WO2013167704A1

WO2013167704A1 - Linear drive device and engine comprising same

Info

Publication number: WO2013167704A1
Application number: PCT/EP2013/059673
Authority: WO
Inventors: Russell M. Modien; Xiangguang CAO
Original assignee: Continental Automotive Gmbh
Priority date: 2012-05-11
Filing date: 2013-05-08
Publication date: 2013-11-14
Also published as: CN202561210U

Abstract

A linear drive device, comprising: a motor (12), a first gearwheel (11) connected to the motor, a second gearwheel (13) having a spiral groove (14) and being meshed with the first gearwheel, and a support member (15) located in the spiral groove and engaging in linear reciprocal motion as the second spiral gearwheel rotates. Based on the above linear drive device, the present device also provides an engine comprising the linear drive device. Using the technical solution of the present device can simplify existing linear drive devices and engines, reducing the cost thereof.

Description

Linear drive device and engine comprising same Technical field

The present device relates to a linear drive device and an engine comprising the same.

Background art

Linear drive devices, such as actuator assemblies, are widely used in fluid control valves in motor vehicles and other equipment on account of the fact that they can convert rotation into axial motion (linear motion) . Existing linear drive devices are provided with complex elements or components for the purpose of converting rotational motion into axial motion, which increases device complexity so that the device has a large overall size and cannot be easily miniaturized, while also resulting in high manufacturing costs.

The present device proposes a novel linear drive device to solve the above problem.

Content of the device

The problem solved by the present device is the provision of a novel linear drive device to solve the problem of existing linear drive devices being large and difficult to miniaturize.

To solve the above problem, the present device provides a linear drive device comprising: a motor; a first gearwheel connected to the motor; a second gearwheel having a spiral groove, the second gearwheel being meshed with the first gearwheel; a support member located in the spiral groove and engaging in linear reciprocal motion as the second spiral gearwheel rotates.

Optionally, the linear drive device further comprises: a valve stem member and a valve seat nested one within another, the valve stem member being connected to the support member and selectively leaving the valve seat as the support member moves in a linear reciprocating manner .

Optionally, the valve stem member and the support member are connected directly or via a connecting piece.

Optionally, the linear drive device further comprises : a housing in which the motor, the first gearwheel, the second gearwheel and the support member are all located. Optionally, one side of the second gearwheel has the spiral groove, the other side of the second gearwheel has a lug, and a rotation shaft extends out from the center of this other side, the rotation shaft being fixed to the second gearwheel, and the linear drive device further comprises : a torsion spring disposed around the rotation shaft, the torsion spring having two ends, one of which abuts an inside wall of the housing while the other end abuts the lug on the second gearwheel.

Optionally, one side of the second gearwheel has the spiral groove, the other side of the second gearwheel has a lug, and a rotation shaft extends out from the center of this other side, the rotation shaft having a slot parallel to the axial direction and being capable of rotating relative to the second gearwheel, and the linear drive device further comprises : a torsion spring disposed around the rotation shaft, the torsion spring having two ends, one of which abuts the inside of the slot in the rotation shaft while the other end abuts the lug on the second gearwheel. Optionally, the radius of the first gearwheel is less than the radius of the second gearwheel. Optionally, the linear drive device further comprises: a sensor for detecting the position of the support member, the sensor being a non-contact sensor, and a target object for detection by the sensor being fixed on the second gearwheel, the support member, the valve stem member or the connecting piece.

Optionally, the angle of the spiral groove is greater than 90 degrees .

Optionally, the angle of the spiral groove is greater than 180 degrees and less than 320 degrees.

Optionally, the center of the spiral groove coincides with the center of the second gearwheel. Optionally, the housing comprises a housing body and a housing cover, the housing body and the housing cover being joined to form a sealed chamber; and mating faces of the housing body and housing cover are inclined. Based on the above linear drive device, the present device also provides an engine comprising the linear drive device .

The present device has the following advantages compared with the prior art. Space is saved by providing a spiral groove in the second gearwheel (also called the output wheel) and inserting the support member into the spiral groove. In addition to this advantage, and more importantly, since the arc length of the spiral groove in one stroke as the output wheel rotates can be very large, the pressure angle between the groove and the support member is reduced (the pressure angle is related to the ratio of the stroke of the support component to the arc length of the spiral groove) . When the component of transmitted force needed by the support component in the direction of linear motion (the transmitted force between the groove and the support member multiplied by the cosine of the pressure angle) is fixed, a reduction of the pressure angle causes an increase in the cosine thereof, which in turn allows the transmitted force between the groove and the support member to be reduced. Such a reduction in the transmitted force between the groove and the support member allows the existing multi-stage drive to be replaced with a single-stage drive, which can simplify the mechanism of linear drive devices and reduce costs.

In an optional solution, the linear drive device further comprises: a valve stem member and a valve seat nested one within another, wherein the valve stem member is connected to the support member and selectively leaves the valve seat as the support member moves in a linear manner. Taking a cylinder of a motor vehicle engine as an example, a valve stem member in the cylinder must open the cylinder to allow vaporized petrol to enter or exhaust gas to be discharged; it must overcome its own weight or gas pressure, and thus needs a certain opening force. Based on analysis of the above single-stage drive, the linear drive device comprising a valve stem member and a valve seat can simplify the mechanism of motor vehicle cylinders, or reduce the cost of other mechanisms using the linear drive device.

Description of the accompanying drawings

Fig. 1 is a schematic diagram showing the assembled structure of the linear drive device (not including the housing cover);

Fig. 2 is an exploded drawing of the linear drive device;

Fig. 3 is a schematic diagram showing the assembled internal structure of the assembly in Fig. 1 with the housing body removed;

Fig. 4 is a schematic diagram showing the principle of the linear drive device . Particular embodiments

In order that the above object, features and advantages of the present device may be clearer and easier to understand, particular embodiments of the present device are described in detail below with reference to the accompanying drawings. Since the emphasis is on illustrating the principle of the present device, the drawings are not to scale.

The linear drive device is presented below using the conversion of rotational motion to linear motion in the cylinder of a motorized vehicle as an example. Referring to the schematic diagram of the assembled structure in Fig. 1 (not including the housing cover) , the exploded drawing in Fig. 2, and the schematic diagram of the assembled internal structure with the housing body removed in Fig. 3, the linear drive device comprises: a first gearwheel 11, a motor 12, a second gearwheel 13 and a rotation shaft 19 thereof, a support member 15, a valve stem member 16, a valve seat 22, a torsion spring 18, a housing body 20 and a housing cover 23.

Specifically, the first gearwheel 11 is connected to the motor 12 and driven thereby, and so is also called the input wheel. The motor 12 may be any type of DC motor with any torgue, selected according to reguirements . The second gearwheel 13 meshes with the first gearwheel 11, and so is also called the output wheel. In order to increase the transmission ratio, the radius of the first gearwheel 11 is smaller than that of the second gearwheel 13. In the present utility model, a spiral groove 14 is provided in a central region of one side of the second gearwheel 13 (facing out of the paper in Fig. 3) . The spiral shape of the spiral groove 14 indicates a curved line drawn from the center, which moves away from the center with a gradually increasing radius of curvature as it extends. The second gearwheel 13 with the spiral groove 14 can be formed by casting in a mould, welding or a sintering process during manufacturing . In addition, in this embodiment, the center of the spiral groove 14 preferably coincides with the center of the second gearwheel 13, for convenience of machining.

In this embodiment, the support 15 is a bearing nested within the spiral groove 14, and can engage in reciprocating motion in the vertical direction when the second gearwheel 13 rotates due to being driven by the second gearwheel 13 and clamped in the spiral groove 14. In addition, the valve stem member 16 is nested within the valve seat 22. The valve stem member 16 is connected to the support member 15 by a connecting piece 17; specifically, the bearing which acts as the support member 15 has a rotation shaft 21, with no relative rotation taking place therebetween. By welding the rotating shaft 21 to the connecting piece 17, and the connecting piece 17 to the valve stem member 16, the three are fixed together, so that upward or downward motion of the support element 15 drives the valve stem member 16 to move upwards or downwards correspondingly and selectively leave the valve seat 22. The distance by which it leaves the valve seat 22 can also be selected, so as to control the volume of flow passing through.

In addition, to prevent dust or other parts from falling in and causing damage to the linear drive device in the course of gearwheel transmission, a housing is provided outside the above components, and to make installation of the gearwheels therein convenient, this housing is split into a housing body 20 and a housing cover 23 which together form a sealed chamber. Due to the position in which the valve stem member 16 is disposed, the mating faces of the housing body 20 and housing cover 23 are inclined, with a wider edge being perpendicular to the direction of movement of the valve stem member 16. To enhance the sealing effect between the housing body 20 and the housing cover 23, a sealing gasket 24 is provided on their mating surfaces during installation.

To enable the support member 15 and valve stem member 16 to return to their starting positions when the motor 12 experiences a power failure, the linear drive device also comprises a torsion spring

18 in this embodiment. Specifically, a rotation shaft 19 extends outwards from the center of the side of the second gearwheel 13 opposite that on which the spiral groove 14 is provided (facing into the paper in Fig. 3) . To prevent the rotation shaft 19 from obstructing the movement of the valve stem member 16 due to being excessively long, one end of the rotation shaft 19 is flush with the spiral groove 14, and the torsion spring 18 is disposed around the rotation shaft 19. In addition, a lug, or stop (not shown in the drawings), is provided on the other side of the second gearwheel 13. The torsion spring 18 has two ends which can be fixed in two different ways. First way: the rotation shaft 19 is fixed to the second gearwheel 13; one end of the torsion spring 18 abuts an inside wall of the housing 20, while the other end abuts the lug on the second gearwheel 13. Second way: the rotation shaft

19 can rotate relative to the second gearwheel 13; the rotation shaft 19 has a slot parallel to the axial direction (not shown in the drawings), and one end of the torsion spring 18 abuts the inside of the slot in the rotation shaft 19, while the other end abuts the lug on the second gearwheel 13.

In this embodiment, the housing body 20 has a matching projecting structure (not shown in the drawings) for the purpose of locating the rotation shaft 19.

In addition, the torsion spring 18 is in a twisted (compressed) state when installed. The process of operation of the linear drive device in this embodiment is as follows . The motor 12 rotates the first gearwheel 11; the torsion spring 18 hinders the first gearwheel 11 in rotating the second gearwheel 13, which only rotates once the force with which the first gearwheel 11 drives the second gearwheel 13 reaches a certain level exceeding the resistance presented by the torsion spring 18. Once the end point of the unidirectional travel has been reached, the motor 12 rotates in the opposite direction, and the first gearwheel 11 rotates the second gearwheel 13 in the opposite direction, thus driving the support member 15 in a direction (downwards or upwards) opposite to that of the previous upwards or downwards motion, to return to its original position.

In other embodiments, the center of the spiral groove 14 (the center of the circle on which the innermost point of the spiral is located) may be arranged to not coincide with the center of the second gearwheel 13 as reguired, or in other words, the spiral groove 14 may be disposed in a non-central region of the second gearwheel 13. In this case, rotation of the spiral groove 14 resembles the motion of a cam. Whatever the case, it is only necessary for the support member 15 to engage in linear motion as the second gearwheel 13 rotates.

The principles by which single-stage drive can be used in this embodiment are as follows . Referring to Fig. 4, the support member 15 is disposed in the spiral groove 14. As the second gearwheel 13 rotates, the direction of the force F exerted by the spiral groove 14 on the support member 15 is perpendicular to the direction of the tangent to the groove 14 at that point. The direction of movement of the support member 15 and valve stem member 16 is vertically up or down. According to the concept of a pressure angle, i.e. the acute angle between the direction of force and the direction of movement, the angle between the direction of the force F exerted by the spiral groove 14 on the support member 15 and the direction of movement of the support member 15 forms the pressure angle a. In addition, the complementary angle of the pressure angle a at that point on the spiral groove 14 corresponds to the angle between the direction of the instantaneous travel height ΔΗ of the support member 15 and the direction of the instantaneous arc length AL of the spiral groove 14. In a single stroke, the travel height H of the support member 15 is formed by adding together the instantaneous travel heights ΔΗ, while the arc length L of the spiral groove 14 is formed by adding together the instantaneous arc lengths Ah. The angle between the direction of the travel height H and the direction of the arc length L of the spiral groove 14 corresponds to the mean value of the complementary angles of the pressure angles a in a single stroke of the support member 15; the value of H/L can approximately reflect the change in pressure angle.

Taking a cylinder of a motor vehicle engine as an example, the valve stem member 16 in the cylinder must open the cylinder to allow vaporized petrol to enter or exhaust gas to be discharged; it must overcome its own weight or gas pressure, and thus needs a certain opening force. With regard to existing multi-stage drive or the single-stage drive of the present utility model, if it is assumed that the opening force is the same in both cases, then the vertical component F*Cosa of the force F exerted by the spiral groove 14 on the support member 15 is fixed. The arc length L of the spiral groove 14 in the present device can be set to be very long (e.g. the angle of the spiral groove, i.e. the angle subtended at the center of the spiral groove by the starting point and end point of the spiral, is greater than 90 degrees); therefore, for the same travel of valve stem member 16 (the same height H) , a longer arc length L implies a smaller pressure angle a opposite the height H. Thus Cosa can be greater correspondingly. Since the component F*Cosa of the transmitted force acting on the support member 15 in the vertical direction is fixed, from an objective point of view the force F exerted by the spiral groove

14 on the support member 15 can be reduced. Since it is generally acknowledged in the industry that one way of realizing the final transmitted force at the output end is by multi-stage drive amplification, the use of the spiral groove 14 of the present device makes it possible to replace the existing multi-stage drive with a single-stage drive. It can be seen that a smaller pressure angle implies higher transmission efficiency. However, if the angle is too small, the mechanical strength of the spiral groove 14 and support member

15 will suffer, while the torsion spring 18 will become more difficult to machine, and so it is not a case of the smaller, the better. During particular implementation, the angle of the spiral groove 14 is preferably greater than 180 degrees and less than 320 degrees. During particular implementation, the valve stem member 16 can also realize multiple types of flow control within a fixed length of travel; this is achieved by controlling the value of the distance moved up or down by the valve stem member 16. Specifically, a target object for detection by a sensor is fixed on the support member 15, valve stem member 16 or connecting piece 17, while an inductive, reluctance-type or resistive linear sensor is disposed inside the housing cover 23 and accurately senses the specific position of the support member 15 or valve stem member 16 in real time, in a non-contact manner. Thus the flow control is achieved by controlling the distance moved by the support member 15 in the spiral groove 14. The specific position of the support member 15 or valve stem member 16 can be found not just by the linear sensor above but also by an angular sensor. Specifically, a target object for detection by an angular sensor is arranged on the second gearwheel 13, while an inductive, reluctance-type or resistive angular sensor is disposed inside the housing cover 23 and accurately senses the specific position of the support member 15 or valve stem member 16 in real time, in a non-contact manner .

As the curved line drawn from the center moves away from the center with a gradually increasing radius of curvature as it extends, the particular shape of the spiral of the spiral groove 14 may be further optimized as reguired. For example, the radius of curvature may be set to change at a slower rate at the starting point of travel than at other points in the stroke, in order to provide a large driving force at the beginning of the stroke.

It can be seen that a linear drive device used in a cylinder of an engine is taken as an example above. However, the present device is by no means limited to petrol or diesel engines; it may also be used in other liguid or gas valves, or in devices which need to control flow precisely, in which rotational motion is converted to linear motion. Although the present device has been disclosed above by way of preferred embodiments, these are by no means intended to limit the present utility model. Any person skilled in the art could use the methods and technical content disclosed above to make possible changes and amendments to the technical solution of the present utility model, without departing from the spirit and range thereof. Thus any simple amendments, eguivalent variations or embellishments made to the above embodiments on the basis of the technical substance of the present device without departing from the content of the technical solution thereof shall fall within the scope of protection of the technical solution thereof.

Claims

A linear drive device, characterized in that it comprises :

a motor;

a first gearwheel connected to the motor;

a second gearwheel having a spiral groove, the second gearwheel being meshed with the first gearwheel; a support member located in the spiral groove and engaging in linear reciprocal motion as the second spiral gearwheel rotates.

The linear drive device as claimed in claim 1, characterized in that it further comprises: a valve stem member and a valve seat nested one within another, the valve stem member being connected to the support member and selectively leaving the valve seat as the support member moves in a linear reciprocating manner.

The linear drive device as claimed in claim 2, characterized in that the valve stem member and the support member are connected directly or via a connecting piece.

The linear drive device as claimed in claim 1, characterized in that it further comprises: a housing in which the motor, the first gearwheel, the second gearwheel and the support member are all located.

The linear drive device as claimed in claim 4, characterized in that one side of the second gearwheel has the spiral groove, the other side of the second gearwheel has a lug, and a rotation shaft extends out from the center of this other side, the rotation shaft being fixed to the second gearwheel; and the linear drive device further comprises: a torsion spring disposed around the rotation shaft, the torsion spring having two ends, one of which abuts an inside wall of the housing while the other end abuts the lug on the second gearwheel.

The linear drive device as claimed in claim 4, characterized in that one side of the second gearwheel has the spiral groove, the other side of the second gearwheel has a lug, and a rotation shaft extends out from the center of this other side, the rotation shaft having a slot parallel to the axial direction, and the linear drive device further comprises: a torsion spring disposed around the rotation shaft, the torsion spring having two ends, one of which abuts the inside of the slot in the rotation shaft while the other end abuts the lug on the second gearwheel.

The linear drive device as claimed in claim 1, characterized in that the radius of the first gearwheel is less than the radius of the second gearwheel. 8. The linear drive device as claimed in claim 3, characterized in that it further comprises: a sensor for detecting the position of the support member, the sensor being a non-contact sensor, and a target object for detection by the sensor being fixed on the second gearwheel, the support member, the valve stem member or the connecting piece.

The linear drive device as claimed in claim 1, char acterized in that the angle of the spiral groove is greater than 90 degrees.

10. The linear drive device as claimed in claim 9, characterized in that the angle of the spiral groove is greater than 180 degrees and less than 320 degrees. The linear drive device as claimed in claim 1, characterized in that the center of the spiral groove coincides with the center of the second gearwheel.

The linear drive device as claimed in claim 4, characterized in that the housing comprises a housing body and a housing cover, the housing body and the housing cover being joined to form a sealed chamber; and mating faces of the housing body and housing cover are inclined.

An engine, characterized in that it comprises the linear drive device as claimed in any one of claims 1 to 12.