Carpet stretching device

A carpet stretching device includes a housing, a piston unit, a carpet gripping head connected to the housing, a fluid supply unit connected to the housing, and an anchor member. The housing has front and rear ends, and a receiving space between the front and rear ends. The piston unit includes a piston member disposed in the receiving space for moving relative to the housing, a piston rod extending out of the housing through the front end, and a biasing member provided between the rear end of the housing and the piston member. The anchor member is attached to a front end of the piston rod in front of the carpet gripping head.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 093217106, filed on Nov. 2, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a carpet stretching device, more particularly to a carpet stretching device that can stretch a carpet tightly and smoothly on the floor.

2. Description of the Related Art

Referring toFIG. 1, a conventional carpet stretching device1includes an elongated main body13having one end connected to a carpet gripping head14, and the other end connected to a knee plate15. The carpet gripping head14includes a plurality of forwardly extending spikes141disposed on a bottom portion thereof. The carpet stretching device1is operated by placing the carpet gripping head14on the floor such that the spikes141engage the carpet11near the edge thereof.

In use, an installer holds down the carpet gripping head14with his/her hand, and repeatedly strikes the knee plate15with his/her knee, so that the carpet11is urged toward a wall12, after which the carpet11is fixed on the wall12.

Although the conventional carpet stretching device1can achieve its intended purpose, much time is consumed in performing stretching of the entire carpet11. Furthermore, since the installer has to repeatedly strike the knee plate15with his/her knee to urge the carpet11to the wall12as described above, the installer may injure his/her knee over time. Moreover, since the striking force on the knee plate15may differ for each strike, the carpet11may not be evenly stretched on the floor, thereby adversely affecting its final appearance.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a carpet stretching device that can enable an installer to easily and quickly stretch a carpet on the floor.

According to one aspect of this invention, a carpet stretching device comprises a housing, a piston unit, a carpet gripping head connected to the housing, a fluid supply unit connected to the housing, and an anchor member. The housing has a front end, a rear end, and a receiving space between the front and rear ends. The piston unit includes a piston member disposed in the receiving space for moving relative to the housing, a piston rod extending out of the housing through the front end, and a biasing member provided between the rear end of the housing and the piston member. The anchor member is attached to a front end of the piston rod in front of the carpet gripping head.

According to another aspect of this invention, a carpet stretching device comprises a housing, a handgrip connected to the housing, a piston unit, a carpet gripping head, an anchor member, and a fluid supply unit. The piston unit includes a piston member movably disposed within the housing, and a piston rod connected to the piston member and extending out of the housing. The carpet gripping head is connected to one of the housing and the piston rod. The anchor member is attached to the other one of the housing and the piston rod. The fluid supply unit includes a main supply passage provided in the handgrip, a main valve assembly provided in the handgrip and controlling the main supply passage, an auxiliary passage connected fluidly to the main supply passage and the housing, and a safety valve assembly for controlling the auxiliary passage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 2 to 4, the first preferred embodiment of a carpet stretching device2according to the present invention is shown to comprise a housing4, a piston unit5, a carpet gripping head6, a fluid supply unit7, and a knee-applying cushion member8.

The housing4has an open front end421, a closed rear end422, a receiving space41between the front and rear ends421,422, and a cover plate43fastened to the front end421of the housing4to cover the receiving space41. The cover plate43includes an annular protrusion434projecting outwardly from a front face432of the cover plate43at a central portion thereof and having a through hole431, and two rows of teeth433formed respectively on two opposite sides of the annular protrusion434.

The piston unit5includes a piston member51, a hollow piston rod52, an insert rod53, and a biasing member54. The piston member51is disposed within the receiving space41for moving relative to the housing4. The piston rod52has a front end521, and a rear end520. The front end521extends through the piston member51, the front end421of the housing4via the through hole431in the cover plate43, and out of the housing4. The insert rod53has one end connected to the rear end520of the piston rod52, and the other end connected fixedly to the rear end422of the housing4. The insert rod53is extendable into the piston rod52when the piston member51moves toward the rear end422of the housing4, and has a hexagonal cross-section to prevent rotation of the piston rod52when the piston member51moves relative to the housing4. The biasing member54includes a coiled spring extending around the insert rod53, and has two opposite ends abutting respectively against the piston member51and the rear end422of the housing4.

The carpet gripping head6is connected to the cover plate43of the housing4. The carpet gripping head6includes a hollow pin-holding seat612, and an upright connecting portion611connected fixedly to the pin-holding seat612. The pin-holding seat612includes a plurality of forwardly extending short pins622disposed on a bottom portion thereof in a conventional manner, and an operating unit64. The operating unit64includes a flat plate portion641located within the pin-holding seat612, and a rotatable knob642connected to the flat plate portion641and located outwardly of the pin-holding seat612. The flat plate portion641is provided with a plurality of forwardly extending long pins621that extend from a bottom portion thereof. The rotatable knob642is operable so as to extend or retract the long pins621out of or into the pin-holding seat612.

The upright connecting portion611of the carpet gripping head6is substantially U-shaped, and is connected detachably to the front face432of the cover plate43. Two opposite arms613of the connecting portion611are respectively formed with elongated slots614. Each of the arms613has a connecting face formed with a row of teeth615that meshes with the corresponding row of teeth433on the front face432of the cover plate43.

When the connecting portion611is connected to the front face432of the cover plate43, the annular protrusion434of the cover plate43extends between the arms613of the connecting portion611. The height of the pin-holding seat612relative to the cover plate43is adjusted by changing the position of the teeth615on the arms613of the connecting portion611relative to the teeth433on the cover plate43. After the pin-holding seat612is adjusted to a desired height, two screws63are respectively passed through the elongated slots614, and engage threadedly the cover plate43so that the carpet gripping head6is secured to the cover plate43.

An anchor member522is attached to the front end521of the piston rod52in front of the carpet gripping head6, and is formed with a trapezoidal through hole523(seeFIG. 2).

The fluid supply unit7is connected to the housing4, and includes a main supply passage711provided in a handgrip71, a main valve assembly712, and a main trigger72. The handgrip71is connected to the housing4, and is adapted to connect with a power source, such as a high-pressure gas pump (not shown). The main supply passage711is provided in the handgrip71, and is in fluid communication with the receiving space41. The main valve assembly712is provided in the handgrip71to control a supply of fluid through the main supply passage711. The main trigger72is connected to the main valve assembly712for controlling the same.

The knee-applying cushion member8is provided on the rear end422of the housing4.

Referring toFIG. 5, in combination withFIG. 4, prior to laying of a carpet3on the floor9, a foam layer91is first adhered to the floor9in a conventional manner, and a retaining unit92, such as a tack strip, is fixed at a suitable location of the floor9for anchoring of the anchor member522. When the carpet3is to be stretched toward a wall12, the carpet gripping head6is first secured to the cover plate43of the housing4after the height difference between the carpet gripping head6and the cover plate43is decided and after taking into account the thickness of the carpet3. Next, the rotatable knob642is operated so as to extend the long pins621out of the bottom face of the pin-holding seat612and pierce through the carpet3. The anchor member522is then anchored to the retaining unit92so that the short pins622pierce through the carpet3. Afterwards, the installer grasps the handgrip71, and operates the main valve assembly712by pressing the main trigger72so as to permit flow of fluid through the main supply passage711into the receiving space41so that the piston member51is activated.

With reference toFIGS. 4 and 5, the power source functions to introduce a high-pressure gas through the main valve assembly712and the main supply passage711and into a first receiving portion411of the receiving space41that is proximate to the front end421of the housing4and a second receiving portion412of the receiving space41that is proximate to the rear end422of the housing4. When the air pressure in the first receiving portion411is larger than the air pressure in the second receiving portion412, the piston member51is pushed toward the rear end422of the housing4. However, in this embodiment, since the front end521of the piston rod52is anchored to the retaining unit92through the anchor member522, the piston member51cannot move toward the rear end422of the housing4. Instead, the housing4is moved toward the direction of the retaining unit92so that the distance between the piston member51and the rear end422of the housing4is reduced. Simultaneously, the biasing member54is compressed and stores a force, and the carpet gripping head6moves toward the direction of the retaining unit92. The installer may strike the cushion member8with his/her knee, thereby achieving the purpose of stretching the carpet3. During the stretching operation, crimping of the edges of the carpet3may occur. The crimped edges of the carpet3, if produced, can extend through the trapezoidal hole523in the anchor member522, thereby preventing the carpet3from being pinched in the area of the anchor member522.

When the main trigger72is released from its depressed position, the power source cannot activate the piston member51. As a result, the biasing member54releases its storing force, and biases the rear end422of the housing4to its original position shown inFIG. 4.

The installer repeats the aforementioned steps until the edges of the carpet3are stretched toward the wall12, after which a baseboard (not shown) is mounted so as to complete the laying of the carpet3.

It should be noted that the power source in this embodiment is a pneumatic air pump, and operates by introducing high-pressure gas into the receiving space41so as to activate the piston member51. However, the power source is not limited to the disclosed embodiment, and can be hydraulic or mechanical in operation, as long as it is able to activate relative movement between the piston member51and the housing4.

Referring toFIGS. 6 to 8, the second preferred embodiment of the carpet stretching device2according to the present invention is shown to be similar to the first preferred embodiment. However, in this embodiment, the fluid supply unit7further includes an auxiliary passage730, and a safety valve assembly73. The auxiliary passage730includes a first passage section731having two opposite ends connected fluidly and respectively to the main supply passage711and the safety valve assembly73, and a second passage section732having two opposite ends connected fluidly and respectively to the safety valve assembly73and the first receiving portion411of the receiving space41in the housing4.

The safety valve assembly73is mounted on the carpet gripping head6to control the auxiliary passage730. The safety valve assembly73includes a first port7331connected to the first passage section731, a second port7332connected to the second passage section732, a third port7337for fluid connection with the atmosphere, a first valve channel7333in fluid communication with the first and second ports7331,7332(see arrows inFIG. 7), a second valve channel7334in fluid communication with the second and third ports7332,7337(see arrows inFIG. 8), and a plunger735that projects downwardly from the carpet gripping head6and that is adapted to contact the carpet3.

When the plunger735contacts and presses against the carpet3, it pushes a valve disc733to move away from a valve seat7335so that the first valve channel7333is opened. The installer at this time may operate the main valve assembly712by pressing the main trigger72so that the high-pressure gas flows from the main supply passage711, through the first passage section731, the first and second ports7331,7332, the second passage section732, and into the first receiving portion411of the receiving space41so as to produce relative movement between the housing4and the piston member51. As a result, the front end421of the housing4moves away from the piston member51, while the rear end422of the housing4moves toward the piston member51(seeFIG. 5), thereby compressing the biasing member54.

When the plunger735is released from contact with the carpet3, the valve disc733is biased to move toward the valve seat7335so as to interrupt fluid communication between the first and second ports7331,7332so that the high-pressure gas cannot flow from the main supply passage711into the receiving portion411of the housing4. The plunger735is also biased to move away from the valve disc733so as to restore to its original position, as shown inFIG. 6. At the same time, the biasing member54in the housing4releases its storing force so as to bias the rear end422of the housing4away from the piston member51and back to its original position (seeFIG. 6). When the rear end422of the housing4moves gradually away from the piston member51, the high-pressure gas is forced out of the first receiving portion411to flow through the second passage section732, the second port7332, the second valve channel7334, and the third port7337to the atmosphere.

It should be noted that the safety valve assembly73permits through the auxiliary passage730supply of the high-pressure gas to the housing4from the main supply passage711when the safety valve assembly73is activated by pressing of the plunger735against the carpet3. When the plunger735is removed from contact with the carpet3, even if the main trigger72is accidentally pressed by the installer, the high-pressure gas cannot enter the first receiving portion411of the housing4, thereby preventing sudden and undesired relative movement between the housing4and the piston member51, which may be dangerous.

Referring toFIG. 9, in combination withFIG. 6, the piston unit5of this embodiment further includes a stroke adjustment member524extending threadedly into the piston rod52opposite to the insert rod53. The stroke adjustment member524has a rear abutment end525. The insert rod53abuts against the rear abutment end525when the rear end422of the housing4moves toward the piston member51.

When the power source is not activated, the rear abutment end525of the stroke adjustment member524is spaced apart from the insert rod53. When the power source is activated, however, the rear end422of the housing4together with the insert rod53move relative to the piston member51until the insert rod53abuts against the rear abutment end525, as shown inFIG. 9. Since the insert rod53cannot move further after abutting against the rear abutment end525of the stroke adjustment member524, the carpet gripping head6that is connected to the housing4also stops from moving forward so that stretching of the carpet3discontinued. Hence, the carpet3may be stretched to a predetermined position. The distance that the carpet gripping head6can move may be adjusted through the stroke adjustment member524.

Thus, by adjusting the length of the stroke adjustment member524that extends into the piston rod52, the carpet3can be stretched to a desired extent. When the carpet3is to be stretched to a large extent, the depth of the stroke adjustment member524in the piston rod52should be reduced so that a large distance is provided between the rear abutment end525and the insert rod53, and the carpet gripping head6is permitted to advance a large distance. When the degree of stretching the carpet3need not be large, the stroke adjustment member524should be threaded deeply into the piston rod52so that the distance between the rear abutment end525and the insert rod53is small, thereby permitting the carpet gripping head6to advance a smaller distance than when desiring more significant stretching of the carpet3.

From the aforementioned description of the preferred embodiments of the carpet stretching device2of the present invention, it is apparent that the carpet stretching device2has the following advantages:

1. Since the stretching operation of the carpet3is achieved by operating the main valve assembly712, which permits the power source to effect relative movement between the housing4and the piston member51, when the pin-holding seat612is pierced into the carpet3, the installer simply grasps the handgrip71, and operates the main valve assembly712so that the carpet3is stretched by the carpet gripping head6toward the wall12. This reduces the workload of the installer. Furthermore, since the stretching operation of the carpet3is achieved by activating the piston member51through the power source, the housing4can move rapidly relative to the piston member51, which results in quick stretching of the carpet3, thereby minimizing the time required to install the carpet3.

2. Through the presence of the safety valve assembly73to control the auxiliary passage730, when the safety valve assembly73is not operated, the power source cannot be activated by the main valve assembly712, even if the main trigger72is accidentally pressed. Therefore, the carpet stretching device2of the present invention is safe to use.

3. Through the presence of the stroke adjustment member524, the installer can perform on-site adjustment of the amount of stretching the carpet3. Thus, there is no need to purchase multiple carpet stretching devices with differing carpet-stretching levels.