WO2010118720A1 - Torque-sensing apparatus - Google Patents

Abstract

The invention relates to a torque-sensing apparatus for a belt-driven conical pulley transmission, comprising a sensing piston (2; 32; 42; 52), which can be axially displaced relative to a shaft (4) that comprises at least one conducting opening (20), the effective conducting cross-section of which depends on the axial position of the sensing piston. The invention is characterized in that the sensing piston interacts with a seat valve device (38; 46; 60), which in a closed position closes the conducting opening without leakage.

Description

 Torque sensing device

The invention relates to a Drehmomentfühlvorrichtung for a conical-pulley, with a sensor piston which is axially displaceable relative to a shaft having at least one discharge opening whose effective Ableitungsquerschnitt depends on the axial position of the sensor piston.

From the international publication WO 2007/110026 A1 a generic torque sensing device for a conical-pulley belt transmission is known. Due to the design, a certain radial gap must be maintained between the shaft and the sensor piston in order, on the one hand, to ensure a smooth movement of the sensor piston despite deformations under operating load and, on the other hand, to permit unavoidable manufacturing tolerances. The radial gap between the shaft and the sensor piston leads to leakage, the amount of which increases due to viscosity at high temperatures.

The object of the invention is to minimize the leakage in a torque sensing device according to the preamble of claim 1, without the gap height is restricted to unrealistic tolerances.

The object is in a torque sensing device for a conical-pulley, with a sensor piston which is axially displaceable relative to a shaft having at least one discharge opening whose effective Ableitungsquerschnitt depends on the axial position of the sensor piston, achieved in that the sensor piston with a Seat valve device cooperates, which closes the discharge opening in a closed position almost free of leakage. The term axial refers to the axis of rotation or longitudinal axis of the shaft. Axial means in the direction or parallel to the longitudinal axis. In conventional torque sensing devices, as known from International Publication WO 2007/110026 A1, the sensor piston with the discharge opening constitutes a leakage-laden slide valve. The seat valve device according to the invention prevents leakage in the closed position being dissipated via the discharge opening. Thereby, the leakage of the torque sensing device can be significantly reduced. A preferred embodiment of the torque sensing device is characterized in that the poppet valve means comprises a closing body which is coupled in an axial direction with the sensor piston. The coupling in the one axial direction causes the closing body is actuated by the feeler piston. By coupling a entrainment of the closing body in an axial direction is made possible by the sensor piston. The coupling or entrainment of the closing body can be realized for example by a paragraph or by driving cam on the closing body.

Another preferred embodiment of the torque sensing device is characterized in that the closing body is coupled to the sensor piston, that the sensor piston when the closing body has reached its closed position, regardless of the closing body and in the closing direction of the closing body can move on. This ensures that the sensor piston, when the closing body has reached its closed position, can perform a pumping function. Such a pumping function of the sensor piston allows, in particular when extreme torque peaks occur, a rapid pressure build-up in contact chambers of the conical-pulley belt transmission. For the pumping function of the feeler piston, a pumping path of preferably several millimeters is provided in a ramp mechanism of the torque sensing device.

A further preferred embodiment of the torque sensing device is characterized in that the closing body is designed as a closing ring with a closing body sealing edge or closing body sealing surface, which comes to rest in the closed position of the closing body sealingly against a counter-sealing surface or counter-sealing edge. The sealing surfaces and / or sealing edges which come into abutment with one another constitute a sealing seat, by means of which the discharge opening is closed leak-free in the closed position of the closing body. The sealing surface is preferably designed conical.

A further preferred embodiment of the torque sensing device is characterized in that the locking ring has at least one driver, which allows the coupling with the sensor piston in one axial direction. The driver can be designed as a paragraph, cam or stop on the locking ring or closing body. The driver preferably extends radially outward from the closing ring or closing body. A further preferred embodiment of the torque sensing device is characterized in that the counter-sealing surface or counter-sealing edge is formed on the shaft. The mating or counter-sealing edge is preferably formed on a shaft shoulder. The discharge opening is preferably arranged in the region of the shaft shoulder.

Another preferred embodiment of the torque sensing device is characterized in that the counter-sealing surface or counter-sealing edge is formed on a counter-disc, which is fixed to the shaft. The counter-disk is preferably formed from another, in particular more wear-resistant material than the shaft. The counter-disc is preferably designed as a counter-ring disc and, for example, by a press fit, mounted on the shaft.

A further preferred embodiment of the torque sensing device is characterized in that the counter-disc is formed and / or hardened from a different material than the shaft. The material of the counter-disc is preferably selected so that it meets particularly high requirements with regard to the sealing function of the sealing seat.

Another preferred embodiment of the torque sensing device is characterized in that the closing body is biased in its closed position. This prevents unwanted discharge of hydraulic fluid through the discharge port.

Another preferred embodiment of the torque sensing device is characterized in that the closing body is biased by a spring means in its closed position. The spring device can be designed, for example, as a helical compression spring or as a plate spring.

Another preferred embodiment of the torque sensing device is characterized in that the closing body is biased by pressure in its closed position. The pressurization of the closing body may be provided alternatively or in addition to the previously described spring preload of the closing body.

A further preferred exemplary embodiment of the torque sensing device is characterized in that a seal is provided between the closing body and the sensor piston. is ordered. By sealing the interface between the closing body and the sensor piston, the leakage can be further minimized.

A further preferred embodiment of the torque sensing device is characterized in that a seal is arranged between the closing body and the shaft. By sealing the interface between the closing body and the shaft, the leakage can be further minimized.

A further preferred embodiment of the torque sensing device is characterized in that the closing body has at least one control notch. As a result, the closing on the sealing seat shown with the aid of the closing body can be made softer. Thereby, the characteristic of the seat valve according to the invention can be approximated before reaching the closed position of the closing body to the characteristics of a slide valve.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail. Show it:

1 shows a detail of a conventional torque sensing device with a

Sensor piston and a shaft in longitudinal section;

Figure 2 shows a similar section as in Figure 1 according to a first embodiment of the invention;

FIG. 3 shows an enlarged detail IM from FIG. 2 according to another

Embodiment;

Figure 4 shows a similar section as in Figure 1 according to a further embodiment;

Figure 5 shows a similar section as in Figure 1 according to a further embodiment and 6 shows an enlarged detail of Figure 5 according to another embodiment.

In Figure 1, a conventional torque sensing device 1 with a sensor piston 2 and a shaft 4 is fragmentary and shown in longitudinal section. The shaft 4 is rotatable about a longitudinal axis or axis of rotation 5. The sensor piston 2 comprises an axial section 8, with which the sensor piston 2 is displaceably guided on the shaft 4 in the axial direction. From the axial portion 8 of the feeler piston 2, a radial portion 9 extends radially outward. From the radial portion 9, a piston body 10 extends in the diagonal direction, that is at an angle of about 45 degrees to the longitudinal axis 5, to the outside. The axial portion 8 of the feeler piston 2 is integrally connected to the piston body 10 through the radial portion 9. By a double arrow 12 is indicated that the sensor piston 2 can move in operation in both axial directions, that is, in Figure 1 to the left and to the right.

The shaft 4 comprises a longitudinal bore 14, which is designed as a blind hole and from which a transverse bore 15 extends. In addition, the shaft 4 comprises a further longitudinal bore 17, which is also designed as a blind hole and from which a further transverse bore 18 emanates. The outlet opening of the transverse bore 18 is referred to as discharge opening 20. In the state shown in Figure 1, the axial portion 8 of the sensor piston 2 closes the discharge port 20. When the sensor piston 2 moves further to the right, as indicated by a dashed line 22, the discharge port 20 remains closed. When the sensor piston 2 moves to the left in FIG. 1, ie away from the transverse bore 15, the discharge opening 20 is first partially and then completely released from the axial section 8 of the sensor piston 2.

The structure and function of a conventional torque sensing device, as shown in Figure 1 and described above, are known, for example, from International Publication WO 2007/110026 A1, which is hereby incorporated by reference to avoid repetition. The cooperating with the discharge opening 20 sensor piston 2 is a slide valve, in the design caused leakage through the discharge opening 20 also occurs when the discharge port 20 is closed by the axial portion 8 of the sensor piston 2. Depending on the design, the leakage occurring during operation can amount to up to 50 percent of the flow rate of a pump that is used to convey an actuating fluid to confirm a belt pulley worm gear. In the figures 2 to 6 different embodiments of the invention are shown, in which the known slide valve is replaced by a poppet valve, which, as soon as it is closed, leak-free or almost free of leakage. Since the poppet valve, when it reaches its closed position, does not allow any further way for a pumping function of the feeler piston that is important in operation, according to a further essential aspect of the invention, the feeler piston is uncoupled from a closing element in order to enable this pumping function. In this case, the torque sensing device according to the invention can be carried out both in two stages, that is, with two pressure levels, as well as variable. In the two-stage version, the pressure surface of the sensor piston is divided into two partial surfaces. In the variable torque sensing device, the contact pressure of the belt, in particular the chain, depending on the torque and / or the ratio can be varied.

In FIGS. 1 to 6, identical parts are provided with the same reference numerals. To avoid repetition, reference is made to the preceding description of FIG. In the following, the differences between the individual embodiments will be discussed.

In the embodiment shown in Figure 2, the shaft 4 comprises in addition to the transverse bore 18, a further transverse bore 28, which also extends from the longitudinal bore 17. A feeler piston 32 includes a piston body 34 integrally connected to an axial portion 35. Of the axial portion 35, a radial portion 36 is angled radially inwardly. The piston body 34 extends substantially in the diagonal direction and is integrally connected to the axial portion 35 and the radial portion 36. At the junction between the axial portion 35 and the piston body 34, the sensor piston 32 has a radially inwardly extending projection 37.

The torque sensing device 1 shown in Figure 2 comprises a seat valve device 38 with a closing body 39, which is designed as a locking ring. The closing body 39 is biased by a spring device 40, which is designed as a helical compression spring, against a shoulder of the shaft 4. The projection 37 comprises an annular groove in which a seal 33 is received, which is designed for example as an O-ring and seals the interface between the sensor piston 32 and the closing body 39. The projection 37 also acts in an axial direction, in Figure 2 to the left, with a driver 41 together so that the closing body 39 against a movement of the sensor piston 32 to the left, that is away from the transverse bore 15, against the biasing force of the spring means 40 together with the feeler piston 32 is moved to the left. The spring device 40 is arranged in a spring chamber 43, which is designed as an annular space and is bounded by the sensor piston 42 and the shaft 4. The spring chamber 43 is connected via the further transverse bore 28 with the longitudinal bore 17 in connection.

At its end facing away from the spring device 40, the closing body 39 has a sealing edge which, in the closed position shown in FIG. 2, is in close contact with the shaft shoulder, in the region of which the discharge opening 20 is arranged. In the illustrated closed position, the discharge opening 20 is closed without leakage by the closing body 39. When the closing body 39 moves from its illustrated closed position to the left, that is to say away from the transverse bore 15, the discharge opening 20 is first partially and then completely released. In the embodiment shown in Figure 2, the closing body 39 is biased by both the biasing force of the spring 40 and by the pressure in the spring chamber 43 in its closed position. FIG. 2 further shows that the sensor piston 32 can move further to the right, that is, onto the transverse bore 15, independently of the closing body 39 from its position shown in FIG. About the further transverse bore 28 can be reduced in a simple manner effected when moving the closing body 39 back pressure.

FIG. 3 shows a section IM of FIG. 2 enlarged according to a further exemplary embodiment. To represent the sealing seat, an annular disk-shaped counter disk 30, which is formed from a different material than the shaft 4, is arranged on the shaft shoulder. To seal the interface between the counter-disc 30 and the shaft 4, a sealing ring 31 is arranged radially between the shaft shoulder of the shaft 4 and the counter-disc 30. The closing body 39 is in the illustrated closed position with its sealing edge sealingly against a sealing surface of the counter-disc 30 in abutment. The counter-disk 30 is hardened in particular in the region of the sealing surface.

In the exemplary embodiment illustrated in FIG. 4, a sensor piston 42 comprises a piston body 44, from which an axial section 45 extends radially inward. The axial section 45 serves to actuate a seat valve device 46, which comprises a closing body 47. The closing body 47 has at one axial end a sealing edge, which is located on a sealing surface in abutment, which is provided at a shaft shoulder in the region of the discharge opening 20. The closing body 47 is designed as a locking ring and by a spring device 48, which is designed as a helical spring, against the sealing surface on the shaft shoulder biased. The spring device 48 is clamped in the axial direction between the closing body 47 and an axial stop 49. The axial stop 49 may be designed as a press ring with a rectangular cross-section.

The closing body 47 has, at its end facing the spring device 48, a driver 50 which extends radially outwards in the form of a driving cam or in the form of a driver collar. By the driver 50 ensures that the closing body 47 against the biasing force of the spring means 48 in Figure 4 to the left, that is away from the transverse bore 15, moves when the sensor piston 42 due to operation performs such a movement. In a movement of the sensor piston 42 in this axial direction, that is, in Figure 4 to the left, the closing body 47 is thus also moved to the left, so that the discharge opening 20 is first partially and then completely released. In addition, the sensor piston 42, regardless of the closing body 47 to the right, that is on the transverse bore 15 to move.

In the embodiment shown in FIG. 5, a sensor piston 52 comprises a piston body 54, from which an axial portion 55 extends. Of the axial portion 55 in turn, a radial portion 56 is angled radially inwardly. From the radial portion 56, in turn, an axial portion 57 goes out, which is guided with the interposition of a seal 58 on the outer circumference of the shaft 4.

The axial section 55 and the radial section 56 of the feeler piston 52, together with a shaft shoulder 59, define an annular receiving space for a seat valve device 60, which comprises a closing body 62. The closing body 62 has, at its axial end facing the transverse bore 15, a sealing edge which rests against a sealing surface of the shaft shoulder 59 in the closed position shown in FIG. Radially outward, the closing body 62 has at least one connecting channel 63, which connects a first pressure chamber 64 with a second pressure chamber 65. Radially inside a seal 66 is disposed between the closing body 62 and the shaft 4.

The sensor piston 52 has for actuating the closing body 62 on a stop ring 67, which is fixed for example by a press connection to the sensor piston 52. The two pressure chambers 64, 65 are both arranged in the annular receiving space for the seat valve device 60. In the first pressure chamber 64 is a spring device 68 in the form of a helical compression spring in the axial direction between the axial portion 57 of the sensor piston 52 and the closing body 62 clamped. The second pressure chamber 65 is arranged radially outside of the discharge opening 20 and connected thereto when the closing body 62 moves from the closed position shown in FIG. 5 to the left, that is to say away from the transverse bore 15.

The opening movement of the closing body 62 is caused by a movement of the sensor piston 52 to the left, that is, away from the transverse bore 15. The opening movement of the sensor piston 52 is transmitted via the stop ring 67 on the closing body 62 as soon as the stop ring 67 comes into abutment in the region of the connecting channel 63 on the closing body 62. The closing movement of the closing body 62 is effected by a pressure difference between the two pressure chambers 64, 65 and a return pressure in the transverse bore 18 or the longitudinal bore 17. The spring device 68 is optional in the embodiment shown in Figure 5 and helps to overcome the friction caused by the sealing ring 66 when closing the closing body 62.

FIG. 6 shows the detail with the shaft shoulder 59 from FIG. 5 enlarged according to a further exemplary embodiment. In this embodiment, a conical sealing surface 71 is formed to represent the sealing seat on the closing body 62, which bears sealingly against a sealing edge 72 of the shaft shoulder 59. To make the closing movement of the closing body 62 softer in the region of the sealing seat, the closing body 62 has an additional annular body 74 with a control notch 70, which is shown in FIG. 6 in longitudinal section through the shaft 4 and above in the plan view of the closing body 62. By the control notch 70, the characteristic of a slide valve is made possible before reaching the closed position.

LIST OF REFERENCES

Torque sensing device

sensor piston

wave

Longitudinal axis axial section radial section

piston body

double arrow

longitudinal bore

Cross bore further longitudinal bore further cross bore

Discharge opening dashed line further transverse bore

counter-disk

seal

sensor piston

poetry

Piston body axial section radial section

approach

Poppet assembly

closing body

spring means

takeaway

sensor piston

spring chamber

Piston body axial section

Poppet assembly closing body

Spring device axial stop

takeaway

sensor piston

Piston body axial section radial section axial section

poetry

shaft shoulder

Poppet assembly

closing body

Connecting channel first pressure chamber second pressure chamber

poetry

stop ring

spring means

control notch

sealing surface

sealing edge

ring body

Claims

claims A torque sensing apparatus for a conical pulley comprising a sensing piston (2; 32; 42; 52) axially displaceable relative to a shaft (4) having at least one bleed port (20) whose effective bleed cross section is from the axial position of the sensing piston is dependent, characterized in that the sensor piston (32; 42; 52) with a seat valve means (38; 46; 60) cooperates, which closes the discharge opening (20) in a closed position without leakage. A torque sensing device according to claim 1, characterized in that said poppet valve means (38; 46; 60) comprises a closure member (39; 47; 62) coupled in an axial direction to said sensing piston (2; 32; 42; 52) , - 3. A torque sensing device according to claim 2, characterized in that the closing body (39; 47; 62) is so coupled to the sensor piston (2; 32; 42; 52) that the sensor piston (2; 32; 42; 52), when the closing body (39, 47, 62) has reached its closed position, it is possible to continue moving independently of the closing body (39, 47, 62) and in the closing direction of the closing body. 4. A torque sensing device according to claim 2 or 3, characterized in that the closing body (39; 47; 62) is designed as a closing ring with a closing body sealing edge or closing body sealing surface, which comes in the closed position of the closing body sealingly against a counter-sealing surface or counter-sealing edge to rest. 5. A torque sensing device according to claim 4, characterized in that the locking ring has at least one driver (41; 50) which allows the coupling with the sensor piston (42; 52) in the one axial direction. 6. torque sensing device according to claim 4 or 5, characterized in that the counter-sealing surface or counter-sealing edge on the shaft (4) is formed. 7. A torque sensing device according to claim 4 or 5, characterized in that the counter-sealing surface or counter-sealing edge is formed on a counter-disc (30) which is fixed to the shaft (4). 8. A torque sensing device according to claim 7, characterized in that the counter-disc (30) made of a different Materia! as the shaft (4) is formed and / or cured. 9. A torque sensing device according to any one of claims 2 to 8, characterized in that the closing body (39; 47; 62) is biased in its closed position. 10. A torque sensing device according to claim 9, characterized in that the closing body (39; 47; 62) is biased by a spring device (40; 48; 68) into its closed position. 11. A torque sensing device according to claim 9 or 10, characterized in that the closing body (39; 62) is biased by pressure into its closed position. 12. A torque sensing device according to any one of claims 2 to 11, characterized in that between the closing body (39) and the sensor piston (32) a seal (33) is arranged. 13. A torque sensing device according to any one of claims 2 to 12, characterized in that between the closing body (62) and the shaft (4) a seal (66) is arranged. 14. A torque sensing device according to any one of claims 2 to 13, characterized in that the closing body (62) has at least one control notch (70).