provides both a high-strength rigid locking mechanism and a smooth and aesthetically pleasing side surface. Third example: Referring to Fig. 10, the difference between the present embodiment and the first embodiment lies in the different arrangement of the first guide section 1a and the second guide section 2a. In the present embodiment, the first guide section 1a is a sliding bore formed in the lock cylinder 1, and the second guide section 2a is a tubular section extending from the housing 21 towards the lock cylinder 1. In this case, the locking element 3 is a bolt that is inserted radially into the lock cylinder 1 from its side face to press against the second guide section 2a. During installation, the thickness of the door body can first be measured, then the relative distance between the lock cylinder 1 and the unlocking mechanism 2 can be adjusted, and finally both can be locked in place by means of the locking element 3.Finally, the locking cylinder 1 can be fixed to the lock body with a bolt from the side surface of the lock body. To achieve adaptation to this structure, the rotary element 24 is arranged to interact axially and telescopically with the large gear 4, while the other end of the rotary element 24 is attached to the first sleeve 13. That is, a plug cylinder 43 extends axially from one side of the large gear 4 facing the locking cylinder 1. The rotary element 24 is inserted axially and telescopically into the plug cylinder 43. The rotary element 24 is limited in the circumferential direction by the plug cylinder 43. The insertion end of the plug cylinder 43 is flared to facilitate the insertion of the rotary element 24. The first sleeve 13 is relatively short, and the rotary element 24 is inserted into and fixed to the first sleeve 13, for example, by the radial column 131 penetrating the portion of the rotary element 24 inserted into the first sleeve 13, thus fixing the rotary element to the first sleeve 13. The foregoing statements do not constitute a limitation of the technical scope of protection of the present utility model. All modifications, equivalent changes, and alterations made to the above embodiments based on the technical core of the utility model remain within the scope of protection of the technical concept of the utility model.

Claims

A retrofittable intelligent door lock for converting an existing mechanical door lock, characterized in that it comprises: a lock cylinder configured to replace a lock cylinder of the existing mechanical door lock, and having in its center a standard mounting bore for mounting and fastening to an existing lock body via a laterally inserted bolt, wherein an end of the lock cylinder located near the inside of a door body is provided with a first guide section; a release mechanism comprising a housing, a drive source, a gear assembly, and a rotary element; wherein the drive source drives the rotary element to rotate via the gear assembly, and the rotary element is configured to penetrate the lock cylinder to drive its actuation;wherein the housing is provided on a side facing the door body with a second guide section, wherein the second guide section and the first guide section interact with each other in such a way that they are axially slidable and limited in the circumferential direction, so that the unlocking mechanism can axially approach or move away from the locking cylinder; and a locking element which serves to fix the second guide section and the first guide section relative to each other, so that the unlocking mechanism lies tightly against the surface of the door body. Retrofittable intelligent door lock according to claim 1, characterized in that the first guide section is a cylindrical section extending from the lock cylinder towards the unlocking mechanism, while the second guide section is a sliding bore formed on the housing; wherein the locking element comprises a bolt which is inserted into the housing from a side surface in a locking manner to bear against the first guide section; wherein, alternatively, the locking element comprises an elastic pin which is inserted into and mounted in the housing from a side region, and a handle rotatably attached to the housing which serves to drive the elastic pin; wherein a mounting groove for receiving the elastic pin is provided on the housing;wherein the elastic pin is configured to be guided radially through the second guide section and to bear against the first guide section; wherein a rotating section of the handle has a cam contour and is configured to depress the elastic pin according to the lever principle to effect a locking action. Retrofittable intelligent door lock according to claim 2, characterized in that the sliding bore is configured to adapt to a vertical installation position or a horizontal installation position of the housing relative to the locking cylinder. Retrofittable intelligent door lock according to claim 1, characterized in that an end of the locking cylinder located near the outside of the door body is provided with an extension assembly for adapting to the thickness of the door body; wherein the extension assembly comprises a mounting block which is secured to an end region of the locking cylinder by means of a bolt, and a pivot column which is precisely and rotatably mounted in the mounting block and axially limited by it; wherein the mounting block has a first thickness in the axial direction and its outer contour corresponds to the cut outer contour of the locking cylinder, while the pivot column has an axial bore which corresponds to a keyhole of the locking cylinder. Retrofittable intelligent door lock according to claim 1, characterized in that a large gear is provided in the housing which coaxially drives the rotary element to rotate, wherein the housing has a rotary knob on the outside which can coaxially drive the large gear to rotate, and wherein a connecting section between the large gear and the rotary knob is mounted on the housing via a bearing. Retrofittable intelligent door lock according to claim 5, characterized in that the gear assembly comprises a reduction gear set, at the end of which a first gear is provided; wherein a pivot arm is rotatably mounted on a shaft of the first gear, at the free end of which a second gear is provided, which engages with the first gear; wherein, under the drive from the drive source, the second gear is moved such that it pivots towards the large gear and engages with it; wherein, after stopping the drive source by driving the large gear by means of the rotary knob or by driving the first gear in the opposite direction by means of the drive source, the second gear can be disengaged from the large gear. A retrofittable intelligent door lock according to claim 1, characterized in that the lock cylinder comprises: a lock housing in which the standard mounting bore is provided; a locking block in which a radially projecting annular shoulder is provided on the inner wall, the annular shoulder being provided with an axially extending first keyway; an inner connecting piece and an outer connecting piece, both of which are slidably installed in the locking block and are each provided on their outer wall with a key that is tunable to the first keyway; and a first sleeve and a second sleeve, which are slipped over the respective connecting piece on the outside, fixed in the axial direction and rotatably attached to the two ends of the locking block; wherein the inner walls of the first sleeve and the second sleeve are each provided with a second keyway into which the key can slide. Retrofittable intelligent door lock according to claim 7, characterized in that a T-shaped element is inserted in the outer connecting piece, wherein one end of the T-shaped element is fixed to the inner connecting piece; wherein a first spring is provided between the T-shaped element and the outer connecting piece and a second spring is provided between the inner connecting piece and a radial column in the first sleeve, wherein the spring force of the second spring is greater than that of the first spring. Retrofittable intelligent door lock according to claim 8, characterized in that, in the normal state without an inserted key, the keyway of the inner connecting piece engages in the first keyway groove under the influence of the second spring; wherein, in the state with an inserted external key, this key, via the T-shaped element, pushes the inner connecting piece overcoming the compressive force of the second spring so that it is moved axially and leaves the first keyway groove, while at the same time the keyway of the outer connecting piece enters the first keyway groove. Retrofittable intelligent door lock according to claim 1, characterized in that it further comprises a control board provided in the housing in which a wireless communication module is integrated, which is configured to establish a wireless connection with an external mobile device via a Bluetooth module or a 433MHz radio module in order to realize remote unlocking.

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