Patent Description:
As a widely used power tool, a hammer drill is mainly used for opening holes on hard materials such as concrete, bricks and stones, that is, the hammer drill can output an impact force while outputting torque. Generally, an impact frequency is increased so that the working efficiency of the hammer drill can be improved, but the stability of the tool is affected.

<CIT> discloses a hammer drill wherein a distance between the fly piston and the agitating piston is preferably smaller than <NUM>. <CIT> discloses a hammer drill with an optimal impact frequency as in the range between <NUM> and <NUM>.

To solve deficiencies in the existing art, an object of the present disclosure is to provide a power tool with high working efficiency.

To achieve the preceding object, the present disclosure provides the technical solutions described below.

According to the invention, a hammer drill as per claim <NUM> is configured to perform a hammer drilling operation through a tip functional element. The hammer drill includes a motor, a drive mechanism for generating a driving force, an output mechanism for accommodating at least a portion of the tip functional element and capable of being driven by the drive mechanism to drive the tip functional element to rotate about an output axis, and an impact mechanism capable of being driven by the drive mechanism to impact the tip functional element. The output axis extends along a front and rear direction of the hammer drill. The impact mechanism includes an impact rod capable of abutting against the tip functional element, an impact power piece connected to the drive mechanism and used for generating impact power, and an impact block disposed between the impact rod and the impact power piece and capable of reciprocating when impacted by the impact power generated by the impact power piece to impact the impact rod. A gas space is formed between the impact block and the impact power piece. A minimum length of the gas space in a direction of the output axis is in the range from <NUM> to <NUM> inclusive, and an impact frequency of the impact mechanism is greater than or equal to <NUM> BPM.

In one example, the impact power piece includes a cylinder, the cylinder is a semi-closed cavity with an end open, a rear end of the cylinder is closed and connected to the drive mechanism and a front end of the cylinder is open and used for accommodating the impact block along the direction of the output axis, the impact block is partially or fully accommodated in the cylinder, and a rear end surface of the impact block and an inner wall of the cylinder are capable of forming the gas space.

In one example, the output mechanism includes a sleeve, the sleeve is a cylindrical cavity with two ends open, the impact power piece includes a piston disposed within the sleeve and a connecting member, a front end of the connecting member is fixed to the piston and a rear end of the connecting member is connected to the drive mechanism, the impact block is accommodated within the sleeve, and a rear end surface of the impact block, an inner sidewall of the sleeve, and a front end surface of the piston are capable of forming the gas space.

In one example, a weight of the impact block is greater than or equal to <NUM> and less than or equal to <NUM>.

In one example, a length of the impact block is greater than or equal to <NUM> and less than or equal to <NUM>.

In one example, the hammer drill has an impact work of greater than or equal to <NUM> J. In one example, a weight of the hammer drill is less than or equal to <NUM>.

In one example, a weight of the hammer drill is less than or equal to <NUM>.

In one example, an impact frequency of the impact mechanism is greater than or equal to <NUM> BPM.

In one example, the impact power piece includes a cylinder, and the cylinder is a semi-closed cavity with an end open; wherein along the direction of the output axis, a rear end of the cylinder is closed and connected to the drive mechanism, and a front end of the cylinder is open and used for accommodating the impact block; and wherein the impact block is partially or fully accommodated in the cylinder, and a rear end surface of the impact block and an inner wall of the cylinder are capable of forming the gas space.

In one example, the power tool further includes a sleeve. The sleeve is a cylindrical cavity with two ends open, the impact power piece includes a piston disposed within the sleeve, a rear end of the piston is connected to the drive mechanism, the impact block is accommodated within the sleeve, and a rear end surface of the impact block, an inner sidewall of the sleeve and a front end surface of the piston are capable of forming the gas space.

Examples of the present disclosure are described below with reference to the drawings. Further, in the following examples, a hammer drill is shown as one example of a power tool configured to work by driving a tip functional element. The hammer drill is configured to enable the tip functional element mounted on the tool to impact a workpiece along a direction of an output axis or rotate about the direction of the output axis or perform the preceding two actions at the same time.

First, an overall structure of the hammer drill is described. To clearly illustrate the technical solution of the present application, up, down, front, and rear are defined as shown in <FIG> and <FIG>.

As shown in <FIG> and <FIG>, an outer contour of the hammer drill <NUM> is mainly composed of a housing <NUM> formed with a grip <NUM>, and an accommodating space capable of containing various functional components is formed inside the housing <NUM>.

As shown in <FIG>, the hammer drill <NUM> mainly includes the housing <NUM>, a power supply interface <NUM>, a motor <NUM>, a drive mechanism <NUM>, an impact mechanism <NUM>, and an output mechanism <NUM>. In an example, the power supply interface <NUM> can access a battery pack, and the battery pack may be inserted into or separated from the housing <NUM>, that is, the battery pack is not directly mounted on a surface of the housing <NUM>. The specific mounting manner of the battery pack is not limited as long as a power source can be provided. In an example, the power supply interface <NUM> can access alternating current mains power.

In this example, a weight of the hammer drill <NUM> is less than or equal to <NUM>. For example, the weight of the hammer drill <NUM> is <NUM>, <NUM>, or <NUM>. In this example, the weight of the hammer drill <NUM> is less than or equal to <NUM>. In this example, the hammer drill <NUM> has an impact work of greater than or equal to <NUM> J. For example, the hammer drill <NUM> has an impact work of <NUM> J, <NUM> J, <NUM> J, <NUM> J, or the like.

The housing <NUM> is formed with the grip <NUM> for a user to hold, a first accommodating portion <NUM> accommodating the motor <NUM> and the drive mechanism <NUM>, and a second accommodating portion <NUM> accommodating the impact mechanism <NUM> and the output mechanism <NUM>. As shown in <FIG> and <FIG>, an output axis A is defined to more clearly illustrate design positions of different structures. In an example, the output axis A and a straight line on which a mounting direction of a tip functional element <NUM> is located are basically parallel to each other or are the same straight line, the second accommodating portion <NUM> extends along the direction of the output axis A, and the first accommodating portion <NUM> and the second accommodating portion <NUM> are integrally formed to be substantially L-shaped in a side view. In an example, the first accommodating portion <NUM> may extend along the direction of the output axis A, and the first accommodating portion and the second accommodating portion <NUM> are integrally formed to be substantially rectangular in a side view.

The motor <NUM> includes a motor body <NUM> and a motor shaft <NUM>. An included angle between a motor axis B on which the motor shaft <NUM> is located and the output axis A is greater than or equal to <NUM>° and less than or equal to <NUM>°. In an example, the included angle between the motor axis B and the output axis A is approximately <NUM>°. In an example, the motor axis B is basically parallel to the output axis A.

The output mechanism <NUM> includes a sleeve <NUM>, where the sleeve <NUM> can be driven by the drive mechanism <NUM> to rotate about the output axis A. Specifically, the sleeve <NUM> is formed with an accommodating cavity for accommodating the tip functional element <NUM>, where the tip functional element <NUM> may be inserted into the accommodating cavity. A clamping assembly <NUM> may retain the tip functional element <NUM> within the sleeve <NUM>. When the sleeve <NUM> rotates about the output axis A, the tip functional element <NUM> can be driven to rotate. In an example, a sleeve driving wheel <NUM> is fixed to an outer side of the sleeve <NUM> and can be driven by the drive mechanism <NUM> to drive the sleeve <NUM> to rotate.

The impact mechanism <NUM> can be driven by the drive mechanism <NUM> to drive the tip functional element <NUM> to strike the workpiece along the direction of the output axis A. In this example, the impact mechanism <NUM> includes an impact rod <NUM>, an impact block <NUM>, and an impact power piece <NUM>. The impact rod <NUM> can abut against the tip functional element <NUM>. That is to say, after inserted into the sleeve <NUM> from the front to the rear along the direction of the output axis A, the tip functional element <NUM> can be in contact with a front end surface of the impact block <NUM>. A position of the impact rod <NUM> within the sleeve <NUM> is basically unchanged. The impact block <NUM> is disposed at a rear end of the impact rod <NUM> and can be pushed by impact power to reciprocatingly impact the impact rod <NUM> from the rear to the front along the direction of the output axis. When the impact block <NUM> is at an impact position shown in <FIG>, the impact rod <NUM> can transmit an impact force to the tip functional element <NUM> so that the tip functional element <NUM> performs an impact action on a workpiece. The impact power piece <NUM> is disposed behind the impact block <NUM>, and an end of the impact power piece <NUM> is connected to the drive mechanism <NUM> and can be driven by the drive mechanism <NUM> to generate the impact power.

In this example, a weight of the impact block <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. In some examples, the weight of the impact block <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. For example, the weight of the impact block <NUM> is <NUM>, <NUM>, <NUM>, <NUM>, or the like. In this example, a length of the impact block <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. In some examples, the length of the impact block <NUM> is greater than or equal to <NUM> and less than or equal to <NUM>. For example, the length of the impact block <NUM> is <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like.

In this example, a gas space <NUM> can be formed between the impact block <NUM> and the impact power piece <NUM>. The impact power piece <NUM>, when driven by the drive mechanism <NUM>, can compress the gas in the gas space <NUM>, causing the gas pressure in the gas space <NUM> to increase and thereby generating the impact power. That is to say, when driven by the drive mechanism <NUM>, the impact power piece <NUM> can move from the rear to the front along the direction of the output axis A to compress the gas in the gas space <NUM>, and correspondingly, the size of the gas space <NUM> changes. When the gas pressure in the gas space <NUM> is high enough, the impact block <NUM> can be pushed to impact towards the impact rod <NUM>. Specifically, as the impact power piece <NUM> moves from the rear to the front, a length of the gas space <NUM> along the direction of the output axis A continuously decreases, and when the impact block <NUM> impacts the impact rod <NUM>, the impact block <NUM> moves to the impact position. When the impact block <NUM> is at the impact position, the gas space <NUM> has a minimum length along the direction of the output axis A, where a minimum length D is less than or equal to <NUM>. For example, the minimum length of the gas space <NUM> is <NUM>, <NUM>, <NUM>, <NUM>, or the like.

The drive mechanism <NUM> is disposed in the first accommodating portion <NUM>, and can drive the output mechanism <NUM> to drive the tip functional element <NUM> to perform a drilling operation or drive the impact mechanism <NUM> to drive the tip functional element <NUM> to perform an impact operation, or drive the output mechanism <NUM> and the impact mechanism <NUM> simultaneously to cause the tip functional element <NUM> to perform a hammer drilling operation. In an optional example, the drive mechanism <NUM> may selectively control the output mechanism <NUM> or the impact mechanism <NUM> in cooperation with other clutch structures or control structures or switching structures, the specific implementation of which is not described in detail in this example.

In an example, the drive mechanism <NUM> includes a first drive assembly <NUM> and a second drive assembly <NUM>. The first drive assembly <NUM> is used for driving the output mechanism <NUM> and the second drive assembly <NUM> is used for driving the impact mechanism <NUM>. Referring to <FIG> and <FIG>, the first drive assembly <NUM> includes a first drive shaft <NUM>, a first transmission gear <NUM>, and a first drive gear <NUM>, and the second drive assembly <NUM> includes a second drive shaft <NUM>, a second transmission gear <NUM>, and a swing link bearing <NUM>. The first drive shaft <NUM> is approximately parallel to the motor shaft <NUM> and the second drive shaft <NUM> in a vertical direction. A first motor transmission gear <NUM> is disposed on the motor shaft <NUM> and can be engaged with the first transmission gear <NUM> and the second transmission gear <NUM> separately. The rotation of the motor <NUM> can drive the rotation of the first motor transmission gear <NUM>, the first motor transmission gear <NUM> drives the first transmission gear <NUM> and the second transmission gear <NUM> to rotate, and then the first transmission gear <NUM> drives the first drive shaft <NUM> to rotate and the second transmission gear <NUM> drives the second drive shaft <NUM> to rotate. Further, the rotation of the first drive shaft <NUM> can drive the rotation of the first drive gear <NUM>. Since the first drive gear <NUM> is engaged with a first sleeve driving wheel <NUM> fixed outside the sleeve <NUM>, the first sleeve driving wheel <NUM> can drive the sleeve <NUM> to rotate so that the tip functional element <NUM> can perform the drilling operation. In addition, the rotation of the second drive shaft <NUM> can drive the swing link bearing <NUM> to swing reciprocatingly along a front and rear direction. Since the swing link bearing <NUM> is connected to the impact power piece <NUM>, the impact power piece <NUM> can generate the impact power so that the tip functional element <NUM> performs an impact action along the direction of the output axis A. In an example, the first drive gear <NUM> is a bevel gear, and the first sleeve driving wheel <NUM> fixed outside the sleeve <NUM> can be engaged with the bevel gear, thereby changing a transmission direction.

In an embodiment, a support <NUM> is further included and disposed on the motor shaft <NUM> and can support the first drive assembly <NUM> and the second drive assembly <NUM> at an upper end of the motor <NUM>.

Referring to <FIG> and <FIG>, the impact power piece <NUM> includes a piston <NUM> and a connecting member <NUM>, where the connecting member <NUM> is fixed to the piston <NUM>, a front end of the connecting member <NUM> is fixed to the piston <NUM>, and a rear end of the connecting member <NUM> is connected to the swing link bearing <NUM>. Therefore, when the second drive shaft <NUM> rotates to drive the swing link bearing <NUM> to swing reciprocatingly along the front and rear direction, the connecting member <NUM> can drive the piston <NUM> to reciprocate within the sleeve <NUM>. It is to be understood that when a swing link on the swing link bearing <NUM> is closest to the sleeve <NUM>, the piston <NUM> is farthest from a rear end of the sleeve <NUM>; and when the swing link on the swing link bearing <NUM> is farthest from the sleeve <NUM>, the piston <NUM> is closest to the rear end of the sleeve <NUM>. During the forward movement of the piston <NUM> away from the rear end of the sleeve <NUM>, the gas in the gas space <NUM> is compressed and the gas pressure increases so that the impact block <NUM> can be pushed to impact forward to the impact position. As the piston <NUM> moves towards the rear end of the sleeve <NUM>, the gas pressure in the gas space <NUM> gradually decreases, resulting in negative pressure, so that the impact block <NUM> moves backwards away from the impact position. The preceding process is a process in which the impact mechanism <NUM> performs one impact action and is reset. In this example, a rear end surface of the impact block <NUM>, an inner sidewall of the sleeve <NUM>, and a front end surface of the piston <NUM> can form the preceding gas space <NUM>. Optionally, the preceding gas space <NUM> may be a closed space or a non-closed space. For example, a gas hole <NUM> is provided on a wall of the sleeve <NUM> and can provide a passage for gas exchange between the gas space <NUM> and the space outside the sleeve <NUM> during the movement of the piston <NUM>, which can solve the problem of serious heat generation caused by multiple reciprocating movements of the piston <NUM>.

In an example, the structure of a hammer drill is shown in <FIG>. Main differences between the hammer drill shown in <FIG> and the hammer drill shown in <FIG> lie in the drive mechanism <NUM> and an impact mechanism <NUM>. Therefore, in this example, other structures are not described in detail. <FIG> follow the reference numerals in <FIG>, that is, the same parts use the same reference numerals.

In this example, the drive mechanism <NUM> includes a third drive assembly <NUM> and a fourth drive assembly <NUM>. The third drive assembly <NUM> is used for driving the output mechanism <NUM> and the fourth drive assembly <NUM> is used for driving the impact mechanism <NUM>. Referring to <FIG>, the third drive assembly <NUM> includes a third drive shaft <NUM>, a third transmission gear <NUM>, and a third drive gear <NUM>, and the fourth drive assembly <NUM> includes a crank rocker <NUM> disposed on the third drive shaft <NUM>. The crank rocker <NUM> is connected to the impact power piece <NUM> and can directly drive the impact power piece <NUM> to move. In this example, the third drive shaft <NUM> and the motor shaft <NUM> are integrally formed to be substantially perpendicular in a side view. A second motor transmission gear <NUM> is disposed at an upper end of the motor shaft <NUM> and can be engaged with the third transmission gear <NUM> on the third drive shaft <NUM> so that the third drive shaft <NUM> is driven to rotate when the motor rotates. In this example, the third transmission gear <NUM>, the crank rocker <NUM>, and the third drive gear <NUM> are disposed on the third drive shaft <NUM> from the rear to the front. After the third drive shaft <NUM> is driven to rotate, the crank rocker <NUM> is driven to reciprocate along the direction of the output axis A. Since the crank rocker <NUM> is connected to the impact power piece <NUM>, the impact power piece <NUM> can generate the impact power so that the tip functional element <NUM> strikes the workpiece along the direction of the output axis A. The third drive gear <NUM> is engaged with a second sleeve driving wheel <NUM> fixed outside the sleeve <NUM> so that the sleeve <NUM> can be driven to rotate. In this example, the second motor transmission gear <NUM> is a bevel gear, and the third transmission gear <NUM> can be engaged with the bevel gear, thereby changing a transmission direction.

Referring to <FIG>, the impact power piece <NUM> includes a cylinder <NUM>. The cylinder <NUM> is a semi-closed cavity with an end open. Specifically, along the direction of the output axis, a rear end of the cylinder <NUM> is closed and can be connected to the crank rocker <NUM>, and a front end of the cylinder <NUM> is open and used for accommodating the impact block <NUM>. In this example, the cylinder <NUM> is connected to the crank rocker, and when the crank rocker is driven to reciprocate along the direction of the output axis A, the cylinder <NUM> is driven to reciprocate. During the forward movement of the cylinder <NUM>, the gas in the gas space <NUM> is compressed, the gas pressure increases, and when the gas pressure increases to a certain extent, the impact block <NUM> is pushed to impact forward to the impact position. During the backward movement of the cylinder <NUM>, the gas pressure in the gas space <NUM> gradually decreases to a negative pressure, and the impact block <NUM> is driven to move backwards to leave the impact position. The preceding process is a process in which the impact mechanism <NUM> performs one impact action and is reset. In this example, the rear end surface of the impact block <NUM> and an inner wall of the cylinder <NUM> can form the gas space <NUM>, where the inner wall of the cylinder <NUM> mainly includes a sidewall and an inner wall at the rear end of the cylinder <NUM>. The preceding gas space <NUM> may be a closed space or a non-closed space. For example, the gas hole <NUM> is provided on the wall of the cylinder <NUM> and can provide a passage for gas exchange between the gas space <NUM> and the space outside the cylinder <NUM> during the movement of the cylinder <NUM>, which can solve the problem of serious heat generation caused by multiple reciprocating movements of the cylinder <NUM>.

In an example, the drive mechanism <NUM> shown in <FIG> and <FIG> may operate in cooperation with the impact power piece <NUM> shown in <FIG>; and the impact power piece <NUM> shown in <FIG> and <FIG> may operate in cooperation with the drive mechanism <NUM> shown in <FIG>. In the example of the present application, on the basis of ensuring that the gas space <NUM> exists between the impact power piece <NUM> and the impact block <NUM>, other modified structures of the impact power piece <NUM> or the drive mechanism <NUM> may be used.

In an embodiment, a mounting position or angle of the swing link bearing <NUM>, the crank rocker, or another structure may be adjusted so as to adjust the minimum length D of the gas space <NUM> between the impact block <NUM> and the impact power piece <NUM>.

In the example of the present application, the minimum length D of the gas space <NUM> is configured to be less than or equal to <NUM> so that the intensity of the peak gas pressure or the average gas pressure in the gas space <NUM> in the working process of the tool can be enhanced and thus impact energy or the impact work can be increased. In addition, the magnitude of D is minimized so that a length of the entire machine of the tool along the front and rear direction is reduced to some extent and the dimension of the entire machine is shortened.

In an example, the hammer drill <NUM> working with a load has an impact frequency of greater than or equal to <NUM> BPM. For example, the impact frequency is <NUM> BPM, <NUM> BPM, or the like.

In an example, the hammer drill <NUM> further includes a secondary handle <NUM>. The secondary handle <NUM> is detachably mounted on a tool body.

Generally, the hammer drill <NUM> may work with a light load or work with a load, and impact frequencies of the tool in the two manners are different. The so-called working with a light load may be that the tool is in a light-load impact stage and has a light-load impact frequency when the impact rod <NUM> of the tool abuts against the workpiece and the tool starts working or that the tool can work with a light load and has the light-load impact frequency when the material of the workpiece is relatively soft. However, after the initial working of the tool or when the material of the workpiece is relatively hard, the tool works with a relatively large load and has a load impact frequency. It is to be understood that the light-load impact frequency of the tool is greater than the load impact frequency.

In the example of the present application, the hammer drill <NUM> can work at a constant speed or work at a non-constant speed. When the motor <NUM> in the tool works at a constant speed, an increase of a rotational speed or an increase of the impact frequency may result in an impact dead point. The so-called impact dead point means that the gas pressure in the gas space <NUM> at a rear end of the impact block <NUM> changes too fast due to too high an impact frequency and the negative pressure lasts for too short a time to suck the impact block <NUM> away from the impact position. When the motor <NUM> in the tool works at a non-constant speed, the impact frequency of the tool can be continuously increased. The light-load impact frequency is generally greater than or equal to <NUM> BPM. When the impact frequency is continuously increased, the impact dead point may occur. To sum up, the increase of the impact frequency in the working process of the tool has a certain limit, which is a pain point for the tool to reach a higher impact velocity.

In the example of the present application, the minimum length D of the gas space <NUM> along the output axis A is reduced so that the impact dead point can be effectively avoided while the working efficiency of the hammer drill is improved.

In the process of the hammer drill <NUM> in <FIG> working with a load, the impact energy that can be obtained when the minimum length D of the gas space <NUM> along the output axis A or the impact frequency is changed is shown in Table <NUM> below. Since impact efficiency is positively correlated to the impact energy and the impact frequency, the impact efficiency is high when the impact frequency is high and the impact energy is large.

In Table <NUM>, tool A1 and tool A2 are tools corresponding to different working parameters or component parameters after tool A is modified, separately. D is the minimum length of the gas space <NUM> along the output axis A; and the load impact frequency is the impact frequency at which the tool drills the workpiece. The tool common parameter may be one or more of a mass of the impact block, a crank radius, a rocker length, or a cylinder radius and may also be other parameters, which is not limited in the present application. The same tool common parameter is selected for tool A, tool A1, and tool A2 in Table <NUM> and is X, and the value or type of X is not described in detail herein.

As can be seen from the comparison of the second row with the third row in Table <NUM>, when the impact frequency is relatively small and less than <NUM> BPM and only a distance D is shortened, the impact energy obtained by tool A1 is not higher than and even slightly lower than the impact energy obtained by the original tool A whose parameter is not modified. As can be seen from the comparison of the third row with the fourth row in Table <NUM>, on the basis of shortening the distance D, when the impact frequency increases to <NUM> BPM, the impact energy can be greatly increased.

In the process of the hammer drill <NUM> in <FIG> impacting a light load, the impact energy that can be obtained when the minimum length D of the gas space <NUM> along the output axis A or the impact frequency is changed is shown in Table <NUM>.

As shown in Table <NUM>, when the tool has a light-load impact frequency of <NUM> BPM, the velocity of the impact block <NUM> becomes very small as shown in <FIG>, and the impact dead point of the tool may occur. In this case, an increase of the impact frequency makes no sense. As shown in the third row of Table <NUM> and <FIG>, with the light-load impact frequency unchanged, the distance D is shortened so that the tool has a normal impact velocity and normal impact energy and can perform a normal impact without the impact dead point. As can be seen from the comparison of the second row with the third row of Table <NUM>, when the light-load impact frequency is relatively high and reaches a critical value of the impact dead point, the distance D is shortened so that the tool can perform a normal impact. That is, the distance D is shortened so that the tool can reach a relatively high constant speed value when working at a constant speed or the tool can reach a relatively high impact frequency when working at a non-constant speed. As can be seen from the comparison of the third row with the fourth row of Table <NUM>, when the distance D is shortened and the light-load impact frequency is increased, the tool can obtain relatively large impact energy and a relatively high impact velocity, thereby achieving relatively high impact efficiency.

As can be seen from the comparison of Table <NUM> with Table <NUM>, when the distance D is less than <NUM>, for example, <NUM>, the tool can reach a relatively high impact frequency to obtain relatively large impact energy and thus achieve relatively high impact efficiency.

In the process of the hammer drill <NUM> in <FIG> working with a load, the impact energy that can be obtained when the minimum length D of the gas space <NUM> along the output axis A or the impact frequency is changed is shown in Table <NUM>. Since the impact efficiency is positively correlated to the impact energy and the impact frequency, the impact efficiency is high when the impact frequency is high and the impact energy is large.

In Table <NUM>, tool B1 and tool B2 are tools corresponding to different working parameters or component parameters after tool B is modified, separately. D is the minimum length of the gas space <NUM> along the output axis A; and the load impact frequency is the impact frequency at which the tool drills the workpiece. The tool common parameter may be one or more of the mass of the impact block, a swing angle of the swing link bearing, or the cylinder radius and may also be other parameters, which is not limited in the present application. The same tool common parameter is selected for tool B, tool B1, and tool B2 in Table <NUM> and is Y, and the value or type of Y is not described in detail herein.

As can be seen from the comparison of the second row with the third row in Table <NUM>, when the impact frequency is relatively small and less than <NUM> BPM and the distance D is shortened, the impact energy obtained by tool B1 is slightly higher than the impact energy obtained by the original tool B whose parameter is not modified. That is, with the impact frequency unchanged, the distance D is shortened so that the impact efficiency can be improved to some extent. As can be seen from the comparison of the third row with the fourth row in Table <NUM>, on the basis of shortening the distance D, when the impact frequency increases to <NUM> BPM, the impact energy and the impact efficiency can be greatly increased.

Claim 1:
A hammer drill (<NUM>) configured to perform a hammer drilling operation through a tip functional element (<NUM>), comprising:
a motor (<NUM>);
a drive mechanism (<NUM>) for generating a driving force;
an output mechanism (<NUM>) for accommodating at least a portion of the tip functional element and capable of being driven by the drive mechanism to drive the tip functional element to rotate about an output axis (A), wherein the output axis extends along a front and rear direction of the hammer drill; and
an impact mechanism capable of being driven by the drive mechanism to impact the tip functional element;
wherein the impact mechanism comprises:
an impact rod (<NUM>) capable of abutting against the tip functional element;
an impact power piece (<NUM>) connected to the drive mechanism and used for generating impact power; and
an impact block (<NUM>) disposed between the impact rod and the impact power piece and capable of reciprocating when impacted by the impact power generated by the impact power piece to impact the impact rod, wherein a gas space (<NUM>) is formed between the impact block and the impact power piece;
wherein the hammer drill is configured such that:
a minimum length of the gas space in a direction of the output axis is in the range from <NUM> to <NUM>, inclusive; and
an impact frequency of the impact mechanism is greater than or equal to <NUM> BPM.